[RFC PATCH v3 36/37] perf tools: Add bpf_fd field to evsel and config it

Wang Nan
2015-05-17T10:59:20Z

This patch adds a bpf_fd field to 'struct evsel' then introduces method
to config it. In bpf-loader, a bpf_for_each_program() function is added.
Which calls the callback function for each found eBPF program with
their names and file descriptors. In evlist.c, perf_evlist__add_bpf()
is added to add all bpf events into evlist. 'perf record' calls
perf_evlist__add_bpf() if it is wrapped by perf bpf.

Since bpf-loader.c will not built if libelf not found, an empty
bpf_for_each_program() is defined in bpf-loader.h to avoid compiling
error.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
tools/perf/builtin-record.c | 6 ++++++
tools/perf/util/bpf-loader.c | 30 ++++++++++++++++++++++++++++++
tools/perf/util/bpf-loader.h | 18 ++++++++++++++++++
tools/perf/util/evlist.c | 34 ++++++++++++++++++++++++++++++++++
tools/perf/util/evlist.h | 1 +
tools/perf/util/evsel.c | 1 +
tools/perf/util/evsel.h | 1 +
7 files changed, 91 insertions(+)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index c3efdfb..21f3dcb 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -978,6 +978,12 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused)
goto out_symbol_exit;
}

+ if (bpf_wrapper &&
+ perf_evlist__add_bpf(rec->evlist) < 0) {
+ pr_err("Failed to add events from bpf object\n");
+ goto out_symbol_exit;
+ }
+
if (rec->opts.target.tid && !rec->opts.no_inherit_set)
rec->opts.no_inherit = true;

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 7295a3b..b793c69 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -230,3 +230,33 @@ int bpf_load(void)

return 0;
}
+
+int bpf_for_each_program(bpf_prog_iter_callback_t func, void *arg)
+{
+ int i;
+
+ if (!func)
+ return -EINVAL;
+
+ for (i = 0; i < (int)params.nr_progs; i++) {
+ int err, fd;
+ const char *group, *event;
+ struct bpf_prog_handler *prog =
+ params.progs[i].prog;
+ struct perf_probe_event *pevent =
+ params.progs[i].pevent;
+
+ group = pevent->group;
+ event = pevent->event;
+ err = bpf_prog_get_fd(prog, &fd);
+ if (err) {
+ pr_err("Unable to get program fd\n");
+ return -EINVAL;
+ }
+
+ err = func(group, event, fd, arg);
+ if (err)
+ return err;
+ }
+ return 0;
+}
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index 1ccebdf..ffdd535 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -7,10 +7,28 @@
#ifndef __BPF_LOADER_H
#define __BPF_LOADER_H

+#include <linux/compiler.h> // for __maybe_unused
+
int bpf_prepare_load(const char *filename);
int bpf_probe(void);
int bpf_load(void);

int bpf_unprobe(void);
void bpf_clear(void);
+
+typedef int (*bpf_prog_iter_callback_t)(const char *group,
+ const char *event,
+ int fd, void *arg);
+
+#ifdef HAVE_LIBELF_SUPPORT
+int bpf_for_each_program(bpf_prog_iter_callback_t func, void *arg);
+#else
+static inline int
+bpf_for_each_program(bpf_prog_iter_callback_t func __maybe_unused,
+ void *arg __maybe_unused)
+{
+ return 0;
+}
+#endif
+
#endif
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 080be93..cc26317 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -14,6 +14,7 @@
#include "target.h"
#include "evlist.h"
#include "evsel.h"
+#include "bpf-loader.h"
#include "debug.h"
#include <unistd.h>

@@ -194,6 +195,39 @@ error:
return -ENOMEM;
}

+static int add_bpf_event(const char *group, const char *event, int fd,
+ void *arg)
+{
+ struct perf_evlist *evlist = arg;
+ struct perf_evsel *pos;
+ struct list_head list;
+ int err, idx, entries;
+
+ pr_info("add bpf event %s:%s and attach bpf program %d\n",
+ group, event, fd);
+
+ INIT_LIST_HEAD(&list);
+ idx = evlist->nr_entries;
+ err = parse_events_add_tracepoint(&list, &idx, (char *)group,
+ (char *)event);
+ if (err) {
+ pr_err("Failed to add BPF event %s:%s\n",
+ group, event);
+ return err;
+ }
+ list_for_each_entry(pos, &list, node)
+ pos->bpf_fd = fd;
+
+ entries = idx - evlist->nr_entries;
+ perf_evlist__splice_list_tail(evlist, &list, entries);
+ return 0;
+}
+
+int perf_evlist__add_bpf(struct perf_evlist *evlist)
+{
+ return bpf_for_each_program(add_bpf_event, evlist);
+}
+
static int perf_evlist__add_attrs(struct perf_evlist *evlist,
struct perf_event_attr *attrs, size_t nr_attrs)
{
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index b5cce95..032f04d 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -68,6 +68,7 @@ void perf_evlist__delete(struct perf_evlist *evlist);

void perf_evlist__add(struct perf_evlist *evlist, struct perf_evsel *entry);
int perf_evlist__add_default(struct perf_evlist *evlist);
+int perf_evlist__add_bpf(struct perf_evlist *evlist);
int __perf_evlist__add_default_attrs(struct perf_evlist *evlist,
struct perf_event_attr *attrs, size_t nr_attrs);

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 33e3fd8..04d60a7 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -205,6 +205,7 @@ void perf_evsel__init(struct perf_evsel *evsel,
evsel->leader = evsel;
evsel->unit = "";
evsel->scale = 1.0;
+ evsel->bpf_fd = -1;
INIT_LIST_HEAD(&evsel->node);
perf_evsel__object.init(evsel);
evsel->sample_size = __perf_evsel__sample_size(attr->sample_type);
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index e486151..ff1f634 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -100,6 +100,7 @@ struct perf_evsel {
int sample_read;
struct perf_evsel *leader;
char *group_name;
+ int bpf_fd;
};

union u64_swap {
--
1.8.3.4