x86: switch to ->regset_get()

	All instances of ->get() in arch/x86 switched; that might or might
not be worth splitting up.  Notes:

	* for xstateregs_get() the amount we want to store is determined at
the boot time; see init_xstate_size() and update_regset_xstate_info() for
details.  task->thread.fpu.state.xsave ends with a flexible array member and
the amount of data in it depends upon the FPU features supported/enabled.

	* fpregs_get() writes slightly less than full ->thread.fpu.state.fsave
(the last word is not copied); we pass the full size of state.fsave and let
membuf_write() trim to the amount declared by regset - __regset_get() will
make sure that the space in buffer is no more than that.

	* copy_xstate_to_user() and its helpers are gone now.

	* fpregs_soft_get() was getting user_regset_copyout() arguments
wrong.  Since "x86: x86 user_regset math_emu" back in 2008...  I really
doubt that it's worth splitting out for -stable, though - you need
a 486SX box for that to trigger...

[Kevin's braino fix for copy_xstate_to_kernel() essentially duplicated here]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 5 insertions, 14 deletions

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;
 }