perf inject: Try chroot directory when reading build-id

When reading build-id from a DSO, it should consider if it's from a
chroot task.  In that case, the path is different so it needs to prepend
the root directory to access the file correctly.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20220202070828.143303-4-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index fbf43a4..3be581a 100644 (file)
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -25,6 +25,7 @@
 #include "util/synthetic-events.h"
 #include "util/thread.h"
 #include "util/namespaces.h"
+#include "util/util.h"
 
 #include <linux/err.h>
 #include <subcmd/parse-options.h>
@@ -550,6 +551,15 @@ static int dso__read_build_id(struct dso *dso)
        nsinfo__mountns_enter(dso->nsinfo, &nsc);
        if (filename__read_build_id(dso->long_name, &dso->bid) > 0)
                dso->has_build_id = true;
+       else if (dso->nsinfo) {
+               char *new_name;
+
+               new_name = filename_with_chroot(dso->nsinfo->pid,
+                                               dso->long_name);
+               if (new_name && filename__read_build_id(new_name, &dso->bid) > 0)
+                       dso->has_build_id = true;
+               free(new_name);
+       }
        nsinfo__mountns_exit(&nsc);
 
        return dso->has_build_id ? 0 : -1;