Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fpu changes from Ingo Molnar:
 "Various x86 FPU handling cleanups, refactorings and fixes (Borislav
  Petkov, Oleg Nesterov, Rik van Riel)"

* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
  x86/fpu: Kill eager_fpu_init_bp()
  x86/fpu: Don't allocate fpu->state for swapper/0
  x86/fpu: Rename drop_init_fpu() to fpu_reset_state()
  x86/fpu: Fold __drop_fpu() into its sole user
  x86/fpu: Don't abuse drop_init_fpu() in flush_thread()
  x86/fpu: Use restore_init_xstate() instead of math_state_restore() on kthread exec
  x86/fpu: Introduce restore_init_xstate()
  x86/fpu: Document user_fpu_begin()
  x86/fpu: Factor out memset(xstate, 0) in fpu_finit() paths
  x86/fpu: Change xstateregs_get()/set() to use ->xsave.i387 rather than ->fxsave
  x86/fpu: Don't abuse FPU in kernel threads if use_eager_fpu()
  x86/fpu: Always allow FPU in interrupt if use_eager_fpu()
  x86/fpu: __kernel_fpu_begin() should clear fpu_owner_task even if use_eager_fpu()
  x86/fpu: Also check fpu_lazy_restore() when use_eager_fpu()
  x86/fpu: Use task_disable_lazy_fpu_restore() helper
  x86/fpu: Use an explicit if/else in switch_fpu_prepare()
  x86/fpu: Introduce task_disable_lazy_fpu_restore() helper
  x86/fpu: Move lazy restore functions up a few lines
  x86/fpu: Change math_error() to use unlazy_fpu(), kill (now) unused save_init_fpu()
  x86/fpu: Don't do __thread_fpu_end() if use_eager_fpu()
  ...

1 files changed, 26 insertions, 28 deletions

diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 29c740deafec..367f39d35e9c 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -42,8 +42,8 @@ void kernel_fpu_enable(void)
  * be set (so that the clts/stts pair does nothing that is
  * visible in the interrupted kernel thread).
  *
- * Except for the eagerfpu case when we return 1 unless we've already
- * been eager and saved the state in kernel_fpu_begin().
+ * Except for the eagerfpu case when we return true; in the likely case
+ * the thread has FPU but we are not going to set/clear TS.
  */
 static inline bool interrupted_kernel_fpu_idle(void)
 {
@@ -51,7 +51,7 @@ static inline bool interrupted_kernel_fpu_idle(void)
 		return false;
 
 	if (use_eager_fpu())
-		return __thread_has_fpu(current);
+		return true;
 
 	return !__thread_has_fpu(current) &&
 		(read_cr0() & X86_CR0_TS);
@@ -94,9 +94,10 @@ void __kernel_fpu_begin(void)
 
 	if (__thread_has_fpu(me)) {
 		__save_init_fpu(me);
-	} else if (!use_eager_fpu()) {
+	} else {
 		this_cpu_write(fpu_owner_task, NULL);
-		clts();
+		if (!use_eager_fpu())
+			clts();
 	}
 }
 EXPORT_SYMBOL(__kernel_fpu_begin);
@@ -107,7 +108,7 @@ void __kernel_fpu_end(void)
 
 	if (__thread_has_fpu(me)) {
 		if (WARN_ON(restore_fpu_checking(me)))
-			drop_init_fpu(me);
+			fpu_reset_state(me);
 	} else if (!use_eager_fpu()) {
 		stts();
 	}
@@ -120,10 +121,13 @@ void unlazy_fpu(struct task_struct *tsk)
 {
 	preempt_disable();
 	if (__thread_has_fpu(tsk)) {
-		__save_init_fpu(tsk);
-		__thread_fpu_end(tsk);
-	} else
-		tsk->thread.fpu_counter = 0;
+		if (use_eager_fpu()) {
+			__save_fpu(tsk);
+		} else {
+			__save_init_fpu(tsk);
+			__thread_fpu_end(tsk);
+		}
+	}
 	preempt_enable();
 }
 EXPORT_SYMBOL(unlazy_fpu);
@@ -221,11 +225,12 @@ void fpu_finit(struct fpu *fpu)
 		return;
 	}
 
+	memset(fpu->state, 0, xstate_size);
+
 	if (cpu_has_fxsr) {
 		fx_finit(&fpu->state->fxsave);
 	} else {
 		struct i387_fsave_struct *fp = &fpu->state->fsave;
-		memset(fp, 0, xstate_size);
 		fp->cwd = 0xffff037fu;
 		fp->swd = 0xffff0000u;
 		fp->twd = 0xffffffffu;
@@ -247,7 +252,7 @@ int init_fpu(struct task_struct *tsk)
 	if (tsk_used_math(tsk)) {
 		if (cpu_has_fpu && tsk == current)
 			unlazy_fpu(tsk);
-		tsk->thread.fpu.last_cpu = ~0;
+		task_disable_lazy_fpu_restore(tsk);
 		return 0;
 	}
 
@@ -336,6 +341,7 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
 		unsigned int pos, unsigned int count,
 		void *kbuf, void __user *ubuf)
 {
+	struct xsave_struct *xsave = &target->thread.fpu.state->xsave;
 	int ret;
 
 	if (!cpu_has_xsave)
@@ -350,14 +356,12 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
 	 * memory layout in the thread struct, so that we can copy the entire
 	 * xstateregs to the user using one user_regset_copyout().
 	 */
-	memcpy(&target->thread.fpu.state->fxsave.sw_reserved,
-	       xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes));
-
+	memcpy(&xsave->i387.sw_reserved,
+		xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes));
 	/*
 	 * Copy the xstate memory layout.
 	 */
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &target->thread.fpu.state->xsave, 0, -1);
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
 	return ret;
 }
 
@@ -365,8 +369,8 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
 		  unsigned int pos, unsigned int count,
 		  const void *kbuf, const void __user *ubuf)
 {
+	struct xsave_struct *xsave = &target->thread.fpu.state->xsave;
 	int ret;
-	struct xsave_hdr_struct *xsave_hdr;
 
 	if (!cpu_has_xsave)
 		return -ENODEV;
@@ -375,22 +379,16 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
 	if (ret)
 		return ret;
 
-	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
-				 &target->thread.fpu.state->xsave, 0, -1);
-
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
 	/*
 	 * mxcsr reserved bits must be masked to zero for security reasons.
 	 */
-	target->thread.fpu.state->fxsave.mxcsr &= mxcsr_feature_mask;
-
-	xsave_hdr = &target->thread.fpu.state->xsave.xsave_hdr;
-
-	xsave_hdr->xstate_bv &= pcntxt_mask;
+	xsave->i387.mxcsr &= mxcsr_feature_mask;
+	xsave->xsave_hdr.xstate_bv &= pcntxt_mask;
 	/*
 	 * These bits must be zero.
 	 */
-	memset(xsave_hdr->reserved, 0, 48);
-
+	memset(&xsave->xsave_hdr.reserved, 0, 48);
 	return ret;
 }