perf report: More robust error handling
Don't let funny events confuse us, stick to what we know and
try to find sensible data again.
If we find an unknown event, check we're still u64 aligned, and
increment by one u64. This ensures we're bound to happen upon a
valid event soon.
Signed-off-by: Peter Zijlstra <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Corey Ashford <[email protected]>
Cc: Marcelo Tosatti <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: John Kacur <[email protected]>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <[email protected]>
diff --git a/Documentation/perf_counter/builtin-report.c b/Documentation/perf_counter/builtin-report.c
index 2d4e4cc..a58be7f 100644
--- a/Documentation/perf_counter/builtin-report.c
+++ b/Documentation/perf_counter/builtin-report.c
@@ -645,6 +645,7 @@
char *buf;
event_t *event;
int ret, rc = EXIT_FAILURE;
+ uint32_t size;
unsigned long total = 0, total_mmap = 0, total_comm = 0, total_unknown = 0;
input = open(input_name, O_RDONLY);
@@ -680,6 +681,10 @@
more:
event = (event_t *)(buf + head);
+ size = event->header.size;
+ if (!size)
+ size = 8;
+
if (head + event->header.size >= page_size * mmap_window) {
unsigned long shift = page_size * (head / page_size);
int ret;
@@ -692,12 +697,9 @@
goto remap;
}
-
- if (!event->header.size) {
- fprintf(stderr, "zero-sized event at file offset %ld\n", offset + head);
- fprintf(stderr, "skipping %ld bytes of events.\n", stat.st_size - offset - head);
- goto done;
- }
+ size = event->header.size;
+ if (!size)
+ goto broken_event;
if (event->header.misc & PERF_EVENT_MISC_OVERFLOW) {
char level;
@@ -787,15 +789,26 @@
break;
}
default: {
+broken_event:
fprintf(stderr, "%p [%p]: skipping unknown header type: %d\n",
(void *)(offset + head),
(void *)(long)(event->header.size),
event->header.type);
total_unknown++;
+
+ /*
+ * assume we lost track of the stream, check alignment, and
+ * increment a single u64 in the hope to catch on again 'soon'.
+ */
+
+ if (unlikely(head & 7))
+ head &= ~7ULL;
+
+ size = 8;
}
}
- head += event->header.size;
+ head += size;
if (offset + head < stat.st_size)
goto more;
