From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758997AbcIXQ3p (ORCPT ); Sat, 24 Sep 2016 12:29:45 -0400 Received: from terminus.zytor.com ([198.137.202.10]:56926 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754379AbcIXQ3l (ORCPT ); Sat, 24 Sep 2016 12:29:41 -0400 Date: Sat, 24 Sep 2016 09:28:32 -0700 From: tip-bot for Josh Poimboeuf Message-ID: Cc: jpoimboe@redhat.com, hpa@zytor.com, acme@redhat.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@kernel.org, dvlasenk@redhat.com, luto@kernel.org, torvalds@linux-foundation.org, bp@alien8.de, peterz@infradead.org, brgerst@gmail.com Reply-To: brgerst@gmail.com, peterz@infradead.org, bp@alien8.de, torvalds@linux-foundation.org, mingo@kernel.org, dvlasenk@redhat.com, luto@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, acme@redhat.com, hpa@zytor.com, jpoimboe@redhat.com In-Reply-To: <20160923214939.j5o7c67nhepzmh3t@treble> References: <20160923214939.j5o7c67nhepzmh3t@treble> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/asm] x86/alternatives: Add stack frame dependency to alternative_call_2() Git-Commit-ID: 317c2ce77d8ab73c24f4fb9c75e5bb441fbe3e30 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 317c2ce77d8ab73c24f4fb9c75e5bb441fbe3e30 Gitweb: http://git.kernel.org/tip/317c2ce77d8ab73c24f4fb9c75e5bb441fbe3e30 Author: Josh Poimboeuf AuthorDate: Fri, 23 Sep 2016 16:49:39 -0500 Committer: Ingo Molnar CommitDate: Sat, 24 Sep 2016 09:30:03 +0200 x86/alternatives: Add stack frame dependency to alternative_call_2() Linus reported the following objtool warning: kernel/signal.o: warning: objtool: .altinstr_replacement+0x54: call without frame pointer save/setup The warning is valid. It's caused by the fact that gcc placed the call instruction in alternative_call_2()'s inline asm before the frame pointer setup, which breaks frame pointer convention and can result in a bad stack trace. Force a stack frame to be created before the call instruction by listing the stack pointer as an output operand in the inline asm statement. Reported-and-tested-by: Linus Torvalds Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Arnaldo Carvalho de Melo Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20160923214939.j5o7c67nhepzmh3t@treble Signed-off-by: Ingo Molnar --- arch/x86/include/asm/alternative.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h index e77a644..1b02038 100644 --- a/arch/x86/include/asm/alternative.h +++ b/arch/x86/include/asm/alternative.h @@ -217,10 +217,14 @@ static inline int alternatives_text_reserved(void *start, void *end) */ #define alternative_call_2(oldfunc, newfunc1, feature1, newfunc2, feature2, \ output, input...) \ +{ \ + register void *__sp asm(_ASM_SP); \ asm volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\ "call %P[new2]", feature2) \ - : output : [old] "i" (oldfunc), [new1] "i" (newfunc1), \ - [new2] "i" (newfunc2), ## input) + : output, "+r" (__sp) \ + : [old] "i" (oldfunc), [new1] "i" (newfunc1), \ + [new2] "i" (newfunc2), ## input); \ +} /* * use this macro(s) if you need more than one output parameter