Messages in this thread | | | From | Andy Lutomirski <> | Date | Fri, 29 Sep 2017 11:37:52 -0700 | Subject | Re: [PATCH] x86: use register variable to get stack pointer value |
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On Fri, Sep 29, 2017 at 8:38 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote: > 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>
Ok with me. As an alternative, you could leave it as current_stack_pointer(), but either way is fine.
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