[PATCH bpf-next 7/7] tools/bpftool: add perf subcommand

[Yonghong Song <yhs@fb.com>]

The new command "bpftool perf [show]" will traverse
all processes under /proc, and if any fd is associated
with a perf event, it will print out related perf event
information.

Below is an example to show the results using bcc commands.
Running the following 4 bcc commands:
  kprobe:     trace.py '__x64_sys_nanosleep'
  kretprobe:  trace.py 'r::__x64_sys_nanosleep'
  tracepoint: trace.py 't:syscalls:sys_enter_nanosleep'
  uprobe:     trace.py 'p:/home/yhs/a.out:main'

The bpftool command line and result:

  $ bpftool perf
  21711: prog_id 5 kprobe func __x64_sys_write offset 0
  21765: prog_id 7 kretprobe func __x64_sys_nanosleep offset 0
  21767: prog_id 8 tracepoint sys_enter_nanosleep
  21800: prog_id 9 uprobe filename /home/yhs/a.out offset 1159

  $ bpftool -j perf
  {"pid":21711,"prog_id":5,"prog_info":"kprobe","func":"__x64_sys_write","offset":0}, \
  {"pid":21765,"prog_id":7,"prog_info":"kretprobe","func":"__x64_sys_nanosleep","offset":0}, \
  {"pid":21767,"prog_id":8,"prog_info":"tracepoint","tracepoint":"sys_enter_nanosleep"}, \
  {"pid":21800,"prog_id":9,"prog_info":"uprobe","filename":"/home/yhs/a.out","offset":1159}

  $ bpftool prog
  5: kprobe  name probe___x64_sys  tag e495a0c82f2c7a8d  gpl
	  loaded_at 2018-05-15T04:46:37-0700  uid 0
	  xlated 200B  not jited  memlock 4096B  map_ids 4
  7: kprobe  name probe___x64_sys  tag f2fdee479a503abf  gpl
	  loaded_at 2018-05-15T04:48:32-0700  uid 0
	  xlated 200B  not jited  memlock 4096B  map_ids 7
  8: tracepoint  name tracepoint__sys  tag 5390badef2395fcf  gpl
	  loaded_at 2018-05-15T04:48:48-0700  uid 0
	  xlated 200B  not jited  memlock 4096B  map_ids 8
  9: kprobe  name probe_main_1  tag 0a87bdc2e2953b6d  gpl
	  loaded_at 2018-05-15T04:49:52-0700  uid 0
	  xlated 200B  not jited  memlock 4096B  map_ids 9

  $ ps ax | grep "python ./trace.py"
  21711 pts/0    T      0:03 python ./trace.py __x64_sys_write
  21765 pts/0    S+     0:00 python ./trace.py r::__x64_sys_nanosleep
  21767 pts/2    S+     0:00 python ./trace.py t:syscalls:sys_enter_nanosleep
  21800 pts/3    S+     0:00 python ./trace.py p:/home/yhs/a.out:main
  22374 pts/1    S+     0:00 grep --color=auto python ./trace.py

Signed-off-by: Yonghong Song <yhs@fb.com>
---
 tools/bpf/bpftool/main.c |   3 +-
 tools/bpf/bpftool/main.h |   1 +
 tools/bpf/bpftool/perf.c | 188 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 191 insertions(+), 1 deletion(-)
 create mode 100644 tools/bpf/bpftool/perf.c

diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index 1ec852d..eea7f14 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -87,7 +87,7 @@ static int do_help(int argc, char **argv)
 		"       %s batch file FILE\n"
 		"       %s version\n"
 		"\n"
-		"       OBJECT := { prog | map | cgroup }\n"
+		"       OBJECT := { prog | map | cgroup | perf }\n"
 		"       " HELP_SPEC_OPTIONS "\n"
 		"",
 		bin_name, bin_name, bin_name);
@@ -216,6 +216,7 @@ static const struct cmd cmds[] = {
 	{ "prog",	do_prog },
 	{ "map",	do_map },
 	{ "cgroup",	do_cgroup },
+	{ "perf",	do_perf },
 	{ "version",	do_version },
 	{ 0 }
 };
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 6173cd9..63fdb31 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -119,6 +119,7 @@ int do_prog(int argc, char **arg);
 int do_map(int argc, char **arg);
 int do_event_pipe(int argc, char **argv);
 int do_cgroup(int argc, char **arg);
+int do_perf(int argc, char **arg);
 
 int prog_parse_fd(int *argc, char ***argv);
 int map_parse_fd_and_info(int *argc, char ***argv, void *info, __u32 *info_len);
diff --git a/tools/bpf/bpftool/perf.c b/tools/bpf/bpftool/perf.c
new file mode 100644
index 0000000..6d676e4
--- /dev/null
+++ b/tools/bpf/bpftool/perf.c
@@ -0,0 +1,188 @@
+// SPDX-License-Identifier: GPL-2.0+
+// Copyright (C) 2018 Facebook
+// Author: Yonghong Song <yhs@fb.com>
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <ftw.h>
+
+#include <bpf.h>
+
+#include "main.h"
+
+static void print_perf_json(int pid, __u32 prog_id, __u32 prog_info,
+			    char *buf, __u64 probe_offset, __u64 probe_addr)
+{
+	jsonw_start_object(json_wtr);
+	jsonw_int_field(json_wtr, "pid", pid);
+	jsonw_uint_field(json_wtr, "prog_id", prog_id);
+	switch (prog_info) {
+	case BPF_PERF_INFO_TP_NAME:
+		jsonw_string_field(json_wtr, "prog_info", "tracepoint");
+		jsonw_string_field(json_wtr, "tracepoint", buf);
+		break;
+	case BPF_PERF_INFO_KPROBE:
+		jsonw_string_field(json_wtr, "prog_info", "kprobe");
+		if (buf[0] != '\0') {
+			jsonw_string_field(json_wtr, "func", buf);
+			jsonw_lluint_field(json_wtr, "offset", probe_offset);
+		} else {
+			jsonw_lluint_field(json_wtr, "addr", probe_addr);
+		}
+		break;
+	case BPF_PERF_INFO_KRETPROBE:
+		jsonw_string_field(json_wtr, "prog_info", "kretprobe");
+		if (buf[0] != '\0') {
+			jsonw_string_field(json_wtr, "func", buf);
+			jsonw_lluint_field(json_wtr, "offset", probe_offset);
+		} else {
+			jsonw_lluint_field(json_wtr, "addr", probe_addr);
+		}
+		break;
+	case BPF_PERF_INFO_UPROBE:
+		jsonw_string_field(json_wtr, "prog_info", "uprobe");
+		jsonw_string_field(json_wtr, "filename", buf);
+		jsonw_lluint_field(json_wtr, "offset", probe_offset);
+		break;
+	case BPF_PERF_INFO_URETPROBE:
+		jsonw_string_field(json_wtr, "prog_info", "uretprobe");
+		jsonw_string_field(json_wtr, "filename", buf);
+		jsonw_lluint_field(json_wtr, "offset", probe_offset);
+		break;
+	}
+	jsonw_end_object(json_wtr);
+}
+
+static void print_perf_plain(int pid, __u32 prog_id, __u32 prog_info,
+			    char *buf, __u64 probe_offset, __u64 probe_addr)
+{
+	printf("%d: prog_id %u ", pid, prog_id);
+	switch (prog_info) {
+	case BPF_PERF_INFO_TP_NAME:
+		printf("tracepoint %s\n", buf);
+		break;
+	case BPF_PERF_INFO_KPROBE:
+		if (buf[0] != '\0')
+			printf("kprobe func %s offset %llu\n", buf,
+			       probe_offset);
+		else
+			printf("kprobe addr %llu\n", probe_addr);
+		break;
+	case BPF_PERF_INFO_KRETPROBE:
+		if (buf[0] != '\0')
+			printf("kretprobe func %s offset %llu\n", buf,
+			       probe_offset);
+		else
+			printf("kretprobe addr %llu\n", probe_addr);
+		break;
+	case BPF_PERF_INFO_UPROBE:
+		printf("uprobe filename %s offset %llu\n", buf, probe_offset);
+		break;
+	case BPF_PERF_INFO_URETPROBE:
+		printf("uretprobe filename %s offset %llu\n", buf,
+		       probe_offset);
+		break;
+	}
+}
+
+static int show_proc(const char *fpath, const struct stat *sb,
+		     int tflag, struct FTW *ftwbuf)
+{
+	__u64 probe_offset, probe_addr;
+	__u32 prog_id, prog_info;
+	int err, pid = 0, fd = 0;
+	const char *pch;
+	char buf[4096];
+
+	/* prefix always /proc */
+	pch = fpath + 5;
+	if (*pch == '\0')
+		return 0;
+
+	/* pid should be all numbers */
+	pch++;
+	while (*pch >= '0' && *pch <= '9') {
+		pid = pid * 10 + *pch - '0';
+		pch++;
+	}
+	if (*pch == '\0')
+		return 0;
+	if (*pch != '/')
+		return FTW_SKIP_SUBTREE;
+
+	/* check /proc/<pid>/fd directory */
+	pch++;
+	if (*pch == '\0' || *pch != 'f')
+		return FTW_SKIP_SUBTREE;
+	pch++;
+	if (*pch == '\0' || *pch != 'd')
+		return FTW_SKIP_SUBTREE;
+	pch++;
+	if (*pch == '\0')
+		return 0;
+	if (*pch != '/')
+		return FTW_SKIP_SUBTREE;
+
+	/* check /proc/<pid>/fd/<fd_num> */
+	pch++;
+	while (*pch >= '0' && *pch <= '9') {
+		fd = fd * 10 + *pch - '0';
+		pch++;
+	}
+	if (*pch != '\0')
+		return FTW_SKIP_SUBTREE;
+
+	/* query (pid, fd) for potential perf events */
+	err = bpf_trace_event_query(pid, fd, buf, sizeof(buf),
+		&prog_id, &prog_info, &probe_offset, &probe_addr);
+	if (err < 0)
+		return 0;
+
+	if (json_output)
+		print_perf_json(pid, prog_id, prog_info, buf, probe_offset,
+				probe_addr);
+	else
+		print_perf_plain(pid, prog_id, prog_info, buf, probe_offset,
+				 probe_addr);
+
+	return 0;
+}
+
+static int do_show(int argc, char **argv)
+{
+	int nopenfd = 16;
+	int flags = FTW_ACTIONRETVAL | FTW_PHYS;
+
+	if (nftw("/proc", show_proc, nopenfd, flags) == -1) {
+		perror("nftw");
+		return -1;
+	}
+
+	return 0;
+}
+
+static int do_help(int argc, char **argv)
+{
+	fprintf(stderr,
+		"Usage: %s %s { show | help }\n"
+		"",
+		bin_name, argv[-2]);
+
+	return 0;
+}
+
+static const struct cmd cmds[] = {
+	{ "show",	do_show },
+	{ "help",	do_help },
+	{ 0 }
+};
+
+int do_perf(int argc, char **argv)
+{
+	return cmd_select(cmds, argc, argv, do_help);
+}
-- 
2.9.5