perf symbols: Find symbols in different mount namespace

Teach perf how to resolve symbols from binaries that are in a different
mount namespace from the tool.  This allows perf to generate meaningful
stack traces even if the binary resides in a different mount namespace
from the tool.

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/1499305693-1599-2-git-send-email-kjlx@templeofstupid.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/tools/perf/util/namespaces.h b/tools/perf/util/namespaces.h
index 468f1e9a1484..b20f6ead7b2d 100644
--- a/tools/perf/util/namespaces.h
+++ b/tools/perf/util/namespaces.h
@@ -11,6 +11,7 @@
 
 #include "../perf.h"
 #include <linux/list.h>
+#include <linux/refcount.h>
 
 struct namespaces_event;
 
@@ -23,4 +24,36 @@ struct namespaces {
 struct namespaces *namespaces__new(struct namespaces_event *event);
 void namespaces__free(struct namespaces *namespaces);
 
+struct nsinfo {
+        pid_t                   pid;
+        bool                    need_setns;
+        char                    *mntns_path;
+        refcount_t              refcnt;
+};
+
+struct nscookie {
+        int                     oldns;
+        int                     newns;
+};
+
+void nsinfo__init(struct nsinfo *nsi);
+struct nsinfo *nsinfo__new(pid_t pid);
+void nsinfo__delete(struct nsinfo *nsi);
+
+struct nsinfo *nsinfo__get(struct nsinfo *nsi);
+void nsinfo__put(struct nsinfo *nsi);
+
+void nsinfo__mountns_enter(struct nsinfo *nsi, struct nscookie *nc);
+void nsinfo__mountns_exit(struct nscookie *nc);
+
+static inline void __nsinfo__zput(struct nsinfo **nsip)
+{
+        if (nsip) {
+                nsinfo__put(*nsip);
+                *nsip = NULL;
+        }
+}
+
+#define nsinfo__zput(nsi) __nsinfo__zput(&nsi)
+
 #endif  /* __PERF_NAMESPACES_H */