perf maps: Lookup maps in both intitial mountns and inner mountns.

If a process is in a mountns and has symbols in /tmp/perf-<pid>.map,
look first in the namespace using the tgid for the pidns that the
process might be in.  If the map isn't found there, try looking in the
mountns where perf is running, and use the tgid that's appropriate for
perf's pid namespace.  If all else fails, use the original pid.

This allows us to locate a symbol map file in the mount namespace, if it
was generated there.  However, we also try the tool's /tmp in case it's
there instead.

Signed-off-by: Krister Johansen <kjlx@templeofstupid.com>
Tested-by: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas-Mich Richter <tmricht@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1499305693-1599-3-git-send-email-kjlx@templeofstupid.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/tools/perf/util/namespaces.h b/tools/perf/util/namespaces.h
index b20f6ead7b2d..f19aa41119ae 100644
--- a/tools/perf/util/namespaces.h
+++ b/tools/perf/util/namespaces.h
@@ -26,6 +26,8 @@ void namespaces__free(struct namespaces *namespaces);
 
 struct nsinfo {
 	pid_t			pid;
+	pid_t			tgid;
+	pid_t			nstgid;
 	bool			need_setns;
 	char			*mntns_path;
 	refcount_t		refcnt;
@@ -36,8 +38,9 @@ struct nscookie {
 	int			newns;
 };
 
-void nsinfo__init(struct nsinfo *nsi);
+int nsinfo__init(struct nsinfo *nsi);
 struct nsinfo *nsinfo__new(pid_t pid);
+struct nsinfo *nsinfo__copy(struct nsinfo *nsi);
 void nsinfo__delete(struct nsinfo *nsi);
 
 struct nsinfo *nsinfo__get(struct nsinfo *nsi);