lkml.org 
[lkml]   [2015]   [Jan]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] perf: fix dwarf unwind using libunwind.
    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
    >>




    \
     
     \ /
      Last update: 2015-01-13 09:41    [W:5.058 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site