[PATCH perf,bpf 5/5] perf util: generate bpf_prog_info_event for short living bpf programs

From: Song Liu
Date: Wed Nov 21 2018 - 14:55:54 EST

This patch enables perf-record to listen to bpf_event and generate
bpf_prog_info_event for bpf programs loaded and unloaded during
perf-record run.

To minimize latency between bpf_event and following bpf calls, separate
mmap with watermark of 1 is created to process these vip events. Then
a separate dummy event is attached to the special mmap. A separate thread
is used to only poll bpf events.

By default, perf-record will listen to bpf_event. Option no-bpf-event is
added in case the user would opt out.

Signed-off-by: Song Liu <songliubraving@xxxxxx>
---
tools/perf/builtin-record.c | 83 ++++++++++++++++++++++++++++++++++++-
tools/perf/util/evlist.c | 58 ++++++++++++++++++++++----
tools/perf/util/evlist.h | 6 +++
tools/perf/util/evsel.c | 8 ++++
tools/perf/util/evsel.h | 3 ++
5 files changed, 150 insertions(+), 8 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 86dfba937e4e..11e7a8e8597a 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -54,6 +54,7 @@
#include <sys/mman.h>
#include <sys/wait.h>
#include <linux/time64.h>
+#include <bpf/bpf.h>

struct switch_output {
bool enabled;
@@ -80,8 +81,10 @@ struct record {
bool buildid_all;
bool timestamp_filename;
bool timestamp_boundary;
+ bool no_bpf_event;
struct switch_output switch_output;
unsigned long long samples;
+ pthread_mutex_t write_mutex;
};

static volatile int auxtrace_record__snapshot_started;
@@ -381,6 +384,8 @@ static int record__open(struct record *rec)
pos->tracking = 1;
pos->attr.enable_on_exec = 1;
}
+ if (!rec->no_bpf_event)
+ perf_evlist__add_bpf_tracker(evlist);

perf_evlist__config(evlist, opts, &callchain_param);

@@ -562,6 +567,58 @@ static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evli
return rc;
}

+static void record__process_bpf_event(struct record *rec,
+ union perf_event *event)
+{
+ int fd;
+
+ switch (event->bpf_event.type) {
+ case PERF_BPF_EVENT_PROG_LOAD:
+ fd = bpf_prog_get_fd_by_id(event->bpf_event.id);
+ if (fd > 0) {
+ perf_event__synthesize_one_bpf_prog_info(
+ &rec->tool, process_synthesized_event,
+ &rec->session->machines.host, fd);
+ close(fd);
+ }
+ /* fall through */
+ case PERF_BPF_EVENT_PROG_UNLOAD:
+ record__write(rec, NULL, event,
+ event->header.size);
+ break;
+ default:
+ break;
+ }
+}
+
+static int record__mmap_process_vip_events(struct record *rec)
+{
+ int i;
+
+ pthread_mutex_lock(&rec->write_mutex);
+ for (i = 0; i < rec->evlist->nr_mmaps; i++) {
+ struct perf_mmap *map = &rec->evlist->vip_mmap[i];
+ union perf_event *event;
+
+ perf_mmap__read_init(map);
+ while ((event = perf_mmap__read_event(map)) != NULL) {
+ pr_debug("processing vip event of type %d\n",
+ event->header.type);
+ switch (event->header.type) {
+ case PERF_RECORD_BPF_EVENT:
+ record__process_bpf_event(rec, event);
+ break;
+ default:
+ break;
+ }
+ perf_mmap__consume(map);
+ }
+ perf_mmap__read_done(map);
+ }
+ pthread_mutex_unlock(&rec->write_mutex);
+ return 0;
+}
+
static int record__mmap_read_all(struct record *rec)
{
int err;
@@ -855,6 +912,19 @@ static int record__synthesize(struct record *rec, bool tail)
return err;
}

+static void *vip_poll_thread(void *arg)
+{
+ struct record *rec = arg;
+
+ if (rec->no_bpf_event)
+ return NULL;
+ while (!done) {
+ perf_evlist__poll_vip(rec->evlist, 1000);
+ record__mmap_process_vip_events(rec);
+ }
+ return NULL;
+}
+
static int __cmd_record(struct record *rec, int argc, const char **argv)
{
int err;
@@ -867,6 +937,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
struct perf_session *session;
bool disabled = false, draining = false;
int fd;
+ pthread_t thread;

atexit(record__sig_exit);
signal(SIGCHLD, sig_handler);
@@ -1049,6 +1120,8 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
trigger_ready(&auxtrace_snapshot_trigger);
trigger_ready(&switch_output_trigger);
perf_hooks__invoke_record_start();
+
+ pthread_create(&thread, NULL, vip_poll_thread, rec);
for (;;) {
unsigned long long hits = rec->samples;

@@ -1063,7 +1136,10 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
if (trigger_is_hit(&switch_output_trigger) || done || draining)
perf_evlist__toggle_bkw_mmap(rec->evlist, BKW_MMAP_DATA_PENDING);

- if (record__mmap_read_all(rec) < 0) {
+ pthread_mutex_lock(&rec->write_mutex);
+ err = record__mmap_read_all(rec);
+ pthread_mutex_unlock(&rec->write_mutex);
+ if (err < 0) {
trigger_error(&auxtrace_snapshot_trigger);
trigger_error(&switch_output_trigger);
err = -1;
@@ -1164,6 +1240,8 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
record__synthesize_workload(rec, true);

out_child:
+ pthread_join(thread, NULL);
+
if (forks) {
int exit_status;

@@ -1541,6 +1619,7 @@ static struct record record = {
.bpf_prog_info = perf_event__process_bpf_prog_info,
.ordered_events = true,
},
+ .write_mutex = PTHREAD_MUTEX_INITIALIZER,
};

const char record_callchain_help[] = CALLCHAIN_RECORD_HELP
@@ -1689,6 +1768,8 @@ static struct option __record_options[] = {
"signal"),
OPT_BOOLEAN(0, "dry-run", &dry_run,
"Parse options then exit"),
+ OPT_BOOLEAN(0, "no-bpf-event", &record.no_bpf_event,
+ "do not record event on bpf program load/unload"),
OPT_END()
};

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index be440df29615..eb0b12fe7658 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -45,6 +45,7 @@ void perf_evlist__init(struct perf_evlist *evlist, struct cpu_map *cpus,
for (i = 0; i < PERF_EVLIST__HLIST_SIZE; ++i)
INIT_HLIST_HEAD(&evlist->heads[i]);
INIT_LIST_HEAD(&evlist->entries);
+ INIT_LIST_HEAD(&evlist->vip_entries);
perf_evlist__set_maps(evlist, cpus, threads);
fdarray__init(&evlist->pollfd, 64);
evlist->workload.pid = -1;
@@ -177,6 +178,8 @@ void perf_evlist__add(struct perf_evlist *evlist, struct perf_evsel *entry)
{
entry->evlist = evlist;
list_add_tail(&entry->node, &evlist->entries);
+ if (entry->vip)
+ list_add_tail(&entry->vip_node, &evlist->vip_entries);
entry->idx = evlist->nr_entries;
entry->tracking = !entry->idx;

@@ -267,6 +270,27 @@ int perf_evlist__add_dummy(struct perf_evlist *evlist)
return 0;
}

+int perf_evlist__add_bpf_tracker(struct perf_evlist *evlist)
+{
+ struct perf_event_attr attr = {
+ .type = PERF_TYPE_SOFTWARE,
+ .config = PERF_COUNT_SW_DUMMY,
+ .watermark = 1,
+ .bpf_event = 1,
+ .wakeup_watermark = 1,
+ .size = sizeof(attr), /* to capture ABI version */
+ };
+ struct perf_evsel *evsel = perf_evsel__new_idx(&attr,
+ evlist->nr_entries);
+
+ if (evsel == NULL)
+ return -ENOMEM;
+
+ evsel->vip = true;
+ perf_evlist__add(evlist, evsel);
+ return 0;
+}
+
static int perf_evlist__add_attrs(struct perf_evlist *evlist,
struct perf_event_attr *attrs, size_t nr_attrs)
{
@@ -452,15 +476,18 @@ int perf_evlist__alloc_pollfd(struct perf_evlist *evlist)
}

static int __perf_evlist__add_pollfd(struct perf_evlist *evlist, int fd,
- struct perf_mmap *map, short revent)
+ struct perf_mmap *map, short revent,
+ bool vip)
{
- int pos = fdarray__add(&evlist->pollfd, fd, revent | POLLERR | POLLHUP);
+ struct fdarray *pollfd = vip ? &evlist->vip_pollfd : &evlist->pollfd;
+ int pos = fdarray__add(pollfd, fd, revent | POLLERR | POLLHUP);
+
/*
* Save the idx so that when we filter out fds POLLHUP'ed we can
* close the associated evlist->mmap[] entry.
*/
if (pos >= 0) {
- evlist->pollfd.priv[pos].ptr = map;
+ pollfd->priv[pos].ptr = map;

fcntl(fd, F_SETFL, O_NONBLOCK);
}
@@ -470,7 +497,7 @@ static int __perf_evlist__add_pollfd(struct perf_evlist *evlist, int fd,

int perf_evlist__add_pollfd(struct perf_evlist *evlist, int fd)
{
- return __perf_evlist__add_pollfd(evlist, fd, NULL, POLLIN);
+ return __perf_evlist__add_pollfd(evlist, fd, NULL, POLLIN, false);
}

static void perf_evlist__munmap_filtered(struct fdarray *fda, int fd,
@@ -493,6 +520,11 @@ int perf_evlist__poll(struct perf_evlist *evlist, int timeout)
return fdarray__poll(&evlist->pollfd, timeout);
}

+int perf_evlist__poll_vip(struct perf_evlist *evlist, int timeout)
+{
+ return fdarray__poll(&evlist->vip_pollfd, timeout);
+}
+
static void perf_evlist__id_hash(struct perf_evlist *evlist,
struct perf_evsel *evsel,
int cpu, int thread, u64 id)
@@ -770,6 +802,7 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
int evlist_cpu = cpu_map__cpu(evlist->cpus, cpu_idx);

evlist__for_each_entry(evlist, evsel) {
+ struct perf_mmap *vip_maps = evlist->vip_mmap;
struct perf_mmap *maps = evlist->mmap;
int *output = _output;
int fd;
@@ -800,7 +833,11 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,

fd = FD(evsel, cpu, thread);

- if (*output == -1) {
+ if (evsel->vip) {
+ if (perf_mmap__mmap(&vip_maps[idx], mp,
+ fd, evlist_cpu) < 0)
+ return -1;
+ } else if (*output == -1) {
*output = fd;

if (perf_mmap__mmap(&maps[idx], mp, *output, evlist_cpu) < 0)
@@ -822,8 +859,12 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
* Therefore don't add it for polling.
*/
if (!evsel->system_wide &&
- __perf_evlist__add_pollfd(evlist, fd, &maps[idx], revent) < 0) {
- perf_mmap__put(&maps[idx]);
+ __perf_evlist__add_pollfd(
+ evlist, fd,
+ evsel->vip ? &vip_maps[idx] : &maps[idx],
+ revent, evsel->vip) < 0) {
+ perf_mmap__put(evsel->vip ?
+ &vip_maps[idx] : &maps[idx]);
return -1;
}

@@ -1035,6 +1076,9 @@ int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
if (!evlist->mmap)
return -ENOMEM;

+ if (!evlist->vip_mmap)
+ evlist->vip_mmap = perf_evlist__alloc_mmap(evlist, false);
+
if (evlist->pollfd.entries == NULL && perf_evlist__alloc_pollfd(evlist) < 0)
return -ENOMEM;

diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index dc66436add98..3ed19f9fbc97 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -26,6 +26,7 @@ struct record_opts;

struct perf_evlist {
struct list_head entries;
+ struct list_head vip_entries;
struct hlist_head heads[PERF_EVLIST__HLIST_SIZE];
int nr_entries;
int nr_groups;
@@ -42,7 +43,9 @@ struct perf_evlist {
pid_t pid;
} workload;
struct fdarray pollfd;
+ struct fdarray vip_pollfd;
struct perf_mmap *mmap;
+ struct perf_mmap *vip_mmap;
struct perf_mmap *overwrite_mmap;
struct thread_map *threads;
struct cpu_map *cpus;
@@ -84,6 +87,8 @@ int __perf_evlist__add_default_attrs(struct perf_evlist *evlist,

int perf_evlist__add_dummy(struct perf_evlist *evlist);

+int perf_evlist__add_bpf_tracker(struct perf_evlist *evlist);
+
int perf_evlist__add_newtp(struct perf_evlist *evlist,
const char *sys, const char *name, void *handler);

@@ -120,6 +125,7 @@ int perf_evlist__alloc_pollfd(struct perf_evlist *evlist);
int perf_evlist__filter_pollfd(struct perf_evlist *evlist, short revents_and_mask);

int perf_evlist__poll(struct perf_evlist *evlist, int timeout);
+int perf_evlist__poll_vip(struct perf_evlist *evlist, int timeout);

struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id);
struct perf_evsel *perf_evlist__id2evsel_strict(struct perf_evlist *evlist,
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index af9d539e4b6a..94456a493607 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -235,6 +235,7 @@ void perf_evsel__init(struct perf_evsel *evsel,
evsel->evlist = NULL;
evsel->bpf_fd = -1;
INIT_LIST_HEAD(&evsel->node);
+ INIT_LIST_HEAD(&evsel->vip_node);
INIT_LIST_HEAD(&evsel->config_terms);
perf_evsel__object.init(evsel);
evsel->sample_size = __perf_evsel__sample_size(attr->sample_type);
@@ -1795,6 +1796,8 @@ int perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
PERF_SAMPLE_BRANCH_NO_CYCLES);
if (perf_missing_features.group_read && evsel->attr.inherit)
evsel->attr.read_format &= ~(PERF_FORMAT_GROUP|PERF_FORMAT_ID);
+ if (perf_missing_features.bpf_event)
+ evsel->attr.bpf_event = 0;
retry_sample_id:
if (perf_missing_features.sample_id_all)
evsel->attr.sample_id_all = 0;
@@ -1939,6 +1942,11 @@ int perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
perf_missing_features.exclude_guest = true;
pr_debug2("switching off exclude_guest, exclude_host\n");
goto fallback_missing_features;
+ } else if (!perf_missing_features.bpf_event &&
+ evsel->attr.bpf_event) {
+ perf_missing_features.bpf_event = true;
+ pr_debug2("switching off bpf_event\n");
+ goto fallback_missing_features;
} else if (!perf_missing_features.sample_id_all) {
perf_missing_features.sample_id_all = true;
pr_debug2("switching off sample_id_all\n");
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 4107c39f4a54..82b1d3e42603 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -89,6 +89,7 @@ struct perf_stat_evsel;
*/
struct perf_evsel {
struct list_head node;
+ struct list_head vip_node;
struct perf_evlist *evlist;
struct perf_event_attr attr;
char *filter;
@@ -128,6 +129,7 @@ struct perf_evsel {
bool ignore_missing_thread;
bool forced_leader;
bool use_uncore_alias;
+ bool vip; /* vip events have their own mmap */
/* parse modifier helper */
int exclude_GH;
int nr_members;
@@ -163,6 +165,7 @@ struct perf_missing_features {
bool lbr_flags;
bool write_backward;
bool group_read;
+ bool bpf_event;
};

extern struct perf_missing_features perf_missing_features;
--
2.17.1