x86/asm: Use register variable to get stack pointer value
authorAndrey Ryabinin <aryabinin@virtuozzo.com>
Fri, 29 Sep 2017 14:15:36 +0000 (17:15 +0300)
committerIngo Molnar <mingo@kernel.org>
Fri, 29 Sep 2017 17:39:44 +0000 (19:39 +0200)
commit196bd485ee4f03ce4c690bfcf38138abfcd0a4bc
treea3cc45bbdcfb19bb4a46fd0713b34862da6c2657
parentbc829ee36e0ec92383c9d9b88fe08f00d4d592f8
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>
arch/x86/include/asm/asm.h
arch/x86/include/asm/thread_info.h
arch/x86/kernel/irq_32.c
arch/x86/kernel/traps.c
arch/x86/mm/tlb.c