From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753990AbcGHCRr (ORCPT ); Thu, 7 Jul 2016 22:17:47 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:21173 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753538AbcGHCRj (ORCPT ); Thu, 7 Jul 2016 22:17:39 -0400 X-IBM-Helo: d01dlp01.pok.ibm.com X-IBM-MailFrom: gongss@linux.vnet.ibm.com Subject: Re: [PATCH] [RFC V1]s390/perf: fix 'start' address of module's map To: acme@kernel.org, jolsa@kernel.org References: <1467856176-8712-1-git-send-email-gongss@linux.vnet.ibm.com> Cc: dsahern@gmail.com, linux-kernel@vger.kernel.org From: Songshan Gong Date: Fri, 8 Jul 2016 10:17:30 +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: <1467856176-8712-1-git-send-email-gongss@linux.vnet.ibm.com> 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: 16070802-0040-0000-0000-000000C1BE24 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16070802-0041-0000-0000-0000049BE3DB Message-Id: <5c24562a-17ee-d30e-0308-5ec141ff52f1@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-07-07_14:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=2 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1607080019 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ÔÚ 7/7/2016 9:49 AM, Song Shan Gong дµÀ: > 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. > > 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 > --- > tools/perf/arch/s390/util/Build | 2 ++ > tools/perf/arch/s390/util/sym-handling.c | 49 ++++++++++++++++++++++++++++++++ > tools/perf/util/machine.c | 6 ++++ > tools/perf/util/machine.h | 2 ++ > 4 files changed, 59 insertions(+) > create mode 100644 tools/perf/arch/s390/util/sym-handling.c > > diff --git a/tools/perf/arch/s390/util/Build b/tools/perf/arch/s390/util/Build > index 8a61372..5e322ed 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 += sym-handling.o > diff --git a/tools/perf/arch/s390/util/sym-handling.c b/tools/perf/arch/s390/util/sym-handling.c > new file mode 100644 > index 0000000..efe2a50 > --- /dev/null > +++ b/tools/perf/arch/s390/util/sym-handling.c > @@ -0,0 +1,49 @@ > +#include > +#include > +#include > +#include "symbol.h" > +#include "map.h" > +#include "util.h" > +#include "machine.h" > + > +int arch__fix_module_baseaddr(struct machine *machine, > + u64 *start, const char *name) > +{ > + char path[PATH_MAX]; > + char *module_name = strdup(name); > + int len = strlen(module_name); > + FILE *file; > + int err = 0; > + u64 text_start; > + char *line = NULL; > + size_t n; > + char *sep; > + > + module_name[len - 1] = '\0'; > + module_name += 1; > + snprintf(path, PATH_MAX, "%s/sys/module/%s/sections/.text", > + machine->root_dir, module_name); > + file = fopen(path, "r"); > + if (file == NULL) > + return -1; > + > + len = getline(&line, &n, file); > + if (len < 0) { > + err = -1; > + goto out; > + } > + line[--len] = '\0'; /* \n */ > + sep = strrchr(line, 'x'); > + if (sep == NULL) { > + err = -1; > + goto out; > + } > + hex2u64(sep + 1, &text_start); > + > + *start = text_start; > +out: > + free(line); > + fclose(file); > + free(module_name - 1); > + return err; > +} > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c > index b177218..e5c2721 100644 > --- a/tools/perf/util/machine.c > +++ b/tools/perf/util/machine.c > @@ -1091,12 +1091,18 @@ 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_baseaddr(struct machine *machine __maybe_unused, > + 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; > > + arch__fix_module_baseaddr(machine, &start, name); As the description says, I would change the function name to 'arch__fix_module_text_start'; > 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..da7b6c0 100644 > --- a/tools/perf/util/machine.h > +++ b/tools/perf/util/machine.h > @@ -216,6 +216,8 @@ 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_baseaddr(struct machine *machine, 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); > -- SongShan Gong