From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933139Ab0G3SXc (ORCPT ); Fri, 30 Jul 2010 14:23:32 -0400 Received: from kroah.org ([198.145.64.141]:58604 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932327Ab0G3R4G (ORCPT ); Fri, 30 Jul 2010 13:56:06 -0400 X-Mailbox-Line: From gregkh@clark.site Fri Jul 30 10:51:42 2010 Message-Id: <20100730175142.318054023@clark.site> User-Agent: quilt/0.48-11.2 Date: Fri, 30 Jul 2010 10:51:52 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Mikael Pettersson , Khem Raj , Russell King Subject: [095/205] compiler-gcc.h: gcc-4.5 needs noclone and noinline on __naked functions In-Reply-To: <20100730175238.GA3924@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.34-stable review patch. If anyone has any objections, please let us know. ------------------ From: Mikael Pettersson commit 9c695203a7ddbe49dba5f22f4c941d24f47475df upstream. A __naked function is defined in C but with a body completely implemented by asm(), including any prologue and epilogue. These asm() bodies expect standard calling conventions for parameter passing. Older GCCs implement that correctly, but 4.[56] currently do not, see GCC PR44290. In the Linux kernel this breaks ARM, causing most arch/arm/mm/copypage-*.c modules to get miscompiled, resulting in kernel crashes during bootup. Part of the kernel fix is to augment the __naked function attribute to also imply noinline and noclone. This patch implements that, and has been verified to fix boot failures with gcc-4.5 compiled 2.6.34 and 2.6.35-rc1 kernels. The patch is a no-op with older GCCs. Signed-off-by: Mikael Pettersson Signed-off-by: Khem Raj Cc: Russell King Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- include/linux/compiler-gcc.h | 10 +++++++++- include/linux/compiler-gcc4.h | 4 ++++ 2 files changed, 13 insertions(+), 1 deletion(-) --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -58,8 +58,12 @@ * naked functions because then mcount is called without stack and frame pointer * being set up and there is no chance to restore the lr register to the value * before mcount was called. + * + * The asm() bodies of naked functions often depend on standard calling conventions, + * therefore they must be noinline and noclone. GCC 4.[56] currently fail to enforce + * this, so we must do so ourselves. See GCC PR44290. */ -#define __naked __attribute__((naked)) notrace +#define __naked __attribute__((naked)) noinline __noclone notrace #define __noreturn __attribute__((noreturn)) @@ -85,3 +89,7 @@ #define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h) #define gcc_header(x) _gcc_header(x) #include gcc_header(__GNUC__) + +#if !defined(__noclone) +#define __noclone /* not needed */ +#endif --- a/include/linux/compiler-gcc4.h +++ b/include/linux/compiler-gcc4.h @@ -48,6 +48,10 @@ * unreleased. Really, we need to have autoconf for the kernel. */ #define unreachable() __builtin_unreachable() + +/* Mark a function definition as prohibited from being cloned. */ +#define __noclone __attribute__((__noclone__)) + #endif #endif