Messages in this thread | | | Date | Thu, 11 Sep 2014 17:38:06 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 1/1] perf tools: Fix Symbol Address for ET_DYN |
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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,
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