perf symbols: Fix kallsyms perf test on ppc64le

ppc64le functions have a Global Entry Point (GEP) and a Local Entry
Point (LEP). While placing a probe, we always prefer the LEP since it
catches function calls through both the GEP and the LEP. In order to do
this, we fixup the function entry points during elf symbol table lookup
to point to the LEPs. This works, but breaks 'perf test kallsyms' since
the symbols loaded from the symbol table (pointing to the LEP) do not
match the symbols in kallsyms.

To fix this, we do not adjust all the symbols during symbol table load.
Instead, we note down st_other in a newly introduced arch-specific
member of perf symbol structure, and later use this to adjust the probe
trace point.

Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Cc: Mark Wielaard <mjw@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/6be7c2b17e370100c2f79dd444509df7929bdd3e.1460451721.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 85d82f4dc5e9..c82c625395ab 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -2477,7 +2477,8 @@ static int find_probe_functions(struct map *map, char *name,
 
 void __weak arch__fix_tev_from_maps(struct perf_probe_event *pev __maybe_unused,
                                 struct probe_trace_event *tev __maybe_unused,
-                                struct map *map __maybe_unused) { }
+                                struct map *map __maybe_unused,
+                                struct symbol *sym __maybe_unused) { }
 
 /*
  * Find probe function addresses from map.
@@ -2614,7 +2615,7 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev,
                                         strdup_or_goto(pev->args[i].type,
                                                         nomem_out);
                 }
-                arch__fix_tev_from_maps(pev, tev, map);
+                arch__fix_tev_from_maps(pev, tev, map, sym);
         }
         if (ret == skipped) {
                 ret = -ENOENT;