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authorWang Nan <wangnan0@huawei.com>2015-10-14 15:41:17 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2015-10-28 19:11:59 +0300
commit4edf30e39e6cff32390eaff6a1508969b3cd967b (patch)
tree1d5a60b14b9f808b3c0cece5761002ad32f0e274 /tools/perf/util/bpf-loader.c
parent1e5e3ee8ff3877db6943032b54a6ac21c095affd (diff)
downloadlinux-4edf30e39e6cff32390eaff6a1508969b3cd967b.tar.xz
perf bpf: Collect perf_evsel in BPF object files
This patch creates a 'struct perf_evsel' for every probe in a BPF object file(s) and fills 'struct evlist' with them. The previously introduced dummy event is now removed. After this patch, the following command: # perf record --event filter.o ls Can trace on each of the probes defined in filter.o. The core of this patch is bpf__foreach_tev(), which calls a callback function for each 'struct probe_trace_event' event for a bpf program with each associated file descriptors. The add_bpf_event() callback creates evsels by calling parse_events_add_tracepoint(). Since bpf-loader.c will not be built if libbpf is turned off, an empty bpf__foreach_tev() is defined in bpf-loader.h to avoid build errors. Committer notes: Before: # /tmp/oldperf record --event /tmp/foo.o -a usleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.198 MB perf.data ] # perf evlist /tmp/foo.o # perf evlist -v /tmp/foo.o: type: 1, size: 112, config: 0x9, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|CPU|PERIOD, disabled: 1, inherit: 1, mmap: 1, comm: 1, freq: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1 I.e. we create just the PERF_TYPE_SOFTWARE (type: 1), PERF_COUNT_SW_DUMMY(config 0x9) event, now, with this patch: # perf record --event /tmp/foo.o -a usleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.210 MB perf.data ] # perf evlist -v perf_bpf_probe:fork: type: 2, size: 112, config: 0x6bd, { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|CPU|PERIOD|RAW, disabled: 1, inherit: 1, mmap: 1, comm: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1 # We now have a PERF_TYPE_SOFTWARE (type: 1), but the config states 0x6bd, which is how, after setting up the event via the kprobes interface, the 'perf_bpf_probe:fork' event is accessible via the perf_event_open syscall. This is all transient, as soon as the 'perf record' session ends, these probes will go away. To see how it looks like, lets try doing a neverending session, one that expects a control+C to end: # perf record --event /tmp/foo.o -a So, with that in place, we can use 'perf probe' to see what is in place: # perf probe -l perf_bpf_probe:fork (on _do_fork@acme/git/linux/kernel/fork.c) We also can use debugfs: [root@felicio ~]# cat /sys/kernel/debug/tracing/kprobe_events p:perf_bpf_probe/fork _text+638512 Ok, now lets stop and see if we got some forks: [root@felicio linux]# perf record --event /tmp/foo.o -a ^C[ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.325 MB perf.data (111 samples) ] [root@felicio linux]# perf script sshd 1271 [003] 81797.507678: perf_bpf_probe:fork: (ffffffff8109be30) sshd 18309 [000] 81797.524917: perf_bpf_probe:fork: (ffffffff8109be30) sshd 18309 [001] 81799.381603: perf_bpf_probe:fork: (ffffffff8109be30) sshd 18309 [001] 81799.408635: perf_bpf_probe:fork: (ffffffff8109be30) <SNIP> Sure enough, we have 111 forks :-) Callchains seems to work as well: # perf report --stdio --no-child # To display the perf.data header info, please use --header/--header-only options. # # Total Lost Samples: 0 # # Samples: 562 of event 'perf_bpf_probe:fork' # Event count (approx.): 562 # # Overhead Command Shared Object Symbol # ........ ........ ................ ............ # 44.66% sh [kernel.vmlinux] [k] _do_fork | ---_do_fork entry_SYSCALL_64_fastpath __libc_fork make_child 26.16% make [kernel.vmlinux] [k] _do_fork <SNIP> # Signed-off-by: Wang Nan <wangnan0@huawei.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexei Starovoitov <ast@plumgrid.com> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David Ahern <dsahern@gmail.com> Cc: He Kuang <hekuang@huawei.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Kaixu Xia <xiakaixu@huawei.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Zefan Li <lizefan@huawei.com> Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1444826502-49291-7-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/bpf-loader.c')
-rw-r--r--tools/perf/util/bpf-loader.c40
1 files changed, 40 insertions, 0 deletions
diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 727955858d00..aa784a498c48 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -255,6 +255,46 @@ int bpf__load(struct bpf_object *obj)
return 0;
}
+int bpf__foreach_tev(struct bpf_object *obj,
+ bpf_prog_iter_callback_t func,
+ void *arg)
+{
+ struct bpf_program *prog;
+ int err;
+
+ bpf_object__for_each_program(prog, obj) {
+ struct probe_trace_event *tev;
+ struct perf_probe_event *pev;
+ struct bpf_prog_priv *priv;
+ int i, fd;
+
+ err = bpf_program__get_private(prog,
+ (void **)&priv);
+ if (err || !priv) {
+ pr_debug("bpf: failed to get private field\n");
+ return -EINVAL;
+ }
+
+ pev = &priv->pev;
+ for (i = 0; i < pev->ntevs; i++) {
+ tev = &pev->tevs[i];
+
+ fd = bpf_program__fd(prog);
+ if (fd < 0) {
+ pr_debug("bpf: failed to get file descriptor\n");
+ return fd;
+ }
+
+ err = (*func)(tev, fd, arg);
+ if (err) {
+ pr_debug("bpf: call back failed, stop iterate\n");
+ return err;
+ }
+ }
+ }
+ return 0;
+}
+
#define bpf__strerror_head(err, buf, size) \
char sbuf[STRERR_BUFSIZE], *emsg;\
if (!size)\