Re: [PATCH] perf: fix dwarf unwind using libunwind.

Jiri Olsa
2015-01-13T09:24:59Z

On Tue, Jan 13, 2015 at 04:36:53PM +0800, Wang Nan wrote:
> 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.

please also update tests/mate

thanks,
jirka