[PATCH v8 perf,bpf 15/15] perf, bpf: save bpf_prog_info and btf of short living bpf programs

Song Liu
2019-03-11T20:09:13Z

To fully annotate BPF programs with source code mapping, 4 different
information are needed:
1) PERF_RECORD_KSYMBOL
2) PERF_RECORD_BPF_EVENT
3) bpf_prog_info
4) btf

This patch handles 3) and 4) for short living BPF programs. For timely
process of these information, a dedicated event is added to the side
band evlist. When PERF_RECORD_BPF_EVENT is received via the side band
event, the polling thread gathers 3) and 4) vis sys_bpf and store them
in perf_env. These information are saved to perf.data at the end of
perf-record.

Signed-off-by: Song Liu <songliubraving@fb.com>
---
tools/perf/builtin-record.c | 2 +
tools/perf/builtin-top.c | 2 +
tools/perf/util/bpf-event.c | 95 +++++++++++++++++++++++++++++++++++++
tools/perf/util/bpf-event.h | 15 ++++++
4 files changed, 114 insertions(+)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 435b94f1f3b3..8d197762a499 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1207,6 +1207,8 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
goto out_child;
}

+ if (opts->bpf_event)
+ bpf_event__add_sb_event(&sb_evlist, &session->header.env);
perf_evlist__start_sb_thread(sb_evlist, &rec->opts.target);

err = record__synthesize(rec, false);
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index ec69eb040933..0d0da834dd9d 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1655,6 +1655,8 @@ int cmd_top(int argc, const char **argv)

top.record_opts.bpf_event = !top.no_bpf_event;

+ if (top.record_opts.bpf_event)
+ bpf_event__add_sb_event(&sb_evlist, &perf_env);
perf_evlist__start_sb_thread(sb_evlist, target);

status = __cmd_top(&top);
diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
index c0a316af5c2a..32766341e111 100644
--- a/tools/perf/util/bpf-event.c
+++ b/tools/perf/util/bpf-event.c
@@ -12,6 +12,7 @@
#include "machine.h"
#include "env.h"
#include "session.h"
+#include "evlist.h"

#define ptr_to_u64(ptr) ((__u64)(unsigned long)(ptr))

@@ -329,3 +330,97 @@ int perf_event__synthesize_bpf_events(struct perf_session *session,
free(event);
return err;
}
+
+static void perf_env__add_bpf_info(struct perf_env *env, u32 id)
+{
+ struct bpf_prog_info_linear *info_linear;
+ struct bpf_prog_info_node *info_node;
+ struct btf *btf = NULL;
+ u64 arrays;
+ u32 btf_id;
+ int fd;
+
+ fd = bpf_prog_get_fd_by_id(id);
+ if (fd < 0)
+ return;
+
+ arrays = 1UL << BPF_PROG_INFO_JITED_KSYMS;
+ arrays |= 1UL << BPF_PROG_INFO_JITED_FUNC_LENS;
+ arrays |= 1UL << BPF_PROG_INFO_FUNC_INFO;
+ arrays |= 1UL << BPF_PROG_INFO_PROG_TAGS;
+ arrays |= 1UL << BPF_PROG_INFO_JITED_INSNS;
+ arrays |= 1UL << BPF_PROG_INFO_LINE_INFO;
+ arrays |= 1UL << BPF_PROG_INFO_JITED_LINE_INFO;
+
+ info_linear = bpf_program__get_prog_info_linear(fd, arrays);
+ if (IS_ERR_OR_NULL(info_linear)) {
+ pr_debug("%s: failed to get BPF program info. aborting\n", __func__);
+ goto out;
+ }
+
+ btf_id = info_linear->info.btf_id;
+
+ info_node = malloc(sizeof(struct bpf_prog_info_node));
+ if (info_node) {
+ info_node->info_linear = info_linear;
+ perf_env__insert_bpf_prog_info(env, info_node);
+ } else
+ free(info_linear);
+
+ if (btf_id == 0)
+ goto out;
+
+ if (btf__get_from_id(btf_id, &btf)) {
+ pr_debug("%s: failed to get BTF of id %u, aborting\n",
+ __func__, btf_id);
+ goto out;
+ }
+ perf_env__fetch_btf(env, btf_id, btf);
+
+out:
+ free(btf);
+ close(fd);
+}
+
+static int bpf_event__sb_cb(union perf_event *event, void *data)
+{
+ struct perf_env *env = data;
+
+ if (event->header.type != PERF_RECORD_BPF_EVENT)
+ return -1;
+
+ switch (event->bpf_event.type) {
+ case PERF_BPF_EVENT_PROG_LOAD:
+ perf_env__add_bpf_info(env, event->bpf_event.id);
+
+ case PERF_BPF_EVENT_PROG_UNLOAD:
+ /*
+ * Do not free bpf_prog_info and btf of the program here,
+ * as annotation still need them. They will be freed at
+ * the end of the session.
+ */
+ break;
+ default:
+ pr_debug("unexpected bpf_event type of %d\n",
+ event->bpf_event.type);
+ break;
+ }
+
+ return 0;
+}
+
+int bpf_event__add_sb_event(struct perf_evlist **evlist,
+ struct perf_env *env)
+{
+ struct perf_event_attr attr = {
+ .type = PERF_TYPE_SOFTWARE,
+ .config = PERF_COUNT_SW_DUMMY,
+ .sample_id_all = 1,
+ .watermark = 1,
+ .bpf_event = 1,
+ .wakeup_watermark = 1,
+ .size = sizeof(attr), /* to capture ABI version */
+ };
+
+ return perf_evlist__add_sb_event(evlist, &attr, bpf_event__sb_cb, env);
+}
diff --git a/tools/perf/util/bpf-event.h b/tools/perf/util/bpf-event.h
index b9ec394dc7c7..249909c826e7 100644
--- a/tools/perf/util/bpf-event.h
+++ b/tools/perf/util/bpf-event.h
@@ -4,12 +4,17 @@

#include <linux/compiler.h>
#include <linux/rbtree.h>
+#include <pthread.h>
+#include <api/fd/array.h>
#include "event.h"

struct machine;
union perf_event;
+struct perf_env;
struct perf_sample;
struct record_opts;
+struct evlist;
+struct target;

struct bpf_prog_info_node {
struct bpf_prog_info_linear *info_linear;
@@ -31,6 +36,9 @@ int perf_event__synthesize_bpf_events(struct perf_session *session,
perf_event__handler_t process,
struct machine *machine,
struct record_opts *opts);
+int bpf_event__add_sb_event(struct perf_evlist **evlist,
+ struct perf_env *env);
+
#else
static inline int machine__process_bpf_event(struct machine *machine __maybe_unused,
union perf_event *event __maybe_unused,
@@ -46,5 +54,12 @@ static inline int perf_event__synthesize_bpf_events(struct perf_session *session
{
return 0;
}
+
+static int bpf_event__add_sb_event(struct perf_evlist **evlist __maybe_unused,
+ struct perf_env *env __maybe_unused)
+{
+ return 0;
+}
+
#endif // HAVE_LIBBPF_SUPPORT
#endif
--
2.17.1