Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754251AbbGQQ5d (ORCPT ); Fri, 17 Jul 2015 12:57:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36935 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753991AbbGQQ5a (ORCPT ); Fri, 17 Jul 2015 12:57:30 -0400 From: Josh Poimboeuf To: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Cc: Michal Marek , Peter Zijlstra , Andy Lutomirski , Borislav Petkov , Linus Torvalds , Andi Kleen , Pedro Alves , x86@kernel.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH 04/21] x86/hweight: Add stack frame dependency for __arch_hweight*() Date: Fri, 17 Jul 2015 11:47:20 -0500 Message-Id: <0d8517b7ab757e00a13b3abe2b677d9eb23362be.1437150175.git.jpoimboe@redhat.com> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1898 Lines: 56 If __arch_hweight32() or __arch_hweight64() is inlined at the beginning of a function, gcc can insert the call instruction before setting up a stack frame, which breaks frame pointer convention if CONFIG_FRAME_POINTER is enabled and can result in a bad stack trace. Force a stack frame to be created if CONFIG_FRAME_POINTER is enabled by listing the stack pointer as an output operand for the inline asm statement. Signed-off-by: Josh Poimboeuf --- arch/x86/include/asm/arch_hweight.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/arch_hweight.h b/arch/x86/include/asm/arch_hweight.h index 9686c3d..e438a0d 100644 --- a/arch/x86/include/asm/arch_hweight.h +++ b/arch/x86/include/asm/arch_hweight.h @@ -23,10 +23,11 @@ */ static inline unsigned int __arch_hweight32(unsigned int w) { + register void *__sp asm("esp"); unsigned int res = 0; asm (ALTERNATIVE("call __sw_hweight32", POPCNT32, X86_FEATURE_POPCNT) - : "="REG_OUT (res) + : "="REG_OUT (res), "+r" (__sp) : REG_IN (w)); return res; @@ -44,6 +45,7 @@ static inline unsigned int __arch_hweight8(unsigned int w) static inline unsigned long __arch_hweight64(__u64 w) { + register void __maybe_unused *__sp asm("rsp"); unsigned long res = 0; #ifdef CONFIG_X86_32 @@ -51,7 +53,7 @@ static inline unsigned long __arch_hweight64(__u64 w) __arch_hweight32((u32)(w >> 32)); #else asm (ALTERNATIVE("call __sw_hweight64", POPCNT64, X86_FEATURE_POPCNT) - : "="REG_OUT (res) + : "="REG_OUT (res), "+r" (__sp) : REG_IN (w)); #endif /* CONFIG_X86_32 */ -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/