perf symbols: Load kernel maps before using

In order to use kernel maps to read object code, those maps must be
adjusted to map to the dso file offset.  Because lazy-initialization is
used, that is not done until symbols are loaded.  However the maps are
first used by thread__find_addr_map() before symbols are loaded.  So
this patch changes thread__find_addr() to "load" kernel maps before
using them.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1375875537-4509-3-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

4 files changed, 18 insertions, 8 deletions

diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index 5295625c0c00..3a0f5089379c 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -33,7 +33,7 @@ int build_id__mark_dso_hit(struct perf_tool *tool __maybe_unused,
         }
 
         thread__find_addr_map(thread, machine, cpumode, MAP__FUNCTION,
-                              event->ip.ip, &al);
+                              event->ip.ip, &al, NULL);
 
         if (al.map != NULL)
                 al.map->dso->hit = 1;
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 95412705d0d2..cc7c0c9c9ea6 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -592,9 +592,10 @@ int perf_event__process(struct perf_tool *tool __maybe_unused,
 void thread__find_addr_map(struct thread *self,
                            struct machine *machine, u8 cpumode,
                            enum map_type type, u64 addr,
-                           struct addr_location *al)
+                           struct addr_location *al, symbol_filter_t filter)
 {
         struct map_groups *mg = &self->mg;
+        bool load_map = false;
 
         al->thread = self;
         al->addr = addr;
@@ -609,11 +610,13 @@ void thread__find_addr_map(struct thread *self,
         if (cpumode == PERF_RECORD_MISC_KERNEL && perf_host) {
                 al->level = 'k';
                 mg = &machine->kmaps;
+                load_map = true;
         } else if (cpumode == PERF_RECORD_MISC_USER && perf_host) {
                 al->level = '.';
         } else if (cpumode == PERF_RECORD_MISC_GUEST_KERNEL && perf_guest) {
                 al->level = 'g';
                 mg = &machine->kmaps;
+                load_map = true;
         } else {
                 /*
                  * 'u' means guest os user space.
@@ -654,8 +657,15 @@ try_again:
                         mg = &machine->kmaps;
                         goto try_again;
                 }
-        } else
+        } else {
+                /*
+                 * Kernel maps might be changed when loading symbols so loading
+                 * must be done prior to using kernel maps.
+                 */
+                if (load_map)
+                        map__load(al->map, filter);
                 al->addr = al->map->map_ip(al->map, al->addr);
+        }
 }
 
 void thread__find_addr_location(struct thread *thread, struct machine *machine,
@@ -663,7 +673,7 @@ void thread__find_addr_location(struct thread *thread, struct machine *machine,
                                 struct addr_location *al,
                                 symbol_filter_t filter)
 {
-        thread__find_addr_map(thread, machine, cpumode, type, addr, al);
+        thread__find_addr_map(thread, machine, cpumode, type, addr, al, filter);
         if (al->map != NULL)
                 al->sym = map__find_symbol(al->map, al->addr, filter);
         else
@@ -699,7 +709,7 @@ int perf_event__preprocess_sample(const union perf_event *event,
                 machine__create_kernel_maps(machine);
 
         thread__find_addr_map(thread, machine, cpumode, MAP__FUNCTION,
-                              event->ip.ip, al);
+                              event->ip.ip, al, filter);
         dump_printf(" ...... dso: %s\n",
                     al->map ? al->map->dso->long_name :
                         al->level == 'H' ? "[hypervisor]" : "<not found>");
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index 0fe1f9c05865..f98d1d983547 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -41,7 +41,7 @@ static inline struct map *thread__find_map(struct thread *self,
 
 void thread__find_addr_map(struct thread *thread, struct machine *machine,
                            u8 cpumode, enum map_type type, u64 addr,
-                           struct addr_location *al);
+                           struct addr_location *al, symbol_filter_t filter);
 
 void thread__find_addr_location(struct thread *thread, struct machine *machine,
                                 u8 cpumode, enum map_type type, u64 addr,
diff --git a/tools/perf/util/unwind.c b/tools/perf/util/unwind.c
index 958723ba3d2e..5bbd4947c27d 100644
--- a/tools/perf/util/unwind.c
+++ b/tools/perf/util/unwind.c
@@ -272,7 +272,7 @@ static struct map *find_map(unw_word_t ip, struct unwind_info *ui)
         struct addr_location al;
 
         thread__find_addr_map(ui->thread, ui->machine, PERF_RECORD_MISC_USER,
-                              MAP__FUNCTION, ip, &al);
+                              MAP__FUNCTION, ip, &al, NULL);
         return al.map;
 }
 
@@ -349,7 +349,7 @@ static int access_dso_mem(struct unwind_info *ui, unw_word_t addr,
         ssize_t size;
 
         thread__find_addr_map(ui->thread, ui->machine, PERF_RECORD_MISC_USER,
-                              MAP__FUNCTION, addr, &al);
+                              MAP__FUNCTION, addr, &al, NULL);
         if (!al.map) {
                 pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
                 return -1;