Messages in this thread | | | From | Linus Torvalds <> | Date | Fri, 5 Jan 2018 15:50:30 -0800 | Subject | Re: [PATCH v3 01/13] x86/retpoline: Add initial retpoline support |
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On Fri, Jan 5, 2018 at 2:00 PM, Woodhouse, David <dwmw@amazon.co.uk> wrote: > +.macro RETPOLINE_JMP reg:req > + call 1112f > +1111: lfence > + jmp 1111b > +1112: mov %\reg, (%_ASM_SP) > + ret > +.endm > + > +.macro RETPOLINE_CALL reg:req > + jmp 1113f > +1110: RETPOLINE_JMP \reg > +1113: call 1110b > +.endm
Why do these still force a register name?
Is it because this is the only user?
> index 2a4b1f09eb84..90d9a1589a54 100644 > --- a/arch/x86/lib/retpoline.S > +++ b/arch/x86/lib/retpoline.S > @@ -6,19 +6,14 @@ > #include <asm/cpufeatures.h> > #include <asm/alternative-asm.h> > #include <asm/export.h> > +#include <asm/nospec-branch.h> > > -.macro THUNK sp reg > +.macro THUNK reg > .section .text.__x86.indirect_thunk.\reg > > ENTRY(__x86.indirect_thunk.\reg) > CFI_STARTPROC > - ALTERNATIVE_2 "call 2f", __stringify(lfence;jmp *%\reg), X86_FEATURE_K8, __stringify(jmp *%\reg), X86_FEATURE_NO_RETPOLINE > -1: > - lfence > - jmp 1b > -2: > - mov %\reg, (%\sp) > - ret > + NOSPEC_JMP \reg > CFI_ENDPROC
Can we just move those macros into retpoline.S because using them outside that shouldn't happen?
Linus
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