[PATCH v6 perf,bpf 06/15] perf, bpf: save bpf_prog_info in a rbtree in perf_env

Song Liu
2019-03-06T07:15:35Z

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

Some big picture of the next few patches:

To fully annotate BPF programs with source code mapping, 4 different
information are needed:
1) PERF_RECORD_KSYMBOL
2) PERF_RECORD_BPF_EVENT
3) bpf_prog_info
4) btf

Before this set, 1) and 2) in the list are already saved to perf.data
file. For BPF programs that are already loaded before perf run, 1) and 2)
are synthesized by perf_event__synthesize_bpf_events(). For short living
BPF programs, 1) and 2) are generated by kernel.

This set handles 3) and 4) from the list. Again, it is necessary to handle
existing BPF program and short living program separately.

This patch handles 3) for exising BPF programs while synthesizing 1) and
2) in perf_event__synthesize_bpf_events(). These data are stored in
perf_env. The next patch saves these data from perf_env to perf.data as
headers.

Similarly, the two patches after the next saves 4) of existing BPF
programs to perf_env and perf.data.

Another patch later will handle 3) and 4) for short living BPF programs
by monitoring 1) and 2) in a dedicate thread.

Signed-off-by: Song Liu <songliubraving@fb.com>
---
tools/perf/perf.c | 1 +
tools/perf/util/bpf-event.c | 32 +++++++++++++-
tools/perf/util/bpf-event.h | 7 +++-
tools/perf/util/env.c | 84 +++++++++++++++++++++++++++++++++++++
tools/perf/util/env.h | 18 ++++++++
tools/perf/util/session.c | 1 +
6 files changed, 141 insertions(+), 2 deletions(-)

diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index a11cb006f968..72df4b6fa36f 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -298,6 +298,7 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
use_pager = 1;
commit_pager_choice();

+ perf_env__init(&perf_env);
perf_env__set_cmdline(&perf_env, argc, argv);
status = p->fn(argc, argv);
perf_config__exit();
diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
index ff7ee149ec46..ce81b2c43a51 100644
--- a/tools/perf/util/bpf-event.c
+++ b/tools/perf/util/bpf-event.c
@@ -10,6 +10,7 @@
#include "debug.h"
#include "symbol.h"
#include "machine.h"
+#include "env.h"
#include "session.h"

#define ptr_to_u64(ptr) ((__u64)(unsigned long)(ptr))
@@ -54,17 +55,28 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_session *session,
struct bpf_event *bpf_event = &event->bpf_event;
struct bpf_prog_info_linear *info_linear;
struct perf_tool *tool = session->tool;
+ struct bpf_prog_info_node *info_node;
struct bpf_prog_info *info;
struct btf *btf = NULL;
bool has_btf = false;
+ struct perf_env *env;
u32 sub_prog_cnt, i;
int err = 0;
u64 arrays;

+ /*
+ * for perf-record and perf-report use header.env;
+ * otherwise, use global perf_env.
+ */
+ env = session->data ? &session->header.env : &perf_env;
+
arrays = 1UL << BPF_PROG_INFO_JITED_KSYMS;
arrays |= 1UL << BPF_PROG_INFO_JITED_FUNC_LENS;
arrays |= 1UL << BPF_PROG_INFO_FUNC_INFO;
arrays |= 1UL << BPF_PROG_INFO_PROG_TAGS;
+ arrays |= 1UL << BPF_PROG_INFO_JITED_INSNS;
+ arrays |= 1UL << BPF_PROG_INFO_LINE_INFO;
+ arrays |= 1UL << BPF_PROG_INFO_JITED_LINE_INFO;

info_linear = bpf_program__get_prog_info_linear(fd, arrays);
if (IS_ERR_OR_NULL(info_linear)) {
@@ -153,8 +165,8 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_session *session,
machine, process);
}

- /* Synthesize PERF_RECORD_BPF_EVENT */
if (opts->bpf_event) {
+ /* Synthesize PERF_RECORD_BPF_EVENT */
*bpf_event = (struct bpf_event){
.header = {
.type = PERF_RECORD_BPF_EVENT,
@@ -167,6 +179,24 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_session *session,
memcpy(bpf_event->tag, info->tag, BPF_TAG_SIZE);
memset((void *)event + event->header.size, 0, machine->id_hdr_size);
event->header.size += machine->id_hdr_size;
+
+ /* save bpf_prog_info to env */
+ info_node = malloc(sizeof(struct bpf_prog_info_node));
+
+ /*
+ * Do not bail out for !info_node, as we still want to
+ * call perf_tool__process_synth_event()
+ */
+ if (info_node) {
+ info_node->info_linear = info_linear;
+ perf_env__insert_bpf_prog_info(env, info_node);
+ info_linear = NULL;
+ }
+
+ /*
+ * process after saving bpf_prog_info to env, so that
+ * required information is ready for look up
+ */
err = perf_tool__process_synth_event(tool, event,
machine, process);
}
diff --git a/tools/perf/util/bpf-event.h b/tools/perf/util/bpf-event.h
index 6698683612a7..fad932f7404f 100644
--- a/tools/perf/util/bpf-event.h
+++ b/tools/perf/util/bpf-event.h
@@ -3,14 +3,19 @@
#define __PERF_BPF_EVENT_H

#include <linux/compiler.h>
+#include <linux/rbtree.h>
#include "event.h"

struct machine;
union perf_event;
struct perf_sample;
-struct perf_tool;
struct record_opts;

+struct bpf_prog_info_node {
+ struct bpf_prog_info_linear *info_linear;
+ struct rb_node rb_node;
+};
+
#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 4c23779e271a..cdda46f2633f 100644
--- a/tools/perf/util/env.c
+++ b/tools/perf/util/env.c
@@ -3,15 +3,93 @@
#include "env.h"
#include "sane_ctype.h"
#include "util.h"
+#include "bpf-event.h"
#include <errno.h>
#include <sys/utsname.h>
+#include <bpf/libbpf.h>

struct perf_env perf_env;

+void perf_env__insert_bpf_prog_info(struct perf_env *env,
+ struct bpf_prog_info_node *info_node)
+{
+ __u32 prog_id = info_node->info_linear->info.id;
+ struct bpf_prog_info_node *node;
+ struct rb_node *parent = NULL;
+ struct rb_node **p;
+
+ down_write(&env->bpf_progs.lock);
+ p = &env->bpf_progs.infos.rb_node;
+
+ while (*p != NULL) {
+ parent = *p;
+ node = rb_entry(parent, struct bpf_prog_info_node, rb_node);
+ if (prog_id < node->info_linear->info.id) {
+ p = &(*p)->rb_left;
+ } else if (prog_id > node->info_linear->info.id) {
+ p = &(*p)->rb_right;
+ } else {
+ pr_debug("duplicated bpf prog info %u\n", prog_id);
+ goto out;
+ }
+ }
+
+ rb_link_node(&info_node->rb_node, parent, p);
+ rb_insert_color(&info_node->rb_node, &env->bpf_progs.infos);
+out:
+ up_write(&env->bpf_progs.lock);
+}
+
+struct bpf_prog_info_node *perf_env__find_bpf_prog_info(struct perf_env *env,
+ __u32 prog_id)
+{
+ struct bpf_prog_info_node *node = NULL;
+ struct rb_node *n;
+
+ down_read(&env->bpf_progs.lock);
+ n = env->bpf_progs.infos.rb_node;
+
+ while (n) {
+ node = rb_entry(n, struct bpf_prog_info_node, rb_node);
+ if (prog_id < node->info_linear->info.id)
+ n = n->rb_left;
+ else if (prog_id > node->info_linear->info.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)
+{
+ struct rb_root *root;
+ struct rb_node *next;
+
+ down_write(&env->bpf_progs.lock);
+
+ root = &env->bpf_progs.infos;
+ next = rb_first(root);
+
+ while (next) {
+ struct bpf_prog_info_node *node;
+
+ node = rb_entry(next, struct bpf_prog_info_node, rb_node);
+ next = rb_next(&node->rb_node);
+ rb_erase_init(&node->rb_node, root);
+ free(node);
+ }
+ up_write(&env->bpf_progs.lock);
+}
+
void perf_env__exit(struct perf_env *env)
{
int i;

+ perf_env__purge_bpf(env);
zfree(&env->hostname);
zfree(&env->os_release);
zfree(&env->version);
@@ -38,6 +116,12 @@ void perf_env__exit(struct perf_env *env)
zfree(&env->memory_nodes);
}

+void perf_env__init(struct perf_env *env)
+{
+ env->bpf_progs.infos = RB_ROOT;
+ init_rwsem(&env->bpf_progs.lock);
+}
+
int perf_env__set_cmdline(struct perf_env *env, int argc, const char *argv[])
{
int i;
diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
index d01b8355f4ca..e034e5b438e3 100644
--- a/tools/perf/util/env.h
+++ b/tools/perf/util/env.h
@@ -3,7 +3,9 @@
#define __PERF_ENV_H

#include <linux/types.h>
+#include <linux/rbtree.h>
#include "cpumap.h"
+#include "rwsem.h"

struct cpu_topology_map {
int socket_id;
@@ -64,8 +66,19 @@ struct perf_env {
struct memory_node *memory_nodes;
unsigned long long memory_bsize;
u64 clockid_res_ns;
+
+ /*
+ * bpf_info_lock protects bpf rbtrees. This is needed because the
+ * trees are accessed by different threads in perf-top
+ */
+ struct {
+ struct rw_semaphore lock;
+ struct rb_root infos;
+ } bpf_progs;
};

+struct bpf_prog_info_node;
+
extern struct perf_env perf_env;

void perf_env__exit(struct perf_env *env);
@@ -80,4 +93,9 @@ const char *perf_env__arch(struct perf_env *env);
const char *perf_env__raw_arch(struct perf_env *env);
int perf_env__nr_cpus_avail(struct perf_env *env);

+void perf_env__init(struct perf_env *env);
+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);
#endif /* __PERF_ENV_H */
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 026bf04bba74..3c858f1b254e 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -129,6 +129,7 @@ struct perf_session *perf_session__new(struct perf_data *data,
ordered_events__init(&session->ordered_events,
ordered_events__deliver_event, NULL);

+ perf_env__init(&session->header.env);
if (data) {
if (perf_data__open(data))
goto out_delete;
--
2.17.1