Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933972AbbEMKjV (ORCPT ); Wed, 13 May 2015 06:39:21 -0400 Received: from cantor2.suse.de ([195.135.220.15]:40179 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933663AbbEMKjR (ORCPT ); Wed, 13 May 2015 06:39:17 -0400 Message-ID: <555329D2.8090909@suse.cz> Date: Wed, 13 May 2015 12:39:14 +0200 From: Michal Marek User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Josh Poimboeuf CC: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Peter Zijlstra , x86@kernel.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 1/3] x86, stackvalidate: Compile-time stack frame pointer validation References: In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2711 Lines: 69 On 2015-05-11 18:38, Josh Poimboeuf wrote: > Frame pointer based stack traces aren't always reliable. One big reason > is that most asm functions don't set up the frame pointer. > > Fix that by enforcing that all asm functions honor CONFIG_FRAME_POINTER. > This is done with a new stackvalidate host tool which is automatically > run for every compiled .S file and which validates that every asm > function does the proper frame pointer setup. > > Also, to make sure somebody didn't forget to annotate their callable asm code > as a function, flag an error for any return instructions which are hiding > outside of a function. In almost all cases, return instructions are part of > callable functions and should be annotated as such so that we can validate > their frame pointer usage. A whitelist mechanism exists for those few return > instructions which are not actually in callable code. > > It currently only supports x86_64. It *almost* supports x86_32, but the > stackvalidate code doesn't yet know how to deal with 32-bit REL > relocations for the return whitelists. I tried to make the code generic > so that support for other architectures can be plugged in pretty easily. > > As a first step, all reported non-compliances result in warnings. Right > now I'm seeing 200+ warnings. Once we get them all cleaned up, we can > change the warnings to build errors so the asm code can stay clean. > > Signed-off-by: Josh Poimboeuf > --- > MAINTAINERS | 6 + > arch/Kconfig | 4 + > arch/x86/Kconfig | 1 + > arch/x86/Makefile | 6 +- > lib/Kconfig.debug | 11 ++ > scripts/Makefile | 1 + > scripts/Makefile.build | 22 ++- For the kbuild parts: Acked-by: Michal Marek > +int main(int argc, char *argv[]) > +{ > + struct args args; > + struct elf *elf; > + struct section *sec; > + int ret, warnings = 0; > + > + argp_parse(&argp, argc, argv, 0, 0, &args); > + > + elf = elf_open(args.args[0]); > + if (!elf) { > + fprintf(stderr, "error reading elf file %s\n", args.args[0]); > + return 1; > + } > + > + if (is_file_whitelisted(elf)) > + return 0; > + > + list_for_each_entry(sec, &elf->sections, list) { > + ret = validate_section(elf, sec); > + if (ret < 0) > + return -1; return 1? Since this is the exit status of the program. Michal -- 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/