From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751892AbeCNLve (ORCPT ); Wed, 14 Mar 2018 07:51:34 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:47124 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751344AbeCNLvd (ORCPT ); Wed, 14 Mar 2018 07:51:33 -0400 Date: Wed, 14 Mar 2018 12:51:25 +0100 From: Peter Zijlstra To: Andy Whitcroft Cc: Thomas Gleixner , Ingo Molnar , David Woodhouse , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] x86/speculation, objtool: Annotate indirect calls/jumps for objtool on 32bit Message-ID: <20180314115125.GS4043@hirez.programming.kicks-ass.net> References: <20180314112427.22351-1-apw@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180314112427.22351-1-apw@canonical.com> User-Agent: Mutt/1.9.3 (2018-01-21) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > --- > 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)