From 92d140e21f1ce8cf99320afbbcad73879128e6dc Mon Sep 17 00:00:00 2001 From: "Siddha, Suresh B" Date: Sun, 11 Nov 2007 11:27:59 -0800 Subject: x86: fix taking DNA during 64bit sigreturn restore sigcontext is taking a DNA exception while restoring FP context from the user stack, during the sigreturn. Appended patch fixes it by doing clts() if the app doesn't touch FP during the signal handler execution. This will stop generating a DNA, during the fxrstor in the sigreturn. This improves 64-bit lat_sig numbers by ~30% on my core2 platform. Signed-off-by: Suresh Siddha Signed-off-by: Linus Torvalds --- include/asm-x86/i387_64.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/asm-x86') diff --git a/include/asm-x86/i387_64.h b/include/asm-x86/i387_64.h index 0217b74..3a4ffba 100644 --- a/include/asm-x86/i387_64.h +++ b/include/asm-x86/i387_64.h @@ -203,6 +203,11 @@ static inline void save_init_fpu(struct task_struct *tsk) */ static inline int restore_i387(struct _fpstate __user *buf) { + set_used_math(); + if (!(task_thread_info(current)->status & TS_USEDFPU)) { + clts(); + task_thread_info(current)->status |= TS_USEDFPU; + } return restore_fpu_checking((__force struct i387_fxsave_struct *)buf); } -- cgit v1.1