x86/nmi/64: Minor asm simplification
authorAndy Lutomirski <luto@kernel.org>
Wed, 15 Jul 2015 17:29:39 +0000 (10:29 -0700)
committerIngo Molnar <mingo@kernel.org>
Fri, 17 Jul 2015 10:50:13 +0000 (12:50 +0200)
Replace LEA; MOV with an equivalent SUB.  This saves one
instruction.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/entry/entry_64.S

index d8ab2b201fa197c05f24ca3361c94169123cbca4..0fb52526e452cf3b850004c53addb743fedcb12f 100644 (file)
@@ -1420,8 +1420,7 @@ nested_nmi:
         * Modify the "iret" frame to point to repeat_nmi, forcing another
         * iteration of NMI handling.
         */
-       leaq    -1*8(%rsp), %rdx
-       movq    %rdx, %rsp
+       subq    $8, %rsp
        leaq    -10*8(%rsp), %rdx
        pushq   $__KERNEL_DS
        pushq   %rdx