[RFC perf,bpf 4/5] perf util: introduce bpf_prog_info_event

[Song Liu]

This patch introduces struct bpf_prog_info_event to union perf_event.

struct bpf_prog_info_event {
       struct perf_event_header        header;
       u32                             prog_info_len;
       u32                             ksym_table_len;
       u64                             ksym_table;
       struct bpf_prog_info            prog_info;
       char                            data[];
};

struct bpf_prog_info_event contains information about a bpf program.
These events are written to perf.data by perf-record, and processed by
perf-report.

struct bpf_prog_info_event uses arrays for some data (ksym_table, and
arrays in struct bpf_prog_info). To make these arrays easy to serialize,
we allocate continuous memory (data). These array pointers are translated
to offset in bpf_prog_info_event before written to file. And vice-versa
when the event is read from file.

This patch enables synthesizing these events at the beginning of
perf-record run. Next patch will process short living bpf programs that
are created during perf-record.

Signed-off-by: Song Liu <songliubraving@xxxxxx>
---
 tools/perf/builtin-record.c |   5 +
 tools/perf/builtin-report.c |   2 +
 tools/perf/util/Build       |   2 +
 tools/perf/util/bpf-info.c  | 287 ++++++++++++++++++++++++++++++++++++
 tools/perf/util/bpf-info.h  |  29 ++++
 tools/perf/util/event.c     |   1 +
 tools/perf/util/event.h     |  14 ++
 tools/perf/util/session.c   |   4 +
 tools/perf/util/tool.h      |   3 +-
 9 files changed, 346 insertions(+), 1 deletion(-)
 create mode 100644 tools/perf/util/bpf-info.c
 create mode 100644 tools/perf/util/bpf-info.h

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 0980dfe3396b..73b02bde1ebc 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -41,6 +41,7 @@
 #include "util/perf-hooks.h"
 #include "util/time-utils.h"
 #include "util/units.h"
+#include "util/bpf-info.h"
 #include "asm/bug.h"
 
 #include <errno.h>
@@ -850,6 +851,9 @@ static int record__synthesize(struct record *rec, bool tail)
 	err = __machine__synthesize_threads(machine, tool, &opts->target, rec->evlist->threads,
 					    process_synthesized_event, opts->sample_address,
 					    opts->proc_map_timeout, 1);
+
+	err = perf_event__synthesize_bpf_prog_info(
+		&rec->tool, process_synthesized_event, machine);
 out:
 	return err;
 }
@@ -1531,6 +1535,7 @@ static struct record record = {
 		.namespaces	= perf_event__process_namespaces,
 		.mmap		= perf_event__process_mmap,
 		.mmap2		= perf_event__process_mmap2,
+		.bpf_prog_info	= perf_event__process_bpf_prog_info,
 		.ordered_events	= true,
 	},
 };
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index c0703979c51d..4a9a3e8da4e0 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -41,6 +41,7 @@
 #include "util/auxtrace.h"
 #include "util/units.h"
 #include "util/branch.h"
+#include "util/bpf-info.h"
 
 #include <dlfcn.h>
 #include <errno.h>
@@ -981,6 +982,7 @@ int cmd_report(int argc, const char **argv)
 			.auxtrace_info	 = perf_event__process_auxtrace_info,
 			.auxtrace	 = perf_event__process_auxtrace,
 			.feature	 = process_feature_event,
+			.bpf_prog_info	 = perf_event__process_bpf_prog_info,
 			.ordered_events	 = true,
 			.ordering_requires_timestamps = true,
 		},
diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index ecd9f9ceda77..624c7281217c 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -150,6 +150,8 @@ endif
 
 libperf-y += perf-hooks.o
 
+libperf-$(CONFIG_LIBBPF) += bpf-info.o
+
 libperf-$(CONFIG_CXX) += c++/
 
 CFLAGS_config.o   += -DETC_PERFCONFIG="BUILD_STR($(ETC_PERFCONFIG_SQ))"
diff --git a/tools/perf/util/bpf-info.c b/tools/perf/util/bpf-info.c
new file mode 100644
index 000000000000..fa598c4328be
--- /dev/null
+++ b/tools/perf/util/bpf-info.c
@@ -0,0 +1,287 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Facebook
+ */
+#include <errno.h>
+#include <stdio.h>
+#include <bpf/bpf.h>
+#include "bpf-info.h"
+#include "debug.h"
+#include "session.h"
+
+#define KSYM_NAME_LEN 128
+#define BPF_PROG_INFO_MIN_SIZE 128  /* minimal require jited_func_lens */
+
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+	return (__u64) (unsigned long) ptr;
+}
+
+/* fetch information of the bpf program via bpf syscall. */
+struct bpf_prog_info_event *perf_bpf_info__get_bpf_prog_info_event(u32 prog_id)
+{
+	struct bpf_prog_info_event *prog_info_event = NULL;
+	struct bpf_prog_info info = {};
+	u32 info_len = sizeof(info);
+	u32 event_len, i;
+	int fd, err;
+	void *ptr;
+
+	fd = bpf_prog_get_fd_by_id(prog_id);
+	if (fd < 0) {
+		pr_debug("Failed to get fd for prog_id %u\n", prog_id);
+		return NULL;
+	}
+
+	err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
+	if (err) {
+		pr_debug("can't get prog info: %s", strerror(errno));
+		goto close_fd;
+	}
+	if (info_len < BPF_PROG_INFO_MIN_SIZE) {
+		pr_debug("kernel is too old to support proper prog info\n");
+		goto close_fd;
+	}
+
+	/* calculate size of bpf_prog_info_event */
+	event_len = sizeof(struct bpf_prog_info_event);
+	event_len += info_len;
+	event_len -= sizeof(info);
+	event_len += info.jited_prog_len;
+	event_len += info.xlated_prog_len;
+	event_len += info.nr_map_ids * sizeof(u32);
+	event_len += info.nr_jited_ksyms * sizeof(u64);
+	event_len += info.nr_jited_func_lens * sizeof(u32);
+	event_len += info.nr_jited_ksyms * KSYM_NAME_LEN;
+
+	prog_info_event = (struct bpf_prog_info_event *) malloc(event_len);
+	if (!prog_info_event)
+		goto close_fd;
+
+	/* assign pointers for map_ids, jited_prog_insns, etc. */
+	ptr = prog_info_event->data;
+	info.map_ids = ptr_to_u64(ptr);
+	ptr += info.nr_map_ids * sizeof(u32);
+	info.jited_prog_insns = ptr_to_u64(ptr);
+	ptr += info.jited_prog_len;
+	info.xlated_prog_insns = ptr_to_u64(ptr);
+	ptr += info.xlated_prog_len;
+	info.jited_ksyms = ptr_to_u64(ptr);
+	ptr += info.nr_jited_ksyms * sizeof(u64);
+	info.jited_func_lens = ptr_to_u64(ptr);
+	ptr += info.nr_jited_func_lens * sizeof(u32);
+
+	err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
+	if (err) {
+		pr_err("can't get prog info: %s\n", strerror(errno));
+		free(prog_info_event);
+		prog_info_event = NULL;
+		goto close_fd;
+	}
+
+	/* fill data in prog_info_event */
+	prog_info_event->header.type = PERF_RECORD_BPF_PROG_INFO;
+	prog_info_event->header.misc = 0;
+	prog_info_event->prog_info_len = info_len;
+
+	memcpy(&prog_info_event->prog_info, &info, info_len);
+
+	prog_info_event->ksym_table_len = 0;
+	prog_info_event->ksym_table = ptr_to_u64(ptr);
+
+	/* fill in fake symbol name for now, add real name after BTF */
+	if (info.nr_jited_func_lens == 1 && info.name) {  /* only main prog */
+		size_t l;
+
+		assert(info.nr_jited_ksyms == 1);
+		l = snprintf(ptr, KSYM_NAME_LEN, "bpf_prog_%s", info.name);
+		prog_info_event->ksym_table_len += l + 1;
+		ptr += l + 1;
+
+	} else {
+		assert(info.nr_jited_ksyms == info.nr_jited_func_lens);
+
+		for (i = 0; i < info.nr_jited_ksyms; i++) {
+			size_t l;
+
+			l = snprintf(ptr, KSYM_NAME_LEN, "bpf_prog_%d_%d",
+				     info.id, i);
+			prog_info_event->ksym_table_len += l + 1;
+			ptr += l + 1;
+		}
+	}
+
+	prog_info_event->header.size = ptr - (void *)prog_info_event;
+
+close_fd:
+	close(fd);
+	return prog_info_event;
+}
+
+static size_t fprintf_bpf_prog_info(
+	struct bpf_prog_info_event *prog_info_event, FILE *fp)
+{
+	struct bpf_prog_info *info = &prog_info_event->prog_info;
+	unsigned long *jited_ksyms = (unsigned long *)(info->jited_ksyms);
+	char *name_ptr = (char *) prog_info_event->ksym_table;
+	unsigned int i;
+	size_t ret;
+
+	ret = fprintf(fp, "bpf_prog: type: %u id: %u ", info->type, info->id);
+	ret += fprintf(fp, "nr_jited_ksyms: %u\n", info->nr_jited_ksyms);
+
+	for (i = 0; i < info->nr_jited_ksyms; i++) {
+		ret += fprintf(fp, "jited_ksyms[%u]: %lx %s\n",
+			       i, jited_ksyms[i], name_ptr);
+		name_ptr += strlen(name_ptr);
+	}
+	return ret;
+}
+
+size_t perf_event__fprintf_bpf_prog_info(union perf_event *event, FILE *fp)
+{
+	return fprintf_bpf_prog_info(&event->bpf_prog_info, fp);
+}
+
+/*
+ * translate all array ptr to offset from base address, called before
+ * writing the event to file
+ */
+void perf_bpf_info__ptr_to_offset(
+	struct bpf_prog_info_event *prog_info_event)
+{
+	u64 base = ptr_to_u64(prog_info_event);
+
+	prog_info_event->ksym_table -= base;
+	prog_info_event->prog_info.jited_prog_insns -= base;
+	prog_info_event->prog_info.xlated_prog_insns -= base;
+	prog_info_event->prog_info.map_ids -= base;
+	prog_info_event->prog_info.jited_ksyms -= base;
+	prog_info_event->prog_info.jited_func_lens -= base;
+}
+
+/*
+ * translate offset from base address to array pointer, called after
+ * reading the event from file
+ */
+void perf_bpf_info__offset_to_ptr(
+	struct bpf_prog_info_event *prog_info_event)
+{
+	u64 base = ptr_to_u64(prog_info_event);
+
+	prog_info_event->ksym_table += base;
+	prog_info_event->prog_info.jited_prog_insns += base;
+	prog_info_event->prog_info.xlated_prog_insns += base;
+	prog_info_event->prog_info.map_ids += base;
+	prog_info_event->prog_info.jited_ksyms += base;
+	prog_info_event->prog_info.jited_func_lens += base;
+}
+
+int perf_event__synthesize_one_bpf_prog_info(struct perf_tool *tool,
+					     perf_event__handler_t process,
+					     struct machine *machine,
+					     __u32 id)
+{
+	struct bpf_prog_info_event *prog_info_event;
+
+	prog_info_event = perf_bpf_info__get_bpf_prog_info_event(id);
+
+	if (!prog_info_event) {
+		pr_err("Failed to get prog_info_event\n");
+		return -1;
+	}
+	perf_bpf_info__ptr_to_offset(prog_info_event);
+
+	if (perf_tool__process_synth_event(
+		    tool, (union perf_event *)prog_info_event,
+		    machine, process) != 0) {
+		free(prog_info_event);
+		return -1;
+	}
+
+	free(prog_info_event);
+	return 0;
+}
+
+int perf_event__synthesize_bpf_prog_info(struct perf_tool *tool,
+					 perf_event__handler_t process,
+					 struct machine *machine)
+{
+	__u32 id = 0;
+	int err = 0;
+
+	while (true) {
+		err = bpf_prog_get_next_id(id, &id);
+		if (err) {
+			if (errno == ENOENT) {
+				err = 0;
+				break;
+			}
+			fprintf(stderr, "can't get next program: %s%s",
+				strerror(errno),
+				errno == EINVAL ? " -- kernel too old?" : "");
+			err = -1;
+			break;
+		}
+		err = perf_event__synthesize_one_bpf_prog_info(
+			tool, process, machine, id);
+	}
+	return err;
+}
+
+int perf_event__process_bpf_prog_info(struct perf_session *session,
+				      union perf_event *event)
+{
+	struct machine *machine = &session->machines.host;
+	struct bpf_prog_info_event *prog_info_event;
+	struct bpf_prog_info *info;
+	struct symbol *sym;
+	struct map *map;
+	char *name_ptr;
+	int ret = 0;
+	u64 *addrs;
+	u32 *lens;
+	u32 i;
+
+	prog_info_event = (struct bpf_prog_info_event *)
+		malloc(event->header.size);
+	if (!prog_info_event)
+		return -ENOMEM;
+
+	/* copy the data to rw memeory so we can modify it */
+	memcpy(prog_info_event,  &event->bpf_prog_info, event->header.size);
+	info = &prog_info_event->prog_info;
+
+	perf_bpf_info__offset_to_ptr(prog_info_event);
+	name_ptr = (char *) prog_info_event->ksym_table;
+	addrs = (u64 *)info->jited_ksyms;
+	lens = (u32 *)info->jited_func_lens;
+	for (i = 0; i < info->nr_jited_ksyms; i++) {
+		u32 len = info->nr_jited_func_lens == 1 ?
+			len = info->jited_prog_len : lens[i];
+
+		map = map_groups__find(&machine->kmaps, addrs[i]);
+		if (!map) {
+			map = dso__new_map("bpf_prog");
+			if (!map) {
+				ret = -ENOMEM;
+				break;
+			}
+			map->start = addrs[i];
+			map->pgoff = map->start;
+			map->end = map->start + len;
+			map_groups__insert(&machine->kmaps, map);
+		}
+
+		sym = symbol__new(addrs[i], len, 0, 0, name_ptr);
+		if (!sym) {
+			ret = -ENOMEM;
+			break;
+		}
+		dso__insert_symbol(map->dso, sym);
+		name_ptr += strlen(name_ptr) + 1;
+	}
+
+	free(prog_info_event);
+	return ret;
+}
diff --git a/tools/perf/util/bpf-info.h b/tools/perf/util/bpf-info.h
new file mode 100644
index 000000000000..813cad07bacb
--- /dev/null
+++ b/tools/perf/util/bpf-info.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_BPF_INFO_H
+#define __PERF_BPF_INFO_H
+
+#include "event.h"
+#include "machine.h"
+#include "tool.h"
+#include "symbol.h"
+
+struct bpf_prog_info_event *perf_bpf_info__get_bpf_prog_info_event(u32 prog_id);
+
+size_t perf_event__fprintf_bpf_prog_info(union perf_event *event, FILE *fp);
+
+int perf_event__synthesize_one_bpf_prog_info(struct perf_tool *tool,
+					     perf_event__handler_t process,
+					     struct machine *machine,
+					     __u32 id);
+
+int perf_event__synthesize_bpf_prog_info(struct perf_tool *tool,
+					 perf_event__handler_t process,
+					 struct machine *machine);
+
+void perf_bpf_info__ptr_to_offset(struct bpf_prog_info_event *prog_info_event);
+void perf_bpf_info__offset_to_ptr(struct bpf_prog_info_event *prog_info_event);
+
+int perf_event__process_bpf_prog_info(struct perf_session *session,
+				      union perf_event *event);
+
+#endif /* __PERF_BPF_INFO_H */
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 601432afbfb2..33b1c168b83e 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -61,6 +61,7 @@ static const char *perf_event__names[] = {
 	[PERF_RECORD_EVENT_UPDATE]		= "EVENT_UPDATE",
 	[PERF_RECORD_TIME_CONV]			= "TIME_CONV",
 	[PERF_RECORD_HEADER_FEATURE]		= "FEATURE",
+	[PERF_RECORD_BPF_PROG_INFO]		= "BPF_PROG_INFO",
 };
 
 static const char *perf_ns__names[] = {
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index 13a0c64dd0ed..dc64d800eaa6 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -5,6 +5,7 @@
 #include <limits.h>
 #include <stdio.h>
 #include <linux/kernel.h>
+#include <linux/bpf.h>
 
 #include "../perf.h"
 #include "build-id.h"
@@ -258,6 +259,7 @@ enum perf_user_event_type { /* above any possible kernel type */
 	PERF_RECORD_EVENT_UPDATE		= 78,
 	PERF_RECORD_TIME_CONV			= 79,
 	PERF_RECORD_HEADER_FEATURE		= 80,
+	PERF_RECORD_BPF_PROG_INFO		= 81,
 	PERF_RECORD_HEADER_MAX
 };
 
@@ -629,6 +631,17 @@ struct feature_event {
 	char				data[];
 };
 
+#define KSYM_NAME_LEN 128
+
+struct bpf_prog_info_event {
+	struct perf_event_header	header;
+	u32				prog_info_len;
+	u32				ksym_table_len;
+	u64				ksym_table;
+	struct bpf_prog_info		prog_info;
+	char				data[];
+};
+
 union perf_event {
 	struct perf_event_header	header;
 	struct mmap_event		mmap;
@@ -661,6 +674,7 @@ union perf_event {
 	struct time_conv_event		time_conv;
 	struct feature_event		feat;
 	struct bpf_event		bpf_event;
+	struct bpf_prog_info_event	bpf_prog_info;
 };
 
 void perf_event__print_totals(void);
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index dffe5120d2d3..5365ee1dfbec 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -415,6 +415,8 @@ void perf_tool__fill_defaults(struct perf_tool *tool)
 		tool->time_conv = process_event_op2_stub;
 	if (tool->feature == NULL)
 		tool->feature = process_event_op2_stub;
+	if (tool->bpf_prog_info == NULL)
+		tool->bpf_prog_info = process_event_op2_stub;
 }
 
 static void swap_sample_id_all(union perf_event *event, void *data)
@@ -1397,6 +1399,8 @@ static s64 perf_session__process_user_event(struct perf_session *session,
 		return tool->time_conv(session, event);
 	case PERF_RECORD_HEADER_FEATURE:
 		return tool->feature(session, event);
+	case PERF_RECORD_BPF_PROG_INFO:
+		return tool->bpf_prog_info(session, event);
 	default:
 		return -EINVAL;
 	}
diff --git a/tools/perf/util/tool.h b/tools/perf/util/tool.h
index 69ae898ca024..739a4b1188f7 100644
--- a/tools/perf/util/tool.h
+++ b/tools/perf/util/tool.h
@@ -70,7 +70,8 @@ struct perf_tool {
 			stat_config,
 			stat,
 			stat_round,
-			feature;
+			feature,
+			bpf_prog_info;
 	event_op3	auxtrace;
 	bool		ordered_events;
 	bool		ordering_requires_timestamps;
-- 
2.17.1