Merge branch 'work.regset' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull ptrace regset updates from Al Viro:
 "Internal regset API changes:

   - regularize copy_regset_{to,from}_user() callers

   - switch to saner calling conventions for ->get()

   - kill user_regset_copyout()

  The ->put() side of things will have to wait for the next cycle,
  unfortunately.

  The balance is about -1KLoC and replacements for ->get() instances are
  a lot saner"

* 'work.regset' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (41 commits)
  regset: kill user_regset_copyout{,_zero}()
  regset(): kill ->get_size()
  regset: kill ->get()
  csky: switch to ->regset_get()
  xtensa: switch to ->regset_get()
  parisc: switch to ->regset_get()
  nds32: switch to ->regset_get()
  nios2: switch to ->regset_get()
  hexagon: switch to ->regset_get()
  h8300: switch to ->regset_get()
  openrisc: switch to ->regset_get()
  riscv: switch to ->regset_get()
  c6x: switch to ->regset_get()
  ia64: switch to ->regset_get()
  arc: switch to ->regset_get()
  arm: switch to ->regset_get()
  sh: convert to ->regset_get()
  arm64: switch to ->regset_get()
  mips: switch to ->regset_get()
  sparc: switch to ->regset_get()
  ...

41 files changed, 1370 insertions, 2349 deletions

diff --git a/arch/arc/kernel/ptrace.c b/arch/arc/kernel/ptrace.c
index f49a054a1016..883391977fdf 100644
--- a/arch/arc/kernel/ptrace.c
+++ b/arch/arc/kernel/ptrace.c
@@ -18,88 +18,61 @@ static struct callee_regs *task_callee_regs(struct task_struct *tsk)
 
 static int genregs_get(struct task_struct *target,
 		       const struct user_regset *regset,
-		       unsigned int pos, unsigned int count,
-		       void *kbuf, void __user *ubuf)
+		       struct membuf to)
 {
 	const struct pt_regs *ptregs = task_pt_regs(target);
 	const struct callee_regs *cregs = task_callee_regs(target);
-	int ret = 0;
 	unsigned int stop_pc_val;
 
-#define REG_O_CHUNK(START, END, PTR)	\
-	if (!ret)	\
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, PTR, \
-			offsetof(struct user_regs_struct, START), \
-			offsetof(struct user_regs_struct, END));
-
-#define REG_O_ONE(LOC, PTR)	\
-	if (!ret)		\
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, PTR, \
-			offsetof(struct user_regs_struct, LOC), \
-			offsetof(struct user_regs_struct, LOC) + 4);
-
-#define REG_O_ZERO(LOC)		\
-	if (!ret)		\
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf, \
-			offsetof(struct user_regs_struct, LOC), \
-			offsetof(struct user_regs_struct, LOC) + 4);
-
-	REG_O_ZERO(pad);
-	REG_O_ONE(scratch.bta, &ptregs->bta);
-	REG_O_ONE(scratch.lp_start, &ptregs->lp_start);
-	REG_O_ONE(scratch.lp_end, &ptregs->lp_end);
-	REG_O_ONE(scratch.lp_count, &ptregs->lp_count);
-	REG_O_ONE(scratch.status32, &ptregs->status32);
-	REG_O_ONE(scratch.ret, &ptregs->ret);
-	REG_O_ONE(scratch.blink, &ptregs->blink);
-	REG_O_ONE(scratch.fp, &ptregs->fp);
-	REG_O_ONE(scratch.gp, &ptregs->r26);
-	REG_O_ONE(scratch.r12, &ptregs->r12);
-	REG_O_ONE(scratch.r11, &ptregs->r11);
-	REG_O_ONE(scratch.r10, &ptregs->r10);
-	REG_O_ONE(scratch.r9, &ptregs->r9);
-	REG_O_ONE(scratch.r8, &ptregs->r8);
-	REG_O_ONE(scratch.r7, &ptregs->r7);
-	REG_O_ONE(scratch.r6, &ptregs->r6);
-	REG_O_ONE(scratch.r5, &ptregs->r5);
-	REG_O_ONE(scratch.r4, &ptregs->r4);
-	REG_O_ONE(scratch.r3, &ptregs->r3);
-	REG_O_ONE(scratch.r2, &ptregs->r2);
-	REG_O_ONE(scratch.r1, &ptregs->r1);
-	REG_O_ONE(scratch.r0, &ptregs->r0);
-	REG_O_ONE(scratch.sp, &ptregs->sp);
-
-	REG_O_ZERO(pad2);
-
-	REG_O_ONE(callee.r25, &cregs->r25);
-	REG_O_ONE(callee.r24, &cregs->r24);
-	REG_O_ONE(callee.r23, &cregs->r23);
-	REG_O_ONE(callee.r22, &cregs->r22);
-	REG_O_ONE(callee.r21, &cregs->r21);
-	REG_O_ONE(callee.r20, &cregs->r20);
-	REG_O_ONE(callee.r19, &cregs->r19);
-	REG_O_ONE(callee.r18, &cregs->r18);
-	REG_O_ONE(callee.r17, &cregs->r17);
-	REG_O_ONE(callee.r16, &cregs->r16);
-	REG_O_ONE(callee.r15, &cregs->r15);
-	REG_O_ONE(callee.r14, &cregs->r14);
-	REG_O_ONE(callee.r13, &cregs->r13);
-
-	REG_O_ONE(efa, &target->thread.fault_address);
-
-	if (!ret) {
-		if (in_brkpt_trap(ptregs)) {
-			stop_pc_val = target->thread.fault_address;
-			pr_debug("\t\tstop_pc (brk-pt)\n");
-		} else {
-			stop_pc_val = ptregs->ret;
-			pr_debug("\t\tstop_pc (others)\n");
-		}
-
-		REG_O_ONE(stop_pc, &stop_pc_val);
+	membuf_zero(&to, 4);	// pad
+	membuf_store(&to, ptregs->bta);
+	membuf_store(&to, ptregs->lp_start);
+	membuf_store(&to, ptregs->lp_end);
+	membuf_store(&to, ptregs->lp_count);
+	membuf_store(&to, ptregs->status32);
+	membuf_store(&to, ptregs->ret);
+	membuf_store(&to, ptregs->blink);
+	membuf_store(&to, ptregs->fp);
+	membuf_store(&to, ptregs->r26);	// gp
+	membuf_store(&to, ptregs->r12);
+	membuf_store(&to, ptregs->r11);
+	membuf_store(&to, ptregs->r10);
+	membuf_store(&to, ptregs->r9);
+	membuf_store(&to, ptregs->r8);
+	membuf_store(&to, ptregs->r7);
+	membuf_store(&to, ptregs->r6);
+	membuf_store(&to, ptregs->r5);
+	membuf_store(&to, ptregs->r4);
+	membuf_store(&to, ptregs->r3);
+	membuf_store(&to, ptregs->r2);
+	membuf_store(&to, ptregs->r1);
+	membuf_store(&to, ptregs->r0);
+	membuf_store(&to, ptregs->sp);
+	membuf_zero(&to, 4);	// pad2
+	membuf_store(&to, cregs->r25);
+	membuf_store(&to, cregs->r24);
+	membuf_store(&to, cregs->r23);
+	membuf_store(&to, cregs->r22);
+	membuf_store(&to, cregs->r21);
+	membuf_store(&to, cregs->r20);
+	membuf_store(&to, cregs->r19);
+	membuf_store(&to, cregs->r18);
+	membuf_store(&to, cregs->r17);
+	membuf_store(&to, cregs->r16);
+	membuf_store(&to, cregs->r15);
+	membuf_store(&to, cregs->r14);
+	membuf_store(&to, cregs->r13);
+	membuf_store(&to, target->thread.fault_address); // efa
+
+	if (in_brkpt_trap(ptregs)) {
+		stop_pc_val = target->thread.fault_address;
+		pr_debug("\t\tstop_pc (brk-pt)\n");
+	} else {
+		stop_pc_val = ptregs->ret;
+		pr_debug("\t\tstop_pc (others)\n");
 	}
 
-	return ret;
+	return membuf_store(&to, stop_pc_val); // stop_pc
 }
 
 static int genregs_set(struct task_struct *target,
@@ -184,25 +157,20 @@ static int genregs_set(struct task_struct *target,
 #ifdef CONFIG_ISA_ARCV2
 static int arcv2regs_get(struct task_struct *target,
 		       const struct user_regset *regset,
-		       unsigned int pos, unsigned int count,
-		       void *kbuf, void __user *ubuf)
+		       struct membuf to)
 {
 	const struct pt_regs *regs = task_pt_regs(target);
-	int ret, copy_sz;
 
 	if (IS_ENABLED(CONFIG_ARC_HAS_ACCL_REGS))
-		copy_sz = sizeof(struct user_regs_arcv2);
-	else
-		copy_sz = 4;	/* r30 only */
+		/*
+		 * itemized copy not needed like above as layout of regs (r30,r58,r59)
+		 * is exactly same in kernel (pt_regs) and userspace (user_regs_arcv2)
+		 */
+		return membuf_write(&to, &regs->r30, sizeof(struct user_regs_arcv2));
 
-	/*
-	 * itemized copy not needed like above as layout of regs (r30,r58,r59)
-	 * is exactly same in kernel (pt_regs) and userspace (user_regs_arcv2)
-	 */
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &regs->r30,
-				  0, copy_sz);
 
-	return ret;
+	membuf_write(&to, &regs->r30, 4); /* r30 only */
+	return membuf_zero(&to, sizeof(struct user_regs_arcv2) - 4);
 }
 
 static int arcv2regs_set(struct task_struct *target,
@@ -237,7 +205,7 @@ static const struct user_regset arc_regsets[] = {
 	       .n = ELF_NGREG,
 	       .size = sizeof(unsigned long),
 	       .align = sizeof(unsigned long),
-	       .get = genregs_get,
+	       .regset_get = genregs_get,
 	       .set = genregs_set,
 	},
 #ifdef CONFIG_ISA_ARCV2
@@ -246,7 +214,7 @@ static const struct user_regset arc_regsets[] = {
 	       .n = ELF_ARCV2REG,
 	       .size = sizeof(unsigned long),
 	       .align = sizeof(unsigned long),
-	       .get = arcv2regs_get,
+	       .regset_get = arcv2regs_get,
 	       .set = arcv2regs_set,
 	},
 #endif
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index d0f7c8896c96..2771e682220b 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -569,14 +569,9 @@ out:
 
 static int gpr_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	struct pt_regs *regs = task_pt_regs(target);
-
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   regs,
-				   0, sizeof(*regs));
+	return membuf_write(&to, task_pt_regs(target), sizeof(struct pt_regs));
 }
 
 static int gpr_set(struct task_struct *target,
@@ -602,12 +597,10 @@ static int gpr_set(struct task_struct *target,
 
 static int fpa_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &task_thread_info(target)->fpstate,
-				   0, sizeof(struct user_fp));
+	return membuf_write(&to, &task_thread_info(target)->fpstate,
+				 sizeof(struct user_fp));
 }
 
 static int fpa_set(struct task_struct *target,
@@ -642,41 +635,20 @@ static int fpa_set(struct task_struct *target,
  *	vfp_set() ignores this chunk
  *
  * 1 word for the FPSCR
- *
- * The bounds-checking logic built into user_regset_copyout and friends
- * means that we can make a simple sequence of calls to map the relevant data
- * to/from the specified slice of the user regset structure.
  */
 static int vfp_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	int ret;
 	struct thread_info *thread = task_thread_info(target);
 	struct vfp_hard_struct const *vfp = &thread->vfpstate.hard;
-	const size_t user_fpregs_offset = offsetof(struct user_vfp, fpregs);
 	const size_t user_fpscr_offset = offsetof(struct user_vfp, fpscr);
 
 	vfp_sync_hwstate(thread);
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &vfp->fpregs,
-				  user_fpregs_offset,
-				  user_fpregs_offset + sizeof(vfp->fpregs));
-	if (ret)
-		return ret;
-
-	ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-				       user_fpregs_offset + sizeof(vfp->fpregs),
-				       user_fpscr_offset);
-	if (ret)
-		return ret;
-
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &vfp->fpscr,
-				   user_fpscr_offset,
-				   user_fpscr_offset + sizeof(vfp->fpscr));
+	membuf_write(&to, vfp->fpregs, sizeof(vfp->fpregs));
+	membuf_zero(&to, user_fpscr_offset - sizeof(vfp->fpregs));
+	return membuf_store(&to, vfp->fpscr);
 }
 
 /*
@@ -739,7 +711,7 @@ static const struct user_regset arm_regsets[] = {
 		.n = ELF_NGREG,
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = gpr_get,
+		.regset_get = gpr_get,
 		.set = gpr_set
 	},
 	[REGSET_FPR] = {
@@ -751,7 +723,7 @@ static const struct user_regset arm_regsets[] = {
 		.n = sizeof(struct user_fp) / sizeof(u32),
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = fpa_get,
+		.regset_get = fpa_get,
 		.set = fpa_set
 	},
 #ifdef CONFIG_VFP
@@ -764,7 +736,7 @@ static const struct user_regset arm_regsets[] = {
 		.n = ARM_VFPREGS_SIZE / sizeof(u32),
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = vfp_get,
+		.regset_get = vfp_get,
 		.set = vfp_set
 	},
 #endif /* CONFIG_VFP */
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 1e02e98e68dd..d8ebfd813e28 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -474,11 +474,10 @@ static int ptrace_hbp_set_addr(unsigned int note_type,
 
 static int hw_break_get(struct task_struct *target,
 			const struct user_regset *regset,
-			unsigned int pos, unsigned int count,
-			void *kbuf, void __user *ubuf)
+			struct membuf to)
 {
 	unsigned int note_type = regset->core_note_type;
-	int ret, idx = 0, offset, limit;
+	int ret, idx = 0;
 	u32 info, ctrl;
 	u64 addr;
 
@@ -487,49 +486,21 @@ static int hw_break_get(struct task_struct *target,
 	if (ret)
 		return ret;
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &info, 0,
-				  sizeof(info));
-	if (ret)
-		return ret;
-
-	/* Pad */
-	offset = offsetof(struct user_hwdebug_state, pad);
-	ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf, offset,
-				       offset + PTRACE_HBP_PAD_SZ);
-	if (ret)
-		return ret;
-
+	membuf_write(&to, &info, sizeof(info));
+	membuf_zero(&to, sizeof(u32));
 	/* (address, ctrl) registers */
-	offset = offsetof(struct user_hwdebug_state, dbg_regs);
-	limit = regset->n * regset->size;
-	while (count && offset < limit) {
+	while (to.left) {
 		ret = ptrace_hbp_get_addr(note_type, target, idx, &addr);
 		if (ret)
 			return ret;
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &addr,
-					  offset, offset + PTRACE_HBP_ADDR_SZ);
-		if (ret)
-			return ret;
-		offset += PTRACE_HBP_ADDR_SZ;
-
 		ret = ptrace_hbp_get_ctrl(note_type, target, idx, &ctrl);
 		if (ret)
 			return ret;
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &ctrl,
-					  offset, offset + PTRACE_HBP_CTRL_SZ);
-		if (ret)
-			return ret;
-		offset += PTRACE_HBP_CTRL_SZ;
-
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					       offset,
-					       offset + PTRACE_HBP_PAD_SZ);
-		if (ret)
-			return ret;
-		offset += PTRACE_HBP_PAD_SZ;
+		membuf_store(&to, addr);
+		membuf_store(&to, ctrl);
+		membuf_zero(&to, sizeof(u32));
 		idx++;
 	}
-
 	return 0;
 }
 
@@ -589,11 +560,10 @@ static int hw_break_set(struct task_struct *target,
 
 static int gpr_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
 	struct user_pt_regs *uregs = &task_pt_regs(target)->user_regs;
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0, -1);
+	return membuf_write(&to, uregs, sizeof(*uregs));
 }
 
 static int gpr_set(struct task_struct *target, const struct user_regset *regset,
@@ -626,8 +596,7 @@ static int fpr_active(struct task_struct *target, const struct user_regset *regs
  */
 static int __fpr_get(struct task_struct *target,
 		     const struct user_regset *regset,
-		     unsigned int pos, unsigned int count,
-		     void *kbuf, void __user *ubuf, unsigned int start_pos)
+		     struct membuf to)
 {
 	struct user_fpsimd_state *uregs;
 
@@ -635,13 +604,11 @@ static int __fpr_get(struct task_struct *target,
 
 	uregs = &target->thread.uw.fpsimd_state;
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs,
-				   start_pos, start_pos + sizeof(*uregs));
+	return membuf_write(&to, uregs, sizeof(*uregs));
 }
 
 static int fpr_get(struct task_struct *target, const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
 	if (!system_supports_fpsimd())
 		return -EINVAL;
@@ -649,7 +616,7 @@ static int fpr_get(struct task_struct *target, const struct user_regset *regset,
 	if (target == current)
 		fpsimd_preserve_current_state();
 
-	return __fpr_get(target, regset, pos, count, kbuf, ubuf, 0);
+	return __fpr_get(target, regset, to);
 }
 
 static int __fpr_set(struct task_struct *target,
@@ -699,15 +666,12 @@ static int fpr_set(struct task_struct *target, const struct user_regset *regset,
 }
 
 static int tls_get(struct task_struct *target, const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	unsigned long *tls = &target->thread.uw.tp_value;
-
 	if (target == current)
 		tls_preserve_current_state();
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, tls, 0, -1);
+	return membuf_store(&to, target->thread.uw.tp_value);
 }
 
 static int tls_set(struct task_struct *target, const struct user_regset *regset,
@@ -727,13 +691,9 @@ static int tls_set(struct task_struct *target, const struct user_regset *regset,
 
 static int system_call_get(struct task_struct *target,
 			   const struct user_regset *regset,
-			   unsigned int pos, unsigned int count,
-			   void *kbuf, void __user *ubuf)
+			   struct membuf to)
 {
-	int syscallno = task_pt_regs(target)->syscallno;
-
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &syscallno, 0, -1);
+	return membuf_store(&to, task_pt_regs(target)->syscallno);
 }
 
 static int system_call_set(struct task_struct *target,
@@ -780,24 +740,10 @@ static unsigned int sve_size_from_header(struct user_sve_header const *header)
 	return ALIGN(header->size, SVE_VQ_BYTES);
 }
 
-static unsigned int sve_get_size(struct task_struct *target,
-				 const struct user_regset *regset)
-{
-	struct user_sve_header header;
-
-	if (!system_supports_sve())
-		return 0;
-
-	sve_init_header_from_task(&header, target);
-	return sve_size_from_header(&header);
-}
-
 static int sve_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	int ret;
 	struct user_sve_header header;
 	unsigned int vq;
 	unsigned long start, end;
@@ -809,10 +755,7 @@ static int sve_get(struct task_struct *target,
 	sve_init_header_from_task(&header, target);
 	vq = sve_vq_from_vl(header.vl);
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &header,
-				  0, sizeof(header));
-	if (ret)
-		return ret;
+	membuf_write(&to, &header, sizeof(header));
 
 	if (target == current)
 		fpsimd_preserve_current_state();
@@ -821,26 +764,18 @@ static int sve_get(struct task_struct *target,
 
 	BUILD_BUG_ON(SVE_PT_FPSIMD_OFFSET != sizeof(header));
 	if ((header.flags & SVE_PT_REGS_MASK) == SVE_PT_REGS_FPSIMD)
-		return __fpr_get(target, regset, pos, count, kbuf, ubuf,
-				 SVE_PT_FPSIMD_OFFSET);
+		return __fpr_get(target, regset, to);
 
 	/* Otherwise: full SVE case */
 
 	BUILD_BUG_ON(SVE_PT_SVE_OFFSET != sizeof(header));
 	start = SVE_PT_SVE_OFFSET;
 	end = SVE_PT_SVE_FFR_OFFSET(vq) + SVE_PT_SVE_FFR_SIZE(vq);
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  target->thread.sve_state,
-				  start, end);
-	if (ret)
-		return ret;
+	membuf_write(&to, target->thread.sve_state, end - start);
 
 	start = end;
 	end = SVE_PT_SVE_FPSR_OFFSET(vq);
-	ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-				       start, end);
-	if (ret)
-		return ret;
+	membuf_zero(&to, end - start);
 
 	/*
 	 * Copy fpsr, and fpcr which must follow contiguously in
@@ -848,16 +783,11 @@ static int sve_get(struct task_struct *target,
 	 */
 	start = end;
 	end = SVE_PT_SVE_FPCR_OFFSET(vq) + SVE_PT_SVE_FPCR_SIZE;
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &target->thread.uw.fpsimd_state.fpsr,
-				  start, end);
-	if (ret)
-		return ret;
+	membuf_write(&to, &target->thread.uw.fpsimd_state.fpsr, end - start);
 
 	start = end;
 	end = sve_size_from_header(&header);
-	return user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					start, end);
+	return membuf_zero(&to, end - start);
 }
 
 static int sve_set(struct task_struct *target,
@@ -961,8 +891,7 @@ out:
 #ifdef CONFIG_ARM64_PTR_AUTH
 static int pac_mask_get(struct task_struct *target,
 			const struct user_regset *regset,
-			unsigned int pos, unsigned int count,
-			void *kbuf, void __user *ubuf)
+			struct membuf to)
 {
 	/*
 	 * The PAC bits can differ across data and instruction pointers
@@ -978,7 +907,7 @@ static int pac_mask_get(struct task_struct *target,
 	if (!system_supports_address_auth())
 		return -EINVAL;
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &uregs, 0, -1);
+	return membuf_write(&to, &uregs, sizeof(uregs));
 }
 
 #ifdef CONFIG_CHECKPOINT_RESTORE
@@ -1017,8 +946,7 @@ static void pac_address_keys_from_user(struct ptrauth_keys_user *keys,
 
 static int pac_address_keys_get(struct task_struct *target,
 				const struct user_regset *regset,
-				unsigned int pos, unsigned int count,
-				void *kbuf, void __user *ubuf)
+				struct membuf to)
 {
 	struct ptrauth_keys_user *keys = &target->thread.keys_user;
 	struct user_pac_address_keys user_keys;
@@ -1028,8 +956,7 @@ static int pac_address_keys_get(struct task_struct *target,
 
 	pac_address_keys_to_user(&user_keys, keys);
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &user_keys, 0, -1);
+	return membuf_write(&to, &user_keys, sizeof(user_keys));
 }
 
 static int pac_address_keys_set(struct task_struct *target,
@@ -1068,8 +995,7 @@ static void pac_generic_keys_from_user(struct ptrauth_keys_user *keys,
 
 static int pac_generic_keys_get(struct task_struct *target,
 				const struct user_regset *regset,
-				unsigned int pos, unsigned int count,
-				void *kbuf, void __user *ubuf)
+				struct membuf to)
 {
 	struct ptrauth_keys_user *keys = &target->thread.keys_user;
 	struct user_pac_generic_keys user_keys;
@@ -1079,8 +1005,7 @@ static int pac_generic_keys_get(struct task_struct *target,
 
 	pac_generic_keys_to_user(&user_keys, keys);
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &user_keys, 0, -1);
+	return membuf_write(&to, &user_keys, sizeof(user_keys));
 }
 
 static int pac_generic_keys_set(struct task_struct *target,
@@ -1134,7 +1059,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = sizeof(struct user_pt_regs) / sizeof(u64),
 		.size = sizeof(u64),
 		.align = sizeof(u64),
-		.get = gpr_get,
+		.regset_get = gpr_get,
 		.set = gpr_set
 	},
 	[REGSET_FPR] = {
@@ -1147,7 +1072,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.size = sizeof(u32),
 		.align = sizeof(u32),
 		.active = fpr_active,
-		.get = fpr_get,
+		.regset_get = fpr_get,
 		.set = fpr_set
 	},
 	[REGSET_TLS] = {
@@ -1155,7 +1080,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = 1,
 		.size = sizeof(void *),
 		.align = sizeof(void *),
-		.get = tls_get,
+		.regset_get = tls_get,
 		.set = tls_set,
 	},
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
@@ -1164,7 +1089,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = sizeof(struct user_hwdebug_state) / sizeof(u32),
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = hw_break_get,
+		.regset_get = hw_break_get,
 		.set = hw_break_set,
 	},
 	[REGSET_HW_WATCH] = {
@@ -1172,7 +1097,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = sizeof(struct user_hwdebug_state) / sizeof(u32),
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = hw_break_get,
+		.regset_get = hw_break_get,
 		.set = hw_break_set,
 	},
 #endif
@@ -1181,7 +1106,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = 1,
 		.size = sizeof(int),
 		.align = sizeof(int),
-		.get = system_call_get,
+		.regset_get = system_call_get,
 		.set = system_call_set,
 	},
 #ifdef CONFIG_ARM64_SVE
@@ -1191,9 +1116,8 @@ static const struct user_regset aarch64_regsets[] = {
 				  SVE_VQ_BYTES),
 		.size = SVE_VQ_BYTES,
 		.align = SVE_VQ_BYTES,
-		.get = sve_get,
+		.regset_get = sve_get,
 		.set = sve_set,
-		.get_size = sve_get_size,
 	},
 #endif
 #ifdef CONFIG_ARM64_PTR_AUTH
@@ -1202,7 +1126,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = sizeof(struct user_pac_mask) / sizeof(u64),
 		.size = sizeof(u64),
 		.align = sizeof(u64),
-		.get = pac_mask_get,
+		.regset_get = pac_mask_get,
 		/* this cannot be set dynamically */
 	},
 #ifdef CONFIG_CHECKPOINT_RESTORE
@@ -1211,7 +1135,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = sizeof(struct user_pac_address_keys) / sizeof(__uint128_t),
 		.size = sizeof(__uint128_t),
 		.align = sizeof(__uint128_t),
-		.get = pac_address_keys_get,
+		.regset_get = pac_address_keys_get,
 		.set = pac_address_keys_set,
 	},
 	[REGSET_PACG_KEYS] = {
@@ -1219,7 +1143,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = sizeof(struct user_pac_generic_keys) / sizeof(__uint128_t),
 		.size = sizeof(__uint128_t),
 		.align = sizeof(__uint128_t),
-		.get = pac_generic_keys_get,
+		.regset_get = pac_generic_keys_get,
 		.set = pac_generic_keys_set,
 	},
 #endif
@@ -1237,57 +1161,31 @@ enum compat_regset {
 	REGSET_COMPAT_VFP,
 };
 
-static int compat_gpr_get(struct task_struct *target,
-			  const struct user_regset *regset,
-			  unsigned int pos, unsigned int count,
-			  void *kbuf, void __user *ubuf)
+static inline compat_ulong_t compat_get_user_reg(struct task_struct *task, int idx)
 {
-	int ret = 0;
-	unsigned int i, start, num_regs;
+	struct pt_regs *regs = task_pt_regs(task);
 
-	/* Calculate the number of AArch32 registers contained in count */
-	num_regs = count / regset->size;
-
-	/* Convert pos into an register number */
-	start = pos / regset->size;
-
-	if (start + num_regs > regset->n)
-		return -EIO;
-
-	for (i = 0; i < num_regs; ++i) {
-		unsigned int idx = start + i;
-		compat_ulong_t reg;
-
-		switch (idx) {
-		case 15:
-			reg = task_pt_regs(target)->pc;
-			break;
-		case 16:
-			reg = task_pt_regs(target)->pstate;
-			reg = pstate_to_compat_psr(reg);
-			break;
-		case 17:
-			reg = task_pt_regs(target)->orig_x0;
-			break;
-		default:
-			reg = task_pt_regs(target)->regs[idx];
-		}
-
-		if (kbuf) {
-			memcpy(kbuf, &reg, sizeof(reg));
-			kbuf += sizeof(reg);
-		} else {
-			ret = copy_to_user(ubuf, &reg, sizeof(reg));
-			if (ret) {
-				ret = -EFAULT;
-				break;
-			}
-
-			ubuf += sizeof(reg);
-		}
+	switch (idx) {
+	case 15:
+		return regs->pc;
+	case 16:
+		return pstate_to_compat_psr(regs->pstate);
+	case 17:
+		return regs->orig_x0;
+	default:
+		return regs->regs[idx];
 	}
+}
 
-	return ret;
+static int compat_gpr_get(struct task_struct *target,
+			  const struct user_regset *regset,
+			  struct membuf to)
+{
+	int i = 0;
+
+	while (to.left)
+		membuf_store(&to, compat_get_user_reg(target, i++));
+	return 0;
 }
 
 static int compat_gpr_set(struct task_struct *target,
@@ -1354,12 +1252,10 @@ static int compat_gpr_set(struct task_struct *target,
 
 static int compat_vfp_get(struct task_struct *target,
 			  const struct user_regset *regset,
-			  unsigned int pos, unsigned int count,
-			  void *kbuf, void __user *ubuf)
+			  struct membuf to)
 {
 	struct user_fpsimd_state *uregs;
 	compat_ulong_t fpscr;
-	int ret, vregs_end_pos;
 
 	if (!system_supports_fpsimd())
 		return -EINVAL;
@@ -1373,19 +1269,10 @@ static int compat_vfp_get(struct task_struct *target,
 	 * The VFP registers are packed into the fpsimd_state, so they all sit
 	 * nicely together for us. We just need to create the fpscr separately.
 	 */
-	vregs_end_pos = VFP_STATE_SIZE - sizeof(compat_ulong_t);
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs,
-				  0, vregs_end_pos);
-
-	if (count && !ret) {
-		fpscr = (uregs->fpsr & VFP_FPSCR_STAT_MASK) |
-			(uregs->fpcr & VFP_FPSCR_CTRL_MASK);
-
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &fpscr,
-					  vregs_end_pos, VFP_STATE_SIZE);
-	}
-
-	return ret;
+	membuf_write(&to, uregs, VFP_STATE_SIZE - sizeof(compat_ulong_t));
+	fpscr = (uregs->fpsr & VFP_FPSCR_STAT_MASK) |
+		(uregs->fpcr & VFP_FPSCR_CTRL_MASK);
+	return membuf_store(&to, fpscr);
 }
 
 static int compat_vfp_set(struct task_struct *target,
@@ -1420,11 +1307,10 @@ static int compat_vfp_set(struct task_struct *target,
 }
 
 static int compat_tls_get(struct task_struct *target,
-			  const struct user_regset *regset, unsigned int pos,
-			  unsigned int count, void *kbuf, void __user *ubuf)
+			  const struct user_regset *regset,
+			  struct membuf to)
 {
-	compat_ulong_t tls = (compat_ulong_t)target->thread.uw.tp_value;
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &tls, 0, -1);
+	return membuf_store(&to, (compat_ulong_t)target->thread.uw.tp_value);
 }
 
 static int compat_tls_set(struct task_struct *target,
@@ -1449,7 +1335,7 @@ static const struct user_regset aarch32_regsets[] = {
 		.n = COMPAT_ELF_NGREG,
 		.size = sizeof(compat_elf_greg_t),
 		.align = sizeof(compat_elf_greg_t),
-		.get = compat_gpr_get,
+		.regset_get = compat_gpr_get,
 		.set = compat_gpr_set
 	},
 	[REGSET_COMPAT_VFP] = {
@@ -1458,7 +1344,7 @@ static const struct user_regset aarch32_regsets[] = {
 		.size = sizeof(compat_ulong_t),
 		.align = sizeof(compat_ulong_t),
 		.active = fpr_active,
-		.get = compat_vfp_get,
+		.regset_get = compat_vfp_get,
 		.set = compat_vfp_set
 	},
 };
@@ -1474,7 +1360,7 @@ static const struct user_regset aarch32_ptrace_regsets[] = {
 		.n = COMPAT_ELF_NGREG,
 		.size = sizeof(compat_elf_greg_t),
 		.align = sizeof(compat_elf_greg_t),
-		.get = compat_gpr_get,
+		.regset_get = compat_gpr_get,
 		.set = compat_gpr_set
 	},
 	[REGSET_FPR] = {
@@ -1482,7 +1368,7 @@ static const struct user_regset aarch32_ptrace_regsets[] = {
 		.n = VFP_STATE_SIZE / sizeof(compat_ulong_t),
 		.size = sizeof(compat_ulong_t),
 		.align = sizeof(compat_ulong_t),
-		.get = compat_vfp_get,
+		.regset_get = compat_vfp_get,
 		.set = compat_vfp_set
 	},
 	[REGSET_TLS] = {
@@ -1490,7 +1376,7 @@ static const struct user_regset aarch32_ptrace_regsets[] = {
 		.n = 1,
 		.size = sizeof(compat_ulong_t),
 		.align = sizeof(compat_ulong_t),
-		.get = compat_tls_get,
+		.regset_get = compat_tls_get,
 		.set = compat_tls_set,
 	},
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
@@ -1499,7 +1385,7 @@ static const struct user_regset aarch32_ptrace_regsets[] = {
 		.n = sizeof(struct user_hwdebug_state) / sizeof(u32),
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = hw_break_get,
+		.regset_get = hw_break_get,
 		.set = hw_break_set,
 	},
 	[REGSET_HW_WATCH] = {
@@ -1507,7 +1393,7 @@ static const struct user_regset aarch32_ptrace_regsets[] = {
 		.n = sizeof(struct user_hwdebug_state) / sizeof(u32),
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = hw_break_get,
+		.regset_get = hw_break_get,
 		.set = hw_break_set,
 	},
 #endif
@@ -1516,7 +1402,7 @@ static const struct user_regset aarch32_ptrace_regsets[] = {
 		.n = 1,
 		.size = sizeof(int),
 		.align = sizeof(int),
-		.get = system_call_get,
+		.regset_get = system_call_get,
 		.set = system_call_set,
 	},
 };
@@ -1541,9 +1427,7 @@ static int compat_ptrace_read_user(struct task_struct *tsk, compat_ulong_t off,
 	else if (off == COMPAT_PT_TEXT_END_ADDR)
 		tmp = tsk->mm->end_code;
 	else if (off < sizeof(compat_elf_gregset_t))
-		return copy_regset_to_user(tsk, &user_aarch32_view,
-					   REGSET_COMPAT_GPR, off,
-					   sizeof(compat_ulong_t), ret);
+		tmp = compat_get_user_reg(tsk, off >> 2);
 	else if (off >= COMPAT_USER_SZ)
 		return -EIO;
 	else
@@ -1555,8 +1439,8 @@ static int compat_ptrace_read_user(struct task_struct *tsk, compat_ulong_t off,
 static int compat_ptrace_write_user(struct task_struct *tsk, compat_ulong_t off,
 				    compat_ulong_t val)
 {
-	int ret;
-	mm_segment_t old_fs = get_fs();
+	struct pt_regs newregs = *task_pt_regs(tsk);
+	unsigned int idx = off / 4;
 
 	if (off & 3 || off >= COMPAT_USER_SZ)
 		return -EIO;
@@ -1564,14 +1448,25 @@ static int compat_ptrace_write_user(struct task_struct *tsk, compat_ulong_t off,
 	if (off >= sizeof(compat_elf_gregset_t))
 		return 0;
 
-	set_fs(KERNEL_DS);
-	ret = copy_regset_from_user(tsk, &user_aarch32_view,
-				    REGSET_COMPAT_GPR, off,
-				    sizeof(compat_ulong_t),
-				    &val);
-	set_fs(old_fs);
+	switch (idx) {
+	case 15:
+		newregs.pc = val;
+		break;
+	case 16:
+		newregs.pstate = compat_psr_to_pstate(val);
+		break;
+	case 17:
+		newregs.orig_x0 = val;
+		break;
+	default:
+		newregs.regs[idx] = val;
+	}
 
-	return ret;
+	if (!valid_user_regs(&newregs.user_regs, tsk))
+		return -EINVAL;
+
+	*task_pt_regs(tsk) = newregs;
+	return 0;
 }
 
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
diff --git a/arch/c6x/kernel/ptrace.c b/arch/c6x/kernel/ptrace.c
index 67af1562da86..3cdaa8cf0ed6 100644
--- a/arch/c6x/kernel/ptrace.c
+++ b/arch/c6x/kernel/ptrace.c
@@ -57,14 +57,9 @@ static inline int put_reg(struct task_struct *task,
 
 static int gpr_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	struct pt_regs *regs = task_pt_regs(target);
-
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   regs,
-				   0, sizeof(*regs));
+	return membuf_write(&to, task_pt_regs(target), sizeof(struct pt_regs));
 }
 
 enum c6x_regset {
@@ -77,7 +72,7 @@ static const struct user_regset c6x_regsets[] = {
 		.n = ELF_NGREG,
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = gpr_get,
+		.regset_get = gpr_get,
 	},
 };
 
diff --git a/arch/csky/kernel/ptrace.c b/arch/csky/kernel/ptrace.c
index b06612c408c4..d822144906ac 100644
--- a/arch/csky/kernel/ptrace.c
+++ b/arch/csky/kernel/ptrace.c
@@ -76,17 +76,14 @@ enum csky_regset {
 
 static int gpr_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	struct pt_regs *regs;
-
-	regs = task_pt_regs(target);
+	struct pt_regs *regs = task_pt_regs(target);
 
 	/* Abiv1 regs->tls is fake and we need sync here. */
 	regs->tls = task_thread_info(target)->tp_value;
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, regs, 0, -1);
+	return membuf_write(&to, regs, sizeof(regs));
 }
 
 static int gpr_set(struct task_struct *target,
@@ -114,8 +111,7 @@ static int gpr_set(struct task_struct *target,
 
 static int fpr_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
 	struct user_fp *regs = (struct user_fp *)&target->thread.user_fp;
 
@@ -131,9 +127,9 @@ static int fpr_get(struct task_struct *target,
 	for (i = 0; i < 32; i++)
 		tmp.vr[64 + i] = regs->vr[32 + i];
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &tmp, 0, -1);
+	return membuf_write(&to, &tmp, sizeof(tmp));
 #else
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, regs, 0, -1);
+	return membuf_write(&to, regs, sizeof(*regs));
 #endif
 }
 
@@ -173,16 +169,16 @@ static const struct user_regset csky_regsets[] = {
 		.n = sizeof(struct pt_regs) / sizeof(u32),
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = &gpr_get,
-		.set = &gpr_set,
+		.regset_get = gpr_get,
+		.set = gpr_set,
 	},
 	[REGSET_FPR] = {
 		.core_note_type = NT_PRFPREG,
 		.n = sizeof(struct user_fp) / sizeof(u32),
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = &fpr_get,
-		.set = &fpr_set,
+		.regset_get = fpr_get,
+		.set = fpr_set,
 	},
 };
 
diff --git a/arch/h8300/kernel/ptrace.c b/arch/h8300/kernel/ptrace.c
index 0dc1c8f622bc..a11db009d0ea 100644
--- a/arch/h8300/kernel/ptrace.c
+++ b/arch/h8300/kernel/ptrace.c
@@ -87,20 +87,15 @@ int h8300_put_reg(struct task_struct *task, int regno, unsigned long data)
 
 static int regs_get(struct task_struct *target,
 		    const struct user_regset *regset,
-		    unsigned int pos, unsigned int count,
-		    void *kbuf, void __user *ubuf)
+		    struct membuf to)
 {
 	int r;
-	struct user_regs_struct regs;
-	long *reg = (long *)&regs;
 
-	/* build user regs in buffer */
-	BUILD_BUG_ON(sizeof(regs) % sizeof(long) != 0);
-	for (r = 0; r < sizeof(regs) / sizeof(long); r++)
-		*reg++ = h8300_get_reg(target, r);
+	BUILD_BUG_ON(sizeof(struct user_regs_struct) % sizeof(long) != 0);
+	for (r = 0; r < ELF_NGREG; r++)
+		membuf_store(&to, h8300_get_reg(target, r));
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &regs, 0, sizeof(regs));
+	return 0;
 }
 
 static int regs_set(struct task_struct *target,
@@ -139,7 +134,7 @@ static const struct user_regset h8300_regsets[] = {
 		.n		= ELF_NGREG,
 		.size		= sizeof(long),
 		.align		= sizeof(long),
-		.get		= regs_get,
+		.regset_get		= regs_get,
 		.set		= regs_set,
 	},
 };
diff --git a/arch/hexagon/kernel/ptrace.c b/arch/hexagon/kernel/ptrace.c
index dcbf7ea960cc..a5a89e944257 100644
--- a/arch/hexagon/kernel/ptrace.c
+++ b/arch/hexagon/kernel/ptrace.c
@@ -35,58 +35,38 @@ void user_disable_single_step(struct task_struct *child)
 
 static int genregs_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   srtuct membuf to)
 {
-	int ret;
-	unsigned int dummy;
 	struct pt_regs *regs = task_pt_regs(target);
 
-
-	if (!regs)
-		return -EIO;
-
 	/* The general idea here is that the copyout must happen in
 	 * exactly the same order in which the userspace expects these
 	 * regs. Now, the sequence in userspace does not match the
 	 * sequence in the kernel, so everything past the 32 gprs
 	 * happens one at a time.
 	 */
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &regs->r00, 0, 32*sizeof(unsigned long));
-
-#define ONEXT(KPT_REG, USR_REG) \
-	if (!ret) \
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, \
-			KPT_REG, offsetof(struct user_regs_struct, USR_REG), \
-			offsetof(struct user_regs_struct, USR_REG) + \
-				 sizeof(unsigned long));
-
+	membuf_write(&to, &regs->r00, 32*sizeof(unsigned long));
 	/* Must be exactly same sequence as struct user_regs_struct */
-	ONEXT(&regs->sa0, sa0);
-	ONEXT(&regs->lc0, lc0);
-	ONEXT(&regs->sa1, sa1);
-	ONEXT(&regs->lc1, lc1);
-	ONEXT(&regs->m0, m0);
-	ONEXT(&regs->m1, m1);
-	ONEXT(&regs->usr, usr);
-	ONEXT(&regs->preds, p3_0);
-	ONEXT(&regs->gp, gp);
-	ONEXT(&regs->ugp, ugp);
-	ONEXT(&pt_elr(regs), pc);
-	dummy = pt_cause(regs);
-	ONEXT(&dummy, cause);
-	ONEXT(&pt_badva(regs), badva);
+	membuf_store(&to, regs->sa0);
+	membuf_store(&to, regs->lc0);
+	membuf_store(&to, regs->sa1);
+	membuf_store(&to, regs->lc1);
+	membuf_store(&to, regs->m0);
+	membuf_store(&to, regs->m1);
+	membuf_store(&to, regs->usr);
+	membuf_store(&to, regs->p3_0);
+	membuf_store(&to, regs->gp);
+	membuf_store(&to, regs->ugp);
+	membuf_store(&to, pt_elr(regs)); // pc
+	membuf_store(&to, (unsigned long)pt_cause(regs)); // cause
+	membuf_store(&to, pt_badva(regs)); // badva
 #if CONFIG_HEXAGON_ARCH_VERSION >=4
-	ONEXT(&regs->cs0, cs0);
-	ONEXT(&regs->cs1, cs1);
+	membuf_store(&to, regs->cs0);
+	membuf_store(&to, regs->cs1);
+	return membuf_zero(&to, sizeof(unsigned long));
+#else
+	return membuf_zero(&to, 3 * sizeof(unsigned long));
 #endif
-
-	/* Pad the rest with zeros, if needed */
-	if (!ret)
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					offsetof(struct user_regs_struct, pad1), -1);
-	return ret;
 }
 
 static int genregs_set(struct task_struct *target,
@@ -159,7 +139,7 @@ static const struct user_regset hexagon_regsets[] = {
 		.n = ELF_NGREG,
 		.size = sizeof(unsigned long),
 		.align = sizeof(unsigned long),
-		.get = genregs_get,
+		.regset_get = genregs_get,
 		.set = genregs_set,
 	},
 };
diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c
index 82aaacf64583..33ca9fa0fbf5 100644
--- a/arch/ia64/kernel/ptrace.c
+++ b/arch/ia64/kernel/ptrace.c
@@ -1273,52 +1273,43 @@ struct regset_getset {
 	int ret;
 };
 
+static const ptrdiff_t pt_offsets[32] =
+{
+#define R(n) offsetof(struct pt_regs, r##n)
+	[0] = -1, R(1), R(2), R(3),
+	[4] = -1, [5] = -1, [6] = -1, [7] = -1,
+	R(8), R(9), R(10), R(11), R(12), R(13), R(14), R(15),
+	R(16), R(17), R(18), R(19), R(20), R(21), R(22), R(23),
+	R(24), R(25), R(26), R(27), R(28), R(29), R(30), R(31),
+#undef R
+};
+
 static int
 access_elf_gpreg(struct task_struct *target, struct unw_frame_info *info,
 		unsigned long addr, unsigned long *data, int write_access)
 {
-	struct pt_regs *pt;
-	unsigned long *ptr = NULL;
-	int ret;
-	char nat = 0;
+	struct pt_regs *pt = task_pt_regs(target);
+	unsigned reg = addr / sizeof(unsigned long);
+	ptrdiff_t d = pt_offsets[reg];
 
-	pt = task_pt_regs(target);
-	switch (addr) {
-	case ELF_GR_OFFSET(1):
-		ptr = &pt->r1;
-		break;
-	case ELF_GR_OFFSET(2):
-	case ELF_GR_OFFSET(3):
-		ptr = (void *)&pt->r2 + (addr - ELF_GR_OFFSET(2));
-		break;
-	case ELF_GR_OFFSET(4) ... ELF_GR_OFFSET(7):
+	if (d >= 0) {
+		unsigned long *ptr = (void *)pt + d;
+		if (write_access)
+			*ptr = *data;
+		else
+			*data = *ptr;
+		return 0;
+	} else {
+		char nat = 0;
 		if (write_access) {
 			/* read NaT bit first: */
 			unsigned long dummy;
-
-			ret = unw_get_gr(info, addr/8, &dummy, &nat);
+			int ret = unw_get_gr(info, reg, &dummy, &nat);
 			if (ret < 0)
 				return ret;
 		}
-		return unw_access_gr(info, addr/8, data, &nat, write_access);
-	case ELF_GR_OFFSET(8) ... ELF_GR_OFFSET(11):
-		ptr = (void *)&pt->r8 + addr - ELF_GR_OFFSET(8);
-		break;
-	case ELF_GR_OFFSET(12):
-	case ELF_GR_OFFSET(13):
-		ptr = (void *)&pt->r12 + addr - ELF_GR_OFFSET(12);
-		break;
-	case ELF_GR_OFFSET(14):
-		ptr = &pt->r14;
-		break;
-	case ELF_GR_OFFSET(15):
-		ptr = &pt->r15;
+		return unw_access_gr(info, reg, data, &nat, write_access);
 	}
-	if (write_access)
-		*ptr = *data;
-	else
-		*data = *ptr;
-	return 0;
 }
 
 static int
@@ -1490,7 +1481,7 @@ static int
 access_elf_reg(struct task_struct *target, struct unw_frame_info *info,
 		unsigned long addr, unsigned long *data, int write_access)
 {
-	if (addr >= ELF_GR_OFFSET(1) && addr <= ELF_GR_OFFSET(15))
+	if (addr >= ELF_GR_OFFSET(1) && addr <= ELF_GR_OFFSET(31))
 		return access_elf_gpreg(target, info, addr, data, write_access);
 	else if (addr >= ELF_BR_OFFSET(0) && addr <= ELF_BR_OFFSET(7))
 		return access_elf_breg(target, info, addr, data, write_access);
@@ -1498,12 +1489,17 @@ access_elf_reg(struct task_struct *target, struct unw_frame_info *info,
 		return access_elf_areg(target, info, addr, data, write_access);
 }
 
+struct regset_membuf {
+	struct membuf to;
+	int ret;
+};
+
 void do_gpregs_get(struct unw_frame_info *info, void *arg)
 {
-	struct pt_regs *pt;
-	struct regset_getset *dst = arg;
-	elf_greg_t tmp[16];
-	unsigned int i, index, min_copy;
+	struct regset_membuf *dst = arg;
+	struct membuf to = dst->to;
+	unsigned int n;
+	elf_greg_t reg;
 
 	if (unw_unwind_to_user(info) < 0)
 		return;
@@ -1521,165 +1517,53 @@ void do_gpregs_get(struct unw_frame_info *info, void *arg)
 
 
 	/* Skip r0 */
-	if (dst->count > 0 && dst->pos < ELF_GR_OFFSET(1)) {
-		dst->ret = user_regset_copyout_zero(&dst->pos, &dst->count,
-						      &dst->u.get.kbuf,
-						      &dst->u.get.ubuf,
-						      0, ELF_GR_OFFSET(1));
-		if (dst->ret || dst->count == 0)
+	membuf_zero(&to, 8);
+	for (n = 8; to.left && n < ELF_AR_END_OFFSET; n += 8) {
+		if (access_elf_reg(info->task, info, n, &reg, 0) < 0) {
+			dst->ret = -EIO;
 			return;
-	}
-
-	/* gr1 - gr15 */
-	if (dst->count > 0 && dst->pos < ELF_GR_OFFSET(16)) {
-		index = (dst->pos - ELF_GR_OFFSET(1)) / sizeof(elf_greg_t);
-		min_copy = ELF_GR_OFFSET(16) > (dst->pos + dst->count) ?
-			 (dst->pos + dst->count) : ELF_GR_OFFSET(16);
-		for (i = dst->pos; i < min_copy; i += sizeof(elf_greg_t),
-				index++)
-			if (access_elf_reg(dst->target, info, i,
-						&tmp[index], 0) < 0) {
-				dst->ret = -EIO;
-				return;
-			}
-		dst->ret = user_regset_copyout(&dst->pos, &dst->count,
-				&dst->u.get.kbuf, &dst->u.get.ubuf, tmp,
-				ELF_GR_OFFSET(1), ELF_GR_OFFSET(16));
-		if (dst->ret || dst->count == 0)
-			return;
-	}
-
-	/* r16-r31 */
-	if (dst->count > 0 && dst->pos < ELF_NAT_OFFSET) {
-		pt = task_pt_regs(dst->target);
-		dst->ret = user_regset_copyout(&dst->pos, &dst->count,
-				&dst->u.get.kbuf, &dst->u.get.ubuf, &pt->r16,
-				ELF_GR_OFFSET(16), ELF_NAT_OFFSET);
-		if (dst->ret || dst->count == 0)
-			return;
-	}
-
-	/* nat, pr, b0 - b7 */
-	if (dst->count > 0 && dst->pos < ELF_CR_IIP_OFFSET) {
-		index = (dst->pos - ELF_NAT_OFFSET) / sizeof(elf_greg_t);
-		min_copy = ELF_CR_IIP_OFFSET > (dst->pos + dst->count) ?
-			 (dst->pos + dst->count) : ELF_CR_IIP_OFFSET;
-		for (i = dst->pos; i < min_copy; i += sizeof(elf_greg_t),
-				index++)
-			if (access_elf_reg(dst->target, info, i,
-						&tmp[index], 0) < 0) {
-				dst->ret = -EIO;
-				return;
-			}
-		dst->ret = user_regset_copyout(&dst->pos, &dst->count,
-				&dst->u.get.kbuf, &dst->u.get.ubuf, tmp,
-				ELF_NAT_OFFSET, ELF_CR_IIP_OFFSET);
-		if (dst->ret || dst->count == 0)
-			return;
-	}
-
-	/* ip cfm psr ar.rsc ar.bsp ar.bspstore ar.rnat
-	 * ar.ccv ar.unat ar.fpsr ar.pfs ar.lc ar.ec ar.csd ar.ssd
-	 */
-	if (dst->count > 0 && dst->pos < (ELF_AR_END_OFFSET)) {
-		index = (dst->pos - ELF_CR_IIP_OFFSET) / sizeof(elf_greg_t);
-		min_copy = ELF_AR_END_OFFSET > (dst->pos + dst->count) ?
-			 (dst->pos + dst->count) : ELF_AR_END_OFFSET;
-		for (i = dst->pos; i < min_copy; i += sizeof(elf_greg_t),
-				index++)
-			if (access_elf_reg(dst->target, info, i,
-						&tmp[index], 0) < 0) {
-				dst->ret = -EIO;
-				return;
-			}
-		dst->ret = user_regset_copyout(&dst->pos, &dst->count,
-				&dst->u.get.kbuf, &dst->u.get.ubuf, tmp,
-				ELF_CR_IIP_OFFSET, ELF_AR_END_OFFSET);
+		}
+		membuf_store(&to, reg);
 	}
 }
 
 void do_gpregs_set(struct unw_frame_info *info, void *arg)
 {
-	struct pt_regs *pt;
 	struct regset_getset *dst = arg;
-	elf_greg_t tmp[16];
-	unsigned int i, index;
 
 	if (unw_unwind_to_user(info) < 0)
 		return;
 
+	if (!dst->count)
+		return;
 	/* Skip r0 */
-	if (dst->count > 0 && dst->pos < ELF_GR_OFFSET(1)) {
+	if (dst->pos < ELF_GR_OFFSET(1)) {
 		dst->ret = user_regset_copyin_ignore(&dst->pos, &dst->count,
 						       &dst->u.set.kbuf,
 						       &dst->u.set.ubuf,
 						       0, ELF_GR_OFFSET(1));
-		if (dst->ret || dst->count == 0)
-			return;
-	}
-
-	/* gr1-gr15 */
-	if (dst->count > 0 && dst->pos < ELF_GR_OFFSET(16)) {
-		i = dst->pos;
-		index = (dst->pos - ELF_GR_OFFSET(1)) / sizeof(elf_greg_t);
-		dst->ret = user_regset_copyin(&dst->pos, &dst->count,
-				&dst->u.set.kbuf, &dst->u.set.ubuf, tmp,
-				ELF_GR_OFFSET(1), ELF_GR_OFFSET(16));
 		if (dst->ret)
 			return;
-		for ( ; i < dst->pos; i += sizeof(elf_greg_t), index++)
-			if (access_elf_reg(dst->target, info, i,
-						&tmp[index], 1) < 0) {
-				dst->ret = -EIO;
-				return;
-			}
-		if (dst->count == 0)
-			return;
-	}
-
-	/* gr16-gr31 */
-	if (dst->count > 0 && dst->pos < ELF_NAT_OFFSET) {
-		pt = task_pt_regs(dst->target);
-		dst->ret = user_regset_copyin(&dst->pos, &dst->count,
-				&dst->u.set.kbuf, &dst->u.set.ubuf, &pt->r16,
-				ELF_GR_OFFSET(16), ELF_NAT_OFFSET);
-		if (dst->ret || dst->count == 0)
-			return;
 	}
 
-	/* nat, pr, b0 - b7 */
-	if (dst->count > 0 && dst->pos < ELF_CR_IIP_OFFSET) {
-		i = dst->pos;
-		index = (dst->pos - ELF_NAT_OFFSET) / sizeof(elf_greg_t);
-		dst->ret = user_regset_copyin(&dst->pos, &dst->count,
-				&dst->u.set.kbuf, &dst->u.set.ubuf, tmp,
-				ELF_NAT_OFFSET, ELF_CR_IIP_OFFSET);
-		if (dst->ret)
-			return;
-		for (; i < dst->pos; i += sizeof(elf_greg_t), index++)
-			if (access_elf_reg(dst->target, info, i,
-						&tmp[index], 1) < 0) {
-				dst->ret = -EIO;
-				return;
-			}
-		if (dst->count == 0)
-			return;
-	}
+	while (dst->count && dst->pos < ELF_AR_END_OFFSET) {
+		unsigned int n, from, to;
+		elf_greg_t tmp[16];
 
-	/* ip cfm psr ar.rsc ar.bsp ar.bspstore ar.rnat
-	 * ar.ccv ar.unat ar.fpsr ar.pfs ar.lc ar.ec ar.csd ar.ssd
-	 */
-	if (dst->count > 0 && dst->pos < (ELF_AR_END_OFFSET)) {
-		i = dst->pos;
-		index = (dst->pos - ELF_CR_IIP_OFFSET) / sizeof(elf_greg_t);
+		from = dst->pos;
+		to = from + sizeof(tmp);
+		if (to > ELF_AR_END_OFFSET)
+			to = ELF_AR_END_OFFSET;
+		/* get up to 16 values */
 		dst->ret = user_regset_copyin(&dst->pos, &dst->count,
 				&dst->u.set.kbuf, &dst->u.set.ubuf, tmp,
-				ELF_CR_IIP_OFFSET, ELF_AR_END_OFFSET);
+				from, to);
 		if (dst->ret)
 			return;
-		for ( ; i < dst->pos; i += sizeof(elf_greg_t), index++)
-			if (access_elf_reg(dst->target, info, i,
-						&tmp[index], 1) < 0) {
+		/* now copy them into registers */
+		for (n = 0; from < dst->pos; from += sizeof(elf_greg_t), n++)
+			if (access_elf_reg(dst->target, info, from,
+						&tmp[n], 1) < 0) {
 				dst->ret = -EIO;
 				return;
 			}
@@ -1690,60 +1574,36 @@ void do_gpregs_set(struct unw_frame_info *info, void *arg)
 
 void do_fpregs_get(struct unw_frame_info *info, void *arg)
 {
-	struct regset_getset *dst = arg;
-	struct task_struct *task = dst->target;
-	elf_fpreg_t tmp[30];
-	int index, min_copy, i;
+	struct task_struct *task = info->task;
+	struct regset_membuf *dst = arg;
+	struct membuf to = dst->to;
+	elf_fpreg_t reg;
+	unsigned int n;
 
 	if (unw_unwind_to_user(info) < 0)
 		return;
 
 	/* Skip pos 0 and 1 */
-	if (dst->count > 0 && dst->pos < ELF_FP_OFFSET(2)) {
-		dst->ret = user_regset_copyout_zero(&dst->pos, &dst->count,
-						      &dst->u.get.kbuf,
-						      &dst->u.get.ubuf,
-						      0, ELF_FP_OFFSET(2));
-		if (dst->count == 0 || dst->ret)
-			return;
-	}
+	membuf_zero(&to, 2 * sizeof(elf_fpreg_t));
 
 	/* fr2-fr31 */
-	if (dst->count > 0 && dst->pos < ELF_FP_OFFSET(32)) {
-		index = (dst->pos - ELF_FP_OFFSET(2)) / sizeof(elf_fpreg_t);
-
-		min_copy = min(((unsigned int)ELF_FP_OFFSET(32)),
-				dst->pos + dst->count);
-		for (i = dst->pos; i < min_copy; i += sizeof(elf_fpreg_t),
-				index++)
-			if (unw_get_fr(info, i / sizeof(elf_fpreg_t),
-					 &tmp[index])) {
-				dst->ret = -EIO;
-				return;
-			}
-		dst->ret = user_regset_copyout(&dst->pos, &dst->count,
-				&dst->u.get.kbuf, &dst->u.get.ubuf, tmp,
-				ELF_FP_OFFSET(2), ELF_FP_OFFSET(32));
-		if (dst->count == 0 || dst->ret)
+	for (n = 2; to.left && n < 32; n++) {
+		if (unw_get_fr(info, n, &reg)) {
+			dst->ret = -EIO;
 			return;
+		}
+		membuf_write(&to, &reg, sizeof(reg));
 	}
 
 	/* fph */
-	if (dst->count > 0) {
-		ia64_flush_fph(dst->target);
-		if (task->thread.flags & IA64_THREAD_FPH_VALID)
-			dst->ret = user_regset_copyout(
-				&dst->pos, &dst->count,
-				&dst->u.get.kbuf, &dst->u.get.ubuf,
-				&dst->target->thread.fph,
-				ELF_FP_OFFSET(32), -1);
-		else
-			/* Zero fill instead.  */
-			dst->ret = user_regset_copyout_zero(
-				&dst->pos, &dst->count,
-				&dst->u.get.kbuf, &dst->u.get.ubuf,
-				ELF_FP_OFFSET(32), -1);
-	}
+	if (!to.left)
+		return;
+
+	ia64_flush_fph(task);
+	if (task->thread.flags & IA64_THREAD_FPH_VALID)
+		membuf_write(&to, &task->thread.fph, 96 * sizeof(reg));
+	else
+		membuf_zero(&to, 96 * sizeof(reg));
 }
 
 void do_fpregs_set(struct unw_frame_info *info, void *arg)
@@ -1819,6 +1679,20 @@ void do_fpregs_set(struct unw_frame_info *info, void *arg)
 	}
 }
 
+static void
+unwind_and_call(void (*call)(struct unw_frame_info *, void *),
+	       struct task_struct *target, void *data)
+{
+	if (target == current)
+		unw_init_running(call, data);
+	else {
+		struct unw_frame_info info;
+		memset(&info, 0, sizeof(info));
+		unw_init_from_blocked_task(&info, target);
+		(*call)(&info, data);
+	}
+}
+
 static int
 do_regset_call(void (*call)(struct unw_frame_info *, void *),
 	       struct task_struct *target,
@@ -1830,27 +1704,18 @@ do_regset_call(void (*call)(struct unw_frame_info *, void *),
 				 .pos = pos, .count = count,
 				 .u.set = { .kbuf = kbuf, .ubuf = ubuf },
 				 .ret = 0 };
-
-	if (target == current)
-		unw_init_running(call, &info);
-	else {
-		struct unw_frame_info ufi;
-		memset(&ufi, 0, sizeof(ufi));
-		unw_init_from_blocked_task(&ufi, target);
-		(*call)(&ufi, &info);
-	}
-
+	unwind_and_call(call, target, &info);
 	return info.ret;
 }
 
 static int
 gpregs_get(struct task_struct *target,
 	   const struct user_regset *regset,
-	   unsigned int pos, unsigned int count,
-	   void *kbuf, void __user *ubuf)
+	   struct membuf to)
 {
-	return do_regset_call(do_gpregs_get, target, regset, pos, count,
-		kbuf, ubuf);
+	struct regset_membuf info = {.to = to};
+	unwind_and_call(do_gpregs_get, target, &info);
+	return info.ret;
 }
 
 static int gpregs_set(struct task_struct *target,
@@ -1892,11 +1757,11 @@ fpregs_active(struct task_struct *target, const struct user_regset *regset)
 
 static int fpregs_get(struct task_struct *target,
 		const struct user_regset *regset,
-		unsigned int pos, unsigned int count,
-		void *kbuf, void __user *ubuf)
+		struct membuf to)
 {
-	return do_regset_call(do_fpregs_get, target, regset, pos, count,
-		kbuf, ubuf);
+	struct regset_membuf info = {.to = to};
+	unwind_and_call(do_fpregs_get, target, &info);
+	return info.ret;
 }
 
 static int fpregs_set(struct task_struct *target,
@@ -1913,7 +1778,6 @@ access_uarea(struct task_struct *child, unsigned long addr,
 	      unsigned long *data, int write_access)
 {
 	unsigned int pos = -1; /* an invalid value */
-	int ret;
 	unsigned long *ptr, regnum;
 
 	if ((addr & 0x7) != 0) {
@@ -1945,14 +1809,39 @@ access_uarea(struct task_struct *child, unsigned long addr,
 	}
 
 	if (pos != -1) {
-		if (write_access)
-			ret = fpregs_set(child, NULL, pos,
-				sizeof(unsigned long), data, NULL);
-		else
-			ret = fpregs_get(child, NULL, pos,
-				sizeof(unsigned long), data, NULL);
-		if (ret != 0)
-			return -1;
+		unsigned reg = pos / sizeof(elf_fpreg_t);
+		int which_half = (pos / sizeof(unsigned long)) & 1;
+
+		if (reg < 32) { /* fr2-fr31 */
+			struct unw_frame_info info;
+			elf_fpreg_t fpreg;
+
+			memset(&info, 0, sizeof(info));
+			unw_init_from_blocked_task(&info, child);
+			if (unw_unwind_to_user(&info) < 0)
+				return 0;
+
+			if (unw_get_fr(&info, reg, &fpreg))
+				return -1;
+			if (write_access) {
+				fpreg.u.bits[which_half] = *data;
+				if (unw_set_fr(&info, reg, fpreg))
+					return -1;
+			} else {
+				*data = fpreg.u.bits[which_half];
+			}
+		} else { /* fph */
+			elf_fpreg_t *p = &child->thread.fph[reg - 32];
+			unsigned long *bits = &p->u.bits[which_half];
+
+			ia64_sync_fph(child);
+			if (write_access)
+				*bits = *data;
+			else if (child->thread.flags & IA64_THREAD_FPH_VALID)
+				*data = *bits;
+			else
+				*data = 0;
+		}
 		return 0;
 	}
 
@@ -2038,15 +1927,14 @@ access_uarea(struct task_struct *child, unsigned long addr,
 	}
 
 	if (pos != -1) {
-		if (write_access)
-			ret = gpregs_set(child, NULL, pos,
-				sizeof(unsigned long), data, NULL);
-		else
-			ret = gpregs_get(child, NULL, pos,
-				sizeof(unsigned long), data, NULL);
-		if (ret != 0)
-			return -1;
-		return 0;
+		struct unw_frame_info info;
+
+		memset(&info, 0, sizeof(info));
+		unw_init_from_blocked_task(&info, child);
+		if (unw_unwind_to_user(&info) < 0)
+			return 0;
+
+		return access_elf_reg(child, &info, pos, data, write_access);
 	}
 
 	/* access debug registers */
@@ -2112,14 +2000,14 @@ static const struct user_regset native_regsets[] = {
 		.core_note_type = NT_PRSTATUS,
 		.n = ELF_NGREG,
 		.size = sizeof(elf_greg_t), .align = sizeof(elf_greg_t),
-		.get = gpregs_get, .set = gpregs_set,
+		.regset_get = gpregs_get, .set = gpregs_set,
 		.writeback = gpregs_writeback
 	},
 	{
 		.core_note_type = NT_PRFPREG,
 		.n = ELF_NFPREG,
 		.size = sizeof(elf_fpreg_t), .align = sizeof(elf_fpreg_t),
-		.get = fpregs_get, .set = fpregs_set, .active = fpregs_active
+		.regset_get = fpregs_get, .set = fpregs_set, .active = fpregs_active
 	},
 };
 
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index 2a61641c680b..db7c5be1d4a3 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -210,15 +210,13 @@ int ptrace_set_watch_regs(struct task_struct *child,
 
 static int gpr32_get(struct task_struct *target,
 		     const struct user_regset *regset,
-		     unsigned int pos, unsigned int count,
-		     void *kbuf, void __user *ubuf)
+		     struct membuf to)
 {
 	struct pt_regs *regs = task_pt_regs(target);
 	u32 uregs[ELF_NGREG] = {};
 
 	mips_dump_regs32(uregs, regs);
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0,
-				   sizeof(uregs));
+	return membuf_write(&to, uregs, sizeof(uregs));
 }
 
 static int gpr32_set(struct task_struct *target,
@@ -277,15 +275,13 @@ static int gpr32_set(struct task_struct *target,
 
 static int gpr64_get(struct task_struct *target,
 		     const struct user_regset *regset,
-		     unsigned int pos, unsigned int count,
-		     void *kbuf, void __user *ubuf)
+		     struct membuf to)
 {
 	struct pt_regs *regs = task_pt_regs(target);
 	u64 uregs[ELF_NGREG] = {};
 
 	mips_dump_regs64(uregs, regs);
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0,
-				   sizeof(uregs));
+	return membuf_write(&to, uregs, sizeof(uregs));
 }
 
 static int gpr64_set(struct task_struct *target,
@@ -408,13 +404,11 @@ int ptrace_setfpregs(struct task_struct *child, __u32 __user *data)
  * !CONFIG_CPU_HAS_MSA variant.  FP context's general register slots
  * correspond 1:1 to buffer slots.  Only general registers are copied.
  */
-static int fpr_get_fpa(struct task_struct *target,
-		       unsigned int *pos, unsigned int *count,
-		       void **kbuf, void __user **ubuf)
+static void fpr_get_fpa(struct task_struct *target,
+		       struct membuf *to)
 {
-	return user_regset_copyout(pos, count, kbuf, ubuf,
-				   &target->thread.fpu,
-				   0, NUM_FPU_REGS * sizeof(elf_fpreg_t));
+	membuf_write(to, &target->thread.fpu,
+			NUM_FPU_REGS * sizeof(elf_fpreg_t));
 }
 
 /*
@@ -423,25 +417,13 @@ static int fpr_get_fpa(struct task_struct *target,
  * general register slots are copied to buffer slots.  Only general
  * registers are copied.
  */
-static int fpr_get_msa(struct task_struct *target,
-		       unsigned int *pos, unsigned int *count,
-		       void **kbuf, void __user **ubuf)
+static void fpr_get_msa(struct task_struct *target, struct membuf *to)
 {
 	unsigned int i;
-	u64 fpr_val;
-	int err;
-
-	BUILD_BUG_ON(sizeof(fpr_val) != sizeof(elf_fpreg_t));
-	for (i = 0; i < NUM_FPU_REGS; i++) {
-		fpr_val = get_fpr64(&target->thread.fpu.fpr[i], 0);
-		err = user_regset_copyout(pos, count, kbuf, ubuf,
-					  &fpr_val, i * sizeof(elf_fpreg_t),
-					  (i + 1) * sizeof(elf_fpreg_t));
-		if (err)
-			return err;
-	}
 
-	return 0;
+	BUILD_BUG_ON(sizeof(u64) != sizeof(elf_fpreg_t));
+	for (i = 0; i < NUM_FPU_REGS; i++)
+		membuf_store(to, get_fpr64(&target->thread.fpu.fpr[i], 0));
 }
 
 /*
@@ -451,31 +433,16 @@ static int fpr_get_msa(struct task_struct *target,
  */
 static int fpr_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	const int fcr31_pos = NUM_FPU_REGS * sizeof(elf_fpreg_t);
-	const int fir_pos = fcr31_pos + sizeof(u32);
-	int err;
-
 	if (sizeof(target->thread.fpu.fpr[0]) == sizeof(elf_fpreg_t))
-		err = fpr_get_fpa(target, &pos, &count, &kbuf, &ubuf);
+		fpr_get_fpa(target, &to);
 	else
-		err = fpr_get_msa(target, &pos, &count, &kbuf, &ubuf);
-	if (err)
-		return err;
-
-	err = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &target->thread.fpu.fcr31,
-				  fcr31_pos, fcr31_pos + sizeof(u32));
-	if (err)
-		return err;
+		fpr_get_msa(target, &to);
 
-	err = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &boot_cpu_data.fpu_id,
-				  fir_pos, fir_pos + sizeof(u32));
-
-	return err;
+	membuf_write(&to, &target->thread.fpu.fcr31, sizeof(u32));
+	membuf_write(&to, &boot_cpu_data.fpu_id, sizeof(u32));
+	return 0;
 }
 
 /*
@@ -576,14 +543,9 @@ static int fpr_set(struct task_struct *target,
 /* Copy the FP mode setting to the supplied NT_MIPS_FP_MODE buffer.  */
 static int fp_mode_get(struct task_struct *target,
 		       const struct user_regset *regset,
-		       unsigned int pos, unsigned int count,
-		       void *kbuf, void __user *ubuf)
+		       struct membuf to)
 {
-	int fp_mode;
-
-	fp_mode = mips_get_process_fp_mode(target);
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &fp_mode, 0,
-				   sizeof(fp_mode));
+	return membuf_store(&to, (int)mips_get_process_fp_mode(target));
 }
 
 /*
@@ -630,13 +592,12 @@ struct msa_control_regs {
 	unsigned int msacsr;
 };
 
-static int copy_pad_fprs(struct task_struct *target,
+static void copy_pad_fprs(struct task_struct *target,
 			 const struct user_regset *regset,
-			 unsigned int *ppos, unsigned int *pcount,
-			 void **pkbuf, void __user **pubuf,
+			 struct membuf *to,
 			 unsigned int live_sz)
 {
-	int i, j, start, start_pad, err;
+	int i, j;
 	unsigned long long fill = ~0ull;
 	unsigned int cp_sz, pad_sz;
 
@@ -644,28 +605,16 @@ static int copy_pad_fprs(struct task_struct *target,
 	pad_sz = regset->size - cp_sz;
 	WARN_ON(pad_sz % sizeof(fill));
 
-	i = start = err = 0;
-	for (; i < NUM_FPU_REGS; i++, start += regset->size) {
-		err |= user_regset_copyout(ppos, pcount, pkbuf, pubuf,
-					   &target->thread.fpu.fpr[i],
-					   start, start + cp_sz);
-
-		start_pad = start + cp_sz;
-		for (j = 0; j < (pad_sz / sizeof(fill)); j++) {
-			err |= user_regset_copyout(ppos, pcount, pkbuf, pubuf,
-						   &fill, start_pad,
-						   start_pad + sizeof(fill));
-			start_pad += sizeof(fill);
-		}
+	for (i = 0; i < NUM_FPU_REGS; i++) {
+		membuf_write(to, &target->thread.fpu.fpr[i], cp_sz);
+		for (j = 0; j < (pad_sz / sizeof(fill)); j++)
+			membuf_store(to, fill);
 	}
-
-	return err;
 }
 
 static int msa_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
 	const unsigned int wr_size = NUM_FPU_REGS * regset->size;
 	const struct msa_control_regs ctrl_regs = {
@@ -674,32 +623,23 @@ static int msa_get(struct task_struct *target,
 		.msair = boot_cpu_data.msa_id,
 		.msacsr = target->thread.fpu.msacsr,
 	};
-	int err;
 
 	if (!tsk_used_math(target)) {
 		/* The task hasn't used FP or MSA, fill with 0xff */
-		err = copy_pad_fprs(target, regset, &pos, &count,
-				    &kbuf, &ubuf, 0);
+		copy_pad_fprs(target, regset, &to, 0);
 	} else if (!test_tsk_thread_flag(target, TIF_MSA_CTX_LIVE)) {
 		/* Copy scalar FP context, fill the rest with 0xff */
-		err = copy_pad_fprs(target, regset, &pos, &count,
-				    &kbuf, &ubuf, 8);
+		copy_pad_fprs(target, regset, &to, 8);
 	} else if (sizeof(target->thread.fpu.fpr[0]) == regset->size) {
 		/* Trivially copy the vector registers */
-		err = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &target->thread.fpu.fpr,
-					  0, wr_size);
+		membuf_write(&to, &target->thread.fpu.fpr, wr_size);
 	} else {
 		/* Copy as much context as possible, fill the rest with 0xff */
-		err = copy_pad_fprs(target, regset, &pos, &count,
-				    &kbuf, &ubuf,
-				    sizeof(target->thread.fpu.fpr[0]));
+		copy_pad_fprs(target, regset, &to,
+				sizeof(target->thread.fpu.fpr[0]));
 	}
 
-	err |= user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &ctrl_regs, wr_size,
-				   wr_size + sizeof(ctrl_regs));
-	return err;
+	return membuf_write(&to, &ctrl_regs, sizeof(ctrl_regs));
 }
 
 static int msa_set(struct task_struct *target,
@@ -752,34 +692,20 @@ static int msa_set(struct task_struct *target,
  */
 static int dsp32_get(struct task_struct *target,
 		     const struct user_regset *regset,
-		     unsigned int pos, unsigned int count,
-		     void *kbuf, void __user *ubuf)
+		     struct membuf to)
 {
-	unsigned int start, num_regs, i;
 	u32 dspregs[NUM_DSP_REGS + 1];
+	unsigned int i;
 
-	BUG_ON(count % sizeof(u32));
+	BUG_ON(to.left % sizeof(u32));
 
 	if (!cpu_has_dsp)
 		return -EIO;
 
-	start = pos / sizeof(u32);
-	num_regs = count / sizeof(u32);
-
-	if (start + num_regs > NUM_DSP_REGS + 1)
-		return -EIO;
-
-	for (i = start; i < num_regs; i++)
-		switch (i) {
-		case 0 ... NUM_DSP_REGS - 1:
-			dspregs[i] = target->thread.dsp.dspr[i];
-			break;
-		case NUM_DSP_REGS:
-			dspregs[i] = target->thread.dsp.dspcontrol;
-			break;
-		}
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, dspregs, 0,
-				   sizeof(dspregs));
+	for (i = 0; i < NUM_DSP_REGS; i++)
+		dspregs[i] = target->thread.dsp.dspr[i];
+	dspregs[NUM_DSP_REGS] = target->thread.dsp.dspcontrol;
+	return membuf_write(&to, dspregs, sizeof(dspregs));
 }
 
 /*
@@ -832,34 +758,20 @@ static int dsp32_set(struct task_struct *target,
  */
 static int dsp64_get(struct task_struct *target,
 		     const struct user_regset *regset,
-		     unsigned int pos, unsigned int count,
-		     void *kbuf, void __user *ubuf)
+		     struct membuf to)
 {
-	unsigned int start, num_regs, i;
 	u64 dspregs[NUM_DSP_REGS + 1];
+	unsigned int i;
 
-	BUG_ON(count % sizeof(u64));
+	BUG_ON(to.left % sizeof(u64));
 
 	if (!cpu_has_dsp)
 		return -EIO;
 
-	start = pos / sizeof(u64);
-	num_regs = count / sizeof(u64);
-
-	if (start + num_regs > NUM_DSP_REGS + 1)
-		return -EIO;
-
-	for (i = start; i < num_regs; i++)
-		switch (i) {
-		case 0 ... NUM_DSP_REGS - 1:
-			dspregs[i] = target->thread.dsp.dspr[i];
-			break;
-		case NUM_DSP_REGS:
-			dspregs[i] = target->thread.dsp.dspcontrol;
-			break;
-		}
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, dspregs, 0,
-				   sizeof(dspregs));
+	for (i = 0; i < NUM_DSP_REGS; i++)
+		dspregs[i] = target->thread.dsp.dspr[i];
+	dspregs[NUM_DSP_REGS] = target->thread.dsp.dspcontrol;
+	return membuf_write(&to, dspregs, sizeof(dspregs));
 }
 
 /*
@@ -1018,7 +930,7 @@ static const struct user_regset mips_regsets[] = {
 		.n		= ELF_NGREG,
 		.size		= sizeof(unsigned int),
 		.align		= sizeof(unsigned int),
-		.get		= gpr32_get,
+		.regset_get		= gpr32_get,
 		.set		= gpr32_set,
 	},
 	[REGSET_DSP] = {
@@ -1026,7 +938,7 @@ static const struct user_regset mips_regsets[] = {
 		.n		= NUM_DSP_REGS + 1,
 		.size		= sizeof(u32),
 		.align		= sizeof(u32),
-		.get		= dsp32_get,
+		.regset_get		= dsp32_get,
 		.set		= dsp32_set,
 		.active		= dsp_active,
 	},
@@ -1036,7 +948,7 @@ static const struct user_regset mips_regsets[] = {
 		.n		= ELF_NFPREG,
 		.size		= sizeof(elf_fpreg_t),
 		.align		= sizeof(elf_fpreg_t),
-		.get		= fpr_get,
+		.regset_get		= fpr_get,
 		.set		= fpr_set,
 	},
 	[REGSET_FP_MODE] = {
@@ -1044,7 +956,7 @@ static const struct user_regset mips_regsets[] = {
 		.n		= 1,
 		.size		= sizeof(int),
 		.align		= sizeof(int),
-		.get		= fp_mode_get,
+		.regset_get		= fp_mode_get,
 		.set		= fp_mode_set,
 	},
 #endif
@@ -1054,7 +966,7 @@ static const struct user_regset mips_regsets[] = {
 		.n		= NUM_FPU_REGS + 1,
 		.size		= 16,
 		.align		= 16,
-		.get		= msa_get,
+		.regset_get		= msa_get,
 		.set		= msa_set,
 	},
 #endif
@@ -1078,7 +990,7 @@ static const struct user_regset mips64_regsets[] = {
 		.n		= ELF_NGREG,
 		.size		= sizeof(unsigned long),
 		.align		= sizeof(unsigned long),
-		.get		= gpr64_get,
+		.regset_get		= gpr64_get,
 		.set		= gpr64_set,
 	},
 	[REGSET_DSP] = {
@@ -1086,7 +998,7 @@ static const struct user_regset mips64_regsets[] = {
 		.n		= NUM_DSP_REGS + 1,
 		.size		= sizeof(u64),
 		.align		= sizeof(u64),
-		.get		= dsp64_get,
+		.regset_get		= dsp64_get,
 		.set		= dsp64_set,
 		.active		= dsp_active,
 	},
@@ -1096,7 +1008,7 @@ static const struct user_regset mips64_regsets[] = {
 		.n		= 1,
 		.size		= sizeof(int),
 		.align		= sizeof(int),
-		.get		= fp_mode_get,
+		.regset_get		= fp_mode_get,
 		.set		= fp_mode_set,
 	},
 	[REGSET_FPR] = {
@@ -1104,7 +1016,7 @@ static const struct user_regset mips64_regsets[] = {
 		.n		= ELF_NFPREG,
 		.size		= sizeof(elf_fpreg_t),
 		.align		= sizeof(elf_fpreg_t),
-		.get		= fpr_get,
+		.regset_get		= fpr_get,
 		.set		= fpr_set,
 	},
 #endif
@@ -1114,7 +1026,7 @@ static const struct user_regset mips64_regsets[] = {
 		.n		= NUM_FPU_REGS + 1,
 		.size		= 16,
 		.align		= 16,
-		.get		= msa_get,
+		.regset_get		= msa_get,
 		.set		= msa_set,
 	},
 #endif
diff --git a/arch/nds32/kernel/ptrace.c b/arch/nds32/kernel/ptrace.c
index eaaf7a999b20..d0eda870fbc2 100644
--- a/arch/nds32/kernel/ptrace.c
+++ b/arch/nds32/kernel/ptrace.c
@@ -13,11 +13,10 @@ enum nds32_regset {
 
 static int gpr_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user * ubuf)
+		   struct membuf to)
 {
-	struct user_pt_regs *uregs = &task_pt_regs(target)->user_regs;
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0, -1);
+	return membuf_write(&to, &task_pt_regs(target)->user_regs,
+				sizeof(struct user_pt_regs));
 }
 
 static int gpr_set(struct task_struct *target, const struct user_regset *regset,
@@ -41,7 +40,7 @@ static const struct user_regset nds32_regsets[] = {
 			.n = sizeof(struct user_pt_regs) / sizeof(u32),
 			.size = sizeof(elf_greg_t),
 			.align = sizeof(elf_greg_t),
-			.get = gpr_get,
+			.regset_get = gpr_get,
 			.set = gpr_set}
 };
 
diff --git a/arch/nios2/kernel/ptrace.c b/arch/nios2/kernel/ptrace.c
index de97bcb7dd44..a6ea9e1b4f61 100644
--- a/arch/nios2/kernel/ptrace.c
+++ b/arch/nios2/kernel/ptrace.c
@@ -21,45 +21,24 @@
 
 static int genregs_get(struct task_struct *target,
 		       const struct user_regset *regset,
-		       unsigned int pos, unsigned int count,
-		       void *kbuf, void __user *ubuf)
+		       struct membuf to)
 {
 	const struct pt_regs *regs = task_pt_regs(target);
 	const struct switch_stack *sw = (struct switch_stack *)regs - 1;
-	int ret = 0;
-
-#define REG_O_ZERO_RANGE(START, END)		\
-	if (!ret)					\
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf, \
-			START * 4, (END * 4) + 4);
-
-#define REG_O_ONE(PTR, LOC)	\
-	if (!ret)			\
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, PTR, \
-			LOC * 4, (LOC * 4) + 4);
 
-#define REG_O_RANGE(PTR, START, END)	\
-	if (!ret)				\
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, PTR, \
-			START * 4, (END * 4) + 4);
-
-	REG_O_ZERO_RANGE(PTR_R0, PTR_R0);
-	REG_O_RANGE(&regs->r1, PTR_R1, PTR_R7);
-	REG_O_RANGE(&regs->r8, PTR_R8, PTR_R15);
-	REG_O_RANGE(sw, PTR_R16, PTR_R23);
-	REG_O_ZERO_RANGE(PTR_R24, PTR_R25); /* et and bt */
-	REG_O_ONE(&regs->gp, PTR_GP);
-	REG_O_ONE(&regs->sp, PTR_SP);
-	REG_O_ONE(&regs->fp, PTR_FP);
-	REG_O_ONE(&regs->ea, PTR_EA);
-	REG_O_ZERO_RANGE(PTR_BA, PTR_BA);
-	REG_O_ONE(&regs->ra, PTR_RA);
-	REG_O_ONE(&regs->ea, PTR_PC); /* use ea for PC */
-	if (!ret)
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					 PTR_STATUS * 4, -1);
-
-	return ret;
+	membuf_zero(&to, 4); // R0
+	membuf_write(&to, &regs->r1, 7 * 4); // R1..R7
+	membuf_write(&to, &regs->r8, 8 * 4); // R8..R15
+	membuf_write(&to, sw, 8 * 4); // R16..R23
+	membuf_zero(&to, 2 * 4); /* et and bt */
+	membuf_store(&to, regs->gp);
+	membuf_store(&to, regs->sp);
+	membuf_store(&to, regs->fp);
+	membuf_store(&to, regs->ea);
+	membuf_zero(&to, 4); // PTR_BA
+	membuf_store(&to, regs->ra);
+	membuf_store(&to, regs->ea); /* use ea for PC */
+	return membuf_zero(&to, (NUM_PTRACE_REG - PTR_PC) * 4);
 }
 
 /*
@@ -121,7 +100,7 @@ static const struct user_regset nios2_regsets[] = {
 		.n = NUM_PTRACE_REG,
 		.size = sizeof(unsigned long),
 		.align = sizeof(unsigned long),
-		.get = genregs_get,
+		.regset_get = genregs_get,
 		.set = genregs_set,
 	}
 };
diff --git a/arch/openrisc/kernel/ptrace.c b/arch/openrisc/kernel/ptrace.c
index c8f47a623754..4d60ae2a12fa 100644
--- a/arch/openrisc/kernel/ptrace.c
+++ b/arch/openrisc/kernel/ptrace.c
@@ -44,29 +44,15 @@
  */
 static int genregs_get(struct task_struct *target,
 		       const struct user_regset *regset,
-		       unsigned int pos, unsigned int count,
-		       void *kbuf, void __user * ubuf)
+		       struct membuf to)
 {
 	const struct pt_regs *regs = task_pt_regs(target);
-	int ret;
 
 	/* r0 */
-	ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf, 0, 4);
-
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  regs->gpr+1, 4, 4*32);
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &regs->pc, 4*32, 4*33);
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &regs->sr, 4*33, 4*34);
-	if (!ret)
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					       4*34, -1);
-
-	return ret;
+	membuf_zero(&to, 4);
+	membuf_write(&to, regs->gpr + 1, 31 * 4);
+	membuf_store(&to, regs->pc);
+	return membuf_store(&to, regs->sr);
 }
 
 /*
@@ -114,7 +100,7 @@ static const struct user_regset or1k_regsets[] = {
 			    .n = ELF_NGREG,
 			    .size = sizeof(long),
 			    .align = sizeof(long),
-			    .get = genregs_get,
+			    .regset_get = genregs_get,
 			    .set = genregs_set,
 			    },
 };
diff --git a/arch/parisc/kernel/ptrace.c b/arch/parisc/kernel/ptrace.c
index b51418ad8655..2127974982df 100644
--- a/arch/parisc/kernel/ptrace.c
+++ b/arch/parisc/kernel/ptrace.c
@@ -391,31 +391,11 @@ void do_syscall_trace_exit(struct pt_regs *regs)
 
 static int fpr_get(struct task_struct *target,
 		     const struct user_regset *regset,
-		     unsigned int pos, unsigned int count,
-		     void *kbuf, void __user *ubuf)
+		     struct membuf to)
 {
 	struct pt_regs *regs = task_regs(target);
-	__u64 *k = kbuf;
-	__u64 __user *u = ubuf;
-	__u64 reg;
-
-	pos /= sizeof(reg);
-	count /= sizeof(reg);
-
-	if (kbuf)
-		for (; count > 0 && pos < ELF_NFPREG; --count)
-			*k++ = regs->fr[pos++];
-	else
-		for (; count > 0 && pos < ELF_NFPREG; --count)
-			if (__put_user(regs->fr[pos++], u++))
-				return -EFAULT;
 
-	kbuf = k;
-	ubuf = u;
-	pos *= sizeof(reg);
-	count *= sizeof(reg);
-	return user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					ELF_NFPREG * sizeof(reg), -1);
+	return membuf_write(&to, regs->fr, ELF_NFPREG * sizeof(__u64));
 }
 
 static int fpr_set(struct task_struct *target,
@@ -527,30 +507,14 @@ static void set_reg(struct pt_regs *regs, int num, unsigned long val)
 
 static int gpr_get(struct task_struct *target,
 		     const struct user_regset *regset,
-		     unsigned int pos, unsigned int count,
-		     void *kbuf, void __user *ubuf)
+		     struct membuf to)
 {
 	struct pt_regs *regs = task_regs(target);
-	unsigned long *k = kbuf;
-	unsigned long __user *u = ubuf;
-	unsigned long reg;
+	unsigned int pos;
 
-	pos /= sizeof(reg);
-	count /= sizeof(reg);
-
-	if (kbuf)
-		for (; count > 0 && pos < ELF_NGREG; --count)
-			*k++ = get_reg(regs, pos++);
-	else
-		for (; count > 0 && pos < ELF_NGREG; --count)
-			if (__put_user(get_reg(regs, pos++), u++))
-				return -EFAULT;
-	kbuf = k;
-	ubuf = u;
-	pos *= sizeof(reg);
-	count *= sizeof(reg);
-	return user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					ELF_NGREG * sizeof(reg), -1);
+	for (pos = 0; pos < ELF_NGREG; pos++)
+		membuf_store(&to, get_reg(regs, pos));
+	return 0;
 }
 
 static int gpr_set(struct task_struct *target,
@@ -588,12 +552,12 @@ static const struct user_regset native_regsets[] = {
 	[REGSET_GENERAL] = {
 		.core_note_type = NT_PRSTATUS, .n = ELF_NGREG,
 		.size = sizeof(long), .align = sizeof(long),
-		.get = gpr_get, .set = gpr_set
+		.regset_get = gpr_get, .set = gpr_set
 	},
 	[REGSET_FP] = {
 		.core_note_type = NT_PRFPREG, .n = ELF_NFPREG,
 		.size = sizeof(__u64), .align = sizeof(__u64),
-		.get = fpr_get, .set = fpr_set
+		.regset_get = fpr_get, .set = fpr_set
 	}
 };
 
@@ -607,31 +571,15 @@ static const struct user_regset_view user_parisc_native_view = {
 
 static int gpr32_get(struct task_struct *target,
 		     const struct user_regset *regset,
-		     unsigned int pos, unsigned int count,
-		     void *kbuf, void __user *ubuf)
+		     struct membuf to)
 {
 	struct pt_regs *regs = task_regs(target);
-	compat_ulong_t *k = kbuf;
-	compat_ulong_t __user *u = ubuf;
-	compat_ulong_t reg;
+	unsigned int pos;
 
-	pos /= sizeof(reg);
-	count /= sizeof(reg);
+	for (pos = 0; pos < ELF_NGREG; pos++)
+		membuf_store(&to, (compat_ulong_t)get_reg(regs, pos));
 
-	if (kbuf)
-		for (; count > 0 && pos < ELF_NGREG; --count)
-			*k++ = get_reg(regs, pos++);
-	else
-		for (; count > 0 && pos < ELF_NGREG; --count)
-			if (__put_user((compat_ulong_t) get_reg(regs, pos++), u++))
-				return -EFAULT;
-
-	kbuf = k;
-	ubuf = u;
-	pos *= sizeof(reg);
-	count *= sizeof(reg);
-	return user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					ELF_NGREG * sizeof(reg), -1);
+	return 0;
 }
 
 static int gpr32_set(struct task_struct *target,
@@ -672,12 +620,12 @@ static const struct user_regset compat_regsets[] = {
 	[REGSET_GENERAL] = {
 		.core_note_type = NT_PRSTATUS, .n = ELF_NGREG,
 		.size = sizeof(compat_long_t), .align = sizeof(compat_long_t),
-		.get = gpr32_get, .set = gpr32_set
+		.regset_get = gpr32_get, .set = gpr32_set
 	},
 	[REGSET_FP] = {
 		.core_note_type = NT_PRFPREG, .n = ELF_NFPREG,
 		.size = sizeof(__u64), .align = sizeof(__u64),
-		.get = fpr_get, .set = fpr_set
+		.regset_get = fpr_get, .set = fpr_set
 	}
 };
 
diff --git a/arch/powerpc/kernel/ptrace/ptrace-altivec.c b/arch/powerpc/kernel/ptrace/ptrace-altivec.c
index dd8b75dfbd06..0d9bc4bd4972 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-altivec.c
+++ b/arch/powerpc/kernel/ptrace/ptrace-altivec.c
@@ -41,38 +41,25 @@ int vr_active(struct task_struct *target, const struct user_regset *regset)
  * };
  */
 int vr_get(struct task_struct *target, const struct user_regset *regset,
-	   unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+	   struct membuf to)
 {
-	int ret;
+	union {
+		elf_vrreg_t reg;
+		u32 word;
+	} vrsave;
 
 	flush_altivec_to_thread(target);
 
 	BUILD_BUG_ON(offsetof(struct thread_vr_state, vscr) !=
 		     offsetof(struct thread_vr_state, vr[32]));
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &target->thread.vr_state, 0,
-				  33 * sizeof(vector128));
-	if (!ret) {
-		/*
-		 * Copy out only the low-order word of vrsave.
-		 */
-		int start, end;
-		union {
-			elf_vrreg_t reg;
-			u32 word;
-		} vrsave;
-		memset(&vrsave, 0, sizeof(vrsave));
-
-		vrsave.word = target->thread.vrsave;
-
-		start = 33 * sizeof(vector128);
-		end = start + sizeof(vrsave);
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &vrsave,
-					  start, end);
-	}
-
-	return ret;
+	membuf_write(&to, &target->thread.vr_state, 33 * sizeof(vector128));
+	/*
+	 * Copy out only the low-order word of vrsave.
+	 */
+	memset(&vrsave, 0, sizeof(vrsave));
+	vrsave.word = target->thread.vrsave;
+	return membuf_write(&to, &vrsave, sizeof(vrsave));
 }
 
 /*
diff --git a/arch/powerpc/kernel/ptrace/ptrace-decl.h b/arch/powerpc/kernel/ptrace/ptrace-decl.h
index 3c8a81999292..67447a6197eb 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-decl.h
+++ b/arch/powerpc/kernel/ptrace/ptrace-decl.h
@@ -63,8 +63,7 @@ enum powerpc_regset {
 
 /* ptrace-(no)vsx */
 
-int fpr_get(struct task_struct *target, const struct user_regset *regset,
-	    unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf);
+user_regset_get2_fn fpr_get;
 int fpr_set(struct task_struct *target, const struct user_regset *regset,
 	    unsigned int pos, unsigned int count,
 	    const void *kbuf, const void __user *ubuf);
@@ -72,8 +71,7 @@ int fpr_set(struct task_struct *target, const struct user_regset *regset,
 /* ptrace-vsx */
 
 int vsr_active(struct task_struct *target, const struct user_regset *regset);
-int vsr_get(struct task_struct *target, const struct user_regset *regset,
-	    unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf);
+user_regset_get2_fn vsr_get;
 int vsr_set(struct task_struct *target, const struct user_regset *regset,
 	    unsigned int pos, unsigned int count,
 	    const void *kbuf, const void __user *ubuf);
@@ -81,8 +79,7 @@ int vsr_set(struct task_struct *target, const struct user_regset *regset,
 /* ptrace-altivec */
 
 int vr_active(struct task_struct *target, const struct user_regset *regset);
-int vr_get(struct task_struct *target, const struct user_regset *regset,
-	   unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf);
+user_regset_get2_fn vr_get;
 int vr_set(struct task_struct *target, const struct user_regset *regset,
 	   unsigned int pos, unsigned int count,
 	   const void *kbuf, const void __user *ubuf);
@@ -90,8 +87,7 @@ int vr_set(struct task_struct *target, const struct user_regset *regset,
 /* ptrace-spe */
 
 int evr_active(struct task_struct *target, const struct user_regset *regset);
-int evr_get(struct task_struct *target, const struct user_regset *regset,
-	    unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf);
+user_regset_get2_fn evr_get;
 int evr_set(struct task_struct *target, const struct user_regset *regset,
 	    unsigned int pos, unsigned int count,
 	    const void *kbuf, const void __user *ubuf);
@@ -100,9 +96,8 @@ int evr_set(struct task_struct *target, const struct user_regset *regset,
 
 int gpr32_get_common(struct task_struct *target,
 		     const struct user_regset *regset,
-		     unsigned int pos, unsigned int count,
-			    void *kbuf, void __user *ubuf,
-			    unsigned long *regs);
+		     struct membuf to,
+		     unsigned long *regs);
 int gpr32_set_common(struct task_struct *target,
 		     const struct user_regset *regset,
 		     unsigned int pos, unsigned int count,
@@ -118,55 +113,46 @@ static inline void flush_tmregs_to_thread(struct task_struct *tsk) { }
 #endif
 
 int tm_cgpr_active(struct task_struct *target, const struct user_regset *regset);
-int tm_cgpr_get(struct task_struct *target, const struct user_regset *regset,
-		unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf);
+user_regset_get2_fn tm_cgpr_get;
 int tm_cgpr_set(struct task_struct *target, const struct user_regset *regset,
 		unsigned int pos, unsigned int count,
 		const void *kbuf, const void __user *ubuf);
 int tm_cfpr_active(struct task_struct *target, const struct user_regset *regset);
-int tm_cfpr_get(struct task_struct *target, const struct user_regset *regset,
-		unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf);
+user_regset_get2_fn tm_cfpr_get;
 int tm_cfpr_set(struct task_struct *target, const struct user_regset *regset,
 		unsigned int pos, unsigned int count,
 		const void *kbuf, const void __user *ubuf);
 int tm_cvmx_active(struct task_struct *target, const struct user_regset *regset);
-int tm_cvmx_get(struct task_struct *target, const struct user_regset *regset,
-		unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf);
+user_regset_get2_fn tm_cvmx_get;
 int tm_cvmx_set(struct task_struct *target, const struct user_regset *regset,
 		unsigned int pos, unsigned int count,
 		const void *kbuf, const void __user *ubuf);
 int tm_cvsx_active(struct task_struct *target, const struct user_regset *regset);
-int tm_cvsx_get(struct task_struct *target, const struct user_regset *regset,
-		unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf);
+user_regset_get2_fn tm_cvsx_get;
 int tm_cvsx_set(struct task_struct *target, const struct user_regset *regset,
 		unsigned int pos, unsigned int count,
 		const void *kbuf, const void __user *ubuf);
 int tm_spr_active(struct task_struct *target, const struct user_regset *regset);
-int tm_spr_get(struct task_struct *target, const struct user_regset *regset,
-	       unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf);
+user_regset_get2_fn tm_spr_get;
 int tm_spr_set(struct task_struct *target, const struct user_regset *regset,
 	       unsigned int pos, unsigned int count,
 	       const void *kbuf, const void __user *ubuf);
 int tm_tar_active(struct task_struct *target, const struct user_regset *regset);
-int tm_tar_get(struct task_struct *target, const struct user_regset *regset,
-	       unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf);
+user_regset_get2_fn tm_tar_get;
 int tm_tar_set(struct task_struct *target, const struct user_regset *regset,
 	       unsigned int pos, unsigned int count,
 	       const void *kbuf, const void __user *ubuf);
 int tm_ppr_active(struct task_struct *target, const struct user_regset *regset);
-int tm_ppr_get(struct task_struct *target, const struct user_regset *regset,
-	       unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf);
+user_regset_get2_fn tm_ppr_get;
 int tm_ppr_set(struct task_struct *target, const struct user_regset *regset,
 	       unsigned int pos, unsigned int count,
 	       const void *kbuf, const void __user *ubuf);
 int tm_dscr_active(struct task_struct *target, const struct user_regset *regset);
-int tm_dscr_get(struct task_struct *target, const struct user_regset *regset,
-		unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf);
+user_regset_get2_fn tm_dscr_get;
 int tm_dscr_set(struct task_struct *target, const struct user_regset *regset,
 		unsigned int pos, unsigned int count,
 		const void *kbuf, const void __user *ubuf);
-int tm_cgpr32_get(struct task_struct *target, const struct user_regset *regset,
-		  unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf);
+user_regset_get2_fn tm_cgpr32_get;
 int tm_cgpr32_set(struct task_struct *target, const struct user_regset *regset,
 		  unsigned int pos, unsigned int count,
 		  const void *kbuf, const void __user *ubuf);
diff --git a/arch/powerpc/kernel/ptrace/ptrace-novsx.c b/arch/powerpc/kernel/ptrace/ptrace-novsx.c
index b2dc4e92d11a..b3b36835658a 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-novsx.c
+++ b/arch/powerpc/kernel/ptrace/ptrace-novsx.c
@@ -19,15 +19,14 @@
  * };
  */
 int fpr_get(struct task_struct *target, const struct user_regset *regset,
-	    unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+	    struct membuf to)
 {
 	BUILD_BUG_ON(offsetof(struct thread_fp_state, fpscr) !=
 		     offsetof(struct thread_fp_state, fpr[32]));
 
 	flush_fp_to_thread(target);
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &target->thread.fp_state, 0, -1);
+	return membuf_write(&to, &target->thread.fp_state, 33 * sizeof(u64));
 }
 
 /*
diff --git a/arch/powerpc/kernel/ptrace/ptrace-spe.c b/arch/powerpc/kernel/ptrace/ptrace-spe.c
index 68b86b4a4be4..47034d069045 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-spe.c
+++ b/arch/powerpc/kernel/ptrace/ptrace-spe.c
@@ -23,25 +23,17 @@ int evr_active(struct task_struct *target, const struct user_regset *regset)
 }
 
 int evr_get(struct task_struct *target, const struct user_regset *regset,
-	    unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+	    struct membuf to)
 {
-	int ret;
-
 	flush_spe_to_thread(target);
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &target->thread.evr,
-				  0, sizeof(target->thread.evr));
+	membuf_write(&to, &target->thread.evr, sizeof(target->thread.evr));
 
 	BUILD_BUG_ON(offsetof(struct thread_struct, acc) + sizeof(u64) !=
 		     offsetof(struct thread_struct, spefscr));
 
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &target->thread.acc,
-					  sizeof(target->thread.evr), -1);
-
-	return ret;
+	return membuf_write(&to, &target->thread.acc,
+				sizeof(u64) + sizeof(u32));
 }
 
 int evr_set(struct task_struct *target, const struct user_regset *regset,
diff --git a/arch/powerpc/kernel/ptrace/ptrace-tm.c b/arch/powerpc/kernel/ptrace/ptrace-tm.c
index 32d62c606681..54f2d076206f 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-tm.c
+++ b/arch/powerpc/kernel/ptrace/ptrace-tm.c
@@ -70,10 +70,7 @@ int tm_cgpr_active(struct task_struct *target, const struct user_regset *regset)
  * tm_cgpr_get - get CGPR registers
  * @target:	The target task.
  * @regset:	The user regset structure.
- * @pos:	The buffer position.
- * @count:	Number of bytes to copy.
- * @kbuf:	Kernel buffer to copy from.
- * @ubuf:	User buffer to copy into.
+ * @to:		Destination of copy.
  *
  * This function gets transaction checkpointed GPR registers.
  *
@@ -87,10 +84,8 @@ int tm_cgpr_active(struct task_struct *target, const struct user_regset *regset)
  * };
  */
 int tm_cgpr_get(struct task_struct *target, const struct user_regset *regset,
-		unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+		struct membuf to)
 {
-	int ret;
-
 	if (!cpu_has_feature(CPU_FTR_TM))
 		return -ENODEV;
 
@@ -101,31 +96,18 @@ int tm_cgpr_get(struct task_struct *target, const struct user_regset *regset,
 	flush_fp_to_thread(target);
 	flush_altivec_to_thread(target);
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &target->thread.ckpt_regs,
-				  0, offsetof(struct pt_regs, msr));
-	if (!ret) {
-		unsigned long msr = get_user_ckpt_msr(target);
-
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &msr,
-					  offsetof(struct pt_regs, msr),
-					  offsetof(struct pt_regs, msr) +
-					  sizeof(msr));
-	}
+	membuf_write(&to, &target->thread.ckpt_regs,
+			offsetof(struct pt_regs, msr));
+	membuf_store(&to, get_user_ckpt_msr(target));
 
 	BUILD_BUG_ON(offsetof(struct pt_regs, orig_gpr3) !=
 		     offsetof(struct pt_regs, msr) + sizeof(long));
 
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &target->thread.ckpt_regs.orig_gpr3,
-					  offsetof(struct pt_regs, orig_gpr3),
-					  sizeof(struct user_pt_regs));
-	if (!ret)
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					       sizeof(struct user_pt_regs), -1);
-
-	return ret;
+	membuf_write(&to, &target->thread.ckpt_regs.orig_gpr3,
+			sizeof(struct user_pt_regs) -
+			offsetof(struct pt_regs, orig_gpr3));
+	return membuf_zero(&to, ELF_NGREG * sizeof(unsigned long) -
+			sizeof(struct user_pt_regs));
 }
 
 /*
@@ -229,10 +211,7 @@ int tm_cfpr_active(struct task_struct *target, const struct user_regset *regset)
  * tm_cfpr_get - get CFPR registers
  * @target:	The target task.
  * @regset:	The user regset structure.
- * @pos:	The buffer position.
- * @count:	Number of bytes to copy.
- * @kbuf:	Kernel buffer to copy from.
- * @ubuf:	User buffer to copy into.
+ * @to:		Destination of copy.
  *
  * This function gets in transaction checkpointed FPR registers.
  *
@@ -247,7 +226,7 @@ int tm_cfpr_active(struct task_struct *target, const struct user_regset *regset)
  *};
  */
 int tm_cfpr_get(struct task_struct *target, const struct user_regset *regset,
-		unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+		struct membuf to)
 {
 	u64 buf[33];
 	int i;
@@ -266,7 +245,7 @@ int tm_cfpr_get(struct task_struct *target, const struct user_regset *regset,
 	for (i = 0; i < 32 ; i++)
 		buf[i] = target->thread.TS_CKFPR(i);
 	buf[32] = target->thread.ckfp_state.fpscr;
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, buf, 0, -1);
+	return membuf_write(&to, buf, sizeof(buf));
 }
 
 /**
@@ -344,10 +323,7 @@ int tm_cvmx_active(struct task_struct *target, const struct user_regset *regset)
  * tm_cvmx_get - get CMVX registers
  * @target:	The target task.
  * @regset:	The user regset structure.
- * @pos:	The buffer position.
- * @count:	Number of bytes to copy.
- * @kbuf:	Kernel buffer to copy from.
- * @ubuf:	User buffer to copy into.
+ * @to:		Destination of copy.
  *
  * This function gets in transaction checkpointed VMX registers.
  *
@@ -363,10 +339,12 @@ int tm_cvmx_active(struct task_struct *target, const struct user_regset *regset)
  *};
  */
 int tm_cvmx_get(struct task_struct *target, const struct user_regset *regset,
-		unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+		struct membuf to)
 {
-	int ret;
-
+	union {
+		elf_vrreg_t reg;
+		u32 word;
+	} vrsave;
 	BUILD_BUG_ON(TVSO(vscr) != TVSO(vr[32]));
 
 	if (!cpu_has_feature(CPU_FTR_TM))
@@ -380,23 +358,13 @@ int tm_cvmx_get(struct task_struct *target, const struct user_regset *regset,
 	flush_fp_to_thread(target);
 	flush_altivec_to_thread(target);
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &target->thread.ckvr_state,
-				  0, 33 * sizeof(vector128));
-	if (!ret) {
-		/*
-		 * Copy out only the low-order word of vrsave.
-		 */
-		union {
-			elf_vrreg_t reg;
-			u32 word;
-		} vrsave;
-		memset(&vrsave, 0, sizeof(vrsave));
-		vrsave.word = target->thread.ckvrsave;
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &vrsave,
-					  33 * sizeof(vector128), -1);
-	}
-
-	return ret;
+	membuf_write(&to, &target->thread.ckvr_state, 33 * sizeof(vector128));
+	/*
+	 * Copy out only the low-order word of vrsave.
+	 */
+	memset(&vrsave, 0, sizeof(vrsave));
+	vrsave.word = target->thread.ckvrsave;
+	return membuf_write(&to, &vrsave, sizeof(vrsave));
 }
 
 /**
@@ -484,10 +452,7 @@ int tm_cvsx_active(struct task_struct *target, const struct user_regset *regset)
  * tm_cvsx_get - get CVSX registers
  * @target:	The target task.
  * @regset:	The user regset structure.
- * @pos:	The buffer position.
- * @count:	Number of bytes to copy.
- * @kbuf:	Kernel buffer to copy from.
- * @ubuf:	User buffer to copy into.
+ * @to:		Destination of copy.
  *
  * This function gets in transaction checkpointed VSX registers.
  *
@@ -501,10 +466,10 @@ int tm_cvsx_active(struct task_struct *target, const struct user_regset *regset)
  *};
  */
 int tm_cvsx_get(struct task_struct *target, const struct user_regset *regset,
-		unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+		struct membuf to)
 {
 	u64 buf[32];
-	int ret, i;
+	int i;
 
 	if (!cpu_has_feature(CPU_FTR_TM))
 		return -ENODEV;
@@ -520,10 +485,7 @@ int tm_cvsx_get(struct task_struct *target, const struct user_regset *regset,
 
 	for (i = 0; i < 32 ; i++)
 		buf[i] = target->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET];
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  buf, 0, 32 * sizeof(double));
-
-	return ret;
+	return membuf_write(&to, buf, 32 * sizeof(double));
 }
 
 /**
@@ -597,10 +559,7 @@ int tm_spr_active(struct task_struct *target, const struct user_regset *regset)
  * tm_spr_get - get the TM related SPR registers
  * @target:	The target task.
  * @regset:	The user regset structure.
- * @pos:	The buffer position.
- * @count:	Number of bytes to copy.
- * @kbuf:	Kernel buffer to copy from.
- * @ubuf:	User buffer to copy into.
+ * @to:		Destination of copy.
  *
  * This function gets transactional memory related SPR registers.
  * The userspace interface buffer layout is as follows.
@@ -612,10 +571,8 @@ int tm_spr_active(struct task_struct *target, const struct user_regset *regset)
  * };
  */
 int tm_spr_get(struct task_struct *target, const struct user_regset *regset,
-	       unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+	       struct membuf to)
 {
-	int ret;
-
 	/* Build tests */
 	BUILD_BUG_ON(TSO(tm_tfhar) + sizeof(u64) != TSO(tm_texasr));
 	BUILD_BUG_ON(TSO(tm_texasr) + sizeof(u64) != TSO(tm_tfiar));
@@ -630,21 +587,11 @@ int tm_spr_get(struct task_struct *target, const struct user_regset *regset,
 	flush_altivec_to_thread(target);
 
 	/* TFHAR register */
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &target->thread.tm_tfhar, 0, sizeof(u64));
-
+	membuf_write(&to, &target->thread.tm_tfhar, sizeof(u64));
 	/* TEXASR register */
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &target->thread.tm_texasr, sizeof(u64),
-					  2 * sizeof(u64));
-
+	membuf_write(&to, &target->thread.tm_texasr, sizeof(u64));
 	/* TFIAR register */
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &target->thread.tm_tfiar,
-					  2 * sizeof(u64), 3 * sizeof(u64));
-	return ret;
+	return membuf_write(&to, &target->thread.tm_tfiar, sizeof(u64));
 }
 
 /**
@@ -714,19 +661,15 @@ int tm_tar_active(struct task_struct *target, const struct user_regset *regset)
 }
 
 int tm_tar_get(struct task_struct *target, const struct user_regset *regset,
-	       unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+	       struct membuf to)
 {
-	int ret;
-
 	if (!cpu_has_feature(CPU_FTR_TM))
 		return -ENODEV;
 
 	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
 		return -ENODATA;
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &target->thread.tm_tar, 0, sizeof(u64));
-	return ret;
+	return membuf_write(&to, &target->thread.tm_tar, sizeof(u64));
 }
 
 int tm_tar_set(struct task_struct *target, const struct user_regset *regset,
@@ -759,19 +702,15 @@ int tm_ppr_active(struct task_struct *target, const struct user_regset *regset)
 
 
 int tm_ppr_get(struct task_struct *target, const struct user_regset *regset,
-	       unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+	       struct membuf to)
 {
-	int ret;
-
 	if (!cpu_has_feature(CPU_FTR_TM))
 		return -ENODEV;
 
 	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
 		return -ENODATA;
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &target->thread.tm_ppr, 0, sizeof(u64));
-	return ret;
+	return membuf_write(&to, &target->thread.tm_ppr, sizeof(u64));
 }
 
 int tm_ppr_set(struct task_struct *target, const struct user_regset *regset,
@@ -803,19 +742,15 @@ int tm_dscr_active(struct task_struct *target, const struct user_regset *regset)
 }
 
 int tm_dscr_get(struct task_struct *target, const struct user_regset *regset,
-		unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+		struct membuf to)
 {
-	int ret;
-
 	if (!cpu_has_feature(CPU_FTR_TM))
 		return -ENODEV;
 
 	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
 		return -ENODATA;
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &target->thread.tm_dscr, 0, sizeof(u64));
-	return ret;
+	return membuf_write(&to, &target->thread.tm_dscr, sizeof(u64));
 }
 
 int tm_dscr_set(struct task_struct *target, const struct user_regset *regset,
@@ -836,10 +771,11 @@ int tm_dscr_set(struct task_struct *target, const struct user_regset *regset,
 }
 
 int tm_cgpr32_get(struct task_struct *target, const struct user_regset *regset,
-		  unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+		  struct membuf to)
 {
-	return gpr32_get_common(target, regset, pos, count, kbuf, ubuf,
+	gpr32_get_common(target, regset, to,
 				&target->thread.ckpt_regs.gpr[0]);
+	return membuf_zero(&to, ELF_NGREG * sizeof(u32));
 }
 
 int tm_cgpr32_set(struct task_struct *target, const struct user_regset *regset,
diff --git a/arch/powerpc/kernel/ptrace/ptrace-view.c b/arch/powerpc/kernel/ptrace/ptrace-view.c
index caeb5822a8f4..13208a9a02ca 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-view.c
+++ b/arch/powerpc/kernel/ptrace/ptrace-view.c
@@ -215,9 +215,9 @@ int ptrace_put_reg(struct task_struct *task, int regno, unsigned long data)
 }
 
 static int gpr_get(struct task_struct *target, const struct user_regset *regset,
-		   unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	int i, ret;
+	int i;
 
 	if (target->thread.regs == NULL)
 		return -EIO;
@@ -228,30 +228,17 @@ static int gpr_get(struct task_struct *target, const struct user_regset *regset,
 			target->thread.regs->gpr[i] = NV_REG_POISON;
 	}
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  target->thread.regs,
-				  0, offsetof(struct pt_regs, msr));
-	if (!ret) {
-		unsigned long msr = get_user_msr(target);
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &msr,
-					  offsetof(struct pt_regs, msr),
-					  offsetof(struct pt_regs, msr) +
-					  sizeof(msr));
-	}
+	membuf_write(&to, target->thread.regs, offsetof(struct pt_regs, msr));
+	membuf_store(&to, get_user_msr(target));
 
 	BUILD_BUG_ON(offsetof(struct pt_regs, orig_gpr3) !=
 		     offsetof(struct pt_regs, msr) + sizeof(long));
 
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &target->thread.regs->orig_gpr3,
-					  offsetof(struct pt_regs, orig_gpr3),
-					  sizeof(struct user_pt_regs));
-	if (!ret)
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					       sizeof(struct user_pt_regs), -1);
-
-	return ret;
+	membuf_write(&to, &target->thread.regs->orig_gpr3,
+			sizeof(struct user_pt_regs) -
+			offsetof(struct pt_regs, orig_gpr3));
+	return membuf_zero(&to, ELF_NGREG * sizeof(unsigned long) -
+				 sizeof(struct user_pt_regs));
 }
 
 static int gpr_set(struct task_struct *target, const struct user_regset *regset,
@@ -309,10 +296,9 @@ static int gpr_set(struct task_struct *target, const struct user_regset *regset,
 
 #ifdef CONFIG_PPC64
 static int ppr_get(struct task_struct *target, const struct user_regset *regset,
-		   unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &target->thread.regs->ppr, 0, sizeof(u64));
+	return membuf_write(&to, &target->thread.regs->ppr, sizeof(u64));
 }
 
 static int ppr_set(struct task_struct *target, const struct user_regset *regset,
@@ -324,10 +310,9 @@ static int ppr_set(struct task_struct *target, const struct user_regset *regset,
 }
 
 static int dscr_get(struct task_struct *target, const struct user_regset *regset,
-		    unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+		    struct membuf to)
 {
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &target->thread.dscr, 0, sizeof(u64));
+	return membuf_write(&to, &target->thread.dscr, sizeof(u64));
 }
 static int dscr_set(struct task_struct *target, const struct user_regset *regset,
 		    unsigned int pos, unsigned int count, const void *kbuf,
@@ -339,10 +324,9 @@ static int dscr_set(struct task_struct *target, const struct user_regset *regset
 #endif
 #ifdef CONFIG_PPC_BOOK3S_64
 static int tar_get(struct task_struct *target, const struct user_regset *regset,
-		   unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &target->thread.tar, 0, sizeof(u64));
+	return membuf_write(&to, &target->thread.tar, sizeof(u64));
 }
 static int tar_set(struct task_struct *target, const struct user_regset *regset,
 		   unsigned int pos, unsigned int count, const void *kbuf,
@@ -364,7 +348,7 @@ static int ebb_active(struct task_struct *target, const struct user_regset *regs
 }
 
 static int ebb_get(struct task_struct *target, const struct user_regset *regset,
-		   unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
 	/* Build tests */
 	BUILD_BUG_ON(TSO(ebbrr) + sizeof(unsigned long) != TSO(ebbhr));
@@ -376,8 +360,7 @@ static int ebb_get(struct task_struct *target, const struct user_regset *regset,
 	if (!target->thread.used_ebb)
 		return -ENODATA;
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &target->thread.ebbrr,
-				   0, 3 * sizeof(unsigned long));
+	return membuf_write(&to, &target->thread.ebbrr, 3 * sizeof(unsigned long));
 }
 
 static int ebb_set(struct task_struct *target, const struct user_regset *regset,
@@ -420,7 +403,7 @@ static int pmu_active(struct task_struct *target, const struct user_regset *regs
 }
 
 static int pmu_get(struct task_struct *target, const struct user_regset *regset,
-		   unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
 	/* Build tests */
 	BUILD_BUG_ON(TSO(siar) + sizeof(unsigned long) != TSO(sdar));
@@ -431,8 +414,7 @@ static int pmu_get(struct task_struct *target, const struct user_regset *regset,
 	if (!cpu_has_feature(CPU_FTR_ARCH_207S))
 		return -ENODEV;
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &target->thread.siar,
-				   0, 5 * sizeof(unsigned long));
+	return membuf_write(&to, &target->thread.siar, 5 * sizeof(unsigned long));
 }
 
 static int pmu_set(struct task_struct *target, const struct user_regset *regset,
@@ -486,7 +468,7 @@ static int pkey_active(struct task_struct *target, const struct user_regset *reg
 }
 
 static int pkey_get(struct task_struct *target, const struct user_regset *regset,
-		    unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+		    struct membuf to)
 {
 	BUILD_BUG_ON(TSO(amr) + sizeof(unsigned long) != TSO(iamr));
 	BUILD_BUG_ON(TSO(iamr) + sizeof(unsigned long) != TSO(uamor));
@@ -494,8 +476,7 @@ static int pkey_get(struct task_struct *target, const struct user_regset *regset
 	if (!arch_pkeys_enabled())
 		return -ENODEV;
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &target->thread.amr,
-				   0, ELF_NPKEY * sizeof(unsigned long));
+	return membuf_write(&to, &target->thread.amr, ELF_NPKEY * sizeof(unsigned long));
 }
 
 static int pkey_set(struct task_struct *target, const struct user_regset *regset,
@@ -529,110 +510,110 @@ static const struct user_regset native_regsets[] = {
 	[REGSET_GPR] = {
 		.core_note_type = NT_PRSTATUS, .n = ELF_NGREG,
 		.size = sizeof(long), .align = sizeof(long),
-		.get = gpr_get, .set = gpr_set
+		.regset_get = gpr_get, .set = gpr_set
 	},
 	[REGSET_FPR] = {
 		.core_note_type = NT_PRFPREG, .n = ELF_NFPREG,
 		.size = sizeof(double), .align = sizeof(double),
-		.get = fpr_get, .set = fpr_set
+		.regset_get = fpr_get, .set = fpr_set
 	},
 #ifdef CONFIG_ALTIVEC
 	[REGSET_VMX] = {
 		.core_note_type = NT_PPC_VMX, .n = 34,
 		.size = sizeof(vector128), .align = sizeof(vector128),
-		.active = vr_active, .get = vr_get, .set = vr_set
+		.active = vr_active, .regset_get = vr_get, .set = vr_set
 	},
 #endif
 #ifdef CONFIG_VSX
 	[REGSET_VSX] = {
 		.core_note_type = NT_PPC_VSX, .n = 32,
 		.size = sizeof(double), .align = sizeof(double),
-		.active = vsr_active, .get = vsr_get, .set = vsr_set
+		.active = vsr_active, .regset_get = vsr_get, .set = vsr_set
 	},
 #endif
 #ifdef CONFIG_SPE
 	[REGSET_SPE] = {
 		.core_note_type = NT_PPC_SPE, .n = 35,
 		.size = sizeof(u32), .align = sizeof(u32),
-		.active = evr_active, .get = evr_get, .set = evr_set
+		.active = evr_active, .regset_get = evr_get, .set = evr_set
 	},
 #endif
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
 	[REGSET_TM_CGPR] = {
 		.core_note_type = NT_PPC_TM_CGPR, .n = ELF_NGREG,
 		.size = sizeof(long), .align = sizeof(long),
-		.active = tm_cgpr_active, .get = tm_cgpr_get, .set = tm_cgpr_set
+		.active = tm_cgpr_active, .regset_get = tm_cgpr_get, .set = tm_cgpr_set
 	},
 	[REGSET_TM_CFPR] = {
 		.core_note_type = NT_PPC_TM_CFPR, .n = ELF_NFPREG,
 		.size = sizeof(double), .align = sizeof(double),
-		.active = tm_cfpr_active, .get = tm_cfpr_get, .set = tm_cfpr_set
+		.active = tm_cfpr_active, .regset_get = tm_cfpr_get, .set = tm_cfpr_set
 	},
 	[REGSET_TM_CVMX] = {
 		.core_note_type = NT_PPC_TM_CVMX, .n = ELF_NVMX,
 		.size = sizeof(vector128), .align = sizeof(vector128),
-		.active = tm_cvmx_active, .get = tm_cvmx_get, .set = tm_cvmx_set
+		.active = tm_cvmx_active, .regset_get = tm_cvmx_get, .set = tm_cvmx_set
 	},
 	[REGSET_TM_CVSX] = {
 		.core_note_type = NT_PPC_TM_CVSX, .n = ELF_NVSX,
 		.size = sizeof(double), .align = sizeof(double),
-		.active = tm_cvsx_active, .get = tm_cvsx_get, .set = tm_cvsx_set
+		.active = tm_cvsx_active, .regset_get = tm_cvsx_get, .set = tm_cvsx_set
 	},
 	[REGSET_TM_SPR] = {
 		.core_note_type = NT_PPC_TM_SPR, .n = ELF_NTMSPRREG,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.active = tm_spr_active, .get = tm_spr_get, .set = tm_spr_set
+		.active = tm_spr_active, .regset_get = tm_spr_get, .set = tm_spr_set
 	},
 	[REGSET_TM_CTAR] = {
 		.core_note_type = NT_PPC_TM_CTAR, .n = 1,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.active = tm_tar_active, .get = tm_tar_get, .set = tm_tar_set
+		.active = tm_tar_active, .regset_get = tm_tar_get, .set = tm_tar_set
 	},
 	[REGSET_TM_CPPR] = {
 		.core_note_type = NT_PPC_TM_CPPR, .n = 1,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.active = tm_ppr_active, .get = tm_ppr_get, .set = tm_ppr_set
+		.active = tm_ppr_active, .regset_get = tm_ppr_get, .set = tm_ppr_set
 	},
 	[REGSET_TM_CDSCR] = {
 		.core_note_type = NT_PPC_TM_CDSCR, .n = 1,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.active = tm_dscr_active, .get = tm_dscr_get, .set = tm_dscr_set
+		.active = tm_dscr_active, .regset_get = tm_dscr_get, .set = tm_dscr_set
 	},
 #endif
 #ifdef CONFIG_PPC64
 	[REGSET_PPR] = {
 		.core_note_type = NT_PPC_PPR, .n = 1,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.get = ppr_get, .set = ppr_set
+		.regset_get = ppr_get, .set = ppr_set
 	},
 	[REGSET_DSCR] = {
 		.core_note_type = NT_PPC_DSCR, .n = 1,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.get = dscr_get, .set = dscr_set
+		.regset_get = dscr_get, .set = dscr_set
 	},
 #endif
 #ifdef CONFIG_PPC_BOOK3S_64
 	[REGSET_TAR] = {
 		.core_note_type = NT_PPC_TAR, .n = 1,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.get = tar_get, .set = tar_set
+		.regset_get = tar_get, .set = tar_set
 	},
 	[REGSET_EBB] = {
 		.core_note_type = NT_PPC_EBB, .n = ELF_NEBB,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.active = ebb_active, .get = ebb_get, .set = ebb_set
+		.active = ebb_active, .regset_get = ebb_get, .set = ebb_set
 	},
 	[REGSET_PMR] = {
 		.core_note_type = NT_PPC_PMU, .n = ELF_NPMU,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.active = pmu_active, .get = pmu_get, .set = pmu_set
+		.active = pmu_active, .regset_get = pmu_get, .set = pmu_set
 	},
 #endif
 #ifdef CONFIG_PPC_MEM_KEYS
 	[REGSET_PKEY] = {
 		.core_note_type = NT_PPC_PKEY, .n = ELF_NPKEY,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.active = pkey_active, .get = pkey_get, .set = pkey_set
+		.active = pkey_active, .regset_get = pkey_get, .set = pkey_set
 	},
 #endif
 };
@@ -646,49 +627,16 @@ const struct user_regset_view user_ppc_native_view = {
 
 int gpr32_get_common(struct task_struct *target,
 		     const struct user_regset *regset,
-		     unsigned int pos, unsigned int count,
-			    void *kbuf, void __user *ubuf,
-			    unsigned long *regs)
+		     struct membuf to, unsigned long *regs)
 {
-	compat_ulong_t *k = kbuf;
-	compat_ulong_t __user *u = ubuf;
-	compat_ulong_t reg;
-
-	pos /= sizeof(reg);
-	count /= sizeof(reg);
-
-	if (kbuf)
-		for (; count > 0 && pos < PT_MSR; --count)
-			*k++ = regs[pos++];
-	else
-		for (; count > 0 && pos < PT_MSR; --count)
-			if (__put_user((compat_ulong_t)regs[pos++], u++))
-				return -EFAULT;
-
-	if (count > 0 && pos == PT_MSR) {
-		reg = get_user_msr(target);
-		if (kbuf)
-			*k++ = reg;
-		else if (__put_user(reg, u++))
-			return -EFAULT;
-		++pos;
-		--count;
-	}
-
-	if (kbuf)
-		for (; count > 0 && pos < PT_REGS_COUNT; --count)
-			*k++ = regs[pos++];
-	else
-		for (; count > 0 && pos < PT_REGS_COUNT; --count)
-			if (__put_user((compat_ulong_t)regs[pos++], u++))
-				return -EFAULT;
+	int i;
 
-	kbuf = k;
-	ubuf = u;
-	pos *= sizeof(reg);
-	count *= sizeof(reg);
-	return user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					PT_REGS_COUNT * sizeof(reg), -1);
+	for (i = 0; i < PT_MSR; i++)
+		membuf_store(&to, (u32)regs[i]);
+	membuf_store(&to, (u32)get_user_msr(target));
+	for (i++ ; i < PT_REGS_COUNT; i++)
+		membuf_store(&to, (u32)regs[i]);
+	return membuf_zero(&to, (ELF_NGREG - PT_REGS_COUNT) * sizeof(u32));
 }
 
 int gpr32_set_common(struct task_struct *target,
@@ -761,8 +709,7 @@ int gpr32_set_common(struct task_struct *target,
 
 static int gpr32_get(struct task_struct *target,
 		     const struct user_regset *regset,
-		     unsigned int pos, unsigned int count,
-		     void *kbuf, void __user *ubuf)
+		     struct membuf to)
 {
 	int i;
 
@@ -777,7 +724,7 @@ static int gpr32_get(struct task_struct *target,
 		for (i = 14; i < 32; i++)
 			target->thread.regs->gpr[i] = NV_REG_POISON;
 	}
-	return gpr32_get_common(target, regset, pos, count, kbuf, ubuf,
+	return gpr32_get_common(target, regset, to,
 			&target->thread.regs->gpr[0]);
 }
 
@@ -801,25 +748,25 @@ static const struct user_regset compat_regsets[] = {
 	[REGSET_GPR] = {
 		.core_note_type = NT_PRSTATUS, .n = ELF_NGREG,
 		.size = sizeof(compat_long_t), .align = sizeof(compat_long_t),
-		.get = gpr32_get, .set = gpr32_set
+		.regset_get = gpr32_get, .set = gpr32_set
 	},
 	[REGSET_FPR] = {
 		.core_note_type = NT_PRFPREG, .n = ELF_NFPREG,
 		.size = sizeof(double), .align = sizeof(double),
-		.get = fpr_get, .set = fpr_set
+		.regset_get = fpr_get, .set = fpr_set
 	},
 #ifdef CONFIG_ALTIVEC
 	[REGSET_VMX] = {
 		.core_note_type = NT_PPC_VMX, .n = 34,
 		.size = sizeof(vector128), .align = sizeof(vector128),
-		.active = vr_active, .get = vr_get, .set = vr_set
+		.active = vr_active, .regset_get = vr_get, .set = vr_set
 	},
 #endif
 #ifdef CONFIG_SPE
 	[REGSET_SPE] = {
 		.core_note_type = NT_PPC_SPE, .n = 35,
 		.size = sizeof(u32), .align = sizeof(u32),
-		.active = evr_active, .get = evr_get, .set = evr_set
+		.active = evr_active, .regset_get = evr_get, .set = evr_set
 	},
 #endif
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
@@ -827,66 +774,66 @@ static const struct user_regset compat_regsets[] = {
 		.core_note_type = NT_PPC_TM_CGPR, .n = ELF_NGREG,
 		.size = sizeof(long), .align = sizeof(long),
 		.active = tm_cgpr_active,
-		.get = tm_cgpr32_get, .set = tm_cgpr32_set
+		.regset_get = tm_cgpr32_get, .set = tm_cgpr32_set
 	},
 	[REGSET_TM_CFPR] = {
 		.core_note_type = NT_PPC_TM_CFPR, .n = ELF_NFPREG,
 		.size = sizeof(double), .align = sizeof(double),
-		.active = tm_cfpr_active, .get = tm_cfpr_get, .set = tm_cfpr_set
+		.active = tm_cfpr_active, .regset_get = tm_cfpr_get, .set = tm_cfpr_set
 	},
 	[REGSET_TM_CVMX] = {
 		.core_note_type = NT_PPC_TM_CVMX, .n = ELF_NVMX,
 		.size = sizeof(vector128), .align = sizeof(vector128),
-		.active = tm_cvmx_active, .get = tm_cvmx_get, .set = tm_cvmx_set
+		.active = tm_cvmx_active, .regset_get = tm_cvmx_get, .set = tm_cvmx_set
 	},
 	[REGSET_TM_CVSX] = {
 		.core_note_type = NT_PPC_TM_CVSX, .n = ELF_NVSX,
 		.size = sizeof(double), .align = sizeof(double),
-		.active = tm_cvsx_active, .get = tm_cvsx_get, .set = tm_cvsx_set
+		.active = tm_cvsx_active, .regset_get = tm_cvsx_get, .set = tm_cvsx_set
 	},
 	[REGSET_TM_SPR] = {
 		.core_note_type = NT_PPC_TM_SPR, .n = ELF_NTMSPRREG,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.active = tm_spr_active, .get = tm_spr_get, .set = tm_spr_set
+		.active = tm_spr_active, .regset_get = tm_spr_get, .set = tm_spr_set
 	},
 	[REGSET_TM_CTAR] = {
 		.core_note_type = NT_PPC_TM_CTAR, .n = 1,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.active = tm_tar_active, .get = tm_tar_get, .set = tm_tar_set
+		.active = tm_tar_active, .regset_get = tm_tar_get, .set = tm_tar_set
 	},
 	[REGSET_TM_CPPR] = {
 		.core_note_type = NT_PPC_TM_CPPR, .n = 1,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.active = tm_ppr_active, .get = tm_ppr_get, .set = tm_ppr_set
+		.active = tm_ppr_active, .regset_get = tm_ppr_get, .set = tm_ppr_set
 	},
 	[REGSET_TM_CDSCR] = {
 		.core_note_type = NT_PPC_TM_CDSCR, .n = 1,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.active = tm_dscr_active, .get = tm_dscr_get, .set = tm_dscr_set
+		.active = tm_dscr_active, .regset_get = tm_dscr_get, .set = tm_dscr_set
 	},
 #endif
 #ifdef CONFIG_PPC64
 	[REGSET_PPR] = {
 		.core_note_type = NT_PPC_PPR, .n = 1,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.get = ppr_get, .set = ppr_set
+		.regset_get = ppr_get, .set = ppr_set
 	},
 	[REGSET_DSCR] = {
 		.core_note_type = NT_PPC_DSCR, .n = 1,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.get = dscr_get, .set = dscr_set
+		.regset_get = dscr_get, .set = dscr_set
 	},
 #endif
 #ifdef CONFIG_PPC_BOOK3S_64
 	[REGSET_TAR] = {
 		.core_note_type = NT_PPC_TAR, .n = 1,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.get = tar_get, .set = tar_set
+		.regset_get = tar_get, .set = tar_set
 	},
 	[REGSET_EBB] = {
 		.core_note_type = NT_PPC_EBB, .n = ELF_NEBB,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.active = ebb_active, .get = ebb_get, .set = ebb_set
+		.active = ebb_active, .regset_get = ebb_get, .set = ebb_set
 	},
 #endif
 };
diff --git a/arch/powerpc/kernel/ptrace/ptrace-vsx.c b/arch/powerpc/kernel/ptrace/ptrace-vsx.c
index d53466d49cc0..1da4303128ef 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-vsx.c
+++ b/arch/powerpc/kernel/ptrace/ptrace-vsx.c
@@ -19,7 +19,7 @@
  * };
  */
 int fpr_get(struct task_struct *target, const struct user_regset *regset,
-	    unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+	    struct membuf to)
 {
 	u64 buf[33];
 	int i;
@@ -30,7 +30,7 @@ int fpr_get(struct task_struct *target, const struct user_regset *regset,
 	for (i = 0; i < 32 ; i++)
 		buf[i] = target->thread.TS_FPR(i);
 	buf[32] = target->thread.fp_state.fpscr;
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, buf, 0, -1);
+	return membuf_write(&to, buf, 33 * sizeof(u64));
 }
 
 /*
@@ -95,10 +95,10 @@ int vsr_active(struct task_struct *target, const struct user_regset *regset)
  * };
  */
 int vsr_get(struct task_struct *target, const struct user_regset *regset,
-	    unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf)
+	    struct membuf to)
 {
 	u64 buf[32];
-	int ret, i;
+	int i;
 
 	flush_tmregs_to_thread(target);
 	flush_fp_to_thread(target);
@@ -108,10 +108,7 @@ int vsr_get(struct task_struct *target, const struct user_regset *regset,
 	for (i = 0; i < 32 ; i++)
 		buf[i] = target->thread.fp_state.fpr[i][TS_VSRLOWOFFSET];
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  buf, 0, 32 * sizeof(double));
-
-	return ret;
+	return membuf_write(&to, buf, 32 * sizeof(double));
 }
 
 /*
diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c
index 444dc7b0fd78..2d6395f5ad54 100644
--- a/arch/riscv/kernel/ptrace.c
+++ b/arch/riscv/kernel/ptrace.c
@@ -30,13 +30,10 @@ enum riscv_regset {
 
 static int riscv_gpr_get(struct task_struct *target,
 			 const struct user_regset *regset,
-			 unsigned int pos, unsigned int count,
-			 void *kbuf, void __user *ubuf)
+			 struct membuf to)
 {
-	struct pt_regs *regs;
-
-	regs = task_pt_regs(target);
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, regs, 0, -1);
+	return membuf_write(&to, task_pt_regs(target),
+			    sizeof(struct user_regs_struct));
 }
 
 static int riscv_gpr_set(struct task_struct *target,
@@ -55,21 +52,13 @@ static int riscv_gpr_set(struct task_struct *target,
 #ifdef CONFIG_FPU
 static int riscv_fpr_get(struct task_struct *target,
 			 const struct user_regset *regset,
-			 unsigned int pos, unsigned int count,
-			 void *kbuf, void __user *ubuf)
+			 struct membuf to)
 {
-	int ret;
 	struct __riscv_d_ext_state *fstate = &target->thread.fstate;
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, fstate, 0,
-				  offsetof(struct __riscv_d_ext_state, fcsr));
-	if (!ret) {
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, fstate, 0,
-					  offsetof(struct __riscv_d_ext_state, fcsr) +
-					  sizeof(fstate->fcsr));
-	}
-
-	return ret;
+	membuf_write(&to, fstate, offsetof(struct __riscv_d_ext_state, fcsr));
+	membuf_store(&to, fstate->fcsr);
+	return membuf_zero(&to, 4);	// explicitly pad
 }
 
 static int riscv_fpr_set(struct task_struct *target,
@@ -98,8 +87,8 @@ static const struct user_regset riscv_user_regset[] = {
 		.n = ELF_NGREG,
 		.size = sizeof(elf_greg_t),
 		.align = sizeof(elf_greg_t),
-		.get = &riscv_gpr_get,
-		.set = &riscv_gpr_set,
+		.regset_get = riscv_gpr_get,
+		.set = riscv_gpr_set,
 	},
 #ifdef CONFIG_FPU
 	[REGSET_F] = {
@@ -107,8 +96,8 @@ static const struct user_regset riscv_user_regset[] = {
 		.n = ELF_NFPREG,
 		.size = sizeof(elf_fpreg_t),
 		.align = sizeof(elf_fpreg_t),
-		.get = &riscv_fpr_get,
-		.set = &riscv_fpr_set,
+		.regset_get = riscv_fpr_get,
+		.set = riscv_fpr_set,
 	},
 #endif
 };
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 3cc15c066298..a09b9e98936c 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -945,28 +945,14 @@ asmlinkage void do_syscall_trace_exit(struct pt_regs *regs)
 
 static int s390_regs_get(struct task_struct *target,
 			 const struct user_regset *regset,
-			 unsigned int pos, unsigned int count,
-			 void *kbuf, void __user *ubuf)
+			 struct membuf to)
 {
+	unsigned pos;
 	if (target == current)
 		save_access_regs(target->thread.acrs);
 
-	if (kbuf) {
-		unsigned long *k = kbuf;
-		while (count > 0) {
-			*k++ = __peek_user(target, pos);
-			count -= sizeof(*k);
-			pos += sizeof(*k);
-		}
-	} else {
-		unsigned long __user *u = ubuf;
-		while (count > 0) {
-			if (__put_user(__peek_user(target, pos), u++))
-				return -EFAULT;
-			count -= sizeof(*u);
-			pos += sizeof(*u);
-		}
-	}
+	for (pos = 0; pos < sizeof(s390_regs); pos += sizeof(long))
+		membuf_store(&to, __peek_user(target, pos));
 	return 0;
 }
 
@@ -1007,8 +993,8 @@ static int s390_regs_set(struct task_struct *target,
 }
 
 static int s390_fpregs_get(struct task_struct *target,
-			   const struct user_regset *regset, unsigned int pos,
-			   unsigned int count, void *kbuf, void __user *ubuf)
+			   const struct user_regset *regset,
+			   struct membuf to)
 {
 	_s390_fp_regs fp_regs;
 
@@ -1018,8 +1004,7 @@ static int s390_fpregs_get(struct task_struct *target,
 	fp_regs.fpc = target->thread.fpu.fpc;
 	fpregs_store(&fp_regs, &target->thread.fpu);
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &fp_regs, 0, -1);
+	return membuf_write(&to, &fp_regs, sizeof(fp_regs));
 }
 
 static int s390_fpregs_set(struct task_struct *target,
@@ -1066,20 +1051,9 @@ static int s390_fpregs_set(struct task_struct *target,
 
 static int s390_last_break_get(struct task_struct *target,
 			       const struct user_regset *regset,
-			       unsigned int pos, unsigned int count,
-			       void *kbuf, void __user *ubuf)
+			       struct membuf to)
 {
-	if (count > 0) {
-		if (kbuf) {
-			unsigned long *k = kbuf;
-			*k = target->thread.last_break;
-		} else {
-			unsigned long  __user *u = ubuf;
-			if (__put_user(target->thread.last_break, u))
-				return -EFAULT;
-		}
-	}
-	return 0;
+	return membuf_store(&to, target->thread.last_break);
 }
 
 static int s390_last_break_set(struct task_struct *target,
@@ -1092,16 +1066,13 @@ static int s390_last_break_set(struct task_struct *target,
 
 static int s390_tdb_get(struct task_struct *target,
 			const struct user_regset *regset,
-			unsigned int pos, unsigned int count,
-			void *kbuf, void __user *ubuf)
+			struct membuf to)
 {
 	struct pt_regs *regs = task_pt_regs(target);
-	unsigned char *data;
 
 	if (!(regs->int_code & 0x200))
 		return -ENODATA;
-	data = target->thread.trap_tdb;
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, data, 0, 256);
+	return membuf_write(&to, target->thread.trap_tdb, 256);
 }
 
 static int s390_tdb_set(struct task_struct *target,
@@ -1114,8 +1085,7 @@ static int s390_tdb_set(struct task_struct *target,
 
 static int s390_vxrs_low_get(struct task_struct *target,
 			     const struct user_regset *regset,
-			     unsigned int pos, unsigned int count,
-			     void *kbuf, void __user *ubuf)
+			     struct membuf to)
 {
 	__u64 vxrs[__NUM_VXRS_LOW];
 	int i;
@@ -1126,7 +1096,7 @@ static int s390_vxrs_low_get(struct task_struct *target,
 		save_fpu_regs();
 	for (i = 0; i < __NUM_VXRS_LOW; i++)
 		vxrs[i] = *((__u64 *)(target->thread.fpu.vxrs + i) + 1);
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, vxrs, 0, -1);
+	return membuf_write(&to, vxrs, sizeof(vxrs));
 }
 
 static int s390_vxrs_low_set(struct task_struct *target,
@@ -1155,18 +1125,14 @@ static int s390_vxrs_low_set(struct task_struct *target,
 
 static int s390_vxrs_high_get(struct task_struct *target,
 			      const struct user_regset *regset,
-			      unsigned int pos, unsigned int count,
-			      void *kbuf, void __user *ubuf)
+			      struct membuf to)
 {
-	__vector128 vxrs[__NUM_VXRS_HIGH];
-
 	if (!MACHINE_HAS_VX)
 		return -ENODEV;
 	if (target == current)
 		save_fpu_regs();
-	memcpy(vxrs, target->thread.fpu.vxrs + __NUM_VXRS_LOW, sizeof(vxrs));
-
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, vxrs, 0, -1);
+	return membuf_write(&to, target->thread.fpu.vxrs + __NUM_VXRS_LOW,
+			    __NUM_VXRS_HIGH * sizeof(__vector128));
 }
 
 static int s390_vxrs_high_set(struct task_struct *target,
@@ -1188,12 +1154,9 @@ static int s390_vxrs_high_set(struct task_struct *target,
 
 static int s390_system_call_get(struct task_struct *target,
 				const struct user_regset *regset,
-				unsigned int pos, unsigned int count,
-				void *kbuf, void __user *ubuf)
+				struct membuf to)
 {
-	unsigned int *data = &target->thread.system_call;
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   data, 0, sizeof(unsigned int));
+	return membuf_store(&to, target->thread.system_call);
 }
 
 static int s390_system_call_set(struct task_struct *target,
@@ -1208,8 +1171,7 @@ static int s390_system_call_set(struct task_struct *target,
 
 static int s390_gs_cb_get(struct task_struct *target,
 			  const struct user_regset *regset,
-			  unsigned int pos, unsigned int count,
-			  void *kbuf, void __user *ubuf)
+			  struct membuf to)
 {
 	struct gs_cb *data = target->thread.gs_cb;
 
@@ -1219,8 +1181,7 @@ static int s390_gs_cb_get(struct task_struct *target,
 		return -ENODATA;
 	if (target == current)
 		save_gs_cb(data);
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   data, 0, sizeof(struct gs_cb));
+	return membuf_write(&to, data, sizeof(struct gs_cb));
 }
 
 static int s390_gs_cb_set(struct task_struct *target,
@@ -1264,8 +1225,7 @@ static int s390_gs_cb_set(struct task_struct *target,
 
 static int s390_gs_bc_get(struct task_struct *target,
 			  const struct user_regset *regset,
-			  unsigned int pos, unsigned int count,
-			  void *kbuf, void __user *ubuf)
+			  struct membuf to)
 {
 	struct gs_cb *data = target->thread.gs_bc_cb;
 
@@ -1273,8 +1233,7 @@ static int s390_gs_bc_get(struct task_struct *target,
 		return -ENODEV;
 	if (!data)
 		return -ENODATA;
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   data, 0, sizeof(struct gs_cb));
+	return membuf_write(&to, data, sizeof(struct gs_cb));
 }
 
 static int s390_gs_bc_set(struct task_struct *target,
@@ -1325,8 +1284,7 @@ static bool is_ri_cb_valid(struct runtime_instr_cb *cb)
 
 static int s390_runtime_instr_get(struct task_struct *target,
 				const struct user_regset *regset,
-				unsigned int pos, unsigned int count,
-				void *kbuf, void __user *ubuf)
+				struct membuf to)
 {
 	struct runtime_instr_cb *data = target->thread.ri_cb;
 
@@ -1335,8 +1293,7 @@ static int s390_runtime_instr_get(struct task_struct *target,
 	if (!data)
 		return -ENODATA;
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   data, 0, sizeof(struct runtime_instr_cb));
+	return membuf_write(&to, data, sizeof(struct runtime_instr_cb));
 }
 
 static int s390_runtime_instr_set(struct task_struct *target,
@@ -1392,7 +1349,7 @@ static const struct user_regset s390_regsets[] = {
 		.n = sizeof(s390_regs) / sizeof(long),
 		.size = sizeof(long),
 		.align = sizeof(long),
-		.get = s390_regs_get,
+		.regset_get = s390_regs_get,
 		.set = s390_regs_set,
 	},
 	{
@@ -1400,7 +1357,7 @@ static const struct user_regset s390_regsets[] = {
 		.n = sizeof(s390_fp_regs) / sizeof(long),
 		.size = sizeof(long),
 		.align = sizeof(long),
-		.get = s390_fpregs_get,
+		.regset_get = s390_fpregs_get,
 		.set = s390_fpregs_set,
 	},
 	{
@@ -1408,7 +1365,7 @@ static const struct user_regset s390_regsets[] = {
 		.n = 1,
 		.size = sizeof(unsigned int),
 		.align = sizeof(unsigned int),
-		.get = s390_system_call_get,
+		.regset_get = s390_system_call_get,
 		.set = s390_system_call_set,
 	},
 	{
@@ -1416,7 +1373,7 @@ static const struct user_regset s390_regsets[] = {
 		.n = 1,
 		.size = sizeof(long),
 		.align = sizeof(long),
-		.get = s390_last_break_get,
+		.regset_get = s390_last_break_get,
 		.set = s390_last_break_set,
 	},
 	{
@@ -1424,7 +1381,7 @@ static const struct user_regset s390_regsets[] = {
 		.n = 1,
 		.size = 256,
 		.align = 1,
-		.get = s390_tdb_get,
+		.regset_get = s390_tdb_get,
 		.set = s390_tdb_set,
 	},
 	{
@@ -1432,7 +1389,7 @@ static const struct user_regset s390_regsets[] = {
 		.n = __NUM_VXRS_LOW,
 		.size = sizeof(__u64),
 		.align = sizeof(__u64),
-		.get = s390_vxrs_low_get,
+		.regset_get = s390_vxrs_low_get,
 		.set = s390_vxrs_low_set,
 	},
 	{
@@ -1440,7 +1397,7 @@ static const struct user_regset s390_regsets[] = {
 		.n = __NUM_VXRS_HIGH,
 		.size = sizeof(__vector128),
 		.align = sizeof(__vector128),
-		.get = s390_vxrs_high_get,
+		.regset_get = s390_vxrs_high_get,
 		.set = s390_vxrs_high_set,
 	},
 	{
@@ -1448,7 +1405,7 @@ static const struct user_regset s390_regsets[] = {
 		.n = sizeof(struct gs_cb) / sizeof(__u64),
 		.size = sizeof(__u64),
 		.align = sizeof(__u64),
-		.get = s390_gs_cb_get,
+		.regset_get = s390_gs_cb_get,
 		.set = s390_gs_cb_set,
 	},
 	{
@@ -1456,7 +1413,7 @@ static const struct user_regset s390_regsets[] = {
 		.n = sizeof(struct gs_cb) / sizeof(__u64),
 		.size = sizeof(__u64),
 		.align = sizeof(__u64),
-		.get = s390_gs_bc_get,
+		.regset_get = s390_gs_bc_get,
 		.set = s390_gs_bc_set,
 	},
 	{
@@ -1464,7 +1421,7 @@ static const struct user_regset s390_regsets[] = {
 		.n = sizeof(struct runtime_instr_cb) / sizeof(__u64),
 		.size = sizeof(__u64),
 		.align = sizeof(__u64),
-		.get = s390_runtime_instr_get,
+		.regset_get = s390_runtime_instr_get,
 		.set = s390_runtime_instr_set,
 	},
 };
@@ -1479,28 +1436,15 @@ static const struct user_regset_view user_s390_view = {
 #ifdef CONFIG_COMPAT
 static int s390_compat_regs_get(struct task_struct *target,
 				const struct user_regset *regset,
-				unsigned int pos, unsigned int count,
-				void *kbuf, void __user *ubuf)
+				struct membuf to)
 {
+	unsigned n;
+
 	if (target == current)
 		save_access_regs(target->thread.acrs);
 
-	if (kbuf) {
-		compat_ulong_t *k = kbuf;
-		while (count > 0) {
-			*k++ = __peek_user_compat(target, pos);
-			count -= sizeof(*k);
-			pos += sizeof(*k);
-		}
-	} else {
-		compat_ulong_t __user *u = ubuf;
-		while (count > 0) {
-			if (__put_user(__peek_user_compat(target, pos), u++))
-				return -EFAULT;
-			count -= sizeof(*u);
-			pos += sizeof(*u);
-		}
-	}
+	for (n = 0; n < sizeof(s390_compat_regs); n += sizeof(compat_ulong_t))
+		membuf_store(&to, __peek_user_compat(target, n));
 	return 0;
 }
 
@@ -1542,29 +1486,14 @@ static int s390_compat_regs_set(struct task_struct *target,
 
 static int s390_compat_regs_high_get(struct task_struct *target,
 				     const struct user_regset *regset,
-				     unsigned int pos, unsigned int count,
-				     void *kbuf, void __user *ubuf)
+				     struct membuf to)
 {
 	compat_ulong_t *gprs_high;
+	int i;
 
-	gprs_high = (compat_ulong_t *)
-		&task_pt_regs(target)->gprs[pos / sizeof(compat_ulong_t)];
-	if (kbuf) {
-		compat_ulong_t *k = kbuf;
-		while (count > 0) {
-			*k++ = *gprs_high;
-			gprs_high += 2;
-			count -= sizeof(*k);
-		}
-	} else {
-		compat_ulong_t __user *u = ubuf;
-		while (count > 0) {
-			if (__put_user(*gprs_high, u++))
-				return -EFAULT;
-			gprs_high += 2;
-			count -= sizeof(*u);
-		}
-	}
+	gprs_high = (compat_ulong_t *)task_pt_regs(target)->gprs;
+	for (i = 0; i < NUM_GPRS; i++, gprs_high += 2)
+		membuf_store(&to, *gprs_high);
 	return 0;
 }
 
@@ -1603,23 +1532,11 @@ static int s390_compat_regs_high_set(struct task_struct *target,
 
 static int s390_compat_last_break_get(struct task_struct *target,
 				      const struct user_regset *regset,
-				      unsigned int pos, unsigned int count,
-				      void *kbuf, void __user *ubuf)
+				      struct membuf to)
 {
-	compat_ulong_t last_break;
+	compat_ulong_t last_break = target->thread.last_break;
 
-	if (count > 0) {
-		last_break = target->thread.last_break;
-		if (kbuf) {
-			unsigned long *k = kbuf;
-			*k = last_break;
-		} else {
-			unsigned long  __user *u = ubuf;
-			if (__put_user(last_break, u))
-				return -EFAULT;
-		}
-	}
-	return 0;
+	return membuf_store(&to, (unsigned long)last_break);
 }
 
 static int s390_compat_last_break_set(struct task_struct *target,
@@ -1636,7 +1553,7 @@ static const struct user_regset s390_compat_regsets[] = {
 		.n = sizeof(s390_compat_regs) / sizeof(compat_long_t),
 		.size = sizeof(compat_long_t),
 		.align = sizeof(compat_long_t),
-		.get = s390_compat_regs_get,
+		.regset_get = s390_compat_regs_get,
 		.set = s390_compat_regs_set,
 	},
 	{
@@ -1644,7 +1561,7 @@ static const struct user_regset s390_compat_regsets[] = {
 		.n = sizeof(s390_fp_regs) / sizeof(compat_long_t),
 		.size = sizeof(compat_long_t),
 		.align = sizeof(compat_long_t),
-		.get = s390_fpregs_get,
+		.regset_get = s390_fpregs_get,
 		.set = s390_fpregs_set,
 	},
 	{
@@ -1652,7 +1569,7 @@ static const struct user_regset s390_compat_regsets[] = {
 		.n = 1,
 		.size = sizeof(compat_uint_t),
 		.align = sizeof(compat_uint_t),
-		.get = s390_system_call_get,
+		.regset_get = s390_system_call_get,
 		.set = s390_system_call_set,
 	},
 	{
@@ -1660,7 +1577,7 @@ static const struct user_regset s390_compat_regsets[] = {
 		.n = 1,
 		.size = sizeof(long),
 		.align = sizeof(long),
-		.get = s390_compat_last_break_get,
+		.regset_get = s390_compat_last_break_get,
 		.set = s390_compat_last_break_set,
 	},
 	{
@@ -1668,7 +1585,7 @@ static const struct user_regset s390_compat_regsets[] = {
 		.n = 1,
 		.size = 256,
 		.align = 1,
-		.get = s390_tdb_get,
+		.regset_get = s390_tdb_get,
 		.set = s390_tdb_set,
 	},
 	{
@@ -1676,7 +1593,7 @@ static const struct user_regset s390_compat_regsets[] = {
 		.n = __NUM_VXRS_LOW,
 		.size = sizeof(__u64),
 		.align = sizeof(__u64),
-		.get = s390_vxrs_low_get,
+		.regset_get = s390_vxrs_low_get,
 		.set = s390_vxrs_low_set,
 	},
 	{
@@ -1684,7 +1601,7 @@ static const struct user_regset s390_compat_regsets[] = {
 		.n = __NUM_VXRS_HIGH,
 		.size = sizeof(__vector128),
 		.align = sizeof(__vector128),
-		.get = s390_vxrs_high_get,
+		.regset_get = s390_vxrs_high_get,
 		.set = s390_vxrs_high_set,
 	},
 	{
@@ -1692,7 +1609,7 @@ static const struct user_regset s390_compat_regsets[] = {
 		.n = sizeof(s390_compat_regs_high) / sizeof(compat_long_t),
 		.size = sizeof(compat_long_t),
 		.align = sizeof(compat_long_t),
-		.get = s390_compat_regs_high_get,
+		.regset_get = s390_compat_regs_high_get,
 		.set = s390_compat_regs_high_set,
 	},
 	{
@@ -1700,7 +1617,7 @@ static const struct user_regset s390_compat_regsets[] = {
 		.n = sizeof(struct gs_cb) / sizeof(__u64),
 		.size = sizeof(__u64),
 		.align = sizeof(__u64),
-		.get = s390_gs_cb_get,
+		.regset_get = s390_gs_cb_get,
 		.set = s390_gs_cb_set,
 	},
 	{
@@ -1708,7 +1625,7 @@ static const struct user_regset s390_compat_regsets[] = {
 		.n = sizeof(struct gs_cb) / sizeof(__u64),
 		.size = sizeof(__u64),
 		.align = sizeof(__u64),
-		.get = s390_gs_bc_get,
+		.regset_get = s390_gs_bc_get,
 		.set = s390_gs_bc_set,
 	},
 	{
@@ -1716,7 +1633,7 @@ static const struct user_regset s390_compat_regsets[] = {
 		.n = sizeof(struct runtime_instr_cb) / sizeof(__u64),
 		.size = sizeof(__u64),
 		.align = sizeof(__u64),
-		.get = s390_runtime_instr_get,
+		.regset_get = s390_runtime_instr_get,
 		.set = s390_runtime_instr_set,
 	},
 };
diff --git a/arch/sh/kernel/process_32.c b/arch/sh/kernel/process_32.c
index b0fefd8f53a6..cde0a66116d2 100644
--- a/arch/sh/kernel/process_32.c
+++ b/arch/sh/kernel/process_32.c
@@ -103,9 +103,8 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 
 	fpvalid = !!tsk_used_math(tsk);
 	if (fpvalid)
-		fpvalid = !fpregs_get(tsk, NULL, 0,
-				      sizeof(struct user_fpu_struct),
-				      fpu, NULL);
+		fpvalid = !fpregs_get(tsk, NULL,
+				      (struct membuf){fpu, sizeof(*fpu)});
 #endif
 
 	return fpvalid;
diff --git a/arch/sh/kernel/ptrace_32.c b/arch/sh/kernel/ptrace_32.c
index 64bfb714943e..5c93bdb6c41a 100644
--- a/arch/sh/kernel/ptrace_32.c
+++ b/arch/sh/kernel/ptrace_32.c
@@ -134,26 +134,11 @@ void ptrace_disable(struct task_struct *child)
 
 static int genregs_get(struct task_struct *target,
 		       const struct user_regset *regset,
-		       unsigned int pos, unsigned int count,
-		       void *kbuf, void __user *ubuf)
+		       struct membuf to)
 {
 	const struct pt_regs *regs = task_pt_regs(target);
-	int ret;
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  regs->regs,
-				  0, 16 * sizeof(unsigned long));
-	if (!ret)
-		/* PC, PR, SR, GBR, MACH, MACL, TRA */
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &regs->pc,
-					  offsetof(struct pt_regs, pc),
-					  sizeof(struct pt_regs));
-	if (!ret)
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					       sizeof(struct pt_regs), -1);
-
-	return ret;
+	return membuf_write(&to, regs, sizeof(struct pt_regs));
 }
 
 static int genregs_set(struct task_struct *target,
@@ -182,8 +167,7 @@ static int genregs_set(struct task_struct *target,
 #ifdef CONFIG_SH_FPU
 int fpregs_get(struct task_struct *target,
 	       const struct user_regset *regset,
-	       unsigned int pos, unsigned int count,
-	       void *kbuf, void __user *ubuf)
+	       struct membuf to)
 {
 	int ret;
 
@@ -191,12 +175,8 @@ int fpregs_get(struct task_struct *target,
 	if (ret)
 		return ret;
 
-	if ((boot_cpu_data.flags & CPU_HAS_FPU))
-		return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					   &target->thread.xstate->hardfpu, 0, -1);
-
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &target->thread.xstate->softfpu, 0, -1);
+	return membuf_write(&to, target->thread.xstate,
+			    sizeof(struct user_fpu_struct));
 }
 
 static int fpregs_set(struct task_struct *target,
@@ -230,20 +210,12 @@ static int fpregs_active(struct task_struct *target,
 #ifdef CONFIG_SH_DSP
 static int dspregs_get(struct task_struct *target,
 		       const struct user_regset *regset,
-		       unsigned int pos, unsigned int count,
-		       void *kbuf, void __user *ubuf)
+		       struct membuf to)
 {
 	const struct pt_dspregs *regs =
 		(struct pt_dspregs *)&target->thread.dsp_status.dsp_regs;
-	int ret;
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, regs,
-				  0, sizeof(struct pt_dspregs));
-	if (!ret)
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					       sizeof(struct pt_dspregs), -1);
-
-	return ret;
+	return membuf_write(&to, regs, sizeof(struct pt_dspregs));
 }
 
 static int dspregs_set(struct task_struct *target,
@@ -324,7 +296,7 @@ static const struct user_regset sh_regsets[] = {
 		.n		= ELF_NGREG,
 		.size		= sizeof(long),
 		.align		= sizeof(long),
-		.get		= genregs_get,
+		.regset_get		= genregs_get,
 		.set		= genregs_set,
 	},
 
@@ -334,7 +306,7 @@ static const struct user_regset sh_regsets[] = {
 		.n		= sizeof(struct user_fpu_struct) / sizeof(long),
 		.size		= sizeof(long),
 		.align		= sizeof(long),
-		.get		= fpregs_get,
+		.regset_get		= fpregs_get,
 		.set		= fpregs_set,
 		.active		= fpregs_active,
 	},
@@ -345,7 +317,7 @@ static const struct user_regset sh_regsets[] = {
 		.n		= sizeof(struct pt_dspregs) / sizeof(long),
 		.size		= sizeof(long),
 		.align		= sizeof(long),
-		.get		= dspregs_get,
+		.regset_get		= dspregs_get,
 		.set		= dspregs_set,
 		.active		= dspregs_active,
 	},
diff --git a/arch/sparc/kernel/ptrace_32.c b/arch/sparc/kernel/ptrace_32.c
index 47eb315d411c..5318174a0268 100644
--- a/arch/sparc/kernel/ptrace_32.c
+++ b/arch/sparc/kernel/ptrace_32.c
@@ -83,41 +83,25 @@ static int regwindow32_set(struct task_struct *target,
 
 static int genregs32_get(struct task_struct *target,
 			 const struct user_regset *regset,
-			 unsigned int pos, unsigned int count,
-			 void *kbuf, void __user *ubuf)
+			 struct membuf to)
 {
 	const struct pt_regs *regs = target->thread.kregs;
 	u32 uregs[16];
-	int ret;
 
 	if (target == current)
 		flush_user_windows();
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  regs->u_regs,
-				  0, 16 * sizeof(u32));
-	if (ret || !count)
-		return ret;
-
-	if (pos < 32 * sizeof(u32)) {
-		if (regwindow32_get(target, regs, uregs))
-			return -EFAULT;
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  uregs,
-					  16 * sizeof(u32), 32 * sizeof(u32));
-		if (ret || !count)
-			return ret;
-	}
-
-	uregs[0] = regs->psr;
-	uregs[1] = regs->pc;
-	uregs[2] = regs->npc;
-	uregs[3] = regs->y;
-	uregs[4] = 0;	/* WIM */
-	uregs[5] = 0;	/* TBR */
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  uregs,
-				  32 * sizeof(u32), 38 * sizeof(u32));
+	membuf_write(&to, regs->u_regs, 16 * sizeof(u32));
+	if (!to.left)
+		return 0;
+	if (regwindow32_get(target, regs, uregs))
+		return -EFAULT;
+	membuf_write(&to, uregs, 16 * sizeof(u32));
+	membuf_store(&to, regs->psr);
+	membuf_store(&to, regs->pc);
+	membuf_store(&to, regs->npc);
+	membuf_store(&to, regs->y);
+	return membuf_zero(&to, 2 * sizeof(u32));
 }
 
 static int genregs32_set(struct task_struct *target,
@@ -139,19 +123,18 @@ static int genregs32_set(struct task_struct *target,
 	if (ret || !count)
 		return ret;
 
-	if (pos < 32 * sizeof(u32)) {
-		if (regwindow32_get(target, regs, uregs))
-			return -EFAULT;
-		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
-					 uregs,
-					 16 * sizeof(u32), 32 * sizeof(u32));
-		if (ret)
-			return ret;
-		if (regwindow32_set(target, regs, uregs))
-			return -EFAULT;
-		if (!count)
-			return 0;
-	}
+	if (regwindow32_get(target, regs, uregs))
+		return -EFAULT;
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 uregs,
+				 16 * sizeof(u32), 32 * sizeof(u32));
+	if (ret)
+		return ret;
+	if (regwindow32_set(target, regs, uregs))
+		return -EFAULT;
+	if (!count)
+		return 0;
+
 	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 				 &psr,
 				 32 * sizeof(u32), 33 * sizeof(u32));
@@ -182,46 +165,18 @@ static int genregs32_set(struct task_struct *target,
 
 static int fpregs32_get(struct task_struct *target,
 			const struct user_regset *regset,
-			unsigned int pos, unsigned int count,
-			void *kbuf, void __user *ubuf)
+			struct membuf to)
 {
-	const unsigned long *fpregs = target->thread.float_regs;
-	int ret = 0;
-
 #if 0
 	if (target == current)
 		save_and_clear_fpu();
 #endif
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  fpregs,
-				  0, 32 * sizeof(u32));
-
-	if (!ret)
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					       32 * sizeof(u32),
-					       33 * sizeof(u32));
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &target->thread.fsr,
-					  33 * sizeof(u32),
-					  34 * sizeof(u32));
-
-	if (!ret) {
-		unsigned long val;
-
-		val = (1 << 8) | (8 << 16);
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &val,
-					  34 * sizeof(u32),
-					  35 * sizeof(u32));
-	}
-
-	if (!ret)
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					       35 * sizeof(u32), -1);
-
-	return ret;
+	membuf_write(&to, target->thread.float_regs, 32 * sizeof(u32));
+	membuf_zero(&to, sizeof(u32));
+	membuf_write(&to, &target->thread.fsr, sizeof(u32));
+	membuf_store(&to, (u32)((1 << 8) | (8 << 16)));
+	return membuf_zero(&to, 64 * sizeof(u32));
 }
 
 static int fpregs32_set(struct task_struct *target,
@@ -243,13 +198,11 @@ static int fpregs32_set(struct task_struct *target,
 		user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
 					  32 * sizeof(u32),
 					  33 * sizeof(u32));
-	if (!ret && count > 0) {
+	if (!ret)
 		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 					 &target->thread.fsr,
 					 33 * sizeof(u32),
 					 34 * sizeof(u32));
-	}
-
 	if (!ret)
 		ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
 						34 * sizeof(u32), -1);
@@ -268,7 +221,7 @@ static const struct user_regset sparc32_regsets[] = {
 		.core_note_type = NT_PRSTATUS,
 		.n = 38,
 		.size = sizeof(u32), .align = sizeof(u32),
-		.get = genregs32_get, .set = genregs32_set
+		.regset_get = genregs32_get, .set = genregs32_set
 	},
 	/* Format is:
 	 *	F0 --> F31
@@ -284,10 +237,104 @@ static const struct user_regset sparc32_regsets[] = {
 		.core_note_type = NT_PRFPREG,
 		.n = 99,
 		.size = sizeof(u32), .align = sizeof(u32),
-		.get = fpregs32_get, .set = fpregs32_set
+		.regset_get = fpregs32_get, .set = fpregs32_set
+	},
+};
+
+static int getregs_get(struct task_struct *target,
+			 const struct user_regset *regset,
+			 struct membuf to)
+{
+	const struct pt_regs *regs = target->thread.kregs;
+
+	if (target == current)
+		flush_user_windows();
+
+	membuf_store(&to, regs->psr);
+	membuf_store(&to, regs->pc);
+	membuf_store(&to, regs->npc);
+	membuf_store(&to, regs->y);
+	return membuf_write(&to, regs->u_regs + 1, 15 * sizeof(u32));
+}
+
+static int setregs_set(struct task_struct *target,
+			 const struct user_regset *regset,
+			 unsigned int pos, unsigned int count,
+			 const void *kbuf, const void __user *ubuf)
+{
+	struct pt_regs *regs = target->thread.kregs;
+	u32 v[4];
+	int ret;
+
+	if (target == current)
+		flush_user_windows();
+
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 v,
+				 0, 4 * sizeof(u32));
+	if (ret)
+		return ret;
+	regs->psr = (regs->psr & ~(PSR_ICC | PSR_SYSCALL)) |
+		    (v[0] & (PSR_ICC | PSR_SYSCALL));
+	regs->pc = v[1];
+	regs->npc = v[2];
+	regs->y = v[3];
+	return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 regs->u_regs + 1,
+				 4 * sizeof(u32) , 19 * sizeof(u32));
+}
+
+static int getfpregs_get(struct task_struct *target,
+			const struct user_regset *regset,
+			struct membuf to)
+{
+#if 0
+	if (target == current)
+		save_and_clear_fpu();
+#endif
+	membuf_write(&to, &target->thread.float_regs, 32 * sizeof(u32));
+	membuf_write(&to, &target->thread.fsr, sizeof(u32));
+	return membuf_zero(&to, 35 * sizeof(u32));
+}
+
+static int setfpregs_set(struct task_struct *target,
+			const struct user_regset *regset,
+			unsigned int pos, unsigned int count,
+			const void *kbuf, const void __user *ubuf)
+{
+	unsigned long *fpregs = target->thread.float_regs;
+	int ret;
+
+#if 0
+	if (target == current)
+		save_and_clear_fpu();
+#endif
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 fpregs,
+				 0, 32 * sizeof(u32));
+	if (ret)
+		return ret;
+	return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 &target->thread.fsr,
+				 32 * sizeof(u32),
+				 33 * sizeof(u32));
+}
+
+static const struct user_regset ptrace32_regsets[] = {
+	[REGSET_GENERAL] = {
+		.n = 19, .size = sizeof(u32),
+		.regset_get = getregs_get, .set = setregs_set,
+	},
+	[REGSET_FP] = {
+		.n = 68, .size = sizeof(u32),
+		.regset_get = getfpregs_get, .set = setfpregs_set,
 	},
 };
 
+static const struct user_regset_view ptrace32_view = {
+	.regsets = ptrace32_regsets, .n = ARRAY_SIZE(ptrace32_regsets)
+};
+
 static const struct user_regset_view user_sparc32_view = {
 	.name = "sparc", .e_machine = EM_SPARC,
 	.regsets = sparc32_regsets, .n = ARRAY_SIZE(sparc32_regsets)
@@ -315,74 +362,44 @@ long arch_ptrace(struct task_struct *child, long request,
 {
 	unsigned long addr2 = current->thread.kregs->u_regs[UREG_I4];
 	void __user *addr2p;
-	const struct user_regset_view *view;
 	struct pt_regs __user *pregs;
 	struct fps __user *fps;
 	int ret;
 
-	view = task_user_regset_view(current);
 	addr2p = (void __user *) addr2;
 	pregs = (struct pt_regs __user *) addr;
 	fps = (struct fps __user *) addr;
 
 	switch(request) {
 	case PTRACE_GETREGS: {
-		ret = copy_regset_to_user(child, view, REGSET_GENERAL,
-					  32 * sizeof(u32),
-					  4 * sizeof(u32),
-					  &pregs->psr);
-		if (!ret)
-			copy_regset_to_user(child, view, REGSET_GENERAL,
-					    1 * sizeof(u32),
-					    15 * sizeof(u32),
-					    &pregs->u_regs[0]);
+		ret = copy_regset_to_user(child, &ptrace32_view,
+					  REGSET_GENERAL, 0,
+					  19 * sizeof(u32),
+					  pregs);
 		break;
 	}
 
 	case PTRACE_SETREGS: {
-		ret = copy_regset_from_user(child, view, REGSET_GENERAL,
-					    32 * sizeof(u32),
-					    4 * sizeof(u32),
-					    &pregs->psr);
-		if (!ret)
-			copy_regset_from_user(child, view, REGSET_GENERAL,
-					      1 * sizeof(u32),
-					      15 * sizeof(u32),
-					      &pregs->u_regs[0]);
+		ret = copy_regset_from_user(child, &ptrace32_view,
+					    REGSET_GENERAL, 0,
+					    19 * sizeof(u32),
+					    pregs);
 		break;
 	}
 
 	case PTRACE_GETFPREGS: {
-		ret = copy_regset_to_user(child, view, REGSET_FP,
-					  0 * sizeof(u32),
-					  32 * sizeof(u32),
-					  &fps->regs[0]);
-		if (!ret)
-			ret = copy_regset_to_user(child, view, REGSET_FP,
-						  33 * sizeof(u32),
-						  1 * sizeof(u32),
-						  &fps->fsr);
-
-		if (!ret) {
-			if (__put_user(0, &fps->fpqd) ||
-			    __put_user(0, &fps->flags) ||
-			    __put_user(0, &fps->extra) ||
-			    clear_user(fps->fpq, sizeof(fps->fpq)))
-				ret = -EFAULT;
-		}
+		ret = copy_regset_to_user(child, &ptrace32_view,
+					  REGSET_FP, 0,
+					  68 * sizeof(u32),
+					  fps);
 		break;
 	}
 
 	case PTRACE_SETFPREGS: {
-		ret = copy_regset_from_user(child, view, REGSET_FP,
-					    0 * sizeof(u32),
-					    32 * sizeof(u32),
-					    &fps->regs[0]);
-		if (!ret)
-			ret = copy_regset_from_user(child, view, REGSET_FP,
-						    33 * sizeof(u32),
-						    1 * sizeof(u32),
-						    &fps->fsr);
+		ret = copy_regset_from_user(child, &ptrace32_view,
+					  REGSET_FP, 0,
+					  33 * sizeof(u32),
+					  fps);
 		break;
 	}
 
diff --git a/arch/sparc/kernel/ptrace_64.c b/arch/sparc/kernel/ptrace_64.c
index 7122efb4b1cc..2b92155db8a5 100644
--- a/arch/sparc/kernel/ptrace_64.c
+++ b/arch/sparc/kernel/ptrace_64.c
@@ -246,52 +246,23 @@ enum sparc_regset {
 
 static int genregs64_get(struct task_struct *target,
 			 const struct user_regset *regset,
-			 unsigned int pos, unsigned int count,
-			 void *kbuf, void __user *ubuf)
+			 struct membuf to)
 {
 	const struct pt_regs *regs = task_pt_regs(target);
-	int ret;
+	struct reg_window window;
 
 	if (target == current)
 		flushw_user();
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  regs->u_regs,
-				  0, 16 * sizeof(u64));
-	if (!ret && count && pos < (32 * sizeof(u64))) {
-		struct reg_window window;
-
-		if (regwindow64_get(target, regs, &window))
-			return -EFAULT;
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &window,
-					  16 * sizeof(u64),
-					  32 * sizeof(u64));
-	}
-
-	if (!ret) {
-		/* TSTATE, TPC, TNPC */
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &regs->tstate,
-					  32 * sizeof(u64),
-					  35 * sizeof(u64));
-	}
-
-	if (!ret) {
-		unsigned long y = regs->y;
-
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &y,
-					  35 * sizeof(u64),
-					  36 * sizeof(u64));
-	}
-
-	if (!ret) {
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					       36 * sizeof(u64), -1);
-
-	}
-	return ret;
+	membuf_write(&to, regs->u_regs, 16 * sizeof(u64));
+	if (!to.left)
+		return 0;
+	if (regwindow64_get(target, regs, &window))
+		return -EFAULT;
+	membuf_write(&to, &window, 16 * sizeof(u64));
+	/* TSTATE, TPC, TNPC */
+	membuf_write(&to, &regs->tstate, 3 * sizeof(u64));
+	return membuf_store(&to, (u64)regs->y);
 }
 
 static int genregs64_set(struct task_struct *target,
@@ -370,69 +341,32 @@ static int genregs64_set(struct task_struct *target,
 
 static int fpregs64_get(struct task_struct *target,
 			const struct user_regset *regset,
-			unsigned int pos, unsigned int count,
-			void *kbuf, void __user *ubuf)
+			struct membuf to)
 {
-	const unsigned long *fpregs = task_thread_info(target)->fpregs;
-	unsigned long fprs, fsr, gsr;
-	int ret;
+	struct thread_info *t = task_thread_info(target);
+	unsigned long fprs;
 
 	if (target == current)
 		save_and_clear_fpu();
 
-	fprs = task_thread_info(target)->fpsaved[0];
+	fprs = t->fpsaved[0];
 
 	if (fprs & FPRS_DL)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  fpregs,
-					  0, 16 * sizeof(u64));
+		membuf_write(&to, t->fpregs, 16 * sizeof(u64));
 	else
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					       0,
-					       16 * sizeof(u64));
-
-	if (!ret) {
-		if (fprs & FPRS_DU)
-			ret = user_regset_copyout(&pos, &count,
-						  &kbuf, &ubuf,
-						  fpregs + 16,
-						  16 * sizeof(u64),
-						  32 * sizeof(u64));
-		else
-			ret = user_regset_copyout_zero(&pos, &count,
-						       &kbuf, &ubuf,
-						       16 * sizeof(u64),
-						       32 * sizeof(u64));
-	}
+		membuf_zero(&to, 16 * sizeof(u64));
 
+	if (fprs & FPRS_DU)
+		membuf_write(&to, t->fpregs + 16, 16 * sizeof(u64));
+	else
+		membuf_zero(&to, 16 * sizeof(u64));
 	if (fprs & FPRS_FEF) {
-		fsr = task_thread_info(target)->xfsr[0];
-		gsr = task_thread_info(target)->gsr[0];
+		membuf_store(&to, t->xfsr[0]);
+		membuf_store(&to, t->gsr[0]);
 	} else {
-		fsr = gsr = 0;
+		membuf_zero(&to, 2 * sizeof(u64));
 	}
-
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &fsr,
-					  32 * sizeof(u64),
-					  33 * sizeof(u64));
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &gsr,
-					  33 * sizeof(u64),
-					  34 * sizeof(u64));
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &fprs,
-					  34 * sizeof(u64),
-					  35 * sizeof(u64));
-
-	if (!ret)
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					       35 * sizeof(u64), -1);
-
-	return ret;
+	return membuf_store(&to, fprs);
 }
 
 static int fpregs64_set(struct task_struct *target,
@@ -490,7 +424,7 @@ static const struct user_regset sparc64_regsets[] = {
 		.core_note_type = NT_PRSTATUS,
 		.n = 36,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.get = genregs64_get, .set = genregs64_set
+		.regset_get = genregs64_get, .set = genregs64_set
 	},
 	/* Format is:
 	 *	F0 --> F63
@@ -502,10 +436,96 @@ static const struct user_regset sparc64_regsets[] = {
 		.core_note_type = NT_PRFPREG,
 		.n = 35,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.get = fpregs64_get, .set = fpregs64_set
+		.regset_get = fpregs64_get, .set = fpregs64_set
+	},
+};
+
+static int getregs64_get(struct task_struct *target,
+			 const struct user_regset *regset,
+			 struct membuf to)
+{
+	const struct pt_regs *regs = task_pt_regs(target);
+
+	if (target == current)
+		flushw_user();
+
+	membuf_write(&to, regs->u_regs + 1, 15 * sizeof(u64));
+	membuf_store(&to, (u64)0);
+	membuf_write(&to, &regs->tstate, 3 * sizeof(u64));
+	return membuf_store(&to, (u64)regs->y);
+}
+
+static int setregs64_set(struct task_struct *target,
+			 const struct user_regset *regset,
+			 unsigned int pos, unsigned int count,
+			 const void *kbuf, const void __user *ubuf)
+{
+	struct pt_regs *regs = task_pt_regs(target);
+	unsigned long y = regs->y;
+	unsigned long tstate;
+	int ret;
+
+	if (target == current)
+		flushw_user();
+
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 regs->u_regs + 1,
+				 0 * sizeof(u64),
+				 15 * sizeof(u64));
+	if (ret)
+		return ret;
+	ret =user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
+				 15 * sizeof(u64), 16 * sizeof(u64));
+	if (ret)
+		return ret;
+	/* TSTATE */
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 &tstate,
+				 16 * sizeof(u64),
+				 17 * sizeof(u64));
+	if (ret)
+		return ret;
+	/* Only the condition codes and the "in syscall"
+	 * state can be modified in the %tstate register.
+	 */
+	tstate &= (TSTATE_ICC | TSTATE_XCC | TSTATE_SYSCALL);
+	regs->tstate &= ~(TSTATE_ICC | TSTATE_XCC | TSTATE_SYSCALL);
+	regs->tstate |= tstate;
+
+	/* TPC, TNPC */
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 &regs->tpc,
+				 17 * sizeof(u64),
+				 19 * sizeof(u64));
+	if (ret)
+		return ret;
+	/* Y */
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 &y,
+				 19 * sizeof(u64),
+				 20 * sizeof(u64));
+	if (!ret)
+		regs->y = y;
+	return ret;
+}
+
+static const struct user_regset ptrace64_regsets[] = {
+	/* Format is:
+	 *      G1 --> G7
+	 *      O0 --> O7
+	 *	0
+	 *      TSTATE, TPC, TNPC, Y
+	 */
+	[REGSET_GENERAL] = {
+		.n = 20, .size = sizeof(u64),
+		.regset_get = getregs64_get, .set = setregs64_set,
 	},
 };
 
+static const struct user_regset_view ptrace64_view = {
+	.regsets = ptrace64_regsets, .n = ARRAY_SIZE(ptrace64_regsets)
+};
+
 static const struct user_regset_view user_sparc64_view = {
 	.name = "sparc64", .e_machine = EM_SPARCV9,
 	.regsets = sparc64_regsets, .n = ARRAY_SIZE(sparc64_regsets)
@@ -514,108 +534,28 @@ static const struct user_regset_view user_sparc64_view = {
 #ifdef CONFIG_COMPAT
 static int genregs32_get(struct task_struct *target,
 			 const struct user_regset *regset,
-			 unsigned int pos, unsigned int count,
-			 void *kbuf, void __user *ubuf)
+			 struct membuf to)
 {
 	const struct pt_regs *regs = task_pt_regs(target);
-	compat_ulong_t __user *reg_window;
-	compat_ulong_t *k = kbuf;
-	compat_ulong_t __user *u = ubuf;
-	compat_ulong_t reg;
+	u32 uregs[16];
+	int i;
 
 	if (target == current)
 		flushw_user();
 
-	pos /= sizeof(reg);
-	count /= sizeof(reg);
-
-	if (kbuf) {
-		for (; count > 0 && pos < 16; count--)
-			*k++ = regs->u_regs[pos++];
-
-		reg_window = (compat_ulong_t __user *) regs->u_regs[UREG_I6];
-		reg_window -= 16;
-		if (target == current) {
-			for (; count > 0 && pos < 32; count--) {
-				if (get_user(*k++, &reg_window[pos++]))
-					return -EFAULT;
-			}
-		} else {
-			for (; count > 0 && pos < 32; count--) {
-				if (access_process_vm(target,
-						      (unsigned long)
-						      &reg_window[pos],
-						      k, sizeof(*k),
-						      FOLL_FORCE)
-				    != sizeof(*k))
-					return -EFAULT;
-				k++;
-				pos++;
-			}
-		}
-	} else {
-		for (; count > 0 && pos < 16; count--) {
-			if (put_user((compat_ulong_t) regs->u_regs[pos++], u++))
-				return -EFAULT;
-		}
-
-		reg_window = (compat_ulong_t __user *) regs->u_regs[UREG_I6];
-		reg_window -= 16;
-		if (target == current) {
-			for (; count > 0 && pos < 32; count--) {
-				if (get_user(reg, &reg_window[pos++]) ||
-				    put_user(reg, u++))
-					return -EFAULT;
-			}
-		} else {
-			for (; count > 0 && pos < 32; count--) {
-				if (access_process_vm(target,
-						      (unsigned long)
-						      &reg_window[pos++],
-						      &reg, sizeof(reg),
-						      FOLL_FORCE)
-				    != sizeof(reg))
-					return -EFAULT;
-				if (put_user(reg, u++))
-					return -EFAULT;
-			}
-		}
-	}
-	while (count > 0) {
-		switch (pos) {
-		case 32: /* PSR */
-			reg = tstate_to_psr(regs->tstate);
-			break;
-		case 33: /* PC */
-			reg = regs->tpc;
-			break;
-		case 34: /* NPC */
-			reg = regs->tnpc;
-			break;
-		case 35: /* Y */
-			reg = regs->y;
-			break;
-		case 36: /* WIM */
-		case 37: /* TBR */
-			reg = 0;
-			break;
-		default:
-			goto finish;
-		}
-
-		if (kbuf)
-			*k++ = reg;
-		else if (put_user(reg, u++))
-			return -EFAULT;
-		pos++;
-		count--;
-	}
-finish:
-	pos *= sizeof(reg);
-	count *= sizeof(reg);
-
-	return user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					38 * sizeof(reg), -1);
+	for (i = 0; i < 16; i++)
+		membuf_store(&to, (u32)regs->u_regs[i]);
+	if (!to.left)
+		return 0;
+	if (get_from_target(target, regs->u_regs[UREG_I6],
+			    uregs, sizeof(uregs)))
+		return -EFAULT;
+	membuf_write(&to, uregs, 16 * sizeof(u32));
+	membuf_store(&to, (u32)tstate_to_psr(regs->tstate));
+	membuf_store(&to, (u32)(regs->tpc));
+	membuf_store(&to, (u32)(regs->tnpc));
+	membuf_store(&to, (u32)(regs->y));
+	return membuf_zero(&to, 2 * sizeof(u32));
 }
 
 static int genregs32_set(struct task_struct *target,
@@ -737,56 +677,24 @@ finish:
 
 static int fpregs32_get(struct task_struct *target,
 			const struct user_regset *regset,
-			unsigned int pos, unsigned int count,
-			void *kbuf, void __user *ubuf)
+			struct membuf to)
 {
-	const unsigned long *fpregs = task_thread_info(target)->fpregs;
-	compat_ulong_t enabled;
-	unsigned long fprs;
-	compat_ulong_t fsr;
-	int ret = 0;
+	struct thread_info *t = task_thread_info(target);
+	bool enabled;
 
 	if (target == current)
 		save_and_clear_fpu();
 
-	fprs = task_thread_info(target)->fpsaved[0];
-	if (fprs & FPRS_FEF) {
-		fsr = task_thread_info(target)->xfsr[0];
-		enabled = 1;
-	} else {
-		fsr = 0;
-		enabled = 0;
-	}
-
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  fpregs,
-				  0, 32 * sizeof(u32));
-
-	if (!ret)
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					       32 * sizeof(u32),
-					       33 * sizeof(u32));
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &fsr,
-					  33 * sizeof(u32),
-					  34 * sizeof(u32));
-
-	if (!ret) {
-		compat_ulong_t val;
-
-		val = (enabled << 8) | (8 << 16);
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  &val,
-					  34 * sizeof(u32),
-					  35 * sizeof(u32));
-	}
+	enabled = t->fpsaved[0] & FPRS_FEF;
 
-	if (!ret)
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					       35 * sizeof(u32), -1);
-
-	return ret;
+	membuf_write(&to, t->fpregs, 32 * sizeof(u32));
+	membuf_zero(&to, sizeof(u32));
+	if (enabled)
+		membuf_store(&to, (u32)t->xfsr[0]);
+	else
+		membuf_zero(&to, sizeof(u32));
+	membuf_store(&to, (u32)((enabled << 8) | (8 << 16)));
+	return membuf_zero(&to, 64 * sizeof(u32));
 }
 
 static int fpregs32_set(struct task_struct *target,
@@ -847,7 +755,7 @@ static const struct user_regset sparc32_regsets[] = {
 		.core_note_type = NT_PRSTATUS,
 		.n = 38,
 		.size = sizeof(u32), .align = sizeof(u32),
-		.get = genregs32_get, .set = genregs32_set
+		.regset_get = genregs32_get, .set = genregs32_set
 	},
 	/* Format is:
 	 *	F0 --> F31
@@ -863,10 +771,133 @@ static const struct user_regset sparc32_regsets[] = {
 		.core_note_type = NT_PRFPREG,
 		.n = 99,
 		.size = sizeof(u32), .align = sizeof(u32),
-		.get = fpregs32_get, .set = fpregs32_set
+		.regset_get = fpregs32_get, .set = fpregs32_set
 	},
 };
 
+static int getregs_get(struct task_struct *target,
+			 const struct user_regset *regset,
+			 struct membuf to)
+{
+	const struct pt_regs *regs = task_pt_regs(target);
+	int i;
+
+	if (target == current)
+		flushw_user();
+
+	membuf_store(&to, (u32)tstate_to_psr(regs->tstate));
+	membuf_store(&to, (u32)(regs->tpc));
+	membuf_store(&to, (u32)(regs->tnpc));
+	membuf_store(&to, (u32)(regs->y));
+	for (i = 1; i < 16; i++)
+		membuf_store(&to, (u32)regs->u_regs[i]);
+	return to.left;
+}
+
+static int setregs_set(struct task_struct *target,
+			 const struct user_regset *regset,
+			 unsigned int pos, unsigned int count,
+			 const void *kbuf, const void __user *ubuf)
+{
+	struct pt_regs *regs = task_pt_regs(target);
+	unsigned long tstate;
+	u32 uregs[19];
+	int i, ret;
+
+	if (target == current)
+		flushw_user();
+
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 uregs,
+				 0, 19 * sizeof(u32));
+	if (ret)
+		return ret;
+
+	tstate = regs->tstate;
+	tstate &= ~(TSTATE_ICC | TSTATE_XCC | TSTATE_SYSCALL);
+	tstate |= psr_to_tstate_icc(uregs[0]);
+	if (uregs[0] & PSR_SYSCALL)
+		tstate |= TSTATE_SYSCALL;
+	regs->tstate = tstate;
+	regs->tpc = uregs[1];
+	regs->tnpc = uregs[2];
+	regs->y = uregs[3];
+
+	for (i = 1; i < 15; i++)
+		regs->u_regs[i] = uregs[3 + i];
+	return 0;
+}
+
+static int getfpregs_get(struct task_struct *target,
+			const struct user_regset *regset,
+			struct membuf to)
+{
+	struct thread_info *t = task_thread_info(target);
+
+	if (target == current)
+		save_and_clear_fpu();
+
+	membuf_write(&to, t->fpregs, 32 * sizeof(u32));
+	if (t->fpsaved[0] & FPRS_FEF)
+		membuf_store(&to, (u32)t->xfsr[0]);
+	else
+		membuf_zero(&to, sizeof(u32));
+	return membuf_zero(&to, 35 * sizeof(u32));
+}
+
+static int setfpregs_set(struct task_struct *target,
+			const struct user_regset *regset,
+			unsigned int pos, unsigned int count,
+			const void *kbuf, const void __user *ubuf)
+{
+	unsigned long *fpregs = task_thread_info(target)->fpregs;
+	unsigned long fprs;
+	int ret;
+
+	if (target == current)
+		save_and_clear_fpu();
+
+	fprs = task_thread_info(target)->fpsaved[0];
+
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 fpregs,
+				 0, 32 * sizeof(u32));
+	if (!ret) {
+		compat_ulong_t fsr;
+		unsigned long val;
+
+		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+					 &fsr,
+					 32 * sizeof(u32),
+					 33 * sizeof(u32));
+		if (!ret) {
+			val = task_thread_info(target)->xfsr[0];
+			val &= 0xffffffff00000000UL;
+			val |= fsr;
+			task_thread_info(target)->xfsr[0] = val;
+		}
+	}
+
+	fprs |= (FPRS_FEF | FPRS_DL);
+	task_thread_info(target)->fpsaved[0] = fprs;
+	return ret;
+}
+
+static const struct user_regset ptrace32_regsets[] = {
+	[REGSET_GENERAL] = {
+		.n = 19, .size = sizeof(u32),
+		.regset_get = getregs_get, .set = setregs_set,
+	},
+	[REGSET_FP] = {
+		.n = 68, .size = sizeof(u32),
+		.regset_get = getfpregs_get, .set = setfpregs_set,
+	},
+};
+
+static const struct user_regset_view ptrace32_view = {
+	.regsets = ptrace32_regsets, .n = ARRAY_SIZE(ptrace32_regsets)
+};
+
 static const struct user_regset_view user_sparc32_view = {
 	.name = "sparc", .e_machine = EM_SPARC,
 	.regsets = sparc32_regsets, .n = ARRAY_SIZE(sparc32_regsets)
@@ -898,7 +929,6 @@ struct compat_fps {
 long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 			compat_ulong_t caddr, compat_ulong_t cdata)
 {
-	const struct user_regset_view *view = task_user_regset_view(current);
 	compat_ulong_t caddr2 = task_pt_regs(current)->u_regs[UREG_I4];
 	struct pt_regs32 __user *pregs;
 	struct compat_fps __user *fps;
@@ -916,58 +946,31 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 		break;
 
 	case PTRACE_GETREGS:
-		ret = copy_regset_to_user(child, view, REGSET_GENERAL,
-					  32 * sizeof(u32),
-					  4 * sizeof(u32),
-					  &pregs->psr);
-		if (!ret)
-			ret = copy_regset_to_user(child, view, REGSET_GENERAL,
-						  1 * sizeof(u32),
-						  15 * sizeof(u32),
-						  &pregs->u_regs[0]);
+		ret = copy_regset_to_user(child, &ptrace32_view,
+					  REGSET_GENERAL, 0,
+					  19 * sizeof(u32),
+					  pregs);
 		break;
 
 	case PTRACE_SETREGS:
-		ret = copy_regset_from_user(child, view, REGSET_GENERAL,
-					    32 * sizeof(u32),
-					    4 * sizeof(u32),
-					    &pregs->psr);
-		if (!ret)
-			ret = copy_regset_from_user(child, view, REGSET_GENERAL,
-						    1 * sizeof(u32),
-						    15 * sizeof(u32),
-						    &pregs->u_regs[0]);
+		ret = copy_regset_from_user(child, &ptrace32_view,
+					  REGSET_GENERAL, 0,
+					  19 * sizeof(u32),
+					  pregs);
 		break;
 
 	case PTRACE_GETFPREGS:
-		ret = copy_regset_to_user(child, view, REGSET_FP,
-					  0 * sizeof(u32),
-					  32 * sizeof(u32),
-					  &fps->regs[0]);
-		if (!ret)
-			ret = copy_regset_to_user(child, view, REGSET_FP,
-						  33 * sizeof(u32),
-						  1 * sizeof(u32),
-						  &fps->fsr);
-		if (!ret) {
-			if (__put_user(0, &fps->flags) ||
-			    __put_user(0, &fps->extra) ||
-			    __put_user(0, &fps->fpqd) ||
-			    clear_user(&fps->fpq[0], 32 * sizeof(unsigned int)))
-				ret = -EFAULT;
-		}
+		ret = copy_regset_to_user(child, &ptrace32_view,
+					  REGSET_FP, 0,
+					  68 * sizeof(u32),
+					  fps);
 		break;
 
 	case PTRACE_SETFPREGS:
-		ret = copy_regset_from_user(child, view, REGSET_FP,
-					    0 * sizeof(u32),
-					    32 * sizeof(u32),
-					    &fps->regs[0]);
-		if (!ret)
-			ret = copy_regset_from_user(child, view, REGSET_FP,
-						    33 * sizeof(u32),
-						    1 * sizeof(u32),
-						    &fps->fsr);
+		ret = copy_regset_from_user(child, &ptrace32_view,
+					  REGSET_FP, 0,
+					  33 * sizeof(u32),
+					  fps);
 		break;
 
 	case PTRACE_READTEXT:
@@ -1026,31 +1029,17 @@ long arch_ptrace(struct task_struct *child, long request,
 		break;
 
 	case PTRACE_GETREGS64:
-		ret = copy_regset_to_user(child, view, REGSET_GENERAL,
-					  1 * sizeof(u64),
-					  15 * sizeof(u64),
-					  &pregs->u_regs[0]);
-		if (!ret) {
-			/* XXX doesn't handle 'y' register correctly XXX */
-			ret = copy_regset_to_user(child, view, REGSET_GENERAL,
-						  32 * sizeof(u64),
-						  4 * sizeof(u64),
-						  &pregs->tstate);
-		}
+		ret = copy_regset_to_user(child, &ptrace64_view,
+					  REGSET_GENERAL, 0,
+					  19 * sizeof(u64),
+					  pregs);
 		break;
 
 	case PTRACE_SETREGS64:
-		ret = copy_regset_from_user(child, view, REGSET_GENERAL,
-					    1 * sizeof(u64),
-					    15 * sizeof(u64),
-					    &pregs->u_regs[0]);
-		if (!ret) {
-			/* XXX doesn't handle 'y' register correctly XXX */
-			ret = copy_regset_from_user(child, view, REGSET_GENERAL,
-						    32 * sizeof(u64),
-						    4 * sizeof(u64),
-						    &pregs->tstate);
-		}
+		ret = copy_regset_from_user(child, &ptrace64_view,
+					  REGSET_GENERAL, 0,
+					  19 * sizeof(u64),
+					  pregs);
 		break;
 
 	case PTRACE_GETFPREGS64:
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 6b10cdaa7c96..0a460f2a3f90 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -34,7 +34,6 @@ extern int  fpu__copy(struct task_struct *dst, struct task_struct *src);
 extern void fpu__clear_user_states(struct fpu *fpu);
 extern void fpu__clear_all(struct fpu *fpu);
 extern int  fpu__exception_code(struct fpu *fpu, int trap_nr);
-extern int  dump_fpu(struct pt_regs *ptregs, struct user_i387_struct *fpstate);
 
 /*
  * Boot time FPU initialization functions:
diff --git a/arch/x86/include/asm/fpu/regset.h b/arch/x86/include/asm/fpu/regset.h
index d5bdffb9d27f..4f928d6a367b 100644
--- a/arch/x86/include/asm/fpu/regset.h
+++ b/arch/x86/include/asm/fpu/regset.h
@@ -8,8 +8,8 @@
 #include <linux/regset.h>
 
 extern user_regset_active_fn regset_fpregs_active, regset_xregset_fpregs_active;
-extern user_regset_get_fn fpregs_get, xfpregs_get, fpregs_soft_get,
-				xstateregs_get;
+extern user_regset_get2_fn fpregs_get, xfpregs_get, fpregs_soft_get,
+				 xstateregs_get;
 extern user_regset_set_fn fpregs_set, xfpregs_set, fpregs_soft_set,
 				 xstateregs_set;
 
diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index 1559554af931..14ab815132d4 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -104,8 +104,8 @@ void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr);
 const void *get_xsave_field_ptr(int xfeature_nr);
 int using_compacted_format(void);
 int xfeature_size(int xfeature_nr);
-int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset, unsigned int size);
-int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset, unsigned int size);
+struct membuf;
+void copy_xstate_to_kernel(struct membuf to, struct xregs_state *xsave);
 int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf);
 int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf);
 void copy_supervisor_to_kernel(struct xregs_state *xsave);
diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index bd1d0649f8ce..c413756ba89f 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -27,8 +27,7 @@ int regset_xregset_fpregs_active(struct task_struct *target, const struct user_r
 }
 
 int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
-		unsigned int pos, unsigned int count,
-		void *kbuf, void __user *ubuf)
+		struct membuf to)
 {
 	struct fpu *fpu = &target->thread.fpu;
 
@@ -38,8 +37,7 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
 	fpu__prepare_read(fpu);
 	fpstate_sanitize_xstate(fpu);
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &fpu->state.fxsave, 0, -1);
+	return membuf_write(&to, &fpu->state.fxsave, sizeof(struct fxregs_state));
 }
 
 int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
@@ -74,12 +72,10 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
 }
 
 int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
-		unsigned int pos, unsigned int count,
-		void *kbuf, void __user *ubuf)
+		struct membuf to)
 {
 	struct fpu *fpu = &target->thread.fpu;
 	struct xregs_state *xsave;
-	int ret;
 
 	if (!boot_cpu_has(X86_FEATURE_XSAVE))
 		return -ENODEV;
@@ -89,10 +85,8 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
 	fpu__prepare_read(fpu);
 
 	if (using_compacted_format()) {
-		if (kbuf)
-			ret = copy_xstate_to_kernel(kbuf, xsave, pos, count);
-		else
-			ret = copy_xstate_to_user(ubuf, xsave, pos, count);
+		copy_xstate_to_kernel(to, xsave);
+		return 0;
 	} else {
 		fpstate_sanitize_xstate(fpu);
 		/*
@@ -105,9 +99,8 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
 		/*
 		 * Copy the xstate memory layout.
 		 */
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
+		return membuf_write(&to, xsave, fpu_user_xstate_size);
 	}
-	return ret;
 }
 
 int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
@@ -293,8 +286,7 @@ void convert_to_fxsr(struct fxregs_state *fxsave,
 }
 
 int fpregs_get(struct task_struct *target, const struct user_regset *regset,
-	       unsigned int pos, unsigned int count,
-	       void *kbuf, void __user *ubuf)
+	       struct membuf to)
 {
 	struct fpu *fpu = &target->thread.fpu;
 	struct user_i387_ia32_struct env;
@@ -302,23 +294,22 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
 	fpu__prepare_read(fpu);
 
 	if (!boot_cpu_has(X86_FEATURE_FPU))
-		return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
+		return fpregs_soft_get(target, regset, to);
 
-	if (!boot_cpu_has(X86_FEATURE_FXSR))
-		return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					   &fpu->state.fsave, 0,
-					   -1);
+	if (!boot_cpu_has(X86_FEATURE_FXSR)) {
+		return membuf_write(&to, &fpu->state.fsave,
+				    sizeof(struct fregs_state));
+	}
 
 	fpstate_sanitize_xstate(fpu);
 
-	if (kbuf && pos == 0 && count == sizeof(env)) {
-		convert_from_fxsr(kbuf, target);
+	if (to.left == sizeof(env)) {
+		convert_from_fxsr(to.p, target);
 		return 0;
 	}
 
 	convert_from_fxsr(&env, target);
-
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &env, 0, -1);
+	return membuf_write(&to, &env, sizeof(env));
 }
 
 int fpregs_set(struct task_struct *target, const struct user_regset *regset,
@@ -356,20 +347,4 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
 	return ret;
 }
 
-/*
- * FPU state for core dumps.
- * This is only used for a.out dumps now.
- * It is declared generically using elf_fpregset_t (which is
- * struct user_i387_struct) but is in fact only used for 32-bit
- * dumps, so on 64-bit it is really struct user_i387_ia32_struct.
- */
-int dump_fpu(struct pt_regs *regs, struct user_i387_struct *ufpu)
-{
-	struct task_struct *tsk = current;
-
-	return !fpregs_get(tsk, NULL, 0, sizeof(struct user_i387_ia32_struct),
-			   ufpu, NULL);
-}
-EXPORT_SYMBOL(dump_fpu);
-
 #endif	/* CONFIG_X86_32 || CONFIG_IA32_EMULATION */
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index 9393a445d73c..a4ec65317a7f 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -170,14 +170,15 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
 	ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
 			 IS_ENABLED(CONFIG_IA32_EMULATION));
 
+	if (!static_cpu_has(X86_FEATURE_FPU)) {
+		struct user_i387_ia32_struct fp;
+		fpregs_soft_get(current, NULL, (struct membuf){.p = &fp,
+						.left = sizeof(fp)});
+		return copy_to_user(buf, &fp, sizeof(fp)) ? -EFAULT : 0;
+	}
+
 	if (!access_ok(buf, size))
 		return -EACCES;
-
-	if (!static_cpu_has(X86_FEATURE_FPU))
-		return fpregs_soft_get(current, NULL, 0,
-			sizeof(struct user_i387_ia32_struct), NULL,
-			(struct _fpstate_32 __user *) buf) ? -1 : 1;
-
 retry:
 	/*
 	 * Load the FPU registers if they are not valid for the current task.
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index be2a68a09d19..7a2bf884fede 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1014,32 +1014,20 @@ static inline bool xfeatures_mxcsr_quirk(u64 xfeatures)
 	return true;
 }
 
-static void fill_gap(unsigned to, void **kbuf, unsigned *pos, unsigned *count)
+static void fill_gap(struct membuf *to, unsigned *last, unsigned offset)
 {
-	if (*pos < to) {
-		unsigned size = to - *pos;
-
-		if (size > *count)
-			size = *count;
-		memcpy(*kbuf, (void *)&init_fpstate.xsave + *pos, size);
-		*kbuf += size;
-		*pos += size;
-		*count -= size;
-	}
+	if (*last >= offset)
+		return;
+	membuf_write(to, (void *)&init_fpstate.xsave + *last, offset - *last);
+	*last = offset;
 }
 
-static void copy_part(unsigned offset, unsigned size, void *from,
-			void **kbuf, unsigned *pos, unsigned *count)
+static void copy_part(struct membuf *to, unsigned *last, unsigned offset,
+		      unsigned size, void *from)
 {
-	fill_gap(offset, kbuf, pos, count);
-	if (size > *count)
-		size = *count;
-	if (size) {
-		memcpy(*kbuf, from, size);
-		*kbuf += size;
-		*pos += size;
-		*count -= size;
-	}
+	fill_gap(to, last, offset);
+	membuf_write(to, from, size);
+	*last = offset + size;
 }
 
 /*
@@ -1049,20 +1037,15 @@ static void copy_part(unsigned offset, unsigned size, void *from,
  * It supports partial copy but pos always starts from zero. This is called
  * from xstateregs_get() and there we check the CPU has XSAVES.
  */
-int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total)
+void copy_xstate_to_kernel(struct membuf to, struct xregs_state *xsave)
 {
 	struct xstate_header header;
 	const unsigned off_mxcsr = offsetof(struct fxregs_state, mxcsr);
-	unsigned count = size_total;
+	unsigned size = to.left;
+	unsigned last = 0;
 	int i;
 
 	/*
-	 * Currently copy_regset_to_user() starts from pos 0:
-	 */
-	if (unlikely(offset_start != 0))
-		return -EFAULT;
-
-	/*
 	 * The destination is a ptrace buffer; we put in only user xstates:
 	 */
 	memset(&header, 0, sizeof(header));
@@ -1070,27 +1053,26 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int of
 	header.xfeatures &= xfeatures_mask_user();
 
 	if (header.xfeatures & XFEATURE_MASK_FP)
-		copy_part(0, off_mxcsr,
-			  &xsave->i387, &kbuf, &offset_start, &count);
+		copy_part(&to, &last, 0, off_mxcsr, &xsave->i387);
 	if (header.xfeatures & (XFEATURE_MASK_SSE | XFEATURE_MASK_YMM))
-		copy_part(off_mxcsr, MXCSR_AND_FLAGS_SIZE,
-			  &xsave->i387.mxcsr, &kbuf, &offset_start, &count);
+		copy_part(&to, &last, off_mxcsr,
+			  MXCSR_AND_FLAGS_SIZE, &xsave->i387.mxcsr);
 	if (header.xfeatures & XFEATURE_MASK_FP)
-		copy_part(offsetof(struct fxregs_state, st_space), 128,
-			  &xsave->i387.st_space, &kbuf, &offset_start, &count);
+		copy_part(&to, &last, offsetof(struct fxregs_state, st_space),
+			  128, &xsave->i387.st_space);
 	if (header.xfeatures & XFEATURE_MASK_SSE)
-		copy_part(xstate_offsets[XFEATURE_SSE], 256,
-			  &xsave->i387.xmm_space, &kbuf, &offset_start, &count);
+		copy_part(&to, &last, xstate_offsets[XFEATURE_SSE],
+			  256, &xsave->i387.xmm_space);
 	/*
 	 * Fill xsave->i387.sw_reserved value for ptrace frame:
 	 */
-	copy_part(offsetof(struct fxregs_state, sw_reserved), 48,
-		  xstate_fx_sw_bytes, &kbuf, &offset_start, &count);
+	copy_part(&to, &last, offsetof(struct fxregs_state, sw_reserved),
+		  48, xstate_fx_sw_bytes);
 	/*
 	 * Copy xregs_state->header:
 	 */
-	copy_part(offsetof(struct xregs_state, header), sizeof(header),
-		  &header, &kbuf, &offset_start, &count);
+	copy_part(&to, &last, offsetof(struct xregs_state, header),
+		  sizeof(header), &header);
 
 	for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 		/*
@@ -1099,104 +1081,12 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int of
 		if ((header.xfeatures >> i) & 1) {
 			void *src = __raw_xsave_addr(xsave, i);
 
-			copy_part(xstate_offsets[i], xstate_sizes[i],
-				  src, &kbuf, &offset_start, &count);
+			copy_part(&to, &last, xstate_offsets[i],
+				  xstate_sizes[i], src);
 		}
 
 	}
-	fill_gap(size_total, &kbuf, &offset_start, &count);
-
-	return 0;
-}
-
-static inline int
-__copy_xstate_to_user(void __user *ubuf, const void *data, unsigned int offset, unsigned int size, unsigned int size_total)
-{
-	if (!size)
-		return 0;
-
-	if (offset < size_total) {
-		unsigned int copy = min(size, size_total - offset);
-
-		if (__copy_to_user(ubuf + offset, data, copy))
-			return -EFAULT;
-	}
-	return 0;
-}
-
-/*
- * Convert from kernel XSAVES compacted format to standard format and copy
- * to a user-space buffer. It supports partial copy but pos always starts from
- * zero. This is called from xstateregs_get() and there we check the CPU
- * has XSAVES.
- */
-int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total)
-{
-	unsigned int offset, size;
-	int ret, i;
-	struct xstate_header header;
-
-	/*
-	 * Currently copy_regset_to_user() starts from pos 0:
-	 */
-	if (unlikely(offset_start != 0))
-		return -EFAULT;
-
-	/*
-	 * The destination is a ptrace buffer; we put in only user xstates:
-	 */
-	memset(&header, 0, sizeof(header));
-	header.xfeatures = xsave->header.xfeatures;
-	header.xfeatures &= xfeatures_mask_user();
-
-	/*
-	 * Copy xregs_state->header:
-	 */
-	offset = offsetof(struct xregs_state, header);
-	size = sizeof(header);
-
-	ret = __copy_xstate_to_user(ubuf, &header, offset, size, size_total);
-	if (ret)
-		return ret;
-
-	for (i = 0; i < XFEATURE_MAX; i++) {
-		/*
-		 * Copy only in-use xstates:
-		 */
-		if ((header.xfeatures >> i) & 1) {
-			void *src = __raw_xsave_addr(xsave, i);
-
-			offset = xstate_offsets[i];
-			size = xstate_sizes[i];
-
-			/* The next component has to fit fully into the output buffer: */
-			if (offset + size > size_total)
-				break;
-
-			ret = __copy_xstate_to_user(ubuf, src, offset, size, size_total);
-			if (ret)
-				return ret;
-		}
-
-	}
-
-	if (xfeatures_mxcsr_quirk(header.xfeatures)) {
-		offset = offsetof(struct fxregs_state, mxcsr);
-		size = MXCSR_AND_FLAGS_SIZE;
-		__copy_xstate_to_user(ubuf, &xsave->i387.mxcsr, offset, size, size_total);
-	}
-
-	/*
-	 * Fill xsave->i387.sw_reserved value for ptrace frame:
-	 */
-	offset = offsetof(struct fxregs_state, sw_reserved);
-	size = sizeof(xstate_fx_sw_bytes);
-
-	ret = __copy_xstate_to_user(ubuf, xstate_fx_sw_bytes, offset, size, size_total);
-	if (ret)
-		return ret;
-
-	return 0;
+	fill_gap(&to, &last, size);
 }
 
 /*
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 3f006489087f..5679aa3fdcb8 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -412,26 +412,12 @@ static unsigned long getreg(struct task_struct *task, unsigned long offset)
 
 static int genregs_get(struct task_struct *target,
 		       const struct user_regset *regset,
-		       unsigned int pos, unsigned int count,
-		       void *kbuf, void __user *ubuf)
+		       struct membuf to)
 {
-	if (kbuf) {
-		unsigned long *k = kbuf;
-		while (count >= sizeof(*k)) {
-			*k++ = getreg(target, pos);
-			count -= sizeof(*k);
-			pos += sizeof(*k);
-		}
-	} else {
-		unsigned long __user *u = ubuf;
-		while (count >= sizeof(*u)) {
-			if (__put_user(getreg(target, pos), u++))
-				return -EFAULT;
-			count -= sizeof(*u);
-			pos += sizeof(*u);
-		}
-	}
+	int reg;
 
+	for (reg = 0; to.left; reg++)
+		membuf_store(&to, getreg(target, reg * sizeof(unsigned long)));
 	return 0;
 }
 
@@ -695,16 +681,14 @@ static int ioperm_active(struct task_struct *target,
 
 static int ioperm_get(struct task_struct *target,
 		      const struct user_regset *regset,
-		      unsigned int pos, unsigned int count,
-		      void *kbuf, void __user *ubuf)
+		      struct membuf to)
 {
 	struct io_bitmap *iobm = target->thread.io_bitmap;
 
 	if (!iobm)
 		return -ENXIO;
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   iobm->bitmap, 0, IO_BITMAP_BYTES);
+	return membuf_write(&to, iobm->bitmap, IO_BITMAP_BYTES);
 }
 
 /*
@@ -1007,28 +991,15 @@ static int getreg32(struct task_struct *child, unsigned regno, u32 *val)
 
 static int genregs32_get(struct task_struct *target,
 			 const struct user_regset *regset,
-			 unsigned int pos, unsigned int count,
-			 void *kbuf, void __user *ubuf)
+			 struct membuf to)
 {
-	if (kbuf) {
-		compat_ulong_t *k = kbuf;
-		while (count >= sizeof(*k)) {
-			getreg32(target, pos, k++);
-			count -= sizeof(*k);
-			pos += sizeof(*k);
-		}
-	} else {
-		compat_ulong_t __user *u = ubuf;
-		while (count >= sizeof(*u)) {
-			compat_ulong_t word;
-			getreg32(target, pos, &word);
-			if (__put_user(word, u++))
-				return -EFAULT;
-			count -= sizeof(*u);
-			pos += sizeof(*u);
-		}
-	}
+	int reg;
 
+	for (reg = 0; to.left; reg++) {
+		u32 val;
+		getreg32(target, reg * 4, &val);
+		membuf_store(&to, val);
+	}
 	return 0;
 }
 
@@ -1238,25 +1209,25 @@ static struct user_regset x86_64_regsets[] __ro_after_init = {
 		.core_note_type = NT_PRSTATUS,
 		.n = sizeof(struct user_regs_struct) / sizeof(long),
 		.size = sizeof(long), .align = sizeof(long),
-		.get = genregs_get, .set = genregs_set
+		.regset_get = genregs_get, .set = genregs_set
 	},
 	[REGSET_FP] = {
 		.core_note_type = NT_PRFPREG,
 		.n = sizeof(struct user_i387_struct) / sizeof(long),
 		.size = sizeof(long), .align = sizeof(long),
-		.active = regset_xregset_fpregs_active, .get = xfpregs_get, .set = xfpregs_set
+		.active = regset_xregset_fpregs_active, .regset_get = xfpregs_get, .set = xfpregs_set
 	},
 	[REGSET_XSTATE] = {
 		.core_note_type = NT_X86_XSTATE,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.active = xstateregs_active, .get = xstateregs_get,
+		.active = xstateregs_active, .regset_get = xstateregs_get,
 		.set = xstateregs_set
 	},
 	[REGSET_IOPERM64] = {
 		.core_note_type = NT_386_IOPERM,
 		.n = IO_BITMAP_LONGS,
 		.size = sizeof(long), .align = sizeof(long),
-		.active = ioperm_active, .get = ioperm_get
+		.active = ioperm_active, .regset_get = ioperm_get
 	},
 };
 
@@ -1279,24 +1250,24 @@ static struct user_regset x86_32_regsets[] __ro_after_init = {
 		.core_note_type = NT_PRSTATUS,
 		.n = sizeof(struct user_regs_struct32) / sizeof(u32),
 		.size = sizeof(u32), .align = sizeof(u32),
-		.get = genregs32_get, .set = genregs32_set
+		.regset_get = genregs32_get, .set = genregs32_set
 	},
 	[REGSET_FP] = {
 		.core_note_type = NT_PRFPREG,
 		.n = sizeof(struct user_i387_ia32_struct) / sizeof(u32),
 		.size = sizeof(u32), .align = sizeof(u32),
-		.active = regset_fpregs_active, .get = fpregs_get, .set = fpregs_set
+		.active = regset_fpregs_active, .regset_get = fpregs_get, .set = fpregs_set
 	},
 	[REGSET_XFP] = {
 		.core_note_type = NT_PRXFPREG,
 		.n = sizeof(struct user32_fxsr_struct) / sizeof(u32),
 		.size = sizeof(u32), .align = sizeof(u32),
-		.active = regset_xregset_fpregs_active, .get = xfpregs_get, .set = xfpregs_set
+		.active = regset_xregset_fpregs_active, .regset_get = xfpregs_get, .set = xfpregs_set
 	},
 	[REGSET_XSTATE] = {
 		.core_note_type = NT_X86_XSTATE,
 		.size = sizeof(u64), .align = sizeof(u64),
-		.active = xstateregs_active, .get = xstateregs_get,
+		.active = xstateregs_active, .regset_get = xstateregs_get,
 		.set = xstateregs_set
 	},
 	[REGSET_TLS] = {
@@ -1305,13 +1276,13 @@ static struct user_regset x86_32_regsets[] __ro_after_init = {
 		.size = sizeof(struct user_desc),
 		.align = sizeof(struct user_desc),
 		.active = regset_tls_active,
-		.get = regset_tls_get, .set = regset_tls_set
+		.regset_get = regset_tls_get, .set = regset_tls_set
 	},
 	[REGSET_IOPERM32] = {
 		.core_note_type = NT_386_IOPERM,
 		.n = IO_BITMAP_BYTES / sizeof(u32),
 		.size = sizeof(u32), .align = sizeof(u32),
-		.active = ioperm_active, .get = ioperm_get
+		.active = ioperm_active, .regset_get = ioperm_get
 	},
 };
 
diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c
index 71d3fef1edc9..64a496a0687f 100644
--- a/arch/x86/kernel/tls.c
+++ b/arch/x86/kernel/tls.c
@@ -256,36 +256,16 @@ int regset_tls_active(struct task_struct *target,
 }
 
 int regset_tls_get(struct task_struct *target, const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
 	const struct desc_struct *tls;
+	struct user_desc v;
+	int pos;
 
-	if (pos >= GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) ||
-	    (pos % sizeof(struct user_desc)) != 0 ||
-	    (count % sizeof(struct user_desc)) != 0)
-		return -EINVAL;
-
-	pos /= sizeof(struct user_desc);
-	count /= sizeof(struct user_desc);
-
-	tls = &target->thread.tls_array[pos];
-
-	if (kbuf) {
-		struct user_desc *info = kbuf;
-		while (count-- > 0)
-			fill_user_desc(info++, GDT_ENTRY_TLS_MIN + pos++,
-				       tls++);
-	} else {
-		struct user_desc __user *u_info = ubuf;
-		while (count-- > 0) {
-			struct user_desc info;
-			fill_user_desc(&info, GDT_ENTRY_TLS_MIN + pos++, tls++);
-			if (__copy_to_user(u_info++, &info, sizeof(info)))
-				return -EFAULT;
-		}
+	for (pos = 0, tls = target->thread.tls_array; to.left; pos++, tls++) {
+		fill_user_desc(&v, GDT_ENTRY_TLS_MIN + pos, tls);
+		membuf_write(&to, &v, sizeof(v));
 	}
-
 	return 0;
 }
 
diff --git a/arch/x86/kernel/tls.h b/arch/x86/kernel/tls.h
index 3a76e1d3535e..fc39447a0c1a 100644
--- a/arch/x86/kernel/tls.h
+++ b/arch/x86/kernel/tls.h
@@ -12,7 +12,7 @@
 #include <linux/regset.h>
 
 extern user_regset_active_fn regset_tls_active;
-extern user_regset_get_fn regset_tls_get;
+extern user_regset_get2_fn regset_tls_get;
 extern user_regset_set_fn regset_tls_set;
 
 #endif	/* _ARCH_X86_KERNEL_TLS_H */
diff --git a/arch/x86/math-emu/fpu_entry.c b/arch/x86/math-emu/fpu_entry.c
index a873da6b46d6..8679a9d6c47f 100644
--- a/arch/x86/math-emu/fpu_entry.c
+++ b/arch/x86/math-emu/fpu_entry.c
@@ -689,12 +689,10 @@ int fpregs_soft_set(struct task_struct *target,
 
 int fpregs_soft_get(struct task_struct *target,
 		    const struct user_regset *regset,
-		    unsigned int pos, unsigned int count,
-		    void *kbuf, void __user *ubuf)
+		    struct membuf to)
 {
 	struct swregs_state *s387 = &target->thread.fpu.state.soft;
 	const void *space = s387->st_space;
-	int ret;
 	int offset = (S387->ftop & 7) * 10, other = 80 - offset;
 
 	RE_ENTRANT_CHECK_OFF;
@@ -709,18 +707,11 @@ int fpregs_soft_get(struct task_struct *target,
 	S387->fos |= 0xffff0000;
 #endif /* PECULIAR_486 */
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, s387, 0,
-				  offsetof(struct swregs_state, st_space));
-
-	/* Copy all registers in stack order. */
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  space + offset, 0, other);
-	if (!ret)
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  space, 0, offset);
+	membuf_write(&to, s387, offsetof(struct swregs_state, st_space));
+	membuf_write(&to, space + offset, other);
+	membuf_write(&to, space, offset);
 
 	RE_ENTRANT_CHECK_ON;
 
-	return ret;
+	return 0;
 }
diff --git a/arch/xtensa/kernel/ptrace.c b/arch/xtensa/kernel/ptrace.c
index ce4a32bd2294..bb3f4797d212 100644
--- a/arch/xtensa/kernel/ptrace.c
+++ b/arch/xtensa/kernel/ptrace.c
@@ -39,8 +39,7 @@
 
 static int gpr_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
 	struct pt_regs *regs = task_pt_regs(target);
 	struct user_pt_regs newregs = {
@@ -63,8 +62,7 @@ static int gpr_get(struct task_struct *target,
 	       regs->areg,
 	       (WSBITS - regs->windowbase) * 16);
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &newregs, 0, -1);
+	return membuf_write(&to, &newregs, sizeof(newregs));
 }
 
 static int gpr_set(struct task_struct *target,
@@ -121,8 +119,7 @@ static int gpr_set(struct task_struct *target,
 
 static int tie_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
 	int ret;
 	struct pt_regs *regs = task_pt_regs(target);
@@ -147,8 +144,7 @@ static int tie_get(struct task_struct *target,
 	newregs->cp6 = ti->xtregs_cp.cp6;
 	newregs->cp7 = ti->xtregs_cp.cp7;
 #endif
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  newregs, 0, -1);
+	ret = membuf_write(&to, newregs, sizeof(*newregs));
 	kfree(newregs);
 	return ret;
 }
@@ -203,7 +199,7 @@ static const struct user_regset xtensa_regsets[] = {
 		.n = sizeof(struct user_pt_regs) / sizeof(u32),
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = gpr_get,
+		.regset_get = gpr_get,
 		.set = gpr_set,
 	},
 	[REGSET_TIE] = {
@@ -211,7 +207,7 @@ static const struct user_regset xtensa_regsets[] = {
 		.n = sizeof(elf_xtregs_t) / sizeof(u32),
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = tie_get,
+		.regset_get = tie_get,
 		.set = tie_set,
 	},
 };
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 9fe3b51c116a..e922a6abdca8 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1821,7 +1821,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
 				 long signr, size_t *total)
 {
 	unsigned int i;
-	unsigned int regset0_size = regset_size(t->task, &view->regsets[0]);
+	int regset0_size;
 
 	/*
 	 * NT_PRSTATUS is the one special case, because the regset data
@@ -1830,8 +1830,10 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
 	 * We assume that regset 0 is NT_PRSTATUS.
 	 */
 	fill_prstatus(&t->prstatus, t->task, signr);
-	(void) view->regsets[0].get(t->task, &view->regsets[0], 0, regset0_size,
-				    &t->prstatus.pr_reg, NULL);
+	regset0_size = regset_get(t->task, &view->regsets[0],
+		   sizeof(t->prstatus.pr_reg), &t->prstatus.pr_reg);
+	if (regset0_size < 0)
+		return 0;
 
 	fill_note(&t->notes[0], "CORE", NT_PRSTATUS,
 		  PRSTATUS_SIZE(t->prstatus, regset0_size), &t->prstatus);
@@ -1846,32 +1848,28 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
 	 */
 	for (i = 1; i < view->n; ++i) {
 		const struct user_regset *regset = &view->regsets[i];
+		int note_type = regset->core_note_type;
+		bool is_fpreg = note_type == NT_PRFPREG;
+		void *data;
+		int ret;
+
 		do_thread_regset_writeback(t->task, regset);
-		if (regset->core_note_type && regset->get &&
-		    (!regset->active || regset->active(t->task, regset) > 0)) {
-			int ret;
-			size_t size = regset_size(t->task, regset);
-			void *data = kzalloc(size, GFP_KERNEL);
-			if (unlikely(!data))
-				return 0;
-			ret = regset->get(t->task, regset,
-					  0, size, data, NULL);
-			if (unlikely(ret))
-				kfree(data);
-			else {
-				if (regset->core_note_type != NT_PRFPREG)
-					fill_note(&t->notes[i], "LINUX",
-						  regset->core_note_type,
-						  size, data);
-				else {
-					SET_PR_FPVALID(&t->prstatus,
-							1, regset0_size);
-					fill_note(&t->notes[i], "CORE",
-						  NT_PRFPREG, size, data);
-				}
-				*total += notesize(&t->notes[i]);
-			}
-		}
+		if (!note_type) // not for coredumps
+			continue;
+		if (regset->active && regset->active(t->task, regset) <= 0)
+			continue;
+
+		ret = regset_get_alloc(t->task, regset, ~0U, &data);
+		if (ret < 0)
+			continue;
+
+		if (is_fpreg)
+			SET_PR_FPVALID(&t->prstatus, 1, regset0_size);
+
+		fill_note(&t->notes[i], is_fpreg ? "CORE" : "LINUX",
+			  note_type, ret, data);
+
+		*total += notesize(&t->notes[i]);
 	}
 
 	return 1;
diff --git a/include/linux/regset.h b/include/linux/regset.h
index 46d6ae68c455..c3403f328257 100644
--- a/include/linux/regset.h
+++ b/include/linux/regset.h
@@ -17,6 +17,52 @@
 struct task_struct;
 struct user_regset;
 
+struct membuf {
+	void *p;
+	size_t left;
+};
+
+static inline int membuf_zero(struct membuf *s, size_t size)
+{
+	if (s->left) {
+		if (size > s->left)
+			size = s->left;
+		memset(s->p, 0, size);
+		s->p += size;
+		s->left -= size;
+	}
+	return s->left;
+}
+
+static inline int membuf_write(struct membuf *s, const void *v, size_t size)
+{
+	if (s->left) {
+		if (size > s->left)
+			size = s->left;
+		memcpy(s->p, v, size);
+		s->p += size;
+		s->left -= size;
+	}
+	return s->left;
+}
+
+/* current s->p must be aligned for v; v must be a scalar */
+#define membuf_store(s, v)				\
+({							\
+	struct membuf *__s = (s);			\
+        if (__s->left) {				\
+		typeof(v) __v = (v);			\
+		size_t __size = sizeof(__v);		\
+		if (unlikely(__size > __s->left)) {	\
+			__size = __s->left;		\
+			memcpy(__s->p, &__v, __size);	\
+		} else {				\
+			*(typeof(__v + 0) *)__s->p = __v;	\
+		}					\
+		__s->p += __size;			\
+		__s->left -= __size;			\
+	}						\
+	__s->left;})
 
 /**
  * user_regset_active_fn - type of @active function in &struct user_regset
@@ -36,26 +82,9 @@ struct user_regset;
 typedef int user_regset_active_fn(struct task_struct *target,
 				  const struct user_regset *regset);
 
-/**
- * user_regset_get_fn - type of @get function in &struct user_regset
- * @target:	thread being examined
- * @regset:	regset being examined
- * @pos:	offset into the regset data to access, in bytes
- * @count:	amount of data to copy, in bytes
- * @kbuf:	if not %NULL, a kernel-space pointer to copy into
- * @ubuf:	if @kbuf is %NULL, a user-space pointer to copy into
- *
- * Fetch register values.  Return %0 on success; -%EIO or -%ENODEV
- * are usual failure returns.  The @pos and @count values are in
- * bytes, but must be properly aligned.  If @kbuf is non-null, that
- * buffer is used and @ubuf is ignored.  If @kbuf is %NULL, then
- * ubuf gives a userland pointer to access directly, and an -%EFAULT
- * return value is possible.
- */
-typedef int user_regset_get_fn(struct task_struct *target,
+typedef int user_regset_get2_fn(struct task_struct *target,
 			       const struct user_regset *regset,
-			       unsigned int pos, unsigned int count,
-			       void *kbuf, void __user *ubuf);
+			       struct membuf to);
 
 /**
  * user_regset_set_fn - type of @set function in &struct user_regset
@@ -104,28 +133,6 @@ typedef int user_regset_writeback_fn(struct task_struct *target,
 				     int immediate);
 
 /**
- * user_regset_get_size_fn - type of @get_size function in &struct user_regset
- * @target:	thread being examined
- * @regset:	regset being examined
- *
- * This call is optional; usually the pointer is %NULL.
- *
- * When provided, this function must return the current size of regset
- * data, as observed by the @get function in &struct user_regset.  The
- * value returned must be a multiple of @size.  The returned size is
- * required to be valid only until the next time (if any) @regset is
- * modified for @target.
- *
- * This function is intended for dynamically sized regsets.  A regset
- * that is statically sized does not need to implement it.
- *
- * This function should not be called directly: instead, callers should
- * call regset_size() to determine the current size of a regset.
- */
-typedef unsigned int user_regset_get_size_fn(struct task_struct *target,
-					     const struct user_regset *regset);
-
-/**
  * struct user_regset - accessible thread CPU state
  * @n:			Number of slots (registers).
  * @size:		Size in bytes of a slot (register).
@@ -136,7 +143,6 @@ typedef unsigned int user_regset_get_size_fn(struct task_struct *target,
  * @set:		Function to store values.
  * @active:		Function to report if regset is active, or %NULL.
  * @writeback:		Function to write data back to user memory, or %NULL.
- * @get_size:		Function to return the regset's size, or %NULL.
  *
  * This data structure describes a machine resource we call a register set.
  * This is part of the state of an individual thread, not necessarily
@@ -144,12 +150,7 @@ typedef unsigned int user_regset_get_size_fn(struct task_struct *target,
  * similar slots, given by @n.  Each slot is @size bytes, and aligned to
  * @align bytes (which is at least @size).  For dynamically-sized
  * regsets, @n must contain the maximum possible number of slots for the
- * regset, and @get_size must point to a function that returns the
- * current regset size.
- *
- * Callers that need to know only the current size of the regset and do
- * not care about its internal structure should call regset_size()
- * instead of inspecting @n or calling @get_size.
+ * regset.
  *
  * For backward compatibility, the @get and @set methods must pad to, or
  * accept, @n * @size bytes, even if the current regset size is smaller.
@@ -185,11 +186,10 @@ typedef unsigned int user_regset_get_size_fn(struct task_struct *target,
  * omitted when there is an @active function and it returns zero.
  */
 struct user_regset {
-	user_regset_get_fn		*get;
+	user_regset_get2_fn		*regset_get;
 	user_regset_set_fn		*set;
 	user_regset_active_fn		*active;
 	user_regset_writeback_fn	*writeback;
-	user_regset_get_size_fn		*get_size;
 	unsigned int			n;
 	unsigned int 			size;
 	unsigned int 			align;
@@ -238,44 +238,6 @@ struct user_regset_view {
  */
 const struct user_regset_view *task_user_regset_view(struct task_struct *tsk);
 
-
-/*
- * These are helpers for writing regset get/set functions in arch code.
- * Because @start_pos and @end_pos are always compile-time constants,
- * these are inlined into very little code though they look large.
- *
- * Use one or more calls sequentially for each chunk of regset data stored
- * contiguously in memory.  Call with constants for @start_pos and @end_pos,
- * giving the range of byte positions in the regset that data corresponds
- * to; @end_pos can be -1 if this chunk is at the end of the regset layout.
- * Each call updates the arguments to point past its chunk.
- */
-
-static inline int user_regset_copyout(unsigned int *pos, unsigned int *count,
-				      void **kbuf,
-				      void __user **ubuf, const void *data,
-				      const int start_pos, const int end_pos)
-{
-	if (*count == 0)
-		return 0;
-	BUG_ON(*pos < start_pos);
-	if (end_pos < 0 || *pos < end_pos) {
-		unsigned int copy = (end_pos < 0 ? *count
-				     : min(*count, end_pos - *pos));
-		data += *pos - start_pos;
-		if (*kbuf) {
-			memcpy(*kbuf, data, copy);
-			*kbuf += copy;
-		} else if (__copy_to_user(*ubuf, data, copy))
-			return -EFAULT;
-		else
-			*ubuf += copy;
-		*pos += copy;
-		*count -= copy;
-	}
-	return 0;
-}
-
 static inline int user_regset_copyin(unsigned int *pos, unsigned int *count,
 				     const void **kbuf,
 				     const void __user **ubuf, void *data,
@@ -301,35 +263,6 @@ static inline int user_regset_copyin(unsigned int *pos, unsigned int *count,
 	return 0;
 }
 
-/*
- * These two parallel the two above, but for portions of a regset layout
- * that always read as all-zero or for which writes are ignored.
- */
-static inline int user_regset_copyout_zero(unsigned int *pos,
-					   unsigned int *count,
-					   void **kbuf, void __user **ubuf,
-					   const int start_pos,
-					   const int end_pos)
-{
-	if (*count == 0)
-		return 0;
-	BUG_ON(*pos < start_pos);
-	if (end_pos < 0 || *pos < end_pos) {
-		unsigned int copy = (end_pos < 0 ? *count
-				     : min(*count, end_pos - *pos));
-		if (*kbuf) {
-			memset(*kbuf, 0, copy);
-			*kbuf += copy;
-		} else if (clear_user(*ubuf, copy))
-			return -EFAULT;
-		else
-			*ubuf += copy;
-		*pos += copy;
-		*count -= copy;
-	}
-	return 0;
-}
-
 static inline int user_regset_copyin_ignore(unsigned int *pos,
 					    unsigned int *count,
 					    const void **kbuf,
@@ -353,31 +286,19 @@ static inline int user_regset_copyin_ignore(unsigned int *pos,
 	return 0;
 }
 
-/**
- * copy_regset_to_user - fetch a thread's user_regset data into user memory
- * @target:	thread to be examined
- * @view:	&struct user_regset_view describing user thread machine state
- * @setno:	index in @view->regsets
- * @offset:	offset into the regset data, in bytes
- * @size:	amount of data to copy, in bytes
- * @data:	user-mode pointer to copy into
- */
-static inline int copy_regset_to_user(struct task_struct *target,
-				      const struct user_regset_view *view,
-				      unsigned int setno,
-				      unsigned int offset, unsigned int size,
-				      void __user *data)
-{
-	const struct user_regset *regset = &view->regsets[setno];
-
-	if (!regset->get)
-		return -EOPNOTSUPP;
+extern int regset_get(struct task_struct *target,
+		      const struct user_regset *regset,
+		      unsigned int size, void *data);
 
-	if (!access_ok(data, size))
-		return -EFAULT;
+extern int regset_get_alloc(struct task_struct *target,
+			    const struct user_regset *regset,
+			    unsigned int size,
+			    void **data);
 
-	return regset->get(target, regset, offset, size, NULL, data);
-}
+extern int copy_regset_to_user(struct task_struct *target,
+			       const struct user_regset_view *view,
+			       unsigned int setno, unsigned int offset,
+			       unsigned int size, void __user *data);
 
 /**
  * copy_regset_from_user - store into thread's user_regset data from user memory
@@ -405,21 +326,4 @@ static inline int copy_regset_from_user(struct task_struct *target,
 	return regset->set(target, regset, offset, size, NULL, data);
 }
 
-/**
- * regset_size - determine the current size of a regset
- * @target:	thread to be examined
- * @regset:	regset to be examined
- *
- * Note that the returned size is valid only until the next time
- * (if any) @regset is modified for @target.
- */
-static inline unsigned int regset_size(struct task_struct *target,
-				       const struct user_regset *regset)
-{
-	if (!regset->get_size)
-		return regset->n * regset->size;
-	else
-		return regset->get_size(target, regset);
-}
-
 #endif	/* <linux/regset.h> */
diff --git a/kernel/Makefile b/kernel/Makefile
index bdeb77e27042..5350fd292910 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -10,7 +10,7 @@ obj-y     = fork.o exec_domain.o panic.o \
 	    extable.o params.o \
 	    kthread.o sys_ni.o nsproxy.o \
 	    notifier.o ksysfs.o cred.o reboot.o \
-	    async.o range.o smpboot.o ucount.o
+	    async.o range.o smpboot.o ucount.o regset.o
 
 obj-$(CONFIG_BPFILTER) += usermode_driver.o
 obj-$(CONFIG_MODULES) += kmod.o
diff --git a/kernel/regset.c b/kernel/regset.c
new file mode 100644
index 000000000000..586823786f39
--- /dev/null
+++ b/kernel/regset.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/regset.h>
+
+static int __regset_get(struct task_struct *target,
+			const struct user_regset *regset,
+			unsigned int size,
+			void **data)
+{
+	void *p = *data, *to_free = NULL;
+	int res;
+
+	if (!regset->regset_get)
+		return -EOPNOTSUPP;
+	if (size > regset->n * regset->size)
+		size = regset->n * regset->size;
+	if (!p) {
+		to_free = p = kzalloc(size, GFP_KERNEL);
+		if (!p)
+			return -ENOMEM;
+	}
+	res = regset->regset_get(target, regset,
+			   (struct membuf){.p = p, .left = size});
+	if (res < 0) {
+		kfree(to_free);
+		return res;
+	}
+	*data = p;
+	return size - res;
+}
+
+int regset_get(struct task_struct *target,
+	       const struct user_regset *regset,
+	       unsigned int size,
+	       void *data)
+{
+	return __regset_get(target, regset, size, &data);
+}
+EXPORT_SYMBOL(regset_get);
+
+int regset_get_alloc(struct task_struct *target,
+		     const struct user_regset *regset,
+		     unsigned int size,
+		     void **data)
+{
+	*data = NULL;
+	return __regset_get(target, regset, size, data);
+}
+EXPORT_SYMBOL(regset_get_alloc);
+
+/**
+ * copy_regset_to_user - fetch a thread's user_regset data into user memory
+ * @target:	thread to be examined
+ * @view:	&struct user_regset_view describing user thread machine state
+ * @setno:	index in @view->regsets
+ * @offset:	offset into the regset data, in bytes
+ * @size:	amount of data to copy, in bytes
+ * @data:	user-mode pointer to copy into
+ */
+int copy_regset_to_user(struct task_struct *target,
+			const struct user_regset_view *view,
+			unsigned int setno,
+			unsigned int offset, unsigned int size,
+			void __user *data)
+{
+	const struct user_regset *regset = &view->regsets[setno];
+	void *buf;
+	int ret;
+
+	ret = regset_get_alloc(target, regset, size, &buf);
+	if (ret > 0)
+		ret = copy_to_user(data, buf, ret) ? -EFAULT : 0;
+	kfree(buf);
+	return ret;
+}