Messages in this thread | | | Date | Tue, 13 Jan 2015 16:36:53 +0800 | From | Wang Nan <> | Subject | Re: [PATCH] perf: fix dwarf unwind using libunwind. |
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On 2015/1/13 15:10, Jiri Olsa wrote: > On Tue, Jan 13, 2015 at 10:54:37AM +0800, Wang Nan wrote: > > SNIP > >> >> +static int elf_is_exec(int fd, const char *name) >> +{ >> + Elf *elf; >> + GElf_Ehdr ehdr; >> + int retval = 0; >> + >> + elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); >> + if (elf == NULL) >> + return 0; >> + if (gelf_getehdr(elf, &ehdr) == NULL) >> + goto out; >> + >> + retval = (ehdr.e_type == ET_EXEC); >> + >> +out: >> + elf_end(elf); >> + pr_debug("unwind: elf_is_exec(%s): %d\n", name, retval); >> + return retval; >> + >> +} > > yuou need to add stub for 'NO_LIBUNWIND_DEBUG_FRAME=1', otherwise: > > CC util/dwarf-aux.o > CC util/unwind-libunwind.o > util/unwind-libunwind.c:188:12: error: ‘elf_is_exec’ defined but not used [-Werror=unused-function] > static int elf_is_exec(int fd, const char *name) > ^ > cc1: all warnings being treated as errors > make[1]: *** [util/unwind-libunwind.o] Error 1 > make[1]: *** Waiting for unfinished jobs.... > make: *** [all] Error 2 > > jirka >
Thanks. I haven't test NO_LIBUNWIND_DEBUG_FRAME=1 case.
I found that it is possible to utilize map->dso->adjust_symbols for this propose so we don't need to introduce another function to check ehdr.e_type. However map->dso->adjust_symbols checks not only ET_EXEC but also ET_REL. What do you think?
I'd like to check it and post another patch.
>> + >> struct table_entry { >> u32 start_ip_offset; >> u32 fde_offset; >> @@ -322,8 +343,12 @@ find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi, >> #ifndef NO_LIBUNWIND_DEBUG_FRAME >> /* Check the .debug_frame section for unwinding info */ >> if (!read_unwind_spec_debug_frame(map->dso, ui->machine, &segbase)) { >> + int fd = dso__data_fd(map->dso, ui->machine); >> + int is_exec = elf_is_exec(fd, map->dso->name); >> + unw_word_t base = is_exec ? 0 : map->start; >> + >> memset(&di, 0, sizeof(di)); >> - if (dwarf_find_debug_frame(0, &di, ip, 0, map->dso->name, >> + if (dwarf_find_debug_frame(0, &di, ip, base, map->dso->name, >> map->start, map->end)) >> return dwarf_search_unwind_table(as, ip, &di, pi, >> need_unwind_info, arg); >> -- >> 1.8.4 >>
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