1 files changed, 61 insertions, 3 deletions

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index bb0fd6da2d56..1a31feb9999f 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -189,6 +189,50 @@ void event__synthesize_threads(int (*process)(event_t *event,
         closedir(proc);
 }
 
+struct process_symbol_args {
+        const char *name;
+        u64        start;
+};
+
+static int find_symbol_cb(void *arg, const char *name, char type, u64 start)
+{
+        struct process_symbol_args *args = arg;
+
+        if (!symbol_type__is_a(type, MAP__FUNCTION) || strcmp(name, args->name))
+                return 0;
+
+        args->start = start;
+        return 1;
+}
+
+int event__synthesize_kernel_mmap(int (*process)(event_t *event,
+                                                 struct perf_session *session),
+                                  struct perf_session *session,
+                                  const char *symbol_name)
+{
+        size_t size;
+        event_t ev = {
+                .header = { .type = PERF_RECORD_MMAP },
+        };
+        /*
+         * We should get this from /sys/kernel/sections/.text, but till that is
+         * available use this, and after it is use this as a fallback for older
+         * kernels.
+         */
+        struct process_symbol_args args = { .name = symbol_name, };
+
+        if (kallsyms__parse(&args, find_symbol_cb) <= 0)
+                return -ENOENT;
+
+        size = snprintf(ev.mmap.filename, sizeof(ev.mmap.filename),
+                        "[kernel.kallsyms.%s]", symbol_name) + 1;
+        size = ALIGN(size, sizeof(u64));
+        ev.mmap.header.size = (sizeof(ev.mmap) - (sizeof(ev.mmap.filename) - size));
+        ev.mmap.start = args.start;
+
+        return process(&ev, session);
+}
+
 static void thread__comm_adjust(struct thread *self)
 {
         char *comm = self->comm;
@@ -240,9 +284,9 @@ int event__process_lost(event_t *self, struct perf_session *session)
 
 int event__process_mmap(event_t *self, struct perf_session *session)
 {
-        struct thread *thread = perf_session__findnew(session, self->mmap.pid);
-        struct map *map = map__new(&self->mmap, MAP__FUNCTION,
-                                   session->cwd, session->cwdlen);
+        struct thread *thread;
+        struct map *map;
+        static const char kmmap_prefix[] = "[kernel.kallsyms.";
 
         dump_printf(" %d/%d: [%p(%p) @ %p]: %s\n",
                     self->mmap.pid, self->mmap.tid,
@@ -251,6 +295,20 @@ int event__process_mmap(event_t *self, struct perf_session *session)
                     (void *)(long)self->mmap.pgoff,
                     self->mmap.filename);
 
+        if (self->mmap.pid == 0 &&
+            memcmp(self->mmap.filename, kmmap_prefix,
+                   sizeof(kmmap_prefix) - 1) == 0) {
+                const char *symbol_name = (self->mmap.filename +
+                                           sizeof(kmmap_prefix) - 1);
+                perf_session__set_kallsyms_ref_reloc_sym(session, symbol_name,
+                                                         self->mmap.start);
+                return 0;
+        }
+
+        thread = perf_session__findnew(session, self->mmap.pid);
+        map = map__new(&self->mmap, MAP__FUNCTION,
+                       session->cwd, session->cwdlen);
+
         if (thread == NULL || map == NULL)
                 dump_printf("problem processing PERF_RECORD_MMAP, skipping event.\n");
         else