tools/perf/builtin-probe.c

   1 /*
   2  * builtin-probe.c
   3  *
   4  * Builtin probe command: Set up probe events by C expression
   5  *
   6  * Written by Masami Hiramatsu <mhiramat@redhat.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  21  *
  22  */
  23 #define _GNU_SOURCE
  24 #include <sys/utsname.h>
  25 #include <sys/types.h>
  26 #include <sys/stat.h>
  27 #include <fcntl.h>
  28 #include <errno.h>
  29 #include <stdio.h>
  30 #include <unistd.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33
  34 #undef _GNU_SOURCE
  35 #include "perf.h"
  36 #include "builtin.h"
  37 #include "util/util.h"
  38 #include "util/parse-options.h"
  39 #include "util/parse-events.h"  /* For debugfs_path */
  40 #include "util/probe-finder.h"
  41
  42 /* Default vmlinux search paths */
  43 #define NR_SEARCH_PATH 3
  44 const char *default_search_path[NR_SEARCH_PATH] = {
  45 "/lib/modules/%s/build/vmlinux",                /* Custom build kernel */
  46 "/usr/lib/debug/lib/modules/%s/vmlinux",        /* Red Hat debuginfo */
  47 "/boot/vmlinux-debug-%s",                       /* Ubuntu */
  48 };
  49
  50 #define MAX_PATH_LEN 256
  51 #define MAX_PROBES 128
  52
  53 /* Session management structure */
  54 static struct {
  55         char *vmlinux;
  56         char *release;
  57         int need_dwarf;
  58         int nr_probe;
  59         struct probe_point probes[MAX_PROBES];
  60         char *events[MAX_PROBES];
  61 } session;
  62
  63 static void semantic_error(const char *msg)
  64 {
  65         fprintf(stderr, "Semantic error: %s\n", msg);
  66         exit(1);
  67 }
  68
  69 static void perror_exit(const char *msg)
  70 {
  71         perror(msg);
  72         exit(1);
  73 }
  74
  75 #define MAX_PROBE_ARGS 128
  76
  77 static int parse_probepoint(const struct option *opt __used,
  78                             const char *str, int unset __used)
  79 {
  80         char *argv[MAX_PROBE_ARGS + 2]; /* Event + probe + args */
  81         int argc, i;
  82         char *arg, *ptr;
  83         struct probe_point *pp = &session.probes[session.nr_probe];
  84         char **event = &session.events[session.nr_probe];
  85         int retp = 0;
  86
  87         if (!str)       /* The end of probe points */
  88                 return 0;
  89
  90         debug("Probe-define(%d): %s\n", session.nr_probe, str);
  91         if (++session.nr_probe == MAX_PROBES)
  92                 semantic_error("Too many probes");
  93
  94         /* Separate arguments, similar to argv_split */
  95         argc = 0;
  96         do {
  97                 /* Skip separators */
  98                 while (isspace(*str))
  99                         str++;
 100
 101                 /* Add an argument */
 102                 if (*str != '\0') {
 103                         const char *s = str;
 104
 105                         /* Skip the argument */
 106                         while (!isspace(*str) && *str != '\0')
 107                                 str++;
 108
 109                         /* Duplicate the argument */
 110                         argv[argc] = strndup(s, str - s);
 111                         if (argv[argc] == NULL)
 112                                 perror_exit("strndup");
 113                         if (++argc == MAX_PROBE_ARGS)
 114                                 semantic_error("Too many arguments");
 115                         debug("argv[%d]=%s\n", argc, argv[argc - 1]);
 116                 }
 117         } while (*str != '\0');
 118         if (argc < 2)
 119                 semantic_error("Need event-name and probe-point at least.");
 120
 121         /* Parse the event name */
 122         if (argv[0][0] == 'r')
 123                 retp = 1;
 124         else if (argv[0][0] != 'p')
 125                 semantic_error("You must specify 'p'(kprobe) or"
 126                                 " 'r'(kretprobe) first.");
 127         /* TODO: check event name */
 128         *event = argv[0];
 129
 130         /* Parse probe point */
 131         arg = argv[1];
 132         if (arg[0] == '@') {
 133                 /* Source Line */
 134                 arg++;
 135                 ptr = strchr(arg, ':');
 136                 if (!ptr || !isdigit(ptr[1]))
 137                         semantic_error("Line number is required.");
 138                 *ptr++ = '\0';
 139                 if (strlen(arg) == 0)
 140                         semantic_error("No file name.");
 141                 pp->file = strdup(arg);
 142                 pp->line = atoi(ptr);
 143                 if (!pp->file || !pp->line)
 144                         semantic_error("Failed to parse line.");
 145                 debug("file:%s line:%d\n", pp->file, pp->line);
 146         } else {
 147                 /* Function name */
 148                 ptr = strchr(arg, '+');
 149                 if (ptr) {
 150                         if (!isdigit(ptr[1]))
 151                                 semantic_error("Offset is required.");
 152                         *ptr++ = '\0';
 153                         pp->offset = atoi(ptr);
 154                 } else
 155                         ptr = arg;
 156                 ptr = strchr(ptr, '@');
 157                 if (ptr) {
 158                         *ptr++ = '\0';
 159                         pp->file = strdup(ptr);
 160                 }
 161                 pp->function = strdup(arg);
 162                 debug("symbol:%s file:%s offset:%d\n",
 163                       pp->function, pp->file, pp->offset);
 164         }
 165         free(argv[1]);
 166         if (pp->file)
 167                 session.need_dwarf = 1;
 168
 169         /* Copy arguments */
 170         pp->nr_args = argc - 2;
 171         if (pp->nr_args > 0) {
 172                 pp->args = (char **)malloc(sizeof(char *) * pp->nr_args);
 173                 if (!pp->args)
 174                         perror_exit("malloc");
 175                 memcpy(pp->args, &argv[2], sizeof(char *) * pp->nr_args);
 176         }
 177
 178         /* Ensure return probe has no C argument */
 179         for (i = 0; i < pp->nr_args; i++)
 180                 if (is_c_varname(pp->args[i])) {
 181                         if (retp)
 182                                 semantic_error("You can't specify local"
 183                                                 " variable for kretprobe");
 184                         session.need_dwarf = 1;
 185                 }
 186
 187         debug("%d arguments\n", pp->nr_args);
 188         return 0;
 189 }
 190
 191 #ifndef NO_LIBDWARF
 192 static int open_default_vmlinux(void)
 193 {
 194         struct utsname uts;
 195         char fname[MAX_PATH_LEN];
 196         int fd, ret, i;
 197
 198         ret = uname(&uts);
 199         if (ret) {
 200                 debug("uname() failed.\n");
 201                 return -errno;
 202         }
 203         session.release = uts.release;
 204         for (i = 0; i < NR_SEARCH_PATH; i++) {
 205                 ret = snprintf(fname, MAX_PATH_LEN,
 206                                default_search_path[i], session.release);
 207                 if (ret >= MAX_PATH_LEN || ret < 0) {
 208                         debug("Filename(%d,%s) is too long.\n", i, uts.release);
 209                         errno = E2BIG;
 210                         return -E2BIG;
 211                 }
 212                 debug("try to open %s\n", fname);
 213                 fd = open(fname, O_RDONLY);
 214                 if (fd >= 0)
 215                         break;
 216         }
 217         return fd;
 218 }
 219 #endif
 220
 221 static const char * const probe_usage[] = {
 222         "perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]",
 223         NULL
 224 };
 225
 226 static const struct option options[] = {
 227 #ifndef NO_LIBDWARF
 228         OPT_STRING('k', "vmlinux", &session.vmlinux, "file",
 229                 "vmlinux/module pathname"),
 230 #endif
 231         OPT_CALLBACK('P', "probe", NULL,
 232 #ifdef NO_LIBDWARF
 233                 "p|r:[GRP/]NAME FUNC[+OFFS] [ARG ...]",
 234 #else
 235                 "p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]",
 236 #endif
 237                 "probe point definition, where\n"
 238                 "\t\tp:\tkprobe probe\n"
 239                 "\t\tr:\tkretprobe probe\n"
 240                 "\t\tGRP:\tGroup name (optional)\n"
 241                 "\t\tNAME:\tEvent name\n"
 242                 "\t\tFUNC:\tFunction name\n"
 243                 "\t\tOFFS:\tOffset from function entry (in byte)\n"
 244 #ifdef NO_LIBDWARF
 245                 "\t\tARG:\tProbe argument (only \n"
 246 #else
 247                 "\t\tSRC:\tSource code path\n"
 248                 "\t\tLINE:\tLine number\n"
 249                 "\t\tARG:\tProbe argument (local variable name or\n"
 250 #endif
 251                 "\t\t\tkprobe-tracer argument format is supported.)\n",
 252                 parse_probepoint),
 253         OPT_END()
 254 };
 255
 256 static int write_new_event(int fd, const char *buf)
 257 {
 258         int ret;
 259
 260         printf("Adding new event: %s\n", buf);
 261         ret = write(fd, buf, strlen(buf));
 262         if (ret <= 0)
 263                 perror("Error: Failed to create event");
 264
 265         return ret;
 266 }
 267
 268 #define MAX_CMDLEN 256
 269
 270 static int synthesize_probepoint(struct probe_point *pp)
 271 {
 272         char *buf;
 273         int i, len, ret;
 274         pp->probes[0] = buf = (char *)calloc(MAX_CMDLEN, sizeof(char));
 275         if (!buf)
 276                 perror_exit("calloc");
 277         ret = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
 278         if (ret <= 0 || ret >= MAX_CMDLEN)
 279                 goto error;
 280         len = ret;
 281
 282         for (i = 0; i < pp->nr_args; i++) {
 283                 ret = snprintf(&buf[len], MAX_CMDLEN - len, " %s",
 284                                pp->args[i]);
 285                 if (ret <= 0 || ret >= MAX_CMDLEN - len)
 286                         goto error;
 287                 len += ret;
 288         }
 289         pp->found = 1;
 290         return pp->found;
 291 error:
 292         free(pp->probes[0]);
 293         if (ret > 0)
 294                 ret = -E2BIG;
 295         return ret;
 296 }
 297
 298 int cmd_probe(int argc, const char **argv, const char *prefix __used)
 299 {
 300         int i, j, fd, ret;
 301         struct probe_point *pp;
 302         char buf[MAX_CMDLEN];
 303
 304         argc = parse_options(argc, argv, options, probe_usage,
 305                 PARSE_OPT_STOP_AT_NON_OPTION);
 306         if (argc || session.nr_probe == 0)
 307                 usage_with_options(probe_usage, options);
 308
 309 #ifdef NO_LIBDWARF
 310         if (session.need_dwarf)
 311                 semantic_error("Dwarf-analysis is not supported");
 312 #endif
 313
 314         /* Synthesize probes without dwarf */
 315         for (j = 0; j < session.nr_probe; j++) {
 316 #ifndef NO_LIBDWARF
 317                 if (session.events[j][0] != 'r') {
 318                         session.need_dwarf = 1;
 319                         continue;
 320                 }
 321 #endif
 322                 ret = synthesize_probepoint(&session.probes[j]);
 323                 if (ret == -E2BIG)
 324                         semantic_error("probe point is too long.");
 325                 else if (ret < 0) {
 326                         perror("snprintf");
 327                         return -1;
 328                 }
 329         }
 330
 331 #ifndef NO_LIBDWARF
 332         if (!session.need_dwarf)
 333                 goto setup_probes;
 334
 335         if (session.vmlinux)
 336                 fd = open(session.vmlinux, O_RDONLY);
 337         else
 338                 fd = open_default_vmlinux();
 339         if (fd < 0) {
 340                 perror("vmlinux/module file open");
 341                 return -1;
 342         }
 343
 344         /* Searching probe points */
 345         for (j = 0; j < session.nr_probe; j++) {
 346                 pp = &session.probes[j];
 347                 if (pp->found)
 348                         continue;
 349
 350                 lseek(fd, SEEK_SET, 0);
 351                 ret = find_probepoint(fd, pp);
 352                 if (ret <= 0) {
 353                         fprintf(stderr, "Error: No probe point found.\n");
 354                         return -1;
 355                 }
 356                 debug("probe event %s found\n", session.events[j]);
 357         }
 358         close(fd);
 359
 360 setup_probes:
 361 #endif /* !NO_LIBDWARF */
 362
 363         /* Settng up probe points */
 364         snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
 365         fd = open(buf, O_WRONLY, O_APPEND);
 366         if (fd < 0) {
 367                 perror("kprobe_events open");
 368                 return -1;
 369         }
 370         for (j = 0; j < session.nr_probe; j++) {
 371                 pp = &session.probes[j];
 372                 if (pp->found == 1) {
 373                         snprintf(buf, MAX_CMDLEN, "%s %s\n",
 374                                 session.events[j], pp->probes[0]);
 375                         write_new_event(fd, buf);
 376                 } else
 377                         for (i = 0; i < pp->found; i++) {
 378                                 snprintf(buf, MAX_CMDLEN, "%s%d %s\n",
 379                                         session.events[j], i, pp->probes[i]);
 380                                 write_new_event(fd, buf);
 381                         }
 382         }
 383         close(fd);
 384         return 0;
 385 }
 386