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Message-ID: <5731C844.9080406@huawei.com>
Date: Tue, 10 May 2016 19:38:44 +0800
From: Hekuang <hekuang@...wei.com>
To: Adrian Hunter <adrian.hunter@...el.com>, <peterz@...radead.org>,
<mingo@...hat.com>, <acme@...nel.org>,
<alexander.shishkin@...ux.intel.com>, <jolsa@...hat.com>,
<wangnan0@...wei.com>, <jpoimboe@...hat.com>, <ak@...ux.intel.com>,
<eranian@...gle.com>, <namhyung@...nel.org>,
<sukadev@...ux.vnet.ibm.com>, <masami.hiramatsu.pt@...achi.com>,
<tumanova@...ux.vnet.ibm.com>, <kan.liang@...el.com>,
<penberg@...nel.org>, <dsahern@...il.com>
CC: <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 5/9] perf tools: Add methods to test dso is 64-bit or
32-bit
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 <hekuang@...wei.com>
>>>> ---
>>>> 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);
>>>>
>>
>>
>
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