diff options
| -rw-r--r-- | collector.c | 80 |
1 files changed, 46 insertions, 34 deletions
diff --git a/collector.c b/collector.c index 5f50ce0..d034405 100644 --- a/collector.c +++ b/collector.c @@ -246,17 +246,13 @@ on_read (gpointer data) { counter_t *counter = data; int mask = (N_PAGES * get_page_size() - 1); + int n_bytes = mask + 1; gboolean skip_samples; Collector *collector; uint64_t head, tail; collector = counter->collector; -#if 0 - int n_bytes = mask + 1; - int x; -#endif - tail = counter->tail; head = counter->mmap_page->data_head; @@ -283,7 +279,22 @@ on_read (gpointer data) while (head - tail >= sizeof (struct perf_event_header)) { - struct perf_event_header *header = (void *)(counter->data + (tail & mask)); + struct perf_event_header *header; + guint8 buffer[4096]; + guint8 *free_me; + + free_me = NULL; + + /* Note that: + * + * - perf events are a multiple of 64 bits + * - the perf event header is 64 bits + * - the data area is a multiple of 64 bits + * + * which means there will always be space for one header, which means we + * can safely dereference the size field. + */ + header = (struct perf_event_header *)(counter->data + (tail & mask)); if (header->size > head - tail) { @@ -294,14 +305,36 @@ on_read (gpointer data) break; } - if (!skip_samples || header->type != PERF_EVENT_SAMPLE) + if (counter->data + (tail & mask) + header->size > counter->data + n_bytes) { + int n_before, n_after; + guint8 *b; + + if (header->size > sizeof (buffer)) + free_me = b = g_malloc (header->size); + else + b = buffer; + + n_after = (tail & mask) + header->size - n_bytes; + n_before = header->size - n_after; + + memcpy (b, counter->data + (tail & mask), n_before); + memcpy (b + n_before, counter->data, n_after); + + header = (struct perf_event_header *)b; + } + + if (!skip_samples || header->type != PERF_EVENT_SAMPLE) + { if (header->type == PERF_EVENT_SAMPLE) - collector->n_samples++; + collector->n_samples++; process_event (collector, counter, (counter_event_t *)header); - } - + } + + if (free_me) + g_free (free_me); + tail += header->size; } @@ -334,33 +367,12 @@ static void * map_buffer (counter_t *counter, GError **err) { int n_bytes = N_PAGES * get_page_size(); - void *address, *a; + void *address; - /* We map the ring buffer twice in consecutive address space, - * so that we don't need special-case code to deal with wrapping. - */ - address = mmap (NULL, n_bytes * 2 + get_page_size(), PROT_NONE, - MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); + address = mmap (NULL, n_bytes + get_page_size(), PROT_READ | PROT_WRITE, MAP_SHARED, counter->fd, 0); if (address == MAP_FAILED) - return fail (err, "mmap"); - - a = mmap (address + n_bytes, n_bytes + get_page_size(), - PROT_READ | PROT_WRITE, - MAP_SHARED | MAP_FIXED, counter->fd, 0); - - if (a != address + n_bytes) - return fail (err, "mmap"); - - a = mmap (address, n_bytes + get_page_size(), - PROT_READ | PROT_WRITE, - MAP_SHARED | MAP_FIXED, counter->fd, 0); - - if (a == MAP_FAILED || a != address) - return fail (err, "mmap"); - - if (a != address) - return fail (err, "mmap"); + return fail (err, "mmap"); return address; } |