tools/bpf/bpftool/perf.c

   1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
   2 // Copyright (C) 2018 Facebook
   3 // Author: Yonghong Song <[email protected]>
   4
   5 #ifndef _GNU_SOURCE
   6 #define _GNU_SOURCE
   7 #endif
   8 #include <ctype.h>
   9 #include <errno.h>
  10 #include <fcntl.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13 #include <sys/stat.h>
  14 #include <sys/types.h>
  15 #include <unistd.h>
  16 #include <dirent.h>
  17
  18 #include <bpf/bpf.h>
  19
  20 #include "main.h"
  21
  22 /* 0: undecided, 1: supported, 2: not supported */
  23 static int perf_query_supported;
  24 static bool has_perf_query_support(void)
  25 {
  26         __u64 probe_offset, probe_addr;
  27         __u32 len, prog_id, fd_type;
  28         char buf[256];
  29         int fd;
  30
  31         if (perf_query_supported)
  32                 goto out;
  33
  34         fd = open("/", O_RDONLY);
  35         if (fd < 0) {
  36                 p_err("perf_query_support: cannot open directory \"/\" (%s)",
  37                       strerror(errno));
  38                 goto out;
  39         }
  40
  41         /* the following query will fail as no bpf attachment,
  42          * the expected errno is ENOTSUPP
  43          */
  44         errno = 0;
  45         len = sizeof(buf);
  46         bpf_task_fd_query(getpid(), fd, 0, buf, &len, &prog_id,
  47                           &fd_type, &probe_offset, &probe_addr);
  48
  49         if (errno == 524 /* ENOTSUPP */) {
  50                 perf_query_supported = 1;
  51                 goto close_fd;
  52         }
  53
  54         perf_query_supported = 2;
  55         p_err("perf_query_support: %s", strerror(errno));
  56         fprintf(stderr,
  57                 "HINT: non root or kernel doesn't support TASK_FD_QUERY\n");
  58
  59 close_fd:
  60         close(fd);
  61 out:
  62         return perf_query_supported == 1;
  63 }
  64
  65 static void print_perf_json(int pid, int fd, __u32 prog_id, __u32 fd_type,
  66                             char *buf, __u64 probe_offset, __u64 probe_addr)
  67 {
  68         jsonw_start_object(json_wtr);
  69         jsonw_int_field(json_wtr, "pid", pid);
  70         jsonw_int_field(json_wtr, "fd", fd);
  71         jsonw_uint_field(json_wtr, "prog_id", prog_id);
  72         switch (fd_type) {
  73         case BPF_FD_TYPE_RAW_TRACEPOINT:
  74                 jsonw_string_field(json_wtr, "fd_type", "raw_tracepoint");
  75                 jsonw_string_field(json_wtr, "tracepoint", buf);
  76                 break;
  77         case BPF_FD_TYPE_TRACEPOINT:
  78                 jsonw_string_field(json_wtr, "fd_type", "tracepoint");
  79                 jsonw_string_field(json_wtr, "tracepoint", buf);
  80                 break;
  81         case BPF_FD_TYPE_KPROBE:
  82                 jsonw_string_field(json_wtr, "fd_type", "kprobe");
  83                 if (buf[0] != '\0') {
  84                         jsonw_string_field(json_wtr, "func", buf);
  85                         jsonw_lluint_field(json_wtr, "offset", probe_offset);
  86                 } else {
  87                         jsonw_lluint_field(json_wtr, "addr", probe_addr);
  88                 }
  89                 break;
  90         case BPF_FD_TYPE_KRETPROBE:
  91                 jsonw_string_field(json_wtr, "fd_type", "kretprobe");
  92                 if (buf[0] != '\0') {
  93                         jsonw_string_field(json_wtr, "func", buf);
  94                         jsonw_lluint_field(json_wtr, "offset", probe_offset);
  95                 } else {
  96                         jsonw_lluint_field(json_wtr, "addr", probe_addr);
  97                 }
  98                 break;
  99         case BPF_FD_TYPE_UPROBE:
 100                 jsonw_string_field(json_wtr, "fd_type", "uprobe");
 101                 jsonw_string_field(json_wtr, "filename", buf);
 102                 jsonw_lluint_field(json_wtr, "offset", probe_offset);
 103                 break;
 104         case BPF_FD_TYPE_URETPROBE:
 105                 jsonw_string_field(json_wtr, "fd_type", "uretprobe");
 106                 jsonw_string_field(json_wtr, "filename", buf);
 107                 jsonw_lluint_field(json_wtr, "offset", probe_offset);
 108                 break;
 109         default:
 110                 break;
 111         }
 112         jsonw_end_object(json_wtr);
 113 }
 114
 115 static void print_perf_plain(int pid, int fd, __u32 prog_id, __u32 fd_type,
 116                              char *buf, __u64 probe_offset, __u64 probe_addr)
 117 {
 118         printf("pid %d  fd %d: prog_id %u  ", pid, fd, prog_id);
 119         switch (fd_type) {
 120         case BPF_FD_TYPE_RAW_TRACEPOINT:
 121                 printf("raw_tracepoint  %s\n", buf);
 122                 break;
 123         case BPF_FD_TYPE_TRACEPOINT:
 124                 printf("tracepoint  %s\n", buf);
 125                 break;
 126         case BPF_FD_TYPE_KPROBE:
 127                 if (buf[0] != '\0')
 128                         printf("kprobe  func %s  offset %llu\n", buf,
 129                                probe_offset);
 130                 else
 131                         printf("kprobe  addr %llu\n", probe_addr);
 132                 break;
 133         case BPF_FD_TYPE_KRETPROBE:
 134                 if (buf[0] != '\0')
 135                         printf("kretprobe  func %s  offset %llu\n", buf,
 136                                probe_offset);
 137                 else
 138                         printf("kretprobe  addr %llu\n", probe_addr);
 139                 break;
 140         case BPF_FD_TYPE_UPROBE:
 141                 printf("uprobe  filename %s  offset %llu\n", buf, probe_offset);
 142                 break;
 143         case BPF_FD_TYPE_URETPROBE:
 144                 printf("uretprobe  filename %s  offset %llu\n", buf,
 145                        probe_offset);
 146                 break;
 147         default:
 148                 break;
 149         }
 150 }
 151
 152 static int show_proc(void)
 153 {
 154         struct dirent *proc_de, *pid_fd_de;
 155         __u64 probe_offset, probe_addr;
 156         __u32 len, prog_id, fd_type;
 157         DIR *proc, *pid_fd;
 158         int err, pid, fd;
 159         const char *pch;
 160         char buf[4096];
 161
 162         proc = opendir("/proc");
 163         if (!proc)
 164                 return -1;
 165
 166         while ((proc_de = readdir(proc))) {
 167                 pid = 0;
 168                 pch = proc_de->d_name;
 169
 170                 /* pid should be all numbers */
 171                 while (isdigit(*pch)) {
 172                         pid = pid * 10 + *pch - '0';
 173                         pch++;
 174                 }
 175                 if (*pch != '\0')
 176                         continue;
 177
 178                 err = snprintf(buf, sizeof(buf), "/proc/%s/fd", proc_de->d_name);
 179                 if (err < 0 || err >= (int)sizeof(buf))
 180                         continue;
 181
 182                 pid_fd = opendir(buf);
 183                 if (!pid_fd)
 184                         continue;
 185
 186                 while ((pid_fd_de = readdir(pid_fd))) {
 187                         fd = 0;
 188                         pch = pid_fd_de->d_name;
 189
 190                         /* fd should be all numbers */
 191                         while (isdigit(*pch)) {
 192                                 fd = fd * 10 + *pch - '0';
 193                                 pch++;
 194                         }
 195                         if (*pch != '\0')
 196                                 continue;
 197
 198                         /* query (pid, fd) for potential perf events */
 199                         len = sizeof(buf);
 200                         err = bpf_task_fd_query(pid, fd, 0, buf, &len,
 201                                                 &prog_id, &fd_type,
 202                                                 &probe_offset, &probe_addr);
 203                         if (err < 0)
 204                                 continue;
 205
 206                         if (json_output)
 207                                 print_perf_json(pid, fd, prog_id, fd_type, buf,
 208                                                 probe_offset, probe_addr);
 209                         else
 210                                 print_perf_plain(pid, fd, prog_id, fd_type, buf,
 211                                                  probe_offset, probe_addr);
 212                 }
 213                 closedir(pid_fd);
 214         }
 215         closedir(proc);
 216         return 0;
 217 }
 218
 219 static int do_show(int argc, char **argv)
 220 {
 221         int err;
 222
 223         if (!has_perf_query_support())
 224                 return -1;
 225
 226         if (json_output)
 227                 jsonw_start_array(json_wtr);
 228         err = show_proc();
 229         if (json_output)
 230                 jsonw_end_array(json_wtr);
 231
 232         return err;
 233 }
 234
 235 static int do_help(int argc, char **argv)
 236 {
 237         fprintf(stderr,
 238                 "Usage: %1$s %2$s { show | list }\n"
 239                 "       %1$s %2$s help }\n"
 240                 "\n"
 241                 "       " HELP_SPEC_OPTIONS " }\n"
 242                 "",
 243                 bin_name, argv[-2]);
 244
 245         return 0;
 246 }
 247
 248 static const struct cmd cmds[] = {
 249         { "show",       do_show },
 250         { "list",       do_show },
 251         { "help",       do_help },
 252         { 0 }
 253 };
 254
 255 int do_perf(int argc, char **argv)
 256 {
 257         return cmd_select(cmds, argc, argv, do_help);
 258 }