From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754966AbcG0KK1 (ORCPT ); Wed, 27 Jul 2016 06:10:27 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:40267 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754636AbcG0KKN (ORCPT ); Wed, 27 Jul 2016 06:10:13 -0400 X-IBM-Helo: d03dlp02.boulder.ibm.com X-IBM-MailFrom: gongss@linux.vnet.ibm.com Subject: Re: [PATCH] s390/perf: fix 'start' address of module's map To: Arnaldo Carvalho de Melo , Christian Borntraeger References: <1469070651-6447-1-git-send-email-gongss@linux.vnet.ibm.com> <1469070651-6447-2-git-send-email-gongss@linux.vnet.ibm.com> <20160726195039.GA5200@kernel.org> <5797C49A.1070402@de.ibm.com> <20160726202926.GB5200@kernel.org> Cc: jolsa@kernel.org, dsahern@gmail.com, linux-kernel@vger.kernel.org, Michael Ellerman From: Songshan Gong Date: Wed, 27 Jul 2016 18:10:07 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <20160726202926.GB5200@kernel.org> Content-Type: text/plain; charset=gbk; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16072710-0020-0000-0000-0000096BD192 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16072710-0021-0000-0000-0000541040C2 Message-Id: <49c5951e-fa81-18df-ff9f-8bab61bec422@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-07-27_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1607270105 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ÔÚ 7/27/2016 4:29 AM, Arnaldo Carvalho de Melo дµÀ: > Em Tue, Jul 26, 2016 at 10:14:18PM +0200, Christian Borntraeger escreveu: >> On 07/26/2016 09:50 PM, Arnaldo Carvalho de Melo wrote: >>> Em Thu, Jul 21, 2016 at 11:10:51AM +0800, Song Shan Gong escreveu: >>>> At preset, when creating module's map, perf gets 'start' address by parsing >>>> '/proc/modules', but it's module base address, isn't the start address of >>>> '.text' section. In most archs, it's OK. But for s390, it places 'GOT' and >>>> 'PLT' relocations before '.text' section. So there exists an offset between >>>> module base address and '.text' section, which will incur wrong symbol >>>> resolution for modules. >>> >>> I'll apply this as it fixes the problem for you and we need to get fixes >>> in ASAP to get this into 4.8, but why can't we just use your method for >>> all arches and get rid of this arch__ hook? I.e. if I look here in my >>> x86_64 notebook I see: >>> >>> [acme@jouet linux]$ cat /sys/module/tun/sections/.text >>> 0xffffffffc0af2000 >>> [acme@jouet linux]$ grep tun /proc/modules >>> tun 28672 4 vhost_net, Live 0xffffffffc0af2000 >>> [acme@jouet linux]$ >>> >>> So I could as well use what is in /sys/module/tun/sections/.text instead >>> of reading it from /proc/modules and, in s390, reading it from >>> /sys/module/tun/sections/.text. >>> >>> Do you see any problem with using this approach for _all_ arches? >> >> I think it should work well for _all_ arches but it will probably be >> hard to test this without help. > > Well, we could check for the cases we don't know, i.e. read from both > and warn about cases where it is different, except for s390 where we now > which is the right one to pick. Good idea! > >> I wouldn't be surprised if other architectures than s390 actually have >> the same issue, so doing this for everybody might atually fix this somewhere >> else. > > Would be nice to get info from other arch people, Michael, how this goes > on ppc? > > - Arnaldo > >>> >>> - Arnaldo >>> >>>> Fix this bug by getting 'start' address of module's map from parsing >>>> '/sys/module/[module name]/sections/.text', not from '/proc/modules'. >>>> >>>> Signed-off-by: Song Shan Gong >>>> Acked-by: Jiri Olsa >>>> --- >>>> tools/perf/arch/s390/util/Build | 2 ++ >>>> tools/perf/arch/s390/util/machine.c | 19 +++++++++++++++++++ >>>> tools/perf/util/machine.c | 8 ++++++++ >>>> tools/perf/util/machine.h | 1 + >>>> 4 files changed, 30 insertions(+) >>>> create mode 100644 tools/perf/arch/s390/util/machine.c >>>> >>>> diff --git a/tools/perf/arch/s390/util/Build b/tools/perf/arch/s390/util/Build >>>> index 8a61372..5bd7b92 100644 >>>> --- a/tools/perf/arch/s390/util/Build >>>> +++ b/tools/perf/arch/s390/util/Build >>>> @@ -2,3 +2,5 @@ libperf-y += header.o >>>> libperf-y += kvm-stat.o >>>> >>>> libperf-$(CONFIG_DWARF) += dwarf-regs.o >>>> + >>>> +libperf-y += machine.o >>>> diff --git a/tools/perf/arch/s390/util/machine.c b/tools/perf/arch/s390/util/machine.c >>>> new file mode 100644 >>>> index 0000000..b9a95a1 >>>> --- /dev/null >>>> +++ b/tools/perf/arch/s390/util/machine.c >>>> @@ -0,0 +1,19 @@ >>>> +#include >>>> +#include >>>> +#include >>>> +#include "util.h" >>>> +#include "machine.h" >>>> +#include "api/fs/fs.h" >>>> + >>>> +int arch__fix_module_text_start(u64 *start, const char *name) >>>> +{ >>>> + char path[PATH_MAX]; >>>> + >>>> + snprintf(path, PATH_MAX, "module/%.*s/sections/.text", >>>> + (int)strlen(name) - 2, name + 1); >>>> + >>>> + if (sysfs__read_ull(path, (unsigned long long *)start) < 0) >>>> + return -1; >>>> + >>>> + return 0; >>>> +} >>>> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c >>>> index b177218..97cc9f0 100644 >>>> --- a/tools/perf/util/machine.c >>>> +++ b/tools/perf/util/machine.c >>>> @@ -1091,12 +1091,20 @@ static int machine__set_modules_path(struct machine *machine) >>>> >>>> return map_groups__set_modules_path_dir(&machine->kmaps, modules_path, 0); >>>> } >>>> +int __weak arch__fix_module_text_start(u64 *start __maybe_unused, >>>> + const char *name __maybe_unused) >>>> +{ >>>> + return 0; >>>> +} >>>> >>>> static int machine__create_module(void *arg, const char *name, u64 start) >>>> { >>>> struct machine *machine = arg; >>>> struct map *map; >>>> >>>> + if (arch__fix_module_text_start(&start, name) < 0) >>>> + return -1; >>>> + >>>> map = machine__findnew_module_map(machine, start, name); >>>> if (map == NULL) >>>> return -1; >>>> diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h >>>> index 41ac9cf..20739f7 100644 >>>> --- a/tools/perf/util/machine.h >>>> +++ b/tools/perf/util/machine.h >>>> @@ -216,6 +216,7 @@ struct symbol *machine__find_kernel_function_by_name(struct machine *machine, >>>> >>>> struct map *machine__findnew_module_map(struct machine *machine, u64 start, >>>> const char *filename); >>>> +int arch__fix_module_text_start(u64 *start, const char *name); >>>> >>>> int __machine__load_kallsyms(struct machine *machine, const char *filename, >>>> enum map_type type, bool no_kcore, symbol_filter_t filter); >>>> -- >>>> 2.3.0 >>> > -- SongShan Gong