[PATCH] x86_64: don't save eflags in x86-64 switch_to()

As discussed, the flags register on x86-64 is saved and restored by the
assembly code which sets up struct pt_regs, so we do not need to save
and restore it in the inline assembler which already informs gcc that
we're clobbering the flags.  This patch has been sanity booted and works
okay here.

Signed-off-by: Benjamin LaHaise <benjamin.c.lahaise@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/include/asm-x86_64/system.h b/include/asm-x86_64/system.h
index 1200ea2..a3bca75 100644 (file)
--- a/include/asm-x86_64/system.h
+++ b/include/asm-x86_64/system.h
@@ -20,8 +20,8 @@
 #define __RESTORE(reg,offset) "movq (14-" #offset ")*8(%%rsp),%%" #reg "\n\t"
 
 /* frame pointer must be last for get_wchan */
-#define SAVE_CONTEXT    "pushfq ; pushq %%rbp ; movq %%rsi,%%rbp\n\t"
-#define RESTORE_CONTEXT "movq %%rbp,%%rsi ; popq %%rbp ; popfq\n\t" 
+#define SAVE_CONTEXT    "pushq %%rbp ; movq %%rsi,%%rbp\n\t"
+#define RESTORE_CONTEXT "movq %%rbp,%%rsi ; popq %%rbp\n\t"
 
 #define __EXTRA_CLOBBER  \
        ,"rcx","rbx","rdx","r8","r9","r10","r11","r12","r13","r14","r15"