[PATCH v8 perf,bpf 08/15] perf, bpf: save btf in a rbtree in perf_env

Song Liu
2019-03-11T20:06:40Z

btf contains information necessary to annotate bpf programs. This patch
saves btf for bpf programs loaded in the system.

Signed-off-by: Song Liu <songliubraving@fb.com>
---
tools/perf/util/bpf-event.c | 23 +++++++++++++
tools/perf/util/bpf-event.h | 7 ++++
tools/perf/util/env.c | 66 +++++++++++++++++++++++++++++++++++++
tools/perf/util/env.h | 5 +++
4 files changed, 101 insertions(+)

diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
index 3ae60f74339b..4ef7c833830c 100644
--- a/tools/perf/util/bpf-event.c
+++ b/tools/perf/util/bpf-event.c
@@ -34,6 +34,28 @@ int machine__process_bpf_event(struct machine *machine __maybe_unused,
return 0;
}

+static int perf_env__fetch_btf(struct perf_env *env,
+ u32 btf_id,
+ struct btf *btf)
+{
+ struct btf_node *node;
+ u32 data_size;
+ const void *data;
+
+ data = btf__get_raw_data(btf, &data_size);
+
+ node = malloc(data_size + sizeof(struct btf_node));
+ if (!node)
+ return -1;
+
+ node->id = btf_id;
+ node->data_size = data_size;
+ memcpy(node->data, data, data_size);
+
+ perf_env__insert_btf(env, node);
+ return 0;
+}
+
/*
* Synthesize PERF_RECORD_KSYMBOL and PERF_RECORD_BPF_EVENT for one bpf
* program. One PERF_RECORD_BPF_EVENT is generated for the program. And
@@ -113,6 +135,7 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_session *session,
goto out;
}
has_btf = true;
+ perf_env__fetch_btf(env, info->btf_id, btf);
}

/* Synthesize PERF_RECORD_KSYMBOL */
diff --git a/tools/perf/util/bpf-event.h b/tools/perf/util/bpf-event.h
index fad932f7404f..b9ec394dc7c7 100644
--- a/tools/perf/util/bpf-event.h
+++ b/tools/perf/util/bpf-event.h
@@ -16,6 +16,13 @@ struct bpf_prog_info_node {
struct rb_node rb_node;
};

+struct btf_node {
+ struct rb_node rb_node;
+ u32 id;
+ u32 data_size;
+ char data[];
+};
+
#ifdef HAVE_LIBBPF_SUPPORT
int machine__process_bpf_event(struct machine *machine, union perf_event *event,
struct perf_sample *sample);
diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
index fb82623b0822..84bdf726c6a1 100644
--- a/tools/perf/util/env.c
+++ b/tools/perf/util/env.c
@@ -64,6 +64,58 @@ struct bpf_prog_info_node *perf_env__find_bpf_prog_info(struct perf_env *env,
return node;
}

+void perf_env__insert_btf(struct perf_env *env, struct btf_node *btf_node)
+{
+ struct rb_node *parent = NULL;
+ __u32 btf_id = btf_node->id;
+ struct btf_node *node;
+ struct rb_node **p;
+
+ down_write(&env->bpf_progs.lock);
+ p = &env->bpf_progs.btfs.rb_node;
+
+ while (*p != NULL) {
+ parent = *p;
+ node = rb_entry(parent, struct btf_node, rb_node);
+ if (btf_id < node->id) {
+ p = &(*p)->rb_left;
+ } else if (btf_id > node->id) {
+ p = &(*p)->rb_right;
+ } else {
+ pr_debug("duplicated btf %u\n", btf_id);
+ goto out;
+ }
+ }
+
+ rb_link_node(&btf_node->rb_node, parent, p);
+ rb_insert_color(&btf_node->rb_node, &env->bpf_progs.btfs);
+ env->bpf_progs.btfs_cnt++;
+out:
+ up_write(&env->bpf_progs.lock);
+}
+
+struct btf_node *perf_env__find_btf(struct perf_env *env, __u32 btf_id)
+{
+ struct btf_node *node = NULL;
+ struct rb_node *n;
+
+ down_read(&env->bpf_progs.lock);
+ n = env->bpf_progs.btfs.rb_node;
+
+ while (n) {
+ node = rb_entry(n, struct btf_node, rb_node);
+ if (btf_id < node->id)
+ n = n->rb_left;
+ else if (btf_id > node->id)
+ n = n->rb_right;
+ else
+ break;
+ }
+
+ up_read(&env->bpf_progs.lock);
+ return node;
+}
+
/* purge data in bpf_progs.infos tree */
static void perf_env__purge_bpf(struct perf_env *env)
{
@@ -83,6 +135,19 @@ static void perf_env__purge_bpf(struct perf_env *env)
rb_erase(&node->rb_node, root);
free(node);
}
+
+ root = &env->bpf_progs.btfs;
+ next = rb_first(root);
+
+ while (next) {
+ struct btf_node *node;
+
+ node = rb_entry(next, struct btf_node, rb_node);
+ next = rb_next(&node->rb_node);
+ rb_erase(&node->rb_node, root);
+ free(node);
+ }
+
up_write(&env->bpf_progs.lock);
}

@@ -120,6 +185,7 @@ void perf_env__exit(struct perf_env *env)
void perf_env__init(struct perf_env *env)
{
env->bpf_progs.infos = RB_ROOT;
+ env->bpf_progs.btfs = RB_ROOT;
init_rwsem(&env->bpf_progs.lock);
}

diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
index 24b11c564ba4..4f8e2b485c01 100644
--- a/tools/perf/util/env.h
+++ b/tools/perf/util/env.h
@@ -75,10 +75,13 @@ struct perf_env {
struct rw_semaphore lock;
struct rb_root infos;
u32 infos_cnt;
+ struct rb_root btfs;
+ u32 btfs_cnt;
} bpf_progs;
};

struct bpf_prog_info_node;
+struct btf_node;

extern struct perf_env perf_env;

@@ -99,4 +102,6 @@ void perf_env__insert_bpf_prog_info(struct perf_env *env,
struct bpf_prog_info_node *info_node);
struct bpf_prog_info_node *perf_env__find_bpf_prog_info(struct perf_env *env,
__u32 prog_id);
+void perf_env__insert_btf(struct perf_env *env, struct btf_node *btf_node);
+struct btf_node *perf_env__find_btf(struct perf_env *env, __u32 btf_id);
#endif /* __PERF_ENV_H */
--
2.17.1