Messages in this thread Patch in this message | | | Date | Wed, 14 Mar 2018 12:51:25 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/1] x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32bit |
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On Wed, Mar 14, 2018 at 11:24:27AM +0000, Andy Whitcroft wrote: > In 9e0e3c5130e9 ("x86/speculation, objtool: Annotate indirect calls/jumps > for objtool") we added annotations for CALL_NOSPEC/JMP_NOSPEC on x86 64bit. > We did not annotate the 32bit path. Annotate it similarly. > > Signed-off-by: Andy Whitcroft <apw@canonical.com> > --- > arch/x86/include/asm/nospec-branch.h | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > While reviewing indirect calls in our builds I noted that the > i386 retpoline CALL_NOSPEC is not annotated safe even though > its amd64 equivalent is. I cannot see any reason this is not > also inherantly safe. Peter was there a reason that you did > not annotate this one too? Anyhow, on the assumption this was > just missed, this patch annotates it.
Yeah, just an oversight aided by the fact that I (obviously) never build 32bit kernels.
> diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h > index d0dabeae0505..07886162bdf8 100644 > --- a/arch/x86/include/asm/nospec-branch.h > +++ b/arch/x86/include/asm/nospec-branch.h > @@ -183,7 +183,10 @@ > * otherwise we'll run out of registers. We don't care about CET > * here, anyway. > */ > -# define CALL_NOSPEC ALTERNATIVE("call *%[thunk_target]\n", \ > +# define CALL_NOSPEC \ > + ALTERNATIVE( \ > + ANNOTATE_RETPOLINE_SAFE \ > + "call *%[thunk_target]\n", \ > " jmp 904f;\n" \ > " .align 16\n" \ > "901: call 903f;\n" \
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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