On Fri, Sep 29, 2017 at 11:37:52AM -0700, Andy Lutomirski wrote: > On Fri, Sep 29, 2017 at 8:38 AM, Josh Poimboeuf <[email protected]> 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 <[email protected]> > > > > Reviewed-by: Josh Poimboeuf <[email protected]> > > > Ok with me. As an alternative, you could leave it as > current_stack_pointer(), but either way is fine.
Good point, I think changing current_stack_pointer() to return the global variable would be cleaner. -- Josh
