xref: /openbmc/linux/tools/bpf/bpftool/perf.c (revision b830f94f)
1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2 // Copyright (C) 2018 Facebook
3 // Author: Yonghong Song <yhs@fb.com>
4 
5 #define _GNU_SOURCE
6 #include <ctype.h>
7 #include <errno.h>
8 #include <fcntl.h>
9 #include <stdlib.h>
10 #include <string.h>
11 #include <sys/stat.h>
12 #include <sys/types.h>
13 #include <unistd.h>
14 #include <ftw.h>
15 
16 #include <bpf.h>
17 
18 #include "main.h"
19 
20 /* 0: undecided, 1: supported, 2: not supported */
21 static int perf_query_supported;
22 static bool has_perf_query_support(void)
23 {
24 	__u64 probe_offset, probe_addr;
25 	__u32 len, prog_id, fd_type;
26 	char buf[256];
27 	int fd;
28 
29 	if (perf_query_supported)
30 		goto out;
31 
32 	fd = open("/", O_RDONLY);
33 	if (fd < 0) {
34 		p_err("perf_query_support: cannot open directory \"/\" (%s)",
35 		      strerror(errno));
36 		goto out;
37 	}
38 
39 	/* the following query will fail as no bpf attachment,
40 	 * the expected errno is ENOTSUPP
41 	 */
42 	errno = 0;
43 	len = sizeof(buf);
44 	bpf_task_fd_query(getpid(), fd, 0, buf, &len, &prog_id,
45 			  &fd_type, &probe_offset, &probe_addr);
46 
47 	if (errno == 524 /* ENOTSUPP */) {
48 		perf_query_supported = 1;
49 		goto close_fd;
50 	}
51 
52 	perf_query_supported = 2;
53 	p_err("perf_query_support: %s", strerror(errno));
54 	fprintf(stderr,
55 		"HINT: non root or kernel doesn't support TASK_FD_QUERY\n");
56 
57 close_fd:
58 	close(fd);
59 out:
60 	return perf_query_supported == 1;
61 }
62 
63 static void print_perf_json(int pid, int fd, __u32 prog_id, __u32 fd_type,
64 			    char *buf, __u64 probe_offset, __u64 probe_addr)
65 {
66 	jsonw_start_object(json_wtr);
67 	jsonw_int_field(json_wtr, "pid", pid);
68 	jsonw_int_field(json_wtr, "fd", fd);
69 	jsonw_uint_field(json_wtr, "prog_id", prog_id);
70 	switch (fd_type) {
71 	case BPF_FD_TYPE_RAW_TRACEPOINT:
72 		jsonw_string_field(json_wtr, "fd_type", "raw_tracepoint");
73 		jsonw_string_field(json_wtr, "tracepoint", buf);
74 		break;
75 	case BPF_FD_TYPE_TRACEPOINT:
76 		jsonw_string_field(json_wtr, "fd_type", "tracepoint");
77 		jsonw_string_field(json_wtr, "tracepoint", buf);
78 		break;
79 	case BPF_FD_TYPE_KPROBE:
80 		jsonw_string_field(json_wtr, "fd_type", "kprobe");
81 		if (buf[0] != '\0') {
82 			jsonw_string_field(json_wtr, "func", buf);
83 			jsonw_lluint_field(json_wtr, "offset", probe_offset);
84 		} else {
85 			jsonw_lluint_field(json_wtr, "addr", probe_addr);
86 		}
87 		break;
88 	case BPF_FD_TYPE_KRETPROBE:
89 		jsonw_string_field(json_wtr, "fd_type", "kretprobe");
90 		if (buf[0] != '\0') {
91 			jsonw_string_field(json_wtr, "func", buf);
92 			jsonw_lluint_field(json_wtr, "offset", probe_offset);
93 		} else {
94 			jsonw_lluint_field(json_wtr, "addr", probe_addr);
95 		}
96 		break;
97 	case BPF_FD_TYPE_UPROBE:
98 		jsonw_string_field(json_wtr, "fd_type", "uprobe");
99 		jsonw_string_field(json_wtr, "filename", buf);
100 		jsonw_lluint_field(json_wtr, "offset", probe_offset);
101 		break;
102 	case BPF_FD_TYPE_URETPROBE:
103 		jsonw_string_field(json_wtr, "fd_type", "uretprobe");
104 		jsonw_string_field(json_wtr, "filename", buf);
105 		jsonw_lluint_field(json_wtr, "offset", probe_offset);
106 		break;
107 	}
108 	jsonw_end_object(json_wtr);
109 }
110 
111 static void print_perf_plain(int pid, int fd, __u32 prog_id, __u32 fd_type,
112 			     char *buf, __u64 probe_offset, __u64 probe_addr)
113 {
114 	printf("pid %d  fd %d: prog_id %u  ", pid, fd, prog_id);
115 	switch (fd_type) {
116 	case BPF_FD_TYPE_RAW_TRACEPOINT:
117 		printf("raw_tracepoint  %s\n", buf);
118 		break;
119 	case BPF_FD_TYPE_TRACEPOINT:
120 		printf("tracepoint  %s\n", buf);
121 		break;
122 	case BPF_FD_TYPE_KPROBE:
123 		if (buf[0] != '\0')
124 			printf("kprobe  func %s  offset %llu\n", buf,
125 			       probe_offset);
126 		else
127 			printf("kprobe  addr %llu\n", probe_addr);
128 		break;
129 	case BPF_FD_TYPE_KRETPROBE:
130 		if (buf[0] != '\0')
131 			printf("kretprobe  func %s  offset %llu\n", buf,
132 			       probe_offset);
133 		else
134 			printf("kretprobe  addr %llu\n", probe_addr);
135 		break;
136 	case BPF_FD_TYPE_UPROBE:
137 		printf("uprobe  filename %s  offset %llu\n", buf, probe_offset);
138 		break;
139 	case BPF_FD_TYPE_URETPROBE:
140 		printf("uretprobe  filename %s  offset %llu\n", buf,
141 		       probe_offset);
142 		break;
143 	}
144 }
145 
146 static int show_proc(const char *fpath, const struct stat *sb,
147 		     int tflag, struct FTW *ftwbuf)
148 {
149 	__u64 probe_offset, probe_addr;
150 	__u32 len, prog_id, fd_type;
151 	int err, pid = 0, fd = 0;
152 	const char *pch;
153 	char buf[4096];
154 
155 	/* prefix always /proc */
156 	pch = fpath + 5;
157 	if (*pch == '\0')
158 		return 0;
159 
160 	/* pid should be all numbers */
161 	pch++;
162 	while (isdigit(*pch)) {
163 		pid = pid * 10 + *pch - '0';
164 		pch++;
165 	}
166 	if (*pch == '\0')
167 		return 0;
168 	if (*pch != '/')
169 		return FTW_SKIP_SUBTREE;
170 
171 	/* check /proc/<pid>/fd directory */
172 	pch++;
173 	if (strncmp(pch, "fd", 2))
174 		return FTW_SKIP_SUBTREE;
175 	pch += 2;
176 	if (*pch == '\0')
177 		return 0;
178 	if (*pch != '/')
179 		return FTW_SKIP_SUBTREE;
180 
181 	/* check /proc/<pid>/fd/<fd_num> */
182 	pch++;
183 	while (isdigit(*pch)) {
184 		fd = fd * 10 + *pch - '0';
185 		pch++;
186 	}
187 	if (*pch != '\0')
188 		return FTW_SKIP_SUBTREE;
189 
190 	/* query (pid, fd) for potential perf events */
191 	len = sizeof(buf);
192 	err = bpf_task_fd_query(pid, fd, 0, buf, &len, &prog_id, &fd_type,
193 				&probe_offset, &probe_addr);
194 	if (err < 0)
195 		return 0;
196 
197 	if (json_output)
198 		print_perf_json(pid, fd, prog_id, fd_type, buf, probe_offset,
199 				probe_addr);
200 	else
201 		print_perf_plain(pid, fd, prog_id, fd_type, buf, probe_offset,
202 				 probe_addr);
203 
204 	return 0;
205 }
206 
207 static int do_show(int argc, char **argv)
208 {
209 	int flags = FTW_ACTIONRETVAL | FTW_PHYS;
210 	int err = 0, nopenfd = 16;
211 
212 	if (!has_perf_query_support())
213 		return -1;
214 
215 	if (json_output)
216 		jsonw_start_array(json_wtr);
217 	if (nftw("/proc", show_proc, nopenfd, flags) == -1) {
218 		p_err("%s", strerror(errno));
219 		err = -1;
220 	}
221 	if (json_output)
222 		jsonw_end_array(json_wtr);
223 
224 	return err;
225 }
226 
227 static int do_help(int argc, char **argv)
228 {
229 	fprintf(stderr,
230 		"Usage: %s %s { show | list | help }\n"
231 		"",
232 		bin_name, argv[-2]);
233 
234 	return 0;
235 }
236 
237 static const struct cmd cmds[] = {
238 	{ "show",	do_show },
239 	{ "list",	do_show },
240 	{ "help",	do_help },
241 	{ 0 }
242 };
243 
244 int do_perf(int argc, char **argv)
245 {
246 	return cmd_select(cmds, argc, argv, do_help);
247 }
248