lkml.org 
[lkml]   [2017]   [Sep]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] x86: use register variable to get stack pointer value
On Fri, Sep 29, 2017 at 05:15:36PM +0300, Andrey Ryabinin wrote:
> 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 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 removed function.
>
> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>

Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>

--
Josh

\
 
 \ /
  Last update: 2017-09-29 17:39    [W:0.046 / U:9.280 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site