From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752548AbaA3Jcx (ORCPT ); Thu, 30 Jan 2014 04:32:53 -0500 Received: from mga01.intel.com ([192.55.52.88]:33980 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751107AbaA3Jcu (ORCPT ); Thu, 30 Jan 2014 04:32:50 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.95,748,1384329600"; d="scan'208";a="473142312" Message-ID: <52EA1CAE.7060801@intel.com> Date: Thu, 30 Jan 2014 11:34:38 +0200 From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: Arnaldo Carvalho de Melo CC: Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, David Ahern , Frederic Weisbecker , Jiri Olsa , Mike Galbraith , Namhyung Kim , Paul Mackerras , Stephane Eranian Subject: Re: [PATCH V2 9/9] perf buildid-cache: Check relocation when checking for existing kcore References: <1391004884-10334-1-git-send-email-adrian.hunter@intel.com> <1391004884-10334-10-git-send-email-adrian.hunter@intel.com> <20140129191454.GG3998@ghostprotocols.net> In-Reply-To: <20140129191454.GG3998@ghostprotocols.net> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29/01/14 21:14, Arnaldo Carvalho de Melo wrote: > Em Wed, Jan 29, 2014 at 04:14:44PM +0200, Adrian Hunter escreveu: >> perf buildid-cache does not make another >> copy of kcore if the buildid and modules >> match an existing copy. That does not > > Humm, what is the problem? Having the ref reloc symbol we can fix things > up, no? I.e. just using map->reloc the old kcore copy should be ok to > use, no need to replace the kcore copy in the cache. Or am I missing > something? The current implementation works on the basis that kcore matches the perf data recorded. This is just a fix for that. I am afraid it is that way because it meets my needs. I did not think of allowing for relocation because I need to be able to walk the code. Relocation was one of the things I was trying to avoid. For me making a copy of kcore is far superior because it can be made to have the jump labels mostly the right way around too. e.g. run a dummy perf record while making the copy. > > - Arnaldo > >> take into account the possibility that >> the kernel has been relocated. Extend >> the check to check if the reference >> relocation symbol matches too, otherwise >> do make a copy. >> >> Signed-off-by: Adrian Hunter >> --- >> tools/perf/builtin-buildid-cache.c | 33 +++++++++++++++++++++++++++++---- >> 1 file changed, 29 insertions(+), 4 deletions(-) >> >> diff --git a/tools/perf/builtin-buildid-cache.c b/tools/perf/builtin-buildid-cache.c >> index cfede86..b22dbb1 100644 >> --- a/tools/perf/builtin-buildid-cache.c >> +++ b/tools/perf/builtin-buildid-cache.c >> @@ -63,11 +63,35 @@ static int build_id_cache__kcore_dir(char *dir, size_t sz) >> return 0; >> } >> >> +static bool same_kallsyms_reloc(const char *from_dir, char *to_dir) >> +{ >> + char from[PATH_MAX]; >> + char to[PATH_MAX]; >> + const char *name; >> + u64 addr1 = 0, addr2 = 0; >> + int i; >> + >> + scnprintf(from, sizeof(from), "%s/kallsyms", from_dir); >> + scnprintf(to, sizeof(to), "%s/kallsyms", to_dir); >> + >> + for (i = 0; (name = ref_reloc_sym_names[i]) != NULL; i++) { >> + addr1 = kallsyms__get_function_start(from, name); >> + if (addr1) >> + break; >> + } >> + >> + if (name) >> + addr2 = kallsyms__get_function_start(to, name); >> + >> + return addr1 == addr2; >> +} >> + >> static int build_id_cache__kcore_existing(const char *from_dir, char *to_dir, >> size_t to_dir_sz) >> { >> char from[PATH_MAX]; >> char to[PATH_MAX]; >> + char to_subdir[PATH_MAX]; >> struct dirent *dent; >> int ret = -1; >> DIR *d; >> @@ -86,10 +110,11 @@ static int build_id_cache__kcore_existing(const char *from_dir, char *to_dir, >> continue; >> scnprintf(to, sizeof(to), "%s/%s/modules", to_dir, >> dent->d_name); >> - if (!compare_proc_modules(from, to)) { >> - scnprintf(to, sizeof(to), "%s/%s", to_dir, >> - dent->d_name); >> - strlcpy(to_dir, to, to_dir_sz); >> + scnprintf(to_subdir, sizeof(to_subdir), "%s/%s", >> + to_dir, dent->d_name); >> + if (!compare_proc_modules(from, to) && >> + same_kallsyms_reloc(from_dir, to_subdir)) { >> + strlcpy(to_dir, to_subdir, to_dir_sz); >> ret = 0; >> break; >> } >> -- >> 1.7.11.7 > >