Messages in this thread | | | Date | Fri, 3 Apr 2020 11:16:07 -0500 | From | Josh Poimboeuf <> | Subject | Re: [PATCH 5/7] x86/speculation: Annotate intra-function calls |
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On Fri, Apr 03, 2020 at 11:05:38AM -0500, Josh Poimboeuf wrote: > On Thu, Apr 02, 2020 at 10:22:18AM +0200, Alexandre Chartre wrote: > > .macro RETPOLINE_JMP reg:req > > - call .Ldo_rop_\@ > > + INTRA_FUNCTION_CALL .Ldo_rop_\@ > > .Lspec_trap_\@: > > pause > > lfence > > @@ -102,7 +116,7 @@ > > .Ldo_retpoline_jmp_\@: > > RETPOLINE_JMP \reg > > .Ldo_call_\@: > > - call .Ldo_retpoline_jmp_\@ > > + INTRA_FUNCTION_CALL .Ldo_retpoline_jmp_\@ > > .endm > > There's a catch: this is part of an alternative. Which means if > X86_FEATURE_RETPOLINE isn't set at runtime, then the retpoline won't be > there and the ORC data will be wrong. > > In fact objtool should probably be made smart enough to warn about this > situation, when an alternative changes the stack state. > > The only way I can think of to fix this is to have ORC alternatives :-/
Or they could be converted to use static branches instead of alternatives.
-- Josh
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