* Re: [PATCH 1/1] perf tools: Fix Symbol Address for ET_DYN
[not found] ` <CAPp4yYzRwoTBzH1_TwcdvAOryZppV9-BwnX2bOtN1qrEqrdBww@mail.gmail.com>
@ 2014-09-11 20:38 ` Arnaldo Carvalho de Melo
2014-09-15 18:06 ` Tong Shen
0 siblings, 1 reply; 7+ messages in thread
From: Arnaldo Carvalho de Melo @ 2014-09-11 20:38 UTC (permalink / raw)
To: Tong Shen; +Cc: linux-perf-users, Linux Kernel Mailing List
Em Thu, Sep 11, 2014 at 11:21:40AM -0700, Tong Shen escreveu:
> Hi Arnaldo,
>
> Thanks a lot for the comment!
>
> I fixed the coding style and added a helper function with comments, as
> you suggested :-)
> See attachment.
That is much better, I'm adding lkml to the CC list so that we can give
other people the opportunity to chime in.
- Arnaldo
> On Thu, Sep 11, 2014 at 8:01 AM, Arnaldo Carvalho de Melo
> <acme@kernel.org> wrote:
> > Em Fri, Sep 05, 2014 at 11:38:02AM -0700, Tong Shen escreveu:
> >> Hi linux-perf-users,
> >>
> >> It's actually a patch, and I didn't find a development mailing list
> >> for perf, so I just post it here. If this is not the right place to
> >
> > You can post it here, but please add the maintainers to the CC list, so
> > that we can more quickly see your message.
> >
> > Comments below:
> >
> >> post patches, could someone direct me to it? Thanks in advance!
> >>
> >> In tools/perf/util/symbol-elf.c, we don't adjust symbol address for
> >> ET_DYN type of ELF files because we think ET_DYN is always
> >> relocatable.
> >>
> >> But that's not necessarily true; there are some non-relocatable ET_DYN
> >> ELF files. For those files, we should still adjust symbol address.
> >
> >> Suggested patch: (HTML subpart now allowed in this mailing list...)
> >
> >> +++ b/perf-3.12.0/tools/perf/util/symbol-elf.c
> >> @@ -915,7 +915,10 @@ int dso__load_sym(struct dso *dso, struct map *map,
> >
> >> if ((used_opd && runtime_ss->adjust_symbols)
> >> - || (!used_opd && syms_ss->adjust_symbols)) {
> >> + || (!used_opd && syms_ss->adjust_symbols)
> >> + || (syms_ss->ehdr.e_type == et_dyn
> >> + && shdr.sh_addr != shdr.sh_offset
> >> + && elf_sec__is_text(&shdr, secstrs))) {
> >
> > Please try to follow kernel coding style in these tools, i.e. the &&
> > should be at the end, the expression on each line should be aligned just
> > after the opening parens.
> >
> > If, like in this case, you find something not following that style, take
> > the opportunity to fix it :-)
> >
> > But back to your change, I'll have to look at this code further, just
> > looking at the excerpt above I find it way too confusing, and your patch
> > makes it even more so...
> >
> > Can you introduce some suitably named helper that has those extra
> > conditions you're adding now and then add it to this conditional?
> >
> > I.e. make it somethine like:
> >
> > - if ((used_opd && runtime_ss->adjust_symbols)
> > - || (!used_opd && syms_ss->adjust_symbols)) {
> > + if ((used_opd && runtime_ss->adjust_symbols) ||
> > + (!used_opd && syms_ss->adjust_symbols) ||
> > + syms__some_suitable_name(syms_ss, &shdr)) {
> >
> > And then add your explanation of these kinds of files as a comment over
> > this new function, please?
> >
> >> pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
> >> "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
> >> (u64)sym.st_value, (u64)shdr.sh_addr,
> >
> > Best regards,
> >
> > - Arnaldo
>
>
>
> --
> Best Regards, Tong Shen
> diff --git a/perf-3.12.0/tools/perf/util/symbol-elf.c b/perf-3.12.0/tools/perf/util/symbol-elf.c
> index a9c829b..f9bd488 100644
> --- a/perf-3.12.0/tools/perf/util/symbol-elf.c
> +++ b/perf-3.12.0/tools/perf/util/symbol-elf.c
> @@ -673,6 +673,27 @@ static u64 ref_reloc(struct kmap *kmap)
> return 0;
> }
>
> +/**
> + * is_non_relocatable_dyn - check if ELF file is ET_DYN, but not relocatable
> + * @ehdr: ELF header of the ELF file
> + * @shdr: a section header in the ELF file
> + *
> + * For ELF files with type ET_EXEC and ET_REL, we adjust symbol addresses in
> + * symbol table in dso__load_sym() so that later we can always locate symbols
> + * by sym.st_value + map_address_of_ELF_file.
> + *
> + * But ELF files with type ET_DYN may need adjusting as well, if they are
> + * not relocatable. There's no standard way to tell if an ELF file with type
> + * ET_DYN is relocatable. One possible way to do that is checking if
> + * sh_addr == sh_offset for .text section.
> + */
> +static bool is_non_relocatable_dyn(GElf_Ehdr *ehdr, GElf_Shdr *shdr,
> + Elf_Data *secstrs) {
> + return ehdr->e_type == ET_DYN &&
> + elf_sec__is_text(shdr, secstrs) &&
> + shdr->sh_offset != shdr->sh_addr;
> +}
> +
> int dso__load_sym(struct dso *dso, struct map *map,
> struct symsrc *syms_ss, struct symsrc *runtime_ss,
> symbol_filter_t filter, int kmodule)
> @@ -914,8 +935,9 @@ int dso__load_sym(struct dso *dso, struct map *map,
> goto new_symbol;
> }
>
> - if ((used_opd && runtime_ss->adjust_symbols)
> - || (!used_opd && syms_ss->adjust_symbols)) {
> + if ((used_opd && runtime_ss->adjust_symbols) ||
> + (!used_opd && syms_ss->adjust_symbols) ||
> + is_non_relocatable_dyn(&ehdr, &shdr, secstrs)) {
> pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
> "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
> (u64)sym.st_value, (u64)shdr.sh_addr,
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/1] perf tools: Fix Symbol Address for ET_DYN
2014-09-11 20:38 ` [PATCH 1/1] perf tools: Fix Symbol Address for ET_DYN Arnaldo Carvalho de Melo
@ 2014-09-15 18:06 ` Tong Shen
2014-09-25 0:28 ` Tong Shen
0 siblings, 1 reply; 7+ messages in thread
From: Tong Shen @ 2014-09-15 18:06 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo; +Cc: linux-perf-users, Linux Kernel Mailing List
Gentle ping :-)
On Thu, Sep 11, 2014 at 1:38 PM, Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
> Em Thu, Sep 11, 2014 at 11:21:40AM -0700, Tong Shen escreveu:
>> Hi Arnaldo,
>>
>> Thanks a lot for the comment!
>>
>> I fixed the coding style and added a helper function with comments, as
>> you suggested :-)
>> See attachment.
>
> That is much better, I'm adding lkml to the CC list so that we can give
> other people the opportunity to chime in.
>
> - Arnaldo
>
>> On Thu, Sep 11, 2014 at 8:01 AM, Arnaldo Carvalho de Melo
>> <acme@kernel.org> wrote:
>> > Em Fri, Sep 05, 2014 at 11:38:02AM -0700, Tong Shen escreveu:
>> >> Hi linux-perf-users,
>> >>
>> >> It's actually a patch, and I didn't find a development mailing list
>> >> for perf, so I just post it here. If this is not the right place to
>> >
>> > You can post it here, but please add the maintainers to the CC list, so
>> > that we can more quickly see your message.
>> >
>> > Comments below:
>> >
>> >> post patches, could someone direct me to it? Thanks in advance!
>> >>
>> >> In tools/perf/util/symbol-elf.c, we don't adjust symbol address for
>> >> ET_DYN type of ELF files because we think ET_DYN is always
>> >> relocatable.
>> >>
>> >> But that's not necessarily true; there are some non-relocatable ET_DYN
>> >> ELF files. For those files, we should still adjust symbol address.
>> >
>> >> Suggested patch: (HTML subpart now allowed in this mailing list...)
>> >
>> >> +++ b/perf-3.12.0/tools/perf/util/symbol-elf.c
>> >> @@ -915,7 +915,10 @@ int dso__load_sym(struct dso *dso, struct map *map,
>> >
>> >> if ((used_opd && runtime_ss->adjust_symbols)
>> >> - || (!used_opd && syms_ss->adjust_symbols)) {
>> >> + || (!used_opd && syms_ss->adjust_symbols)
>> >> + || (syms_ss->ehdr.e_type == et_dyn
>> >> + && shdr.sh_addr != shdr.sh_offset
>> >> + && elf_sec__is_text(&shdr, secstrs))) {
>> >
>> > Please try to follow kernel coding style in these tools, i.e. the &&
>> > should be at the end, the expression on each line should be aligned just
>> > after the opening parens.
>> >
>> > If, like in this case, you find something not following that style, take
>> > the opportunity to fix it :-)
>> >
>> > But back to your change, I'll have to look at this code further, just
>> > looking at the excerpt above I find it way too confusing, and your patch
>> > makes it even more so...
>> >
>> > Can you introduce some suitably named helper that has those extra
>> > conditions you're adding now and then add it to this conditional?
>> >
>> > I.e. make it somethine like:
>> >
>> > - if ((used_opd && runtime_ss->adjust_symbols)
>> > - || (!used_opd && syms_ss->adjust_symbols)) {
>> > + if ((used_opd && runtime_ss->adjust_symbols) ||
>> > + (!used_opd && syms_ss->adjust_symbols) ||
>> > + syms__some_suitable_name(syms_ss, &shdr)) {
>> >
>> > And then add your explanation of these kinds of files as a comment over
>> > this new function, please?
>> >
>> >> pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
>> >> "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
>> >> (u64)sym.st_value, (u64)shdr.sh_addr,
>> >
>> > Best regards,
>> >
>> > - Arnaldo
>>
>>
>>
>> --
>> Best Regards, Tong Shen
>
>> diff --git a/perf-3.12.0/tools/perf/util/symbol-elf.c b/perf-3.12.0/tools/perf/util/symbol-elf.c
>> index a9c829b..f9bd488 100644
>> --- a/perf-3.12.0/tools/perf/util/symbol-elf.c
>> +++ b/perf-3.12.0/tools/perf/util/symbol-elf.c
>> @@ -673,6 +673,27 @@ static u64 ref_reloc(struct kmap *kmap)
>> return 0;
>> }
>>
>> +/**
>> + * is_non_relocatable_dyn - check if ELF file is ET_DYN, but not relocatable
>> + * @ehdr: ELF header of the ELF file
>> + * @shdr: a section header in the ELF file
>> + *
>> + * For ELF files with type ET_EXEC and ET_REL, we adjust symbol addresses in
>> + * symbol table in dso__load_sym() so that later we can always locate symbols
>> + * by sym.st_value + map_address_of_ELF_file.
>> + *
>> + * But ELF files with type ET_DYN may need adjusting as well, if they are
>> + * not relocatable. There's no standard way to tell if an ELF file with type
>> + * ET_DYN is relocatable. One possible way to do that is checking if
>> + * sh_addr == sh_offset for .text section.
>> + */
>> +static bool is_non_relocatable_dyn(GElf_Ehdr *ehdr, GElf_Shdr *shdr,
>> + Elf_Data *secstrs) {
>> + return ehdr->e_type == ET_DYN &&
>> + elf_sec__is_text(shdr, secstrs) &&
>> + shdr->sh_offset != shdr->sh_addr;
>> +}
>> +
>> int dso__load_sym(struct dso *dso, struct map *map,
>> struct symsrc *syms_ss, struct symsrc *runtime_ss,
>> symbol_filter_t filter, int kmodule)
>> @@ -914,8 +935,9 @@ int dso__load_sym(struct dso *dso, struct map *map,
>> goto new_symbol;
>> }
>>
>> - if ((used_opd && runtime_ss->adjust_symbols)
>> - || (!used_opd && syms_ss->adjust_symbols)) {
>> + if ((used_opd && runtime_ss->adjust_symbols) ||
>> + (!used_opd && syms_ss->adjust_symbols) ||
>> + is_non_relocatable_dyn(&ehdr, &shdr, secstrs)) {
>> pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
>> "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
>> (u64)sym.st_value, (u64)shdr.sh_addr,
>
--
Best Regards, Tong Shen
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/1] perf tools: Fix Symbol Address for ET_DYN
2014-09-15 18:06 ` Tong Shen
@ 2014-09-25 0:28 ` Tong Shen
2014-09-26 5:45 ` Namhyung Kim
0 siblings, 1 reply; 7+ messages in thread
From: Tong Shen @ 2014-09-25 0:28 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo; +Cc: linux-perf-users, Linux Kernel Mailing List
Gentle Ping :-)
On Mon, Sep 15, 2014 at 11:06 AM, Tong Shen <endlessroad@google.com> wrote:
> Gentle ping :-)
>
> On Thu, Sep 11, 2014 at 1:38 PM, Arnaldo Carvalho de Melo
> <acme@kernel.org> wrote:
>> Em Thu, Sep 11, 2014 at 11:21:40AM -0700, Tong Shen escreveu:
>>> Hi Arnaldo,
>>>
>>> Thanks a lot for the comment!
>>>
>>> I fixed the coding style and added a helper function with comments, as
>>> you suggested :-)
>>> See attachment.
>>
>> That is much better, I'm adding lkml to the CC list so that we can give
>> other people the opportunity to chime in.
>>
>> - Arnaldo
>>
>>> On Thu, Sep 11, 2014 at 8:01 AM, Arnaldo Carvalho de Melo
>>> <acme@kernel.org> wrote:
>>> > Em Fri, Sep 05, 2014 at 11:38:02AM -0700, Tong Shen escreveu:
>>> >> Hi linux-perf-users,
>>> >>
>>> >> It's actually a patch, and I didn't find a development mailing list
>>> >> for perf, so I just post it here. If this is not the right place to
>>> >
>>> > You can post it here, but please add the maintainers to the CC list, so
>>> > that we can more quickly see your message.
>>> >
>>> > Comments below:
>>> >
>>> >> post patches, could someone direct me to it? Thanks in advance!
>>> >>
>>> >> In tools/perf/util/symbol-elf.c, we don't adjust symbol address for
>>> >> ET_DYN type of ELF files because we think ET_DYN is always
>>> >> relocatable.
>>> >>
>>> >> But that's not necessarily true; there are some non-relocatable ET_DYN
>>> >> ELF files. For those files, we should still adjust symbol address.
>>> >
>>> >> Suggested patch: (HTML subpart now allowed in this mailing list...)
>>> >
>>> >> +++ b/perf-3.12.0/tools/perf/util/symbol-elf.c
>>> >> @@ -915,7 +915,10 @@ int dso__load_sym(struct dso *dso, struct map *map,
>>> >
>>> >> if ((used_opd && runtime_ss->adjust_symbols)
>>> >> - || (!used_opd && syms_ss->adjust_symbols)) {
>>> >> + || (!used_opd && syms_ss->adjust_symbols)
>>> >> + || (syms_ss->ehdr.e_type == et_dyn
>>> >> + && shdr.sh_addr != shdr.sh_offset
>>> >> + && elf_sec__is_text(&shdr, secstrs))) {
>>> >
>>> > Please try to follow kernel coding style in these tools, i.e. the &&
>>> > should be at the end, the expression on each line should be aligned just
>>> > after the opening parens.
>>> >
>>> > If, like in this case, you find something not following that style, take
>>> > the opportunity to fix it :-)
>>> >
>>> > But back to your change, I'll have to look at this code further, just
>>> > looking at the excerpt above I find it way too confusing, and your patch
>>> > makes it even more so...
>>> >
>>> > Can you introduce some suitably named helper that has those extra
>>> > conditions you're adding now and then add it to this conditional?
>>> >
>>> > I.e. make it somethine like:
>>> >
>>> > - if ((used_opd && runtime_ss->adjust_symbols)
>>> > - || (!used_opd && syms_ss->adjust_symbols)) {
>>> > + if ((used_opd && runtime_ss->adjust_symbols) ||
>>> > + (!used_opd && syms_ss->adjust_symbols) ||
>>> > + syms__some_suitable_name(syms_ss, &shdr)) {
>>> >
>>> > And then add your explanation of these kinds of files as a comment over
>>> > this new function, please?
>>> >
>>> >> pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
>>> >> "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
>>> >> (u64)sym.st_value, (u64)shdr.sh_addr,
>>> >
>>> > Best regards,
>>> >
>>> > - Arnaldo
>>>
>>>
>>>
>>> --
>>> Best Regards, Tong Shen
>>
>>> diff --git a/perf-3.12.0/tools/perf/util/symbol-elf.c b/perf-3.12.0/tools/perf/util/symbol-elf.c
>>> index a9c829b..f9bd488 100644
>>> --- a/perf-3.12.0/tools/perf/util/symbol-elf.c
>>> +++ b/perf-3.12.0/tools/perf/util/symbol-elf.c
>>> @@ -673,6 +673,27 @@ static u64 ref_reloc(struct kmap *kmap)
>>> return 0;
>>> }
>>>
>>> +/**
>>> + * is_non_relocatable_dyn - check if ELF file is ET_DYN, but not relocatable
>>> + * @ehdr: ELF header of the ELF file
>>> + * @shdr: a section header in the ELF file
>>> + *
>>> + * For ELF files with type ET_EXEC and ET_REL, we adjust symbol addresses in
>>> + * symbol table in dso__load_sym() so that later we can always locate symbols
>>> + * by sym.st_value + map_address_of_ELF_file.
>>> + *
>>> + * But ELF files with type ET_DYN may need adjusting as well, if they are
>>> + * not relocatable. There's no standard way to tell if an ELF file with type
>>> + * ET_DYN is relocatable. One possible way to do that is checking if
>>> + * sh_addr == sh_offset for .text section.
>>> + */
>>> +static bool is_non_relocatable_dyn(GElf_Ehdr *ehdr, GElf_Shdr *shdr,
>>> + Elf_Data *secstrs) {
>>> + return ehdr->e_type == ET_DYN &&
>>> + elf_sec__is_text(shdr, secstrs) &&
>>> + shdr->sh_offset != shdr->sh_addr;
>>> +}
>>> +
>>> int dso__load_sym(struct dso *dso, struct map *map,
>>> struct symsrc *syms_ss, struct symsrc *runtime_ss,
>>> symbol_filter_t filter, int kmodule)
>>> @@ -914,8 +935,9 @@ int dso__load_sym(struct dso *dso, struct map *map,
>>> goto new_symbol;
>>> }
>>>
>>> - if ((used_opd && runtime_ss->adjust_symbols)
>>> - || (!used_opd && syms_ss->adjust_symbols)) {
>>> + if ((used_opd && runtime_ss->adjust_symbols) ||
>>> + (!used_opd && syms_ss->adjust_symbols) ||
>>> + is_non_relocatable_dyn(&ehdr, &shdr, secstrs)) {
>>> pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
>>> "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
>>> (u64)sym.st_value, (u64)shdr.sh_addr,
>>
>
>
>
> --
> Best Regards, Tong Shen
--
Best Regards, Tong Shen
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/1] perf tools: Fix Symbol Address for ET_DYN
2014-09-25 0:28 ` Tong Shen
@ 2014-09-26 5:45 ` Namhyung Kim
2014-09-26 5:53 ` Tong Shen
0 siblings, 1 reply; 7+ messages in thread
From: Namhyung Kim @ 2014-09-26 5:45 UTC (permalink / raw)
To: Tong Shen
Cc: Arnaldo Carvalho de Melo, linux-perf-users, Linux Kernel Mailing List
Hi Tong,
Does a non-relocatable-dyn mean a prelink-ed dso?
Thanks,
Namhyung
On Wed, 24 Sep 2014 17:28:24 -0700, Tong Shen wrote:
> Gentle Ping :-)
>
> On Mon, Sep 15, 2014 at 11:06 AM, Tong Shen <endlessroad@google.com> wrote:
>> Gentle ping :-)
>>
>> On Thu, Sep 11, 2014 at 1:38 PM, Arnaldo Carvalho de Melo
>> <acme@kernel.org> wrote:
>>> Em Thu, Sep 11, 2014 at 11:21:40AM -0700, Tong Shen escreveu:
>>>> Hi Arnaldo,
>>>>
>>>> Thanks a lot for the comment!
>>>>
>>>> I fixed the coding style and added a helper function with comments, as
>>>> you suggested :-)
>>>> See attachment.
>>>
>>> That is much better, I'm adding lkml to the CC list so that we can give
>>> other people the opportunity to chime in.
>>>
>>> - Arnaldo
>>>
>>>> On Thu, Sep 11, 2014 at 8:01 AM, Arnaldo Carvalho de Melo
>>>> <acme@kernel.org> wrote:
>>>> > Em Fri, Sep 05, 2014 at 11:38:02AM -0700, Tong Shen escreveu:
>>>> >> Hi linux-perf-users,
>>>> >>
>>>> >> It's actually a patch, and I didn't find a development mailing list
>>>> >> for perf, so I just post it here. If this is not the right place to
>>>> >
>>>> > You can post it here, but please add the maintainers to the CC list, so
>>>> > that we can more quickly see your message.
>>>> >
>>>> > Comments below:
>>>> >
>>>> >> post patches, could someone direct me to it? Thanks in advance!
>>>> >>
>>>> >> In tools/perf/util/symbol-elf.c, we don't adjust symbol address for
>>>> >> ET_DYN type of ELF files because we think ET_DYN is always
>>>> >> relocatable.
>>>> >>
>>>> >> But that's not necessarily true; there are some non-relocatable ET_DYN
>>>> >> ELF files. For those files, we should still adjust symbol address.
>>>> >
>>>> >> Suggested patch: (HTML subpart now allowed in this mailing list...)
>>>> >
>>>> >> +++ b/perf-3.12.0/tools/perf/util/symbol-elf.c
>>>> >> @@ -915,7 +915,10 @@ int dso__load_sym(struct dso *dso, struct map *map,
>>>> >
>>>> >> if ((used_opd && runtime_ss->adjust_symbols)
>>>> >> - || (!used_opd && syms_ss->adjust_symbols)) {
>>>> >> + || (!used_opd && syms_ss->adjust_symbols)
>>>> >> + || (syms_ss->ehdr.e_type == et_dyn
>>>> >> + && shdr.sh_addr != shdr.sh_offset
>>>> >> + && elf_sec__is_text(&shdr, secstrs))) {
>>>> >
>>>> > Please try to follow kernel coding style in these tools, i.e. the &&
>>>> > should be at the end, the expression on each line should be aligned just
>>>> > after the opening parens.
>>>> >
>>>> > If, like in this case, you find something not following that style, take
>>>> > the opportunity to fix it :-)
>>>> >
>>>> > But back to your change, I'll have to look at this code further, just
>>>> > looking at the excerpt above I find it way too confusing, and your patch
>>>> > makes it even more so...
>>>> >
>>>> > Can you introduce some suitably named helper that has those extra
>>>> > conditions you're adding now and then add it to this conditional?
>>>> >
>>>> > I.e. make it somethine like:
>>>> >
>>>> > - if ((used_opd && runtime_ss->adjust_symbols)
>>>> > - || (!used_opd && syms_ss->adjust_symbols)) {
>>>> > + if ((used_opd && runtime_ss->adjust_symbols) ||
>>>> > + (!used_opd && syms_ss->adjust_symbols) ||
>>>> > + syms__some_suitable_name(syms_ss, &shdr)) {
>>>> >
>>>> > And then add your explanation of these kinds of files as a comment over
>>>> > this new function, please?
>>>> >
>>>> >> pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
>>>> >> "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
>>>> >> (u64)sym.st_value, (u64)shdr.sh_addr,
>>>> >
>>>> > Best regards,
>>>> >
>>>> > - Arnaldo
>>>>
>>>>
>>>>
>>>> --
>>>> Best Regards, Tong Shen
>>>
>>>> diff --git a/perf-3.12.0/tools/perf/util/symbol-elf.c b/perf-3.12.0/tools/perf/util/symbol-elf.c
>>>> index a9c829b..f9bd488 100644
>>>> --- a/perf-3.12.0/tools/perf/util/symbol-elf.c
>>>> +++ b/perf-3.12.0/tools/perf/util/symbol-elf.c
>>>> @@ -673,6 +673,27 @@ static u64 ref_reloc(struct kmap *kmap)
>>>> return 0;
>>>> }
>>>>
>>>> +/**
>>>> + * is_non_relocatable_dyn - check if ELF file is ET_DYN, but not relocatable
>>>> + * @ehdr: ELF header of the ELF file
>>>> + * @shdr: a section header in the ELF file
>>>> + *
>>>> + * For ELF files with type ET_EXEC and ET_REL, we adjust symbol addresses in
>>>> + * symbol table in dso__load_sym() so that later we can always locate symbols
>>>> + * by sym.st_value + map_address_of_ELF_file.
>>>> + *
>>>> + * But ELF files with type ET_DYN may need adjusting as well, if they are
>>>> + * not relocatable. There's no standard way to tell if an ELF file with type
>>>> + * ET_DYN is relocatable. One possible way to do that is checking if
>>>> + * sh_addr == sh_offset for .text section.
>>>> + */
>>>> +static bool is_non_relocatable_dyn(GElf_Ehdr *ehdr, GElf_Shdr *shdr,
>>>> + Elf_Data *secstrs) {
>>>> + return ehdr->e_type == ET_DYN &&
>>>> + elf_sec__is_text(shdr, secstrs) &&
>>>> + shdr->sh_offset != shdr->sh_addr;
>>>> +}
>>>> +
>>>> int dso__load_sym(struct dso *dso, struct map *map,
>>>> struct symsrc *syms_ss, struct symsrc *runtime_ss,
>>>> symbol_filter_t filter, int kmodule)
>>>> @@ -914,8 +935,9 @@ int dso__load_sym(struct dso *dso, struct map *map,
>>>> goto new_symbol;
>>>> }
>>>>
>>>> - if ((used_opd && runtime_ss->adjust_symbols)
>>>> - || (!used_opd && syms_ss->adjust_symbols)) {
>>>> + if ((used_opd && runtime_ss->adjust_symbols) ||
>>>> + (!used_opd && syms_ss->adjust_symbols) ||
>>>> + is_non_relocatable_dyn(&ehdr, &shdr, secstrs)) {
>>>> pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
>>>> "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
>>>> (u64)sym.st_value, (u64)shdr.sh_addr,
>>>
>>
>>
>>
>> --
>> Best Regards, Tong Shen
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/1] perf tools: Fix Symbol Address for ET_DYN
2014-09-26 5:45 ` Namhyung Kim
@ 2014-09-26 5:53 ` Tong Shen
2014-09-29 2:33 ` Namhyung Kim
0 siblings, 1 reply; 7+ messages in thread
From: Tong Shen @ 2014-09-26 5:53 UTC (permalink / raw)
To: Namhyung Kim
Cc: Arnaldo Carvalho de Melo, linux-perf-users, Linux Kernel Mailing List
In my case it's not a prelink-ed dso; but I believe the effect is the same.
Specifically:
- Program headers and section headers contain absolute address;
- Symbol addresses are also absolute;
- There's no relocation in my case.
On Thu, Sep 25, 2014 at 10:45 PM, Namhyung Kim <namhyung@kernel.org> wrote:
> Hi Tong,
>
> Does a non-relocatable-dyn mean a prelink-ed dso?
>
> Thanks,
> Namhyung
>
>
> On Wed, 24 Sep 2014 17:28:24 -0700, Tong Shen wrote:
>> Gentle Ping :-)
>>
>> On Mon, Sep 15, 2014 at 11:06 AM, Tong Shen <endlessroad@google.com> wrote:
>>> Gentle ping :-)
>>>
>>> On Thu, Sep 11, 2014 at 1:38 PM, Arnaldo Carvalho de Melo
>>> <acme@kernel.org> wrote:
>>>> Em Thu, Sep 11, 2014 at 11:21:40AM -0700, Tong Shen escreveu:
>>>>> Hi Arnaldo,
>>>>>
>>>>> Thanks a lot for the comment!
>>>>>
>>>>> I fixed the coding style and added a helper function with comments, as
>>>>> you suggested :-)
>>>>> See attachment.
>>>>
>>>> That is much better, I'm adding lkml to the CC list so that we can give
>>>> other people the opportunity to chime in.
>>>>
>>>> - Arnaldo
>>>>
>>>>> On Thu, Sep 11, 2014 at 8:01 AM, Arnaldo Carvalho de Melo
>>>>> <acme@kernel.org> wrote:
>>>>> > Em Fri, Sep 05, 2014 at 11:38:02AM -0700, Tong Shen escreveu:
>>>>> >> Hi linux-perf-users,
>>>>> >>
>>>>> >> It's actually a patch, and I didn't find a development mailing list
>>>>> >> for perf, so I just post it here. If this is not the right place to
>>>>> >
>>>>> > You can post it here, but please add the maintainers to the CC list, so
>>>>> > that we can more quickly see your message.
>>>>> >
>>>>> > Comments below:
>>>>> >
>>>>> >> post patches, could someone direct me to it? Thanks in advance!
>>>>> >>
>>>>> >> In tools/perf/util/symbol-elf.c, we don't adjust symbol address for
>>>>> >> ET_DYN type of ELF files because we think ET_DYN is always
>>>>> >> relocatable.
>>>>> >>
>>>>> >> But that's not necessarily true; there are some non-relocatable ET_DYN
>>>>> >> ELF files. For those files, we should still adjust symbol address.
>>>>> >
>>>>> >> Suggested patch: (HTML subpart now allowed in this mailing list...)
>>>>> >
>>>>> >> +++ b/perf-3.12.0/tools/perf/util/symbol-elf.c
>>>>> >> @@ -915,7 +915,10 @@ int dso__load_sym(struct dso *dso, struct map *map,
>>>>> >
>>>>> >> if ((used_opd && runtime_ss->adjust_symbols)
>>>>> >> - || (!used_opd && syms_ss->adjust_symbols)) {
>>>>> >> + || (!used_opd && syms_ss->adjust_symbols)
>>>>> >> + || (syms_ss->ehdr.e_type == et_dyn
>>>>> >> + && shdr.sh_addr != shdr.sh_offset
>>>>> >> + && elf_sec__is_text(&shdr, secstrs))) {
>>>>> >
>>>>> > Please try to follow kernel coding style in these tools, i.e. the &&
>>>>> > should be at the end, the expression on each line should be aligned just
>>>>> > after the opening parens.
>>>>> >
>>>>> > If, like in this case, you find something not following that style, take
>>>>> > the opportunity to fix it :-)
>>>>> >
>>>>> > But back to your change, I'll have to look at this code further, just
>>>>> > looking at the excerpt above I find it way too confusing, and your patch
>>>>> > makes it even more so...
>>>>> >
>>>>> > Can you introduce some suitably named helper that has those extra
>>>>> > conditions you're adding now and then add it to this conditional?
>>>>> >
>>>>> > I.e. make it somethine like:
>>>>> >
>>>>> > - if ((used_opd && runtime_ss->adjust_symbols)
>>>>> > - || (!used_opd && syms_ss->adjust_symbols)) {
>>>>> > + if ((used_opd && runtime_ss->adjust_symbols) ||
>>>>> > + (!used_opd && syms_ss->adjust_symbols) ||
>>>>> > + syms__some_suitable_name(syms_ss, &shdr)) {
>>>>> >
>>>>> > And then add your explanation of these kinds of files as a comment over
>>>>> > this new function, please?
>>>>> >
>>>>> >> pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
>>>>> >> "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
>>>>> >> (u64)sym.st_value, (u64)shdr.sh_addr,
>>>>> >
>>>>> > Best regards,
>>>>> >
>>>>> > - Arnaldo
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Best Regards, Tong Shen
>>>>
>>>>> diff --git a/perf-3.12.0/tools/perf/util/symbol-elf.c b/perf-3.12.0/tools/perf/util/symbol-elf.c
>>>>> index a9c829b..f9bd488 100644
>>>>> --- a/perf-3.12.0/tools/perf/util/symbol-elf.c
>>>>> +++ b/perf-3.12.0/tools/perf/util/symbol-elf.c
>>>>> @@ -673,6 +673,27 @@ static u64 ref_reloc(struct kmap *kmap)
>>>>> return 0;
>>>>> }
>>>>>
>>>>> +/**
>>>>> + * is_non_relocatable_dyn - check if ELF file is ET_DYN, but not relocatable
>>>>> + * @ehdr: ELF header of the ELF file
>>>>> + * @shdr: a section header in the ELF file
>>>>> + *
>>>>> + * For ELF files with type ET_EXEC and ET_REL, we adjust symbol addresses in
>>>>> + * symbol table in dso__load_sym() so that later we can always locate symbols
>>>>> + * by sym.st_value + map_address_of_ELF_file.
>>>>> + *
>>>>> + * But ELF files with type ET_DYN may need adjusting as well, if they are
>>>>> + * not relocatable. There's no standard way to tell if an ELF file with type
>>>>> + * ET_DYN is relocatable. One possible way to do that is checking if
>>>>> + * sh_addr == sh_offset for .text section.
>>>>> + */
>>>>> +static bool is_non_relocatable_dyn(GElf_Ehdr *ehdr, GElf_Shdr *shdr,
>>>>> + Elf_Data *secstrs) {
>>>>> + return ehdr->e_type == ET_DYN &&
>>>>> + elf_sec__is_text(shdr, secstrs) &&
>>>>> + shdr->sh_offset != shdr->sh_addr;
>>>>> +}
>>>>> +
>>>>> int dso__load_sym(struct dso *dso, struct map *map,
>>>>> struct symsrc *syms_ss, struct symsrc *runtime_ss,
>>>>> symbol_filter_t filter, int kmodule)
>>>>> @@ -914,8 +935,9 @@ int dso__load_sym(struct dso *dso, struct map *map,
>>>>> goto new_symbol;
>>>>> }
>>>>>
>>>>> - if ((used_opd && runtime_ss->adjust_symbols)
>>>>> - || (!used_opd && syms_ss->adjust_symbols)) {
>>>>> + if ((used_opd && runtime_ss->adjust_symbols) ||
>>>>> + (!used_opd && syms_ss->adjust_symbols) ||
>>>>> + is_non_relocatable_dyn(&ehdr, &shdr, secstrs)) {
>>>>> pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
>>>>> "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
>>>>> (u64)sym.st_value, (u64)shdr.sh_addr,
>>>>
>>>
>>>
>>>
>>> --
>>> Best Regards, Tong Shen
--
Best Regards, Tong Shen
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/1] perf tools: Fix Symbol Address for ET_DYN
2014-09-26 5:53 ` Tong Shen
@ 2014-09-29 2:33 ` Namhyung Kim
2014-09-29 18:13 ` Tong Shen
0 siblings, 1 reply; 7+ messages in thread
From: Namhyung Kim @ 2014-09-29 2:33 UTC (permalink / raw)
To: Tong Shen
Cc: Arnaldo Carvalho de Melo, linux-perf-users, Linux Kernel Mailing List
Hi Tong,
On Thu, 25 Sep 2014 22:53:22 -0700, Tong Shen wrote:
>>>>>> +/**
>>>>>> + * is_non_relocatable_dyn - check if ELF file is ET_DYN, but not relocatable
>>>>>> + * @ehdr: ELF header of the ELF file
>>>>>> + * @shdr: a section header in the ELF file
>>>>>> + *
>>>>>> + * For ELF files with type ET_EXEC and ET_REL, we adjust symbol addresses in
>>>>>> + * symbol table in dso__load_sym() so that later we can always locate symbols
>>>>>> + * by sym.st_value + map_address_of_ELF_file.
>>>>>> + *
>>>>>> + * But ELF files with type ET_DYN may need adjusting as well, if they are
>>>>>> + * not relocatable. There's no standard way to tell if an ELF file with type
>>>>>> + * ET_DYN is relocatable. One possible way to do that is checking if
>>>>>> + * sh_addr == sh_offset for .text section.
>>>>>> + */
>>>>>> +static bool is_non_relocatable_dyn(GElf_Ehdr *ehdr, GElf_Shdr *shdr,
>>>>>> + Elf_Data *secstrs) {
>>>>>> + return ehdr->e_type == ET_DYN &&
>>>>>> + elf_sec__is_text(shdr, secstrs) &&
>>>>>> + shdr->sh_offset != shdr->sh_addr;
>>>>>> +}
>>>>>> +
>>>>>> int dso__load_sym(struct dso *dso, struct map *map,
>>>>>> struct symsrc *syms_ss, struct symsrc *runtime_ss,
>>>>>> symbol_filter_t filter, int kmodule)
>>>>>> @@ -914,8 +935,9 @@ int dso__load_sym(struct dso *dso, struct map *map,
>>>>>> goto new_symbol;
>>>>>> }
>>>>>>
>>>>>> - if ((used_opd && runtime_ss->adjust_symbols)
>>>>>> - || (!used_opd && syms_ss->adjust_symbols)) {
>>>>>> + if ((used_opd && runtime_ss->adjust_symbols) ||
>>>>>> + (!used_opd && syms_ss->adjust_symbols) ||
>>>>>> + is_non_relocatable_dyn(&ehdr, &shdr, secstrs)) {
>>>>>> pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
>>>>>> "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
>>>>>> (u64)sym.st_value, (u64)shdr.sh_addr,
Hmm.. IIUC for normal dso (ET_DYN), shdr->offset == shdr->sh_addr for
text section right? And we always adjust ET_EXEC and ET_REL.. What
about always trying to adjust symbol address then? We may precalculate
adjust offset and subtracting it from symbol values. And the offset of
0 effectively means no adjust. This way we can simplify the logic IMHO.
Thanks,
Namhyung
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/1] perf tools: Fix Symbol Address for ET_DYN
2014-09-29 2:33 ` Namhyung Kim
@ 2014-09-29 18:13 ` Tong Shen
0 siblings, 0 replies; 7+ messages in thread
From: Tong Shen @ 2014-09-29 18:13 UTC (permalink / raw)
To: Namhyung Kim
Cc: Arnaldo Carvalho de Melo, linux-perf-users, Linux Kernel Mailing List
On Sun, Sep 28, 2014 at 7:33 PM, Namhyung Kim <namhyung@kernel.org> wrote:
>
> Hmm.. IIUC for normal dso (ET_DYN), shdr->offset == shdr->sh_addr for
> text section right? And we always adjust ET_EXEC and ET_REL.. What
> about always trying to adjust symbol address then? We may precalculate
> adjust offset and subtracting it from symbol values. And the offset of
> 0 effectively means no adjust. This way we can simplify the logic IMHO.
Yeah I'd like to do that too; but (shdr->offset == shdr->sh_addr for
normal ET_DYN && shdr->offset != shdr->sh_addr for non-relocatable
ET_DYN) is only true for .text section. It does not hold for .data
section.
I didn't dig deep into the code; if we only care about symbols in
.text section (function names), we can do what you said. Otherwise we
may want to keep it the way it is...
--
Best Regards, Tong Shen
^ permalink raw reply [flat|nested] 7+ messages in thread
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