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/event.h"
  39 #include "util/debug.h"
  40 #include "util/parse-options.h"
  41 #include "util/parse-events.h"  /* For debugfs_path */
  42 #include "util/probe-finder.h"
  43
  44 /* Default vmlinux search paths */
  45 #define NR_SEARCH_PATH 3
  46 const char *default_search_path[NR_SEARCH_PATH] = {
  47 "/lib/modules/%s/build/vmlinux",                /* Custom build kernel */
  48 "/usr/lib/debug/lib/modules/%s/vmlinux",        /* Red Hat debuginfo */
  49 "/boot/vmlinux-debug-%s",                       /* Ubuntu */
  50 };
  51
  52 #define MAX_PATH_LEN 256
  53 #define MAX_PROBES 128
  54 #define MAX_PROBE_ARGS 128
  55
  56 /* Session management structure */
  57 static struct {
  58         char *vmlinux;
  59         char *release;
  60         int need_dwarf;
  61         int nr_probe;
  62         struct probe_point probes[MAX_PROBES];
  63         char *events[MAX_PROBES];
  64 } session;
  65
  66 #define semantic_error(msg ...) die("Semantic error :" msg)
  67
  68 /* Parse a probe point. Note that any error must die. */
  69 static void parse_probepoint(const char *str)
  70 {
  71         char *argv[MAX_PROBE_ARGS + 2]; /* Event + probe + args */
  72         int argc, i;
  73         char *arg, *ptr;
  74         struct probe_point *pp = &session.probes[session.nr_probe];
  75         char **event = &session.events[session.nr_probe];
  76         int retp = 0;
  77
  78         pr_debug("probe-definition(%d): %s\n", session.nr_probe, str);
  79         if (++session.nr_probe == MAX_PROBES)
  80                 semantic_error("Too many probes");
  81
  82         /* Separate arguments, similar to argv_split */
  83         argc = 0;
  84         do {
  85                 /* Skip separators */
  86                 while (isspace(*str))
  87                         str++;
  88
  89                 /* Add an argument */
  90                 if (*str != '\0') {
  91                         const char *s = str;
  92
  93                         /* Skip the argument */
  94                         while (!isspace(*str) && *str != '\0')
  95                                 str++;
  96
  97                         /* Duplicate the argument */
  98                         argv[argc] = strndup(s, str - s);
  99                         if (argv[argc] == NULL)
 100                                 die("strndup");
 101                         if (++argc == MAX_PROBE_ARGS)
 102                                 semantic_error("Too many arguments");
 103                         pr_debug("argv[%d]=%s\n", argc, argv[argc - 1]);
 104                 }
 105         } while (*str != '\0');
 106         if (argc < 2)
 107                 semantic_error("Need event-name and probe-point at least.");
 108
 109         /* Parse the event name */
 110         if (argv[0][0] == 'r')
 111                 retp = 1;
 112         else if (argv[0][0] != 'p')
 113                 semantic_error("You must specify 'p'(kprobe) or"
 114                                 " 'r'(kretprobe) first.");
 115         /* TODO: check event name */
 116         *event = argv[0];
 117
 118         /* Parse probe point */
 119         arg = argv[1];
 120         if (arg[0] == '@') {
 121                 /* Source Line */
 122                 arg++;
 123                 ptr = strchr(arg, ':');
 124                 if (!ptr || !isdigit(ptr[1]))
 125                         semantic_error("Line number is required.");
 126                 *ptr++ = '\0';
 127                 if (strlen(arg) == 0)
 128                         semantic_error("No file name.");
 129                 pp->file = strdup(arg);
 130                 pp->line = atoi(ptr);
 131                 if (!pp->file || !pp->line)
 132                         semantic_error("Failed to parse line.");
 133                 pr_debug("file:%s line:%d\n", pp->file, pp->line);
 134         } else {
 135                 /* Function name */
 136                 ptr = strchr(arg, '+');
 137                 if (ptr) {
 138                         if (!isdigit(ptr[1]))
 139                                 semantic_error("Offset is required.");
 140                         *ptr++ = '\0';
 141                         pp->offset = atoi(ptr);
 142                 } else
 143                         ptr = arg;
 144                 ptr = strchr(ptr, '@');
 145                 if (ptr) {
 146                         *ptr++ = '\0';
 147                         pp->file = strdup(ptr);
 148                 }
 149                 pp->function = strdup(arg);
 150                 pr_debug("symbol:%s file:%s offset:%d\n",
 151                          pp->function, pp->file, pp->offset);
 152         }
 153         free(argv[1]);
 154         if (pp->file)
 155                 session.need_dwarf = 1;
 156
 157         /* Copy arguments */
 158         pp->nr_args = argc - 2;
 159         if (pp->nr_args > 0) {
 160                 pp->args = (char **)malloc(sizeof(char *) * pp->nr_args);
 161                 if (!pp->args)
 162                         die("malloc");
 163                 memcpy(pp->args, &argv[2], sizeof(char *) * pp->nr_args);
 164         }
 165
 166         /* Ensure return probe has no C argument */
 167         for (i = 0; i < pp->nr_args; i++)
 168                 if (is_c_varname(pp->args[i])) {
 169                         if (retp)
 170                                 semantic_error("You can't specify local"
 171                                                 " variable for kretprobe");
 172                         session.need_dwarf = 1;
 173                 }
 174
 175         pr_debug("%d arguments\n", pp->nr_args);
 176 }
 177
 178 static int opt_add_probepoint(const struct option *opt __used,
 179                               const char *str, int unset __used)
 180 {
 181         if (str)
 182                 parse_probepoint(str);
 183         return 0;
 184 }
 185
 186 #ifndef NO_LIBDWARF
 187 static int open_default_vmlinux(void)
 188 {
 189         struct utsname uts;
 190         char fname[MAX_PATH_LEN];
 191         int fd, ret, i;
 192
 193         ret = uname(&uts);
 194         if (ret) {
 195                 pr_debug("uname() failed.\n");
 196                 return -errno;
 197         }
 198         session.release = uts.release;
 199         for (i = 0; i < NR_SEARCH_PATH; i++) {
 200                 ret = snprintf(fname, MAX_PATH_LEN,
 201                                default_search_path[i], session.release);
 202                 if (ret >= MAX_PATH_LEN || ret < 0) {
 203                         pr_debug("Filename(%d,%s) is too long.\n", i,
 204                                 uts.release);
 205                         errno = E2BIG;
 206                         return -E2BIG;
 207                 }
 208                 pr_debug("try to open %s\n", fname);
 209                 fd = open(fname, O_RDONLY);
 210                 if (fd >= 0)
 211                         break;
 212         }
 213         return fd;
 214 }
 215 #endif
 216
 217 static const char * const probe_usage[] = {
 218         "perf probe [<options>] 'PROBEDEF' ['PROBEDEF' ...]",
 219         "perf probe [<options>] --add 'PROBEDEF' [--add 'PROBEDEF' ...]",
 220         NULL
 221 };
 222
 223 static const struct option options[] = {
 224         OPT_BOOLEAN('v', "verbose", &verbose,
 225                     "be more verbose (show parsed arguments, etc)"),
 226 #ifndef NO_LIBDWARF
 227         OPT_STRING('k', "vmlinux", &session.vmlinux, "file",
 228                 "vmlinux/module pathname"),
 229 #endif
 230         OPT_CALLBACK('a', "add", NULL,
 231 #ifdef NO_LIBDWARF
 232                 "p|r:[GRP/]NAME FUNC[+OFFS] [ARG ...]",
 233 #else
 234                 "p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]",
 235 #endif
 236                 "probe point definition, where\n"
 237                 "\t\tp:\tkprobe probe\n"
 238                 "\t\tr:\tkretprobe probe\n"
 239                 "\t\tGRP:\tGroup name (optional)\n"
 240                 "\t\tNAME:\tEvent name\n"
 241                 "\t\tFUNC:\tFunction name\n"
 242                 "\t\tOFFS:\tOffset from function entry (in byte)\n"
 243 #ifdef NO_LIBDWARF
 244                 "\t\tARG:\tProbe argument (only \n"
 245 #else
 246                 "\t\tSRC:\tSource code path\n"
 247                 "\t\tLINE:\tLine number\n"
 248                 "\t\tARG:\tProbe argument (local variable name or\n"
 249 #endif
 250                 "\t\t\tkprobe-tracer argument format is supported.)\n",
 251                 opt_add_probepoint),
 252         OPT_END()
 253 };
 254
 255 static int write_new_event(int fd, const char *buf)
 256 {
 257         int ret;
 258
 259         printf("Adding new event: %s\n", buf);
 260         ret = write(fd, buf, strlen(buf));
 261         if (ret <= 0)
 262                 die("failed to create event.");
 263
 264         return ret;
 265 }
 266
 267 #define MAX_CMDLEN 256
 268
 269 static int synthesize_probepoint(struct probe_point *pp)
 270 {
 271         char *buf;
 272         int i, len, ret;
 273         pp->probes[0] = buf = (char *)calloc(MAX_CMDLEN, sizeof(char));
 274         if (!buf)
 275                 die("calloc");
 276         ret = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
 277         if (ret <= 0 || ret >= MAX_CMDLEN)
 278                 goto error;
 279         len = ret;
 280
 281         for (i = 0; i < pp->nr_args; i++) {
 282                 ret = snprintf(&buf[len], MAX_CMDLEN - len, " %s",
 283                                pp->args[i]);
 284                 if (ret <= 0 || ret >= MAX_CMDLEN - len)
 285                         goto error;
 286                 len += ret;
 287         }
 288         pp->found = 1;
 289         return pp->found;
 290 error:
 291         free(pp->probes[0]);
 292         if (ret > 0)
 293                 ret = -E2BIG;
 294         return ret;
 295 }
 296
 297 int cmd_probe(int argc, const char **argv, const char *prefix __used)
 298 {
 299         int i, j, fd, ret;
 300         struct probe_point *pp;
 301         char buf[MAX_CMDLEN];
 302
 303         argc = parse_options(argc, argv, options, probe_usage,
 304                              PARSE_OPT_STOP_AT_NON_OPTION);
 305         for (i = 0; i < argc; i++)
 306                 parse_probe_event(argv[i]);
 307
 308         if (session.nr_probe == 0)
 309                 usage_with_options(probe_usage, options);
 310
 311 #ifdef NO_LIBDWARF
 312         if (session.need_dwarf)
 313                 semantic_error("Dwarf-analysis is not supported");
 314 #endif
 315
 316         /* Synthesize probes without dwarf */
 317         for (j = 0; j < session.nr_probe; j++) {
 318 #ifndef NO_LIBDWARF
 319                 if (session.events[j][0] != 'r') {
 320                         session.need_dwarf = 1;
 321                         continue;
 322                 }
 323 #endif
 324                 ret = synthesize_probepoint(&session.probes[j]);
 325                 if (ret == -E2BIG)
 326                         semantic_error("probe point is too long.");
 327                 else if (ret < 0)
 328                         die("snprintf");
 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                 die("vmlinux/module file open");
 341
 342         /* Searching probe points */
 343         for (j = 0; j < session.nr_probe; j++) {
 344                 pp = &session.probes[j];
 345                 if (pp->found)
 346                         continue;
 347
 348                 lseek(fd, SEEK_SET, 0);
 349                 ret = find_probepoint(fd, pp);
 350                 if (ret <= 0)
 351                         die("No probe point found.\n");
 352                 pr_debug("probe event %s found\n", session.events[j]);
 353         }
 354         close(fd);
 355
 356 setup_probes:
 357 #endif /* !NO_LIBDWARF */
 358
 359         /* Settng up probe points */
 360         snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
 361         fd = open(buf, O_WRONLY, O_APPEND);
 362         if (fd < 0)
 363                 die("kprobe_events open");
 364         for (j = 0; j < session.nr_probe; j++) {
 365                 pp = &session.probes[j];
 366                 if (pp->found == 1) {
 367                         snprintf(buf, MAX_CMDLEN, "%s %s\n",
 368                                 session.events[j], pp->probes[0]);
 369                         write_new_event(fd, buf);
 370                 } else
 371                         for (i = 0; i < pp->found; i++) {
 372                                 snprintf(buf, MAX_CMDLEN, "%s%d %s\n",
 373                                         session.events[j], i, pp->probes[i]);
 374                                 write_new_event(fd, buf);
 375                         }
 376         }
 377         close(fd);
 378         return 0;
 379 }
 380