lkml.org 
[lkml]   [2019]   [Jan]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 06/22] x86/fpu: Don't save fxregs for ia32 frames in copy_fpstate_to_sigframe()
Date
Why does copy_fpstate_to_sigframe() do copy_fxregs_to_kernel() in the
ia32_fxstate case? I don't know. It just does.
Maybe it was required at some point, maybe it was added by accident and
nobody noticed it because it makes no difference.

In copy_fpstate_to_sigframe() we stash the FPU state into the task's
stackframe. Then the CPU's FPU registers (and its fpu->state) are
cleared (handle_signal() does fpu__clear()). So it makes *no* difference
what happens to fpu->state after copy_fpregs_to_sigframe().

Remove copy_fxregs_to_kernel() since it does not matter what it does and
save a few cycles.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/x86/kernel/fpu/signal.c | 3 ---
1 file changed, 3 deletions(-)

diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index c136a4327659d..047390a45e016 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -174,9 +174,6 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
/* Save the live register state to the user directly. */
if (copy_fpregs_to_sigframe(buf_fx))
return -1;
- /* Update the thread's fxstate to save the fsave header. */
- if (ia32_fxstate)
- copy_fxregs_to_kernel(fpu);

/* Save the fsave header for the 32-bit frames. */
if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
--
2.20.1
\
 
 \ /
  Last update: 2019-01-09 12:49    [W:0.524 / U:3.384 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site