As we run "perf c2c" on more applications, we noticed we're missing significant
samples from a common customer's application. Looking at the
/proc/<pid>/maps file for the app, we see "rwxs" and "rwxp" permissions on many
of the shared memory & heap regions, and on all the thread stacks.
Because those regions have the "x" bit set, perf marks them with a MAP_FUNCTION
type. Hence ip_resolve_data() never finds load or store events coming from
them.
We fixed this by re-calling thread__find_addr_location with MAP__FUNCTION in
the case where map is NULL as a last ditch effort to map the sample before
giving up and dropping it.
Reported-by: Joe Mario <jma...@redhat.com>
Tested-by: Joe Mario <jma...@redhat.com>
Signed-off-by: Don Zickus <dzic...@redhat.com>
---
tools/perf/util/machine.c | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 0e5fea9..e62bd87 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1241,6 +1241,16 @@ static void ip__resolve_data(struct machine *machine,
struct thread *thread,
thread__find_addr_location(thread, machine, m, MAP__VARIABLE, addr,
&al);
+ if (al.map == NULL) {
+ /*
+ * some shared data regions have execute bit set which puts
+ * their mapping in the MAP__FUNCTION type array.
+ * Check there as a fallback option before dropping the sample.
+ */
+ thread__find_addr_location(thread, machine, m, MAP__FUNCTION,
addr,
+ &al);
+ }
+
ams->addr = addr;
ams->al_addr = al.addr;
ams->sym = al.sym;
--
1.7.1
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