Messages in this thread | | | Date | Fri, 3 Apr 2020 10:14:49 -0700 (PDT) | From | Alexandre Chartre <> | Subject | Re: [PATCH 5/7] x86/speculation: Annotate intra-function calls |
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On 4/3/20 6:16 PM, Josh Poimboeuf wrote: > 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 :-/
So that means that any alternative that does a stack manipulation isn't currently supported?
alex.
> Or they could be converted to use static branches instead of > alternatives. >
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