From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759152Ab2AFUm1 (ORCPT ); Fri, 6 Jan 2012 15:42:27 -0500 Received: from mail-yx0-f174.google.com ([209.85.213.174]:37452 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752928Ab2AFUmZ (ORCPT ); Fri, 6 Jan 2012 15:42:25 -0500 Message-ID: <4F075CAE.2040709@gmail.com> Date: Fri, 06 Jan 2012 12:42:22 -0800 From: David Daney User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.15) Gecko/20101027 Fedora/3.0.10-1.fc12 Thunderbird/3.0.10 MIME-Version: 1.0 To: Steven Rostedt CC: linux-kernel@vger.kernel.org, David Daney Subject: Re: [PATCH] recordmcount: Fix handling of elf64 big-endian objects. References: <1324345362-12230-1-git-send-email-ddaney.cavm@gmail.com> <1324350542.5916.48.camel@gandalf.stny.rr.com> In-Reply-To: <1324350542.5916.48.camel@gandalf.stny.rr.com> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/19/2011 07:09 PM, Steven Rostedt wrote: > On Mon, 2011-12-19 at 17:42 -0800, David Daney wrote: >> From: David Daney >> >> In ELF64, the sh_flags field is 64-bits wide. recordmcount was >> erroneously treating it as a 32-bit wide field. For little endian >> objects this works because the flags of interest (SHF_EXECINSTR) >> reside in the lower 32 bits of the word, and you get the same result >> with either a 32-bit or 64-bit read. Big endian objects on the >> other hand do not work at all with this error. >> >> The fix: Correctly treat sh_flags as 64-bits wide in elf64 objects. >> >> The symptom I observed was that my >> __start_mcount_loc..__stop_mcount_loc was empty even though ftrace >> function tracing was enabled. >> > > OUCH! > > This looks like something that needs to go to stable. Let me play with > this on my PPC64 tomorrow. > Hi Steven, Any more feedback on this patch? Should I look for it to appear in 3.3? Thanks, David Daney > Thanks! > > -- Steve > >> Signed-off-by: David Daney >> --- >> scripts/recordmcount.h | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h >> index f40a6af6..54e35c1 100644 >> --- a/scripts/recordmcount.h >> +++ b/scripts/recordmcount.h >> @@ -462,7 +462,7 @@ __has_rel_mcount(Elf_Shdr const *const relhdr, /* is SHT_REL or SHT_RELA */ >> succeed_file(); >> } >> if (w(txthdr->sh_type) != SHT_PROGBITS || >> - !(w(txthdr->sh_flags)& SHF_EXECINSTR)) >> + !(_w(txthdr->sh_flags)& SHF_EXECINSTR)) >> return NULL; >> return txtname; >> } > >