perf report: Handle vDSO symbols properly

We were not looking up vDSO symbols properly, because they
are in the kallsyms but are user-mode entries.

Pass negative addresses to the kernel dso object, this
way we resolve them properly:

     0.05%  [kernel]: vread_tsc

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 15 insertions, 0 deletions

diff --git a/Documentation/perf_counter/builtin-report.c b/Documentation/perf_counter/builtin-report.c
index a8d390596d8d..0f88d9ebb34a 100644
--- a/Documentation/perf_counter/builtin-report.c
+++ b/Documentation/perf_counter/builtin-report.c
@@ -728,6 +728,8 @@ more:
                         event->ip.pid,
                         (void *)(long)ip);
 
+                dprintf(" ... thread: %s:%d\n", thread->comm, thread->pid);
+
                 if (thread == NULL) {
                         fprintf(stderr, "problem processing %d event, skipping it.\n",
                                 event->header.type);
@@ -740,6 +742,8 @@ more:
 
                         dso = kernel_dso;
 
+                        dprintf(" ...... dso: %s\n", dso->name);
+
                 } else if (event->header.misc & PERF_EVENT_MISC_USER) {
 
                         show = SHOW_USER;
@@ -749,11 +753,22 @@ more:
                         if (map != NULL) {
                                 dso = map->dso;
                                 ip -= map->start + map->pgoff;
+                        } else {
+                                /*
+                                 * If this is outside of all known maps,
+                                 * and is a negative address, try to look it
+                                 * up in the kernel dso, as it might be a
+                                 * vsyscall (which executes in user-mode):
+                                 */
+                                if ((long long)ip < 0)
+                                        dso = kernel_dso;
                         }
+                        dprintf(" ...... dso: %s\n", dso ? dso->name : "<not found>");
 
                 } else {
                         show = SHOW_HV;
                         level = 'H';
+                        dprintf(" ...... dso: [hypervisor]\n");
                 }
 
                 if (show & show_mask) {