Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932767AbbERU1G (ORCPT ); Mon, 18 May 2015 16:27:06 -0400 Received: from mail-ob0-f181.google.com ([209.85.214.181]:33715 "EHLO mail-ob0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932496AbbERU1D (ORCPT ); Mon, 18 May 2015 16:27:03 -0400 MIME-Version: 1.0 In-Reply-To: <20150518194538.GD23618@pd.tnic> References: <1431973260-24617-1-git-send-email-prarit@redhat.com> <20150518194538.GD23618@pd.tnic> Date: Mon, 18 May 2015 16:27:02 -0400 Message-ID: Subject: Re: [PATCH] x86, cpuinfo fix cpu_data(0) x86_model_id field truncation From: Brian Gerst To: Borislav Petkov Cc: Prarit Bhargava , Linux Kernel Mailing List , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , "the arch/x86 maintainers" , Andy Lutomirski , Denys Vlasenko , Dave Hansen , Peter P Waskiewicz Jr , Igor Mammedov , Fenghua Yu Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2213 Lines: 49 On Mon, May 18, 2015 at 3:45 PM, Borislav Petkov wrote: > On Mon, May 18, 2015 at 02:21:00PM -0400, Prarit Bhargava wrote: >> When comparing 'model name' fields in /proc/cpuinfo it was noticed that >> a simple test comparing the model name fields was failing. After some >> simple investigation it was noticed that, in fact, the model name fields >> are different for each processor. Processor 0's model name field had >> white space removed, while the other processors did not. >> >> Another way of seeing this behaviour is to convert spaces into underscores >> in the output of /proc/cpuinfo, >> >> [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_________________ >> >> which shows two different model name fields even though they should be the >> same. >> >> This occurs because the kernel calls strim() on cpu 0's x86_model_id field > > I'd actually prefer this much simpler patch: > > --- > diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c > index e7d8c7608471..d215e9b26567 100644 > --- a/arch/x86/kernel/cpu/proc.c > +++ b/arch/x86/kernel/cpu/proc.c > @@ -67,7 +67,7 @@ static int show_cpuinfo(struct seq_file *m, void *v) > c->x86_vendor_id[0] ? c->x86_vendor_id : "unknown", > c->x86, > c->x86_model, > - c->x86_model_id[0] ? c->x86_model_id : "unknown"); > + c->x86_model_id[0] ? strim(c->x86_model_id) : "unknown"); > > if (c->x86_mask || c->cpuid_level >= 0) > seq_printf(m, "stepping\t: %d\n", c->x86_mask); The problem here is that strim() modifies the string in place, replacing the first trailing space with a null. I think the best solution is to do the trimming in get_model_name(). It already trims leading spaces for Intel. -- Brian Gerst -- 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/