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   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 #define PERFPROBE_GROUP "perfprobe"
  56
  57 /* Session management structure */
  58 static struct {
  59         char *vmlinux;
  60         char *release;
  61         int need_dwarf;
  62         int nr_probe;
  63         struct probe_point probes[MAX_PROBES];
  64 } session;
  65
  66 #define semantic_error(msg ...) die("Semantic error :" msg)
  67
  68 /* Parse probe point. Return 1 if return probe */
  69 static void parse_probe_point(char *arg, struct probe_point *pp)
  70 {
  71         char *ptr, *tmp;
  72         char c, nc;
  73         /*
  74          * <Syntax>
  75          * perf probe SRC:LN
  76          * perf probe FUNC[+OFFS|%return][@SRC]
  77          */
  78
  79         ptr = strpbrk(arg, ":+@%");
  80         if (ptr) {
  81                 nc = *ptr;
  82                 *ptr++ = '\0';
  83         }
  84
  85         /* Check arg is function or file and copy it */
  86         if (strchr(arg, '.'))   /* File */
  87                 pp->file = strdup(arg);
  88         else                    /* Function */
  89                 pp->function = strdup(arg);
  90         DIE_IF(pp->file == NULL && pp->function == NULL);
  91
  92         /* Parse other options */
  93         while (ptr) {
  94                 arg = ptr;
  95                 c = nc;
  96                 ptr = strpbrk(arg, ":+@%");
  97                 if (ptr) {
  98                         nc = *ptr;
  99                         *ptr++ = '\0';
 100                 }
 101                 switch (c) {
 102                 case ':':       /* Line number */
 103                         pp->line = strtoul(arg, &tmp, 0);
 104                         if (*tmp != '\0')
 105                                 semantic_error("There is non-digit charactor"
 106                                                 " in line number.");
 107                         break;
 108                 case '+':       /* Byte offset from a symbol */
 109                         pp->offset = strtoul(arg, &tmp, 0);
 110                         if (*tmp != '\0')
 111                                 semantic_error("There is non-digit charactor"
 112                                                 " in offset.");
 113                         break;
 114                 case '@':       /* File name */
 115                         if (pp->file)
 116                                 semantic_error("SRC@SRC is not allowed.");
 117                         pp->file = strdup(arg);
 118                         DIE_IF(pp->file == NULL);
 119                         if (ptr)
 120                                 semantic_error("@SRC must be the last "
 121                                                "option.");
 122                         break;
 123                 case '%':       /* Probe places */
 124                         if (strcmp(arg, "return") == 0) {
 125                                 pp->retprobe = 1;
 126                         } else  /* Others not supported yet */
 127                                 semantic_error("%%%s is not supported.", arg);
 128                         break;
 129                 default:
 130                         DIE_IF("Program has a bug.");
 131                         break;
 132                 }
 133         }
 134
 135         /* Exclusion check */
 136         if (pp->line && pp->function)
 137                 semantic_error("Function-relative line number is not"
 138                                 " supported yet.");
 139         if (!pp->line && pp->file && !pp->function)
 140                 semantic_error("File always requires line number.");
 141         if (pp->offset && !pp->function)
 142                 semantic_error("Offset requires an entry function.");
 143         if (pp->retprobe && !pp->function)
 144                 semantic_error("Return probe requires an entry function.");
 145         if (pp->offset && pp->retprobe)
 146                 semantic_error("Offset can't be used with return probe.");
 147
 148         pr_debug("symbol:%s file:%s line:%d offset:%d, return:%d\n",
 149                  pp->function, pp->file, pp->line, pp->offset, pp->retprobe);
 150 }
 151
 152 /* Parse an event definition. Note that any error must die. */
 153 static void parse_probe_event(const char *str)
 154 {
 155         char *argv[MAX_PROBE_ARGS + 2]; /* Event + probe + args */
 156         int argc, i;
 157         struct probe_point *pp = &session.probes[session.nr_probe];
 158
 159         pr_debug("probe-definition(%d): %s\n", session.nr_probe, str);
 160         if (++session.nr_probe == MAX_PROBES)
 161                 semantic_error("Too many probes");
 162
 163         /* Separate arguments, similar to argv_split */
 164         argc = 0;
 165         do {
 166                 /* Skip separators */
 167                 while (isspace(*str))
 168                         str++;
 169
 170                 /* Add an argument */
 171                 if (*str != '\0') {
 172                         const char *s = str;
 173
 174                         /* Skip the argument */
 175                         while (!isspace(*str) && *str != '\0')
 176                                 str++;
 177
 178                         /* Duplicate the argument */
 179                         argv[argc] = strndup(s, str - s);
 180                         if (argv[argc] == NULL)
 181                                 die("strndup");
 182                         if (++argc == MAX_PROBE_ARGS)
 183                                 semantic_error("Too many arguments");
 184                         pr_debug("argv[%d]=%s\n", argc, argv[argc - 1]);
 185                 }
 186         } while (*str != '\0');
 187         if (!argc)
 188                 semantic_error("An empty argument.");
 189
 190         /* Parse probe point */
 191         parse_probe_point(argv[0], pp);
 192         free(argv[0]);
 193         if (pp->file)
 194                 session.need_dwarf = 1;
 195
 196         /* Copy arguments */
 197         pp->nr_args = argc - 1;
 198         if (pp->nr_args > 0) {
 199                 pp->args = (char **)malloc(sizeof(char *) * pp->nr_args);
 200                 if (!pp->args)
 201                         die("malloc");
 202                 memcpy(pp->args, &argv[1], sizeof(char *) * pp->nr_args);
 203         }
 204
 205         /* Ensure return probe has no C argument */
 206         for (i = 0; i < pp->nr_args; i++)
 207                 if (is_c_varname(pp->args[i])) {
 208                         if (pp->retprobe)
 209                                 semantic_error("You can't specify local"
 210                                                 " variable for kretprobe");
 211                         session.need_dwarf = 1;
 212                 }
 213
 214         pr_debug("%d arguments\n", pp->nr_args);
 215 }
 216
 217 static int opt_add_probe_event(const struct option *opt __used,
 218                               const char *str, int unset __used)
 219 {
 220         if (str)
 221                 parse_probe_event(str);
 222         return 0;
 223 }
 224
 225 #ifndef NO_LIBDWARF
 226 static int open_default_vmlinux(void)
 227 {
 228         struct utsname uts;
 229         char fname[MAX_PATH_LEN];
 230         int fd, ret, i;
 231
 232         ret = uname(&uts);
 233         if (ret) {
 234                 pr_debug("uname() failed.\n");
 235                 return -errno;
 236         }
 237         session.release = uts.release;
 238         for (i = 0; i < NR_SEARCH_PATH; i++) {
 239                 ret = snprintf(fname, MAX_PATH_LEN,
 240                                default_search_path[i], session.release);
 241                 if (ret >= MAX_PATH_LEN || ret < 0) {
 242                         pr_debug("Filename(%d,%s) is too long.\n", i,
 243                                 uts.release);
 244                         errno = E2BIG;
 245                         return -E2BIG;
 246                 }
 247                 pr_debug("try to open %s\n", fname);
 248                 fd = open(fname, O_RDONLY);
 249                 if (fd >= 0)
 250                         break;
 251         }
 252         return fd;
 253 }
 254 #endif
 255
 256 static const char * const probe_usage[] = {
 257         "perf probe [<options>] 'PROBEDEF' ['PROBEDEF' ...]",
 258         "perf probe [<options>] --add 'PROBEDEF' [--add 'PROBEDEF' ...]",
 259         NULL
 260 };
 261
 262 static const struct option options[] = {
 263         OPT_BOOLEAN('v', "verbose", &verbose,
 264                     "be more verbose (show parsed arguments, etc)"),
 265 #ifndef NO_LIBDWARF
 266         OPT_STRING('k', "vmlinux", &session.vmlinux, "file",
 267                 "vmlinux/module pathname"),
 268 #endif
 269         OPT_CALLBACK('a', "add", NULL,
 270 #ifdef NO_LIBDWARF
 271                 "FUNC[+OFFS|%return] [ARG ...]",
 272 #else
 273                 "FUNC[+OFFS|%return][@SRC]|SRC:LINE [ARG ...]",
 274 #endif
 275                 "probe point definition, where\n"
 276                 "\t\tGRP:\tGroup name (optional)\n"
 277                 "\t\tNAME:\tEvent name\n"
 278                 "\t\tFUNC:\tFunction name\n"
 279                 "\t\tOFFS:\tOffset from function entry (in byte)\n"
 280                 "\t\t%return:\tPut the probe at function return\n"
 281 #ifdef NO_LIBDWARF
 282                 "\t\tARG:\tProbe argument (only \n"
 283 #else
 284                 "\t\tSRC:\tSource code path\n"
 285                 "\t\tLINE:\tLine number\n"
 286                 "\t\tARG:\tProbe argument (local variable name or\n"
 287 #endif
 288                 "\t\t\tkprobe-tracer argument format is supported.)\n",
 289                 opt_add_probe_event),
 290         OPT_END()
 291 };
 292
 293 static int write_new_event(int fd, const char *buf)
 294 {
 295         int ret;
 296
 297         printf("Adding new event: %s\n", buf);
 298         ret = write(fd, buf, strlen(buf));
 299         if (ret <= 0)
 300                 die("failed to create event.");
 301
 302         return ret;
 303 }
 304
 305 #define MAX_CMDLEN 256
 306
 307 static int synthesize_probe_event(struct probe_point *pp)
 308 {
 309         char *buf;
 310         int i, len, ret;
 311         pp->probes[0] = buf = (char *)calloc(MAX_CMDLEN, sizeof(char));
 312         if (!buf)
 313                 die("calloc");
 314         ret = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
 315         if (ret <= 0 || ret >= MAX_CMDLEN)
 316                 goto error;
 317         len = ret;
 318
 319         for (i = 0; i < pp->nr_args; i++) {
 320                 ret = snprintf(&buf[len], MAX_CMDLEN - len, " %s",
 321                                pp->args[i]);
 322                 if (ret <= 0 || ret >= MAX_CMDLEN - len)
 323                         goto error;
 324                 len += ret;
 325         }
 326         pp->found = 1;
 327         return pp->found;
 328 error:
 329         free(pp->probes[0]);
 330         if (ret > 0)
 331                 ret = -E2BIG;
 332         return ret;
 333 }
 334
 335 int cmd_probe(int argc, const char **argv, const char *prefix __used)
 336 {
 337         int i, j, fd, ret;
 338         struct probe_point *pp;
 339         char buf[MAX_CMDLEN];
 340
 341         argc = parse_options(argc, argv, options, probe_usage,
 342                              PARSE_OPT_STOP_AT_NON_OPTION);
 343         for (i = 0; i < argc; i++)
 344                 parse_probe_event(argv[i]);
 345
 346         if (session.nr_probe == 0)
 347                 usage_with_options(probe_usage, options);
 348
 349 #ifdef NO_LIBDWARF
 350         if (session.need_dwarf)
 351                 semantic_error("Dwarf-analysis is not supported");
 352 #endif
 353
 354         /* Synthesize probes without dwarf */
 355         for (j = 0; j < session.nr_probe; j++) {
 356 #ifndef NO_LIBDWARF
 357                 if (!session.probes[j].retprobe) {
 358                         session.need_dwarf = 1;
 359                         continue;
 360                 }
 361 #endif
 362                 ret = synthesize_probe_event(&session.probes[j]);
 363                 if (ret == -E2BIG)
 364                         semantic_error("probe point is too long.");
 365                 else if (ret < 0)
 366                         die("snprintf");
 367         }
 368
 369 #ifndef NO_LIBDWARF
 370         if (!session.need_dwarf)
 371                 goto setup_probes;
 372
 373         if (session.vmlinux)
 374                 fd = open(session.vmlinux, O_RDONLY);
 375         else
 376                 fd = open_default_vmlinux();
 377         if (fd < 0)
 378                 die("vmlinux/module file open");
 379
 380         /* Searching probe points */
 381         for (j = 0; j < session.nr_probe; j++) {
 382                 pp = &session.probes[j];
 383                 if (pp->found)
 384                         continue;
 385
 386                 lseek(fd, SEEK_SET, 0);
 387                 ret = find_probepoint(fd, pp);
 388                 if (ret <= 0)
 389                         die("No probe point found.\n");
 390         }
 391         close(fd);
 392
 393 setup_probes:
 394 #endif /* !NO_LIBDWARF */
 395
 396         /* Settng up probe points */
 397         snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
 398         fd = open(buf, O_WRONLY, O_APPEND);
 399         if (fd < 0)
 400                 die("kprobe_events open");
 401         for (j = 0; j < session.nr_probe; j++) {
 402                 pp = &session.probes[j];
 403                 if (pp->found == 1) {
 404                         snprintf(buf, MAX_CMDLEN, "%c:%s/%s_%x %s\n",
 405                                 pp->retprobe ? 'r' : 'p', PERFPROBE_GROUP,
 406                                 pp->function, pp->offset, pp->probes[0]);
 407                         write_new_event(fd, buf);
 408                 } else
 409                         for (i = 0; i < pp->found; i++) {
 410                                 snprintf(buf, MAX_CMDLEN, "%c:%s/%s_%x_%d %s\n",
 411                                         pp->retprobe ? 'r' : 'p',
 412                                         PERFPROBE_GROUP,
 413                                         pp->function, pp->offset, i,
 414                                         pp->probes[0]);
 415                                 write_new_event(fd, buf);
 416                         }
 417         }
 418         close(fd);
 419         return 0;
 420 }
 421