[PATCH v4 perf,bpf 08/15] perf, bpf: save btf in a rbtree in perf_env

[Song Liu]

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@xxxxxx>
---
 tools/perf/util/bpf-event.c | 24 ++++++++++++++
 tools/perf/util/bpf-event.h |  7 ++++
 tools/perf/util/env.c       | 65 +++++++++++++++++++++++++++++++++++++
 tools/perf/util/env.h       |  4 +++
 4 files changed, 100 insertions(+)

diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
index ce81b2c43a51..370b830f2433 100644
--- a/tools/perf/util/bpf-event.c
+++ b/tools/perf/util/bpf-event.c
@@ -34,6 +34,29 @@ 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 +136,7 @@ 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 650c14ad7e9b..291b21d8f858 100644
--- a/tools/perf/util/env.c
+++ b/tools/perf/util/env.c
@@ -63,6 +63,57 @@ 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);
+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_prog_infos tree */
 static void perf_env__purge_bpf(struct perf_env *env)
 {
@@ -82,6 +133,19 @@ static void perf_env__purge_bpf(struct perf_env *env)
 		rb_erase_init(&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_init(&node->rb_node, root);
+		free(node);
+	}
+
 	up_write(&env->bpf_progs.lock);
 }
 
@@ -119,6 +183,7 @@ void perf_env__exit(struct perf_env *env)
 static void init_bpf_rb_trees(struct perf_env *env)
 {
 	env->bpf_progs.prog_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 33ef4b2d2a29..b7fc4c71ba6a 100644
--- a/tools/perf/util/env.h
+++ b/tools/perf/util/env.h
@@ -74,10 +74,12 @@ struct perf_env {
 	struct {
 		struct rw_semaphore	lock;
 		struct rb_root		prog_infos;
+		struct rb_root		btfs;
 	} bpf_progs;
 };
 
 struct bpf_prog_info_node;
+struct btf_node;
 
 extern struct perf_env perf_env;
 
@@ -97,4 +99,6 @@ 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