| /* |
| * Copyright (C) 2011-2017, Red Hat Inc, Arnaldo Carvalho de Melo <acme@redhat.com> |
| * |
| * Parts came from evlist.c builtin-{top,stat,record}.c, see those files for further |
| * copyright notes. |
| * |
| * Released under the GPL v2. (and only v2, not any later version) |
| */ |
| |
| #include <sys/mman.h> |
| #include <inttypes.h> |
| #include <asm/bug.h> |
| #include "debug.h" |
| #include "event.h" |
| #include "mmap.h" |
| #include "util.h" /* page_size */ |
| |
| size_t perf_mmap__mmap_len(struct perf_mmap *map) |
| { |
| return map->mask + 1 + page_size; |
| } |
| |
| /* When check_messup is true, 'end' must points to a good entry */ |
| static union perf_event *perf_mmap__read(struct perf_mmap *map, |
| u64 *startp, u64 end) |
| { |
| unsigned char *data = map->base + page_size; |
| union perf_event *event = NULL; |
| int diff = end - *startp; |
| |
| if (diff >= (int)sizeof(event->header)) { |
| size_t size; |
| |
| event = (union perf_event *)&data[*startp & map->mask]; |
| size = event->header.size; |
| |
| if (size < sizeof(event->header) || diff < (int)size) |
| return NULL; |
| |
| /* |
| * Event straddles the mmap boundary -- header should always |
| * be inside due to u64 alignment of output. |
| */ |
| if ((*startp & map->mask) + size != ((*startp + size) & map->mask)) { |
| unsigned int offset = *startp; |
| unsigned int len = min(sizeof(*event), size), cpy; |
| void *dst = map->event_copy; |
| |
| do { |
| cpy = min(map->mask + 1 - (offset & map->mask), len); |
| memcpy(dst, &data[offset & map->mask], cpy); |
| offset += cpy; |
| dst += cpy; |
| len -= cpy; |
| } while (len); |
| |
| event = (union perf_event *)map->event_copy; |
| } |
| |
| *startp += size; |
| } |
| |
| return event; |
| } |
| |
| /* |
| * Read event from ring buffer one by one. |
| * Return one event for each call. |
| * |
| * Usage: |
| * perf_mmap__read_init() |
| * while(event = perf_mmap__read_event()) { |
| * //process the event |
| * perf_mmap__consume() |
| * } |
| * perf_mmap__read_done() |
| */ |
| union perf_event *perf_mmap__read_event(struct perf_mmap *map) |
| { |
| union perf_event *event; |
| |
| /* |
| * Check if event was unmapped due to a POLLHUP/POLLERR. |
| */ |
| if (!refcount_read(&map->refcnt)) |
| return NULL; |
| |
| /* non-overwirte doesn't pause the ringbuffer */ |
| if (!map->overwrite) |
| map->end = perf_mmap__read_head(map); |
| |
| event = perf_mmap__read(map, &map->start, map->end); |
| |
| if (!map->overwrite) |
| map->prev = map->start; |
| |
| return event; |
| } |
| |
| static bool perf_mmap__empty(struct perf_mmap *map) |
| { |
| return perf_mmap__read_head(map) == map->prev && !map->auxtrace_mmap.base; |
| } |
| |
| void perf_mmap__get(struct perf_mmap *map) |
| { |
| refcount_inc(&map->refcnt); |
| } |
| |
| void perf_mmap__put(struct perf_mmap *map) |
| { |
| BUG_ON(map->base && refcount_read(&map->refcnt) == 0); |
| |
| if (refcount_dec_and_test(&map->refcnt)) |
| perf_mmap__munmap(map); |
| } |
| |
| void perf_mmap__consume(struct perf_mmap *map) |
| { |
| if (!map->overwrite) { |
| u64 old = map->prev; |
| |
| perf_mmap__write_tail(map, old); |
| } |
| |
| if (refcount_read(&map->refcnt) == 1 && perf_mmap__empty(map)) |
| perf_mmap__put(map); |
| } |
| |
| int __weak auxtrace_mmap__mmap(struct auxtrace_mmap *mm __maybe_unused, |
| struct auxtrace_mmap_params *mp __maybe_unused, |
| void *userpg __maybe_unused, |
| int fd __maybe_unused) |
| { |
| return 0; |
| } |
| |
| void __weak auxtrace_mmap__munmap(struct auxtrace_mmap *mm __maybe_unused) |
| { |
| } |
| |
| void __weak auxtrace_mmap_params__init(struct auxtrace_mmap_params *mp __maybe_unused, |
| off_t auxtrace_offset __maybe_unused, |
| unsigned int auxtrace_pages __maybe_unused, |
| bool auxtrace_overwrite __maybe_unused) |
| { |
| } |
| |
| void __weak auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp __maybe_unused, |
| struct perf_evlist *evlist __maybe_unused, |
| int idx __maybe_unused, |
| bool per_cpu __maybe_unused) |
| { |
| } |
| |
| void perf_mmap__munmap(struct perf_mmap *map) |
| { |
| if (map->base != NULL) { |
| munmap(map->base, perf_mmap__mmap_len(map)); |
| map->base = NULL; |
| map->fd = -1; |
| refcount_set(&map->refcnt, 0); |
| } |
| auxtrace_mmap__munmap(&map->auxtrace_mmap); |
| } |
| |
| int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd, int cpu) |
| { |
| /* |
| * The last one will be done at perf_mmap__consume(), so that we |
| * make sure we don't prevent tools from consuming every last event in |
| * the ring buffer. |
| * |
| * I.e. we can get the POLLHUP meaning that the fd doesn't exist |
| * anymore, but the last events for it are still in the ring buffer, |
| * waiting to be consumed. |
| * |
| * Tools can chose to ignore this at their own discretion, but the |
| * evlist layer can't just drop it when filtering events in |
| * perf_evlist__filter_pollfd(). |
| */ |
| refcount_set(&map->refcnt, 2); |
| map->prev = 0; |
| map->mask = mp->mask; |
| map->base = mmap(NULL, perf_mmap__mmap_len(map), mp->prot, |
| MAP_SHARED, fd, 0); |
| if (map->base == MAP_FAILED) { |
| pr_debug2("failed to mmap perf event ring buffer, error %d\n", |
| errno); |
| map->base = NULL; |
| return -1; |
| } |
| map->fd = fd; |
| map->cpu = cpu; |
| |
| if (auxtrace_mmap__mmap(&map->auxtrace_mmap, |
| &mp->auxtrace_mp, map->base, fd)) |
| return -1; |
| |
| return 0; |
| } |
| |
| static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end) |
| { |
| struct perf_event_header *pheader; |
| u64 evt_head = *start; |
| int size = mask + 1; |
| |
| pr_debug2("%s: buf=%p, start=%"PRIx64"\n", __func__, buf, *start); |
| pheader = (struct perf_event_header *)(buf + (*start & mask)); |
| while (true) { |
| if (evt_head - *start >= (unsigned int)size) { |
| pr_debug("Finished reading overwrite ring buffer: rewind\n"); |
| if (evt_head - *start > (unsigned int)size) |
| evt_head -= pheader->size; |
| *end = evt_head; |
| return 0; |
| } |
| |
| pheader = (struct perf_event_header *)(buf + (evt_head & mask)); |
| |
| if (pheader->size == 0) { |
| pr_debug("Finished reading overwrite ring buffer: get start\n"); |
| *end = evt_head; |
| return 0; |
| } |
| |
| evt_head += pheader->size; |
| pr_debug3("move evt_head: %"PRIx64"\n", evt_head); |
| } |
| WARN_ONCE(1, "Shouldn't get here\n"); |
| return -1; |
| } |
| |
| /* |
| * Report the start and end of the available data in ringbuffer |
| */ |
| static int __perf_mmap__read_init(struct perf_mmap *md) |
| { |
| u64 head = perf_mmap__read_head(md); |
| u64 old = md->prev; |
| unsigned char *data = md->base + page_size; |
| unsigned long size; |
| |
| md->start = md->overwrite ? head : old; |
| md->end = md->overwrite ? old : head; |
| |
| if (md->start == md->end) |
| return -EAGAIN; |
| |
| size = md->end - md->start; |
| if (size > (unsigned long)(md->mask) + 1) { |
| if (!md->overwrite) { |
| WARN_ONCE(1, "failed to keep up with mmap data. (warn only once)\n"); |
| |
| md->prev = head; |
| perf_mmap__consume(md); |
| return -EAGAIN; |
| } |
| |
| /* |
| * Backward ring buffer is full. We still have a chance to read |
| * most of data from it. |
| */ |
| if (overwrite_rb_find_range(data, md->mask, &md->start, &md->end)) |
| return -EINVAL; |
| } |
| |
| return 0; |
| } |
| |
| int perf_mmap__read_init(struct perf_mmap *map) |
| { |
| /* |
| * Check if event was unmapped due to a POLLHUP/POLLERR. |
| */ |
| if (!refcount_read(&map->refcnt)) |
| return -ENOENT; |
| |
| return __perf_mmap__read_init(map); |
| } |
| |
| int perf_mmap__push(struct perf_mmap *md, void *to, |
| int push(struct perf_mmap *map, void *to, void *buf, size_t size)) |
| { |
| u64 head = perf_mmap__read_head(md); |
| unsigned char *data = md->base + page_size; |
| unsigned long size; |
| void *buf; |
| int rc = 0; |
| |
| rc = perf_mmap__read_init(md); |
| if (rc < 0) |
| return (rc == -EAGAIN) ? 0 : -1; |
| |
| size = md->end - md->start; |
| |
| if ((md->start & md->mask) + size != (md->end & md->mask)) { |
| buf = &data[md->start & md->mask]; |
| size = md->mask + 1 - (md->start & md->mask); |
| md->start += size; |
| |
| if (push(md, to, buf, size) < 0) { |
| rc = -1; |
| goto out; |
| } |
| } |
| |
| buf = &data[md->start & md->mask]; |
| size = md->end - md->start; |
| md->start += size; |
| |
| if (push(md, to, buf, size) < 0) { |
| rc = -1; |
| goto out; |
| } |
| |
| md->prev = head; |
| perf_mmap__consume(md); |
| out: |
| return rc; |
| } |
| |
| /* |
| * Mandatory for overwrite mode |
| * The direction of overwrite mode is backward. |
| * The last perf_mmap__read() will set tail to map->prev. |
| * Need to correct the map->prev to head which is the end of next read. |
| */ |
| void perf_mmap__read_done(struct perf_mmap *map) |
| { |
| /* |
| * Check if event was unmapped due to a POLLHUP/POLLERR. |
| */ |
| if (!refcount_read(&map->refcnt)) |
| return; |
| |
| map->prev = perf_mmap__read_head(map); |
| } |