lkml.org 
[lkml]   [2018]   [Mar]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH 1/1] x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32bit
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>

\
 
 \ /
  Last update: 2018-03-14 12:52    [W:0.047 / U:2.660 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site