path: root/arch/x86/include/asm
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authorAndrey Ryabinin <aryabinin@virtuozzo.com>2017-09-29 17:15:36 +0300
committerIngo Molnar <mingo@kernel.org>2017-09-29 19:39:44 +0200
commit196bd485ee4f03ce4c690bfcf38138abfcd0a4bc (patch)
treea3cc45bbdcfb19bb4a46fd0713b34862da6c2657 /arch/x86/include/asm
parentbc829ee36e0ec92383c9d9b88fe08f00d4d592f8 (diff)
x86/asm: Use register variable to get stack pointer value
Currently we use current_stack_pointer() function to get the value of the stack pointer register. Since commit: f5caf621ee35 ("x86/asm: Fix inline asm call constraints for Clang") ... we have a stack register variable declared. It can be used instead of current_stack_pointer() function which allows to optimize away some excessive "mov %rsp, %<dst>" instructions: -mov %rsp,%rdx -sub %rdx,%rax -cmp $0x3fff,%rax -ja ffffffff810722fd <ist_begin_non_atomic+0x2d> +sub %rsp,%rax +cmp $0x3fff,%rax +ja ffffffff810722fa <ist_begin_non_atomic+0x2a> Remove current_stack_pointer(), rename __asm_call_sp to current_stack_pointer and use it instead of the removed function. Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20170929141537.29167-1-aryabinin@virtuozzo.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm')
2 files changed, 2 insertions, 13 deletions
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 30c3c9ac784a..b0dc91f4bedc 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -141,8 +141,8 @@
* gets set up by the containing function. If you forget to do this, objtool
* may print a "call without frame pointer save/setup" warning.
-register unsigned long __asm_call_sp asm(_ASM_SP);
-#define ASM_CALL_CONSTRAINT "+r" (__asm_call_sp)
+register unsigned long current_stack_pointer asm(_ASM_SP);
+#define ASM_CALL_CONSTRAINT "+r" (current_stack_pointer)
#endif /* _ASM_X86_ASM_H */
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 5161da1a0fa0..89e7eeb5cec1 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -158,17 +158,6 @@ struct thread_info {
#ifndef __ASSEMBLY__
-static inline unsigned long current_stack_pointer(void)
- unsigned long sp;
-#ifdef CONFIG_X86_64
- asm("mov %%rsp,%0" : "=g" (sp));
- asm("mov %%esp,%0" : "=g" (sp));
- return sp;
* Walks up the stack frames to make sure that the specified object is
* entirely contained by a single stack frame.

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