[RFC PATCH v7 34/37] perf tools: Add bpf_fd field to evsel and config it

Wang Nan
2015-06-12T05:36:56Z

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 eBPF programs with their event
structure and file descriptors. In evlist.c, perf_evlist__add_bpf()
is added to add all bpf events into evlist. The event names are found
from probe_trace_event structure. 'perf record' calls
perf_evlist__add_bpf().

Since bpf-loader.c will not be built if libbpf is turned off, 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 | 36 +++++++++++++++++++++++++++++++
tools/perf/util/bpf-loader.h | 13 +++++++++++
tools/perf/util/evlist.c | 51 ++++++++++++++++++++++++++++++++++++++++++++
tools/perf/util/evlist.h | 1 +
tools/perf/util/evsel.c | 1 +
tools/perf/util/evsel.h | 1 +
7 files changed, 109 insertions(+)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 7fcce98..c15865f 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1135,6 +1135,12 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused)
goto out_symbol_exit;
}

+ err = perf_evlist__add_bpf(rec->evlist);
+ if (err < 0) {
+ pr_err("Failed to add events from BPF object(s)\n");
+ goto out_symbol_exit;
+ }
+
symbol__init(NULL);

if (symbol_conf.kptr_restrict)
diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 54bda7e..00fb94f 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -258,3 +258,39 @@ errout:
bpf_object__unload(obj);
return err;
}
+
+int
+bpf__for_each_program(bpf_prog_iter_callback_t func,
+ void *arg)
+{
+ struct bpf_object *obj, *tmp;
+ struct bpf_program *prog;
+ int err;
+
+ bpf_object__for_each(obj, tmp) {
+ bpf_object__for_each_program(prog, obj) {
+ struct bpf_prog_priv *priv;
+ int fd;
+
+ err = bpf_program__get_private(prog,
+ (void **)&priv);
+ if (err || !priv) {
+ pr_err("bpf: failed to get private field\n");
+ return -EINVAL;
+ }
+ err = bpf_program__get_fd(prog, &fd);
+ if (err || fd < 0) {
+ pr_err("bpf: failed to get file descriptor\n");
+ return -EINVAL;
+ }
+
+ err = func(priv->pev, fd, arg);
+ if (err) {
+ pr_err("bpf: call back failed, stop iterate\n");
+ return err;
+ }
+ }
+ }
+
+ return 0;
+}
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index ae0dc9b..da03e12 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -6,10 +6,14 @@
#define __BPF_LOADER_H

#include <linux/compiler.h>
+#include "probe-event.h"
#include "debug.h"

#define PERF_BPF_PROBE_GROUP "perf_bpf_probe"

+typedef int (*bpf_prog_iter_callback_t)(struct perf_probe_event *pev,
+ int fd, void *arg);
+
#ifdef HAVE_LIBBPF_SUPPORT
int bpf__prepare_load(const char *filename, bool source);
int bpf__probe(void);
@@ -17,6 +21,8 @@ int bpf__unprobe(void);
int bpf__load(void);

void bpf__clear(void);
+
+int bpf__for_each_program(bpf_prog_iter_callback_t func, void *arg);
#else
static inline int bpf__prepare_load(const char *filename __maybe_unused,
bool source __maybe_unused)
@@ -29,5 +35,12 @@ static inline int bpf__probe(void) { return 0; }
static inline int bpf__unprobe(void) { return 0; }
static inline int bpf__load(void) { return 0; }
static inline void bpf__clear(void) { }
+
+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 dc1dc2c..08863b6 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 +195,56 @@ error:
return -ENOMEM;
}

+static int add_bpf_event(struct perf_probe_event *pev, int fd,
+ void *arg)
+{
+ struct perf_evlist *evlist = arg;
+ struct perf_evsel *pos;
+ struct list_head list;
+ int err, idx, entries, i;
+
+ if (!pev || !pev->ntevs) {
+ pr_err("Internal error: add bpf event before probing\n");
+ return -EINVAL;
+ }
+
+ pr_debug("add bpf event %s:%s and attach bpf program %d\n",
+ pev->group, pev->event, fd);
+ INIT_LIST_HEAD(&list);
+ idx = evlist->nr_entries;
+
+ for (i = 0; i < pev->ntevs; i++) {
+ struct probe_trace_event *tev = &pev->tevs[i];
+
+ pr_debug("adding %s:%s\n", tev->group, tev->event);
+ err = parse_events_add_tracepoint(&list, &idx,
+ tev->group,
+ tev->event);
+ if (err) {
+ struct perf_evsel *evsel, *tmp;
+
+ pr_err("Failed to add BPF event %s:%s\n",
+ tev->group, tev->event);
+ list_for_each_entry_safe(evsel, tmp, &list, node) {
+ list_del(&evsel->node);
+ perf_evsel__delete(evsel);
+ }
+ return -EINVAL;
+ }
+ }
+
+ 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 955bf31..773e8e9 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -71,6 +71,7 @@ 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 a3e36fc..e5cbfcd 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 21ec082..261de76 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -100,6 +100,7 @@ struct perf_evsel {
unsigned long *per_pkg_mask;
struct perf_evsel *leader;
char *group_name;
+ int bpf_fd;
};

union u64_swap {
--
1.8.3.4