From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751625AbcEJLks (ORCPT ); Tue, 10 May 2016 07:40:48 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:11708 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751212AbcEJLkq (ORCPT ); Tue, 10 May 2016 07:40:46 -0400 Subject: Re: [PATCH v2 5/9] perf tools: Add methods to test dso is 64-bit or 32-bit To: Adrian Hunter , , , , , , , , , , , , , , , , References: <1462866037-30382-1-git-send-email-hekuang@huawei.com> <1462866037-30382-6-git-send-email-hekuang@huawei.com> <573196E5.9080807@intel.com> <5731AEBB.8060200@huawei.com> <5731B94A.3070402@intel.com> CC: From: Hekuang Message-ID: <5731C844.9080406@huawei.com> Date: Tue, 10 May 2016 19:38:44 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <5731B94A.3070402@intel.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.110.55.166] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020201.5731C856.0119,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 25fe009fb78b7579ab344c8ff7ca0ec5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2016/5/10 18:34, Adrian Hunter 写道: > On 10/05/16 12:49, Hekuang wrote: >> hi >> >> 在 2016/5/10 16:08, Adrian Hunter 写道: >>> On 10/05/16 10:40, He Kuang wrote: >>>> 32-bit programs can be run on 64-bit machines, so we should choose >>>> unwind methods according to 'thread->map' instead of the host >>>> architecture. >>>> >>>> This patch adds methods to test whether a dso is 64-bit or 32-bit by >>>> the class info in elf. >>> What about using dso->is_64_bit set by dso__load_sym() ? >> I've noticed this variable, but it's value is not as its name said: >> >> util/dso.c: 1067 dso->is_64_bit = (sizeof(void *) == 8); > That is just initialization i.e. before we know what it is we assume it is > the same as the host. > >> This is only related to the host architecture. >> >> A closer one is 'is_64_bit' in 'struct symsrc', but the value is assigned >> after dso >> loaded. So I think we should provide individual methods to get that value. > Are you saying you don't load dsos? Or that is_64_bit is set incorrectly? > Yes, I know it's the inital value, but the correct value is assigned in function dso__load_sym(), and have a look at the call stack(gdb): #0 dso__load_sym #1 in dso__load #2 in map__load #3 in map__find_symbol #4 in thread__find_addr_location #5 in entry #6 in get_entries #7 in _Ux86__unwind__get_entries #8 in thread__resolve_callchain I think we should choose the right unwind method before dso__load_sym(). i.e. line#7, which is called before dso__load_sym(). I'm not very familiar with this, what's your opinion? Thanks. >> Thanks. >> >>>> Signed-off-by: He Kuang >>>> --- >>>> tools/perf/util/symbol-elf.c | 16 +++++++++++++++ >>>> tools/perf/util/symbol.c | 49 >>>> ++++++++++++++++++++++++++++++++++++++++++++ >>>> tools/perf/util/symbol.h | 2 ++ >>>> 3 files changed, 67 insertions(+) >>>> >>>> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c >>>> index 3f9d679..9f290b9 100644 >>>> --- a/tools/perf/util/symbol-elf.c >>>> +++ b/tools/perf/util/symbol-elf.c >>>> @@ -636,6 +636,22 @@ bool __weak elf__needs_adjust_symbols(GElf_Ehdr ehdr) >>>> return ehdr.e_type == ET_EXEC || ehdr.e_type == ET_REL; >>>> } >>>> +int elf_is_64_bit(char *name) >>>> +{ >>>> + Elf *elf; >>>> + int fd; >>>> + >>>> + fd = open(name, O_RDONLY); >>>> + if (fd < 0) >>>> + return -1; >>>> + >>>> + elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); >>>> + if (elf == NULL) >>>> + return -1; >>>> + >>>> + return (gelf_getclass(elf) == ELFCLASS64); >>>> +} >>>> + >>>> int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name, >>>> enum dso_binary_type type) >>>> { >>>> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c >>>> index 4630751..592bf8c 100644 >>>> --- a/tools/perf/util/symbol.c >>>> +++ b/tools/perf/util/symbol.c >>>> @@ -1395,6 +1395,55 @@ static bool dso__is_compatible_symtab_type(struct >>>> dso *dso, bool kmod, >>>> } >>>> } >>>> +int dso_is_64_bit(struct dso *dso, struct map *map) >>>> +{ >>>> + char *name; >>>> + u_int i; >>>> + bool kmod; >>>> + char *root_dir = (char *) ""; >>>> + struct machine *machine; >>>> + >>>> + if (map->groups && map->groups->machine) >>>> + machine = map->groups->machine; >>>> + else >>>> + machine = NULL; >>>> + >>>> + if (machine) >>>> + root_dir = machine->root_dir; >>>> + >>>> + name = malloc(PATH_MAX); >>>> + if (!name) >>>> + return -1; >>>> + >>>> + kmod = dso->symtab_type == DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE || >>>> + dso->symtab_type == DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP || >>>> + dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE || >>>> + dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE_COMP; >>>> + >>>> + /* >>>> + * Iterate over candidate debug images. >>>> + * Keep track of "interesting" ones (those which have a symtab, dynsym, >>>> + * and/or opd section) for processing. >>>> + */ >>>> + for (i = 0; i < DSO_BINARY_TYPE__SYMTAB_CNT; i++) { >>>> + enum dso_binary_type symtab_type = binary_type_symtab[i]; >>>> + >>>> + if (!dso__is_compatible_symtab_type(dso, kmod, symtab_type)) >>>> + continue; >>>> + >>>> + if (dso__read_binary_type_filename(dso, symtab_type, >>>> + root_dir, name, PATH_MAX)) >>>> + continue; >>>> + >>>> + if (!is_regular_file(name)) >>>> + continue; >>>> + >>>> + return elf_is_64_bit(name); >>>> + } >>>> + >>>> + return -1; >>>> +} >>>> + >>>> int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter) >>>> { >>>> char *name; >>>> diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h >>>> index 4e6910e..d33fbf4 100644 >>>> --- a/tools/perf/util/symbol.h >>>> +++ b/tools/perf/util/symbol.h >>>> @@ -308,6 +308,8 @@ int setup_list(struct strlist **list, const char >>>> *list_str, >>>> const char *list_name); >>>> int setup_intlist(struct intlist **list, const char *list_str, >>>> const char *list_name); >>>> +int elf_is_64_bit(char *name); >>>> +int dso_is_64_bit(struct dso *dso, struct map *map); >>>> #ifdef HAVE_LIBELF_SUPPORT >>>> bool elf__needs_adjust_symbols(GElf_Ehdr ehdr); >>>> >> >> >