From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754003AbbE1M6g (ORCPT ); Thu, 28 May 2015 08:58:36 -0400 Received: from mail.skyhub.de ([78.46.96.112]:59778 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751284AbbE1M6b (ORCPT ); Thu, 28 May 2015 08:58:31 -0400 Date: Thu, 28 May 2015 14:58:19 +0200 From: Borislav Petkov To: Prarit Bhargava Cc: Joe Perches , luto@amacapital.net, peterz@infradead.org, dvlasenk@redhat.com, torvalds@linux-foundation.org, imammedo@redhat.com, brgerst@gmail.com, mingo@kernel.org, dave.hansen@linux.intel.com, fenghua.yu@intel.com, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@suse.de, linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/cpu] x86/cpu: Strip any /proc/ cpuinfo model name field whitespace Message-ID: <20150528125819.GB31800@pd.tnic> References: <1432050210-32036-1-git-send-email-prarit@redhat.com> <1432628901-18044-15-git-send-email-bp@alien8.de> <1432746454.2846.154.camel@perches.com> <20150527190626.GC19407@pd.tnic> <1432754207.2846.162.camel@perches.com> <5566FB97.5020904@redhat.com> <20150528113229.GA31800@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20150528113229.GA31800@pd.tnic> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 28, 2015 at 01:32:29PM +0200, Borislav Petkov wrote: > + while (*p) { > + /* Note the last non-whitespace index */ > + if (!isspace(*p)) > + s = q; > + > + *q++ = *p++; This should be optimized to not copy if there's no preceding whitespace and p == q: From: Borislav Petkov Date: Tue, 26 May 2015 10:28:17 +0200 Subject: [PATCH] x86/cpu: Trim model id whitespace We did try trimming whitespace surrounding the 'model name' field in /proc/cpuinfo since reportedly some userspace uses it in string comparisons and there were discrepancies: [thetango@prarit ~]# grep "^model name" /proc/cpuinfo | uniq -c | sed 's/\ /_/g' ______1_model_name :_AMD_Opteron(TM)_Processor_6272 _____63_model_name :_AMD_Opteron(TM)_Processor_6272_________________ However, there were issues with overlapping buffers, string sizes and non-byte-sized copies in the previous proposed solutions; see Link tags below for the whole farce. So, instead of diddling with this more, let's simply extend what was there originally with trimming any present trailing whitespace. Final result is really simple and obvious. Testing with the most insane model IDs qemu can generate, looks good: .model_id = " My funny model ID CPU ", ______4_model_name :_My_funny_model_ID_CPU .model_id = "My funny model ID CPU ", ______4_model_name :_My_funny_model_ID_CPU .model_id = " My funny model ID CPU", ______4_model_name :_My_funny_model_ID_CPU .model_id = " ", ______4_model_name :__ .model_id = "", ______4_model_name :_15/02 Cc: Andy Lutomirski Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: Fenghua Yu Cc: H. Peter Anvin Cc: Igor Mammedov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1432050210-32036-1-git-send-email-prarit@redhat.com Link: http://lkml.kernel.org/r/1432628901-18044-15-git-send-email-bp@alien8.de Signed-off-by: Borislav Petkov --- arch/x86/kernel/cpu/common.c | 27 ++++++++++++++++++++++----- 1 file changed, 22 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 41a8e9cb30bc..18120a33a2c1 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -5,6 +5,7 @@ #include #include #include +#include #include #include #include @@ -419,6 +420,7 @@ static const struct cpu_dev *cpu_devs[X86_VENDOR_NUM] = {}; static void get_model_name(struct cpuinfo_x86 *c) { unsigned int *v; + char *p, *q, *s; if (c->extended_cpuid_level < 0x80000004) return; @@ -429,11 +431,26 @@ static void get_model_name(struct cpuinfo_x86 *c) cpuid(0x80000004, &v[8], &v[9], &v[10], &v[11]); c->x86_model_id[48] = 0; - /* - * Remove leading whitespace on Intel processors and trailing - * whitespace on AMD processors. - */ - memmove(c->x86_model_id, strim(c->x86_model_id), 48); + /* Trim whitespace */ + p = q = s = &c->x86_model_id[0]; + + while (*p == ' ') + p++; + + while (*p) { + /* Note the last non-whitespace index: */ + if (!isspace(*p)) + s = q; + + /* Only copy if p advanced due to whitespace: */ + if (p != q) + *q = *p; + + p++; + q++; + } + + *(s + 1) = '\0'; } void cpu_detect_cache_sizes(struct cpuinfo_x86 *c) -- 2.3.5 -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. --