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) <pet...@infradead.org>
Reviewed-by: David Woodhouse <d...@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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