Messages in this thread |  | | Subject | Re: [PATCH 04/24] x86,nospec: Annotate indirect calls/jumps | From | David Woodhouse <> | Date | Fri, 26 Jan 2018 10:19:47 +0000 |
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On Tue, 2018-01-23 at 16:25 +0100, Peter Zijlstra wrote: > Annotate the indirect calls/jumps in the CALL_NOSPEC/JUMP_NOSPEC > alternatives. > > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
However...
> /* > + * This should be used immediately before an indirect jump/call. It tells > + * objtool the subsequent indirect jump/call is vouched safe for retpoline > + * builds. > + */ > +.macro ANNOTATE_RETPOLINE_SAFE > + .Lannotate_\@: > + .pushsection .discard.retpoline_safe > + _ASM_PTR .Lannotate_\@ > + .popsection > +.endm
Didn't I just see one of those in patch 3? So this makes two...
> @@ -143,6 +155,12 @@ > ".long 999b - .\n\t" \ > ".popsection\n\t" > > +#define ANNOTATE_RETPOLINE_SAFE \ > + "999:\n\t" \ > + ".pushsection .discard.retpoline_safe\n\t" \ > + _ASM_PTR " 999b\n\t" \ > + ".popsection\n\t" > + > #if defined(CONFIG_X86_64) && defined(RETPOLINE)
... three.
Now, I did briefly toy with the idea of using a .macro from both __ASSEMBLY__ and inline asm, making the latter work by means of asm(".include \"asm/nospec-branch.h\");
In the end I just ended up with the __FILL_RETURN_BUFFER CPP macro which is used from both by other tricks.
Can we look at doing something like that, please?
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