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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
  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 static int parse_probepoint(const struct option *opt __used,
  69                             const char *str, int unset __used)
  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         if (!str)       /* The end of probe points */
  79                 return 0;
  80
  81         eprintf("probe-definition(%d): %s\n", session.nr_probe, str);
  82         if (++session.nr_probe == MAX_PROBES)
  83                 semantic_error("Too many probes");
  84
  85         /* Separate arguments, similar to argv_split */
  86         argc = 0;
  87         do {
  88                 /* Skip separators */
  89                 while (isspace(*str))
  90                         str++;
  91
  92                 /* Add an argument */
  93                 if (*str != '\0') {
  94                         const char *s = str;
  95
  96                         /* Skip the argument */
  97                         while (!isspace(*str) && *str != '\0')
  98                                 str++;
  99
 100                         /* Duplicate the argument */
 101                         argv[argc] = strndup(s, str - s);
 102                         if (argv[argc] == NULL)
 103                                 die("strndup");
 104                         if (++argc == MAX_PROBE_ARGS)
 105                                 semantic_error("Too many arguments");
 106                         eprintf("argv[%d]=%s\n", argc, argv[argc - 1]);
 107                 }
 108         } while (*str != '\0');
 109         if (argc < 2)
 110                 semantic_error("Need event-name and probe-point at least.");
 111
 112         /* Parse the event name */
 113         if (argv[0][0] == 'r')
 114                 retp = 1;
 115         else if (argv[0][0] != 'p')
 116                 semantic_error("You must specify 'p'(kprobe) or"
 117                                 " 'r'(kretprobe) first.");
 118         /* TODO: check event name */
 119         *event = argv[0];
 120
 121         /* Parse probe point */
 122         arg = argv[1];
 123         if (arg[0] == '@') {
 124                 /* Source Line */
 125                 arg++;
 126                 ptr = strchr(arg, ':');
 127                 if (!ptr || !isdigit(ptr[1]))
 128                         semantic_error("Line number is required.");
 129                 *ptr++ = '\0';
 130                 if (strlen(arg) == 0)
 131                         semantic_error("No file name.");
 132                 pp->file = strdup(arg);
 133                 pp->line = atoi(ptr);
 134                 if (!pp->file || !pp->line)
 135                         semantic_error("Failed to parse line.");
 136                 eprintf("file:%s line:%d\n", pp->file, pp->line);
 137         } else {
 138                 /* Function name */
 139                 ptr = strchr(arg, '+');
 140                 if (ptr) {
 141                         if (!isdigit(ptr[1]))
 142                                 semantic_error("Offset is required.");
 143                         *ptr++ = '\0';
 144                         pp->offset = atoi(ptr);
 145                 } else
 146                         ptr = arg;
 147                 ptr = strchr(ptr, '@');
 148                 if (ptr) {
 149                         *ptr++ = '\0';
 150                         pp->file = strdup(ptr);
 151                 }
 152                 pp->function = strdup(arg);
 153                 eprintf("symbol:%s file:%s offset:%d\n",
 154                       pp->function, pp->file, pp->offset);
 155         }
 156         free(argv[1]);
 157         if (pp->file)
 158                 session.need_dwarf = 1;
 159
 160         /* Copy arguments */
 161         pp->nr_args = argc - 2;
 162         if (pp->nr_args > 0) {
 163                 pp->args = (char **)malloc(sizeof(char *) * pp->nr_args);
 164                 if (!pp->args)
 165                         die("malloc");
 166                 memcpy(pp->args, &argv[2], sizeof(char *) * pp->nr_args);
 167         }
 168
 169         /* Ensure return probe has no C argument */
 170         for (i = 0; i < pp->nr_args; i++)
 171                 if (is_c_varname(pp->args[i])) {
 172                         if (retp)
 173                                 semantic_error("You can't specify local"
 174                                                 " variable for kretprobe");
 175                         session.need_dwarf = 1;
 176                 }
 177
 178         eprintf("%d arguments\n", pp->nr_args);
 179         return 0;
 180 }
 181
 182 #ifndef NO_LIBDWARF
 183 static int open_default_vmlinux(void)
 184 {
 185         struct utsname uts;
 186         char fname[MAX_PATH_LEN];
 187         int fd, ret, i;
 188
 189         ret = uname(&uts);
 190         if (ret) {
 191                 eprintf("uname() failed.\n");
 192                 return -errno;
 193         }
 194         session.release = uts.release;
 195         for (i = 0; i < NR_SEARCH_PATH; i++) {
 196                 ret = snprintf(fname, MAX_PATH_LEN,
 197                                default_search_path[i], session.release);
 198                 if (ret >= MAX_PATH_LEN || ret < 0) {
 199                         eprintf("Filename(%d,%s) is too long.\n", i,
 200                                 uts.release);
 201                         errno = E2BIG;
 202                         return -E2BIG;
 203                 }
 204                 eprintf("try to open %s\n", fname);
 205                 fd = open(fname, O_RDONLY);
 206                 if (fd >= 0)
 207                         break;
 208         }
 209         return fd;
 210 }
 211 #endif
 212
 213 static const char * const probe_usage[] = {
 214         "perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]",
 215         NULL
 216 };
 217
 218 static const struct option options[] = {
 219         OPT_BOOLEAN('v', "verbose", &verbose,
 220                     "be more verbose (show parsed arguments, etc)"),
 221 #ifndef NO_LIBDWARF
 222         OPT_STRING('k', "vmlinux", &session.vmlinux, "file",
 223                 "vmlinux/module pathname"),
 224 #endif
 225         OPT_CALLBACK('P', "probe", NULL,
 226 #ifdef NO_LIBDWARF
 227                 "p|r:[GRP/]NAME FUNC[+OFFS] [ARG ...]",
 228 #else
 229                 "p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]",
 230 #endif
 231                 "probe point definition, where\n"
 232                 "\t\tp:\tkprobe probe\n"
 233                 "\t\tr:\tkretprobe probe\n"
 234                 "\t\tGRP:\tGroup name (optional)\n"
 235                 "\t\tNAME:\tEvent name\n"
 236                 "\t\tFUNC:\tFunction name\n"
 237                 "\t\tOFFS:\tOffset from function entry (in byte)\n"
 238 #ifdef NO_LIBDWARF
 239                 "\t\tARG:\tProbe argument (only \n"
 240 #else
 241                 "\t\tSRC:\tSource code path\n"
 242                 "\t\tLINE:\tLine number\n"
 243                 "\t\tARG:\tProbe argument (local variable name or\n"
 244 #endif
 245                 "\t\t\tkprobe-tracer argument format is supported.)\n",
 246                 parse_probepoint),
 247         OPT_END()
 248 };
 249
 250 static int write_new_event(int fd, const char *buf)
 251 {
 252         int ret;
 253
 254         printf("Adding new event: %s\n", buf);
 255         ret = write(fd, buf, strlen(buf));
 256         if (ret <= 0)
 257                 die("failed to create event.");
 258
 259         return ret;
 260 }
 261
 262 #define MAX_CMDLEN 256
 263
 264 static int synthesize_probepoint(struct probe_point *pp)
 265 {
 266         char *buf;
 267         int i, len, ret;
 268         pp->probes[0] = buf = (char *)calloc(MAX_CMDLEN, sizeof(char));
 269         if (!buf)
 270                 die("calloc");
 271         ret = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
 272         if (ret <= 0 || ret >= MAX_CMDLEN)
 273                 goto error;
 274         len = ret;
 275
 276         for (i = 0; i < pp->nr_args; i++) {
 277                 ret = snprintf(&buf[len], MAX_CMDLEN - len, " %s",
 278                                pp->args[i]);
 279                 if (ret <= 0 || ret >= MAX_CMDLEN - len)
 280                         goto error;
 281                 len += ret;
 282         }
 283         pp->found = 1;
 284         return pp->found;
 285 error:
 286         free(pp->probes[0]);
 287         if (ret > 0)
 288                 ret = -E2BIG;
 289         return ret;
 290 }
 291
 292 int cmd_probe(int argc, const char **argv, const char *prefix __used)
 293 {
 294         int i, j, fd, ret;
 295         struct probe_point *pp;
 296         char buf[MAX_CMDLEN];
 297
 298         argc = parse_options(argc, argv, options, probe_usage,
 299                 PARSE_OPT_STOP_AT_NON_OPTION);
 300         if (argc || session.nr_probe == 0)
 301                 usage_with_options(probe_usage, options);
 302
 303 #ifdef NO_LIBDWARF
 304         if (session.need_dwarf)
 305                 semantic_error("Dwarf-analysis is not supported");
 306 #endif
 307
 308         /* Synthesize probes without dwarf */
 309         for (j = 0; j < session.nr_probe; j++) {
 310 #ifndef NO_LIBDWARF
 311                 if (session.events[j][0] != 'r') {
 312                         session.need_dwarf = 1;
 313                         continue;
 314                 }
 315 #endif
 316                 ret = synthesize_probepoint(&session.probes[j]);
 317                 if (ret == -E2BIG)
 318                         semantic_error("probe point is too long.");
 319                 else if (ret < 0)
 320                         die("snprintf");
 321         }
 322
 323 #ifndef NO_LIBDWARF
 324         if (!session.need_dwarf)
 325                 goto setup_probes;
 326
 327         if (session.vmlinux)
 328                 fd = open(session.vmlinux, O_RDONLY);
 329         else
 330                 fd = open_default_vmlinux();
 331         if (fd < 0)
 332                 die("vmlinux/module file open");
 333
 334         /* Searching probe points */
 335         for (j = 0; j < session.nr_probe; j++) {
 336                 pp = &session.probes[j];
 337                 if (pp->found)
 338                         continue;
 339
 340                 lseek(fd, SEEK_SET, 0);
 341                 ret = find_probepoint(fd, pp);
 342                 if (ret <= 0)
 343                         die("No probe point found.\n");
 344                 eprintf("probe event %s found\n", session.events[j]);
 345         }
 346         close(fd);
 347
 348 setup_probes:
 349 #endif /* !NO_LIBDWARF */
 350
 351         /* Settng up probe points */
 352         snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
 353         fd = open(buf, O_WRONLY, O_APPEND);
 354         if (fd < 0)
 355                 die("kprobe_events open");
 356         for (j = 0; j < session.nr_probe; j++) {
 357                 pp = &session.probes[j];
 358                 if (pp->found == 1) {
 359                         snprintf(buf, MAX_CMDLEN, "%s %s\n",
 360                                 session.events[j], pp->probes[0]);
 361                         write_new_event(fd, buf);
 362                 } else
 363                         for (i = 0; i < pp->found; i++) {
 364                                 snprintf(buf, MAX_CMDLEN, "%s%d %s\n",
 365                                         session.events[j], i, pp->probes[i]);
 366                                 write_new_event(fd, buf);
 367                         }
 368         }
 369         close(fd);
 370         return 0;
 371 }
 372