On 2015/03/12 05:23PM, Arnaldo Carvalho de Melo wrote:
> Em Mon, Dec 15, 2014 at 08:20:33PM +0530, Naveen N. Rao escreveu:
> > If using the symbol table, symbol addresses are not being fixed up
> > properly, resulting in probes being placed at wrong addresses:
> >
> > # perf probe do_fork
> > Added new event:
> > probe:do_fork (on do_fork)
> >
> > You can now use it in all perf tools, such as:
> >
> > perf record -e probe:do_fork -aR sleep 1
> >
> > # cat /sys/kernel/debug/tracing/kprobe_events
> > p:probe/do_fork _text+635952
> > # printf "%x" 635952
> > 9b430
> > # grep do_fork /boot/System.map
> > c0000000000ab430 T .do_fork
> >
> > Fix by checking for ELF type ET_DYN used by ppc64 kernels.
>
> Sorry if this was answered already, its been a while since this was
> posted/discussed... Are you completely sure this is not a problem on
> !ppc?
>
> Woudln't it be more conservative to somehow only adjust symbols for this
> ET_DYN type if the arch is ppc? I.e. something like moving that
> adjust_symbols logic to be arch_adjust_symbols(), provide a default and
> then override it for ppc to include also ET_DYN?
I did check and I don't think any other arch kernel uses ET_DYN, but
yes, being conservative, I could just make this a arch helper. Will do.
- Naveen
>
> Looking at the other patches...
>
> - Arnaldo
>
> > Signed-off-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
> > ---
> > tools/perf/util/symbol-elf.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> > index 06fcd1b..7ac4e4c 100644
> > --- a/tools/perf/util/symbol-elf.c
> > +++ b/tools/perf/util/symbol-elf.c
> > @@ -683,7 +683,8 @@ int symsrc__init(struct symsrc *ss, struct dso *dso,
> > const char *name,
> > NULL) != NULL);
> > } else {
> > ss->adjust_symbols = ehdr.e_type == ET_EXEC ||
> > - ehdr.e_type == ET_REL;
> > + ehdr.e_type == ET_REL ||
> > + ehdr.e_type == ET_DYN;
> > }
> >
> > ss->name = strdup(name);
> > --
> > 2.1.3
>
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