tools/perf/util/probe-event.c

   1 /*
   2  * probe-event.c : perf-probe definition to kprobe_events format converter
   3  *
   4  * Written by Masami Hiramatsu <mhiramat@redhat.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  19  *
  20  */
  21
  22 #define _GNU_SOURCE
  23 #include <sys/utsname.h>
  24 #include <sys/types.h>
  25 #include <sys/stat.h>
  26 #include <fcntl.h>
  27 #include <errno.h>
  28 #include <stdio.h>
  29 #include <unistd.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32
  33 #undef _GNU_SOURCE
  34 #include "event.h"
  35 #include "string.h"
  36 #include "debug.h"
  37 #include "parse-events.h"  /* For debugfs_path */
  38 #include "probe-event.h"
  39
  40 #define MAX_CMDLEN 256
  41 #define MAX_PROBE_ARGS 128
  42 #define PERFPROBE_GROUP "probe"
  43
  44 #define semantic_error(msg ...) die("Semantic error :" msg)
  45
  46 /* Parse probepoint definition. */
  47 static void parse_perf_probe_probepoint(char *arg, struct probe_point *pp)
  48 {
  49         char *ptr, *tmp;
  50         char c, nc = 0;
  51         /*
  52          * <Syntax>
  53          * perf probe SRC:LN
  54          * perf probe FUNC[+OFFS|%return][@SRC]
  55          */
  56
  57         ptr = strpbrk(arg, ":+@%");
  58         if (ptr) {
  59                 nc = *ptr;
  60                 *ptr++ = '\0';
  61         }
  62
  63         /* Check arg is function or file and copy it */
  64         if (strchr(arg, '.'))   /* File */
  65                 pp->file = strdup(arg);
  66         else                    /* Function */
  67                 pp->function = strdup(arg);
  68         DIE_IF(pp->file == NULL && pp->function == NULL);
  69
  70         /* Parse other options */
  71         while (ptr) {
  72                 arg = ptr;
  73                 c = nc;
  74                 ptr = strpbrk(arg, ":+@%");
  75                 if (ptr) {
  76                         nc = *ptr;
  77                         *ptr++ = '\0';
  78                 }
  79                 switch (c) {
  80                 case ':':       /* Line number */
  81                         pp->line = strtoul(arg, &tmp, 0);
  82                         if (*tmp != '\0')
  83                                 semantic_error("There is non-digit charactor"
  84                                                 " in line number.");
  85                         break;
  86                 case '+':       /* Byte offset from a symbol */
  87                         pp->offset = strtoul(arg, &tmp, 0);
  88                         if (*tmp != '\0')
  89                                 semantic_error("There is non-digit charactor"
  90                                                 " in offset.");
  91                         break;
  92                 case '@':       /* File name */
  93                         if (pp->file)
  94                                 semantic_error("SRC@SRC is not allowed.");
  95                         pp->file = strdup(arg);
  96                         DIE_IF(pp->file == NULL);
  97                         if (ptr)
  98                                 semantic_error("@SRC must be the last "
  99                                                "option.");
 100                         break;
 101                 case '%':       /* Probe places */
 102                         if (strcmp(arg, "return") == 0) {
 103                                 pp->retprobe = 1;
 104                         } else  /* Others not supported yet */
 105                                 semantic_error("%%%s is not supported.", arg);
 106                         break;
 107                 default:
 108                         DIE_IF("Program has a bug.");
 109                         break;
 110                 }
 111         }
 112
 113         /* Exclusion check */
 114         if (pp->line && pp->offset)
 115                 semantic_error("Offset can't be used with line number.");
 116
 117         if (!pp->line && pp->file && !pp->function)
 118                 semantic_error("File always requires line number.");
 119
 120         if (pp->offset && !pp->function)
 121                 semantic_error("Offset requires an entry function.");
 122
 123         if (pp->retprobe && !pp->function)
 124                 semantic_error("Return probe requires an entry function.");
 125
 126         if ((pp->offset || pp->line) && pp->retprobe)
 127                 semantic_error("Offset/Line can't be used with return probe.");
 128
 129         pr_debug("symbol:%s file:%s line:%d offset:%d, return:%d\n",
 130                  pp->function, pp->file, pp->line, pp->offset, pp->retprobe);
 131 }
 132
 133 /* Parse perf-probe event definition */
 134 int parse_perf_probe_event(const char *str, struct probe_point *pp)
 135 {
 136         char **argv;
 137         int argc, i, need_dwarf = 0;
 138
 139         argv = argv_split(str, &argc);
 140         if (!argv)
 141                 die("argv_split failed.");
 142         if (argc > MAX_PROBE_ARGS + 1)
 143                 semantic_error("Too many arguments");
 144
 145         /* Parse probe point */
 146         parse_perf_probe_probepoint(argv[0], pp);
 147         if (pp->file || pp->line)
 148                 need_dwarf = 1;
 149
 150         /* Copy arguments and ensure return probe has no C argument */
 151         pp->nr_args = argc - 1;
 152         pp->args = zalloc(sizeof(char *) * pp->nr_args);
 153         for (i = 0; i < pp->nr_args; i++) {
 154                 pp->args[i] = strdup(argv[i + 1]);
 155                 if (!pp->args[i])
 156                         die("Failed to copy argument.");
 157                 if (is_c_varname(pp->args[i])) {
 158                         if (pp->retprobe)
 159                                 semantic_error("You can't specify local"
 160                                                 " variable for kretprobe");
 161                         need_dwarf = 1;
 162                 }
 163         }
 164
 165         argv_free(argv);
 166         return need_dwarf;
 167 }
 168
 169 int synthesize_trace_kprobe_event(struct probe_point *pp)
 170 {
 171         char *buf;
 172         int i, len, ret;
 173
 174         pp->probes[0] = buf = zalloc(MAX_CMDLEN);
 175         if (!buf)
 176                 die("Failed to allocate memory by zalloc.");
 177         ret = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
 178         if (ret <= 0 || ret >= MAX_CMDLEN)
 179                 goto error;
 180         len = ret;
 181
 182         for (i = 0; i < pp->nr_args; i++) {
 183                 ret = snprintf(&buf[len], MAX_CMDLEN - len, " %s",
 184                                pp->args[i]);
 185                 if (ret <= 0 || ret >= MAX_CMDLEN - len)
 186                         goto error;
 187                 len += ret;
 188         }
 189         pp->found = 1;
 190
 191         return pp->found;
 192 error:
 193         free(pp->probes[0]);
 194         if (ret > 0)
 195                 ret = -E2BIG;
 196
 197         return ret;
 198 }
 199
 200 static int write_trace_kprobe_event(int fd, const char *buf)
 201 {
 202         int ret;
 203
 204         ret = write(fd, buf, strlen(buf));
 205         if (ret <= 0)
 206                 die("Failed to create event.");
 207         else
 208                 printf("Added new event: %s\n", buf);
 209
 210         return ret;
 211 }
 212
 213 void add_trace_kprobe_events(struct probe_point *probes, int nr_probes)
 214 {
 215         int i, j, fd;
 216         struct probe_point *pp;
 217         char buf[MAX_CMDLEN];
 218
 219         snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
 220         fd = open(buf, O_WRONLY, O_APPEND);
 221         if (fd < 0) {
 222                 if (errno == ENOENT)
 223                         die("kprobe_events file does not exist -"
 224                             " please rebuild with CONFIG_KPROBE_TRACER.");
 225                 else
 226                         die("Could not open kprobe_events file: %s",
 227                             strerror(errno));
 228         }
 229
 230         for (j = 0; j < nr_probes; j++) {
 231                 pp = probes + j;
 232                 if (pp->found == 1) {
 233                         snprintf(buf, MAX_CMDLEN, "%c:%s/%s_%x %s\n",
 234                                 pp->retprobe ? 'r' : 'p', PERFPROBE_GROUP,
 235                                 pp->function, pp->offset, pp->probes[0]);
 236                         write_trace_kprobe_event(fd, buf);
 237                 } else
 238                         for (i = 0; i < pp->found; i++) {
 239                                 snprintf(buf, MAX_CMDLEN, "%c:%s/%s_%x_%d %s\n",
 240                                         pp->retprobe ? 'r' : 'p',
 241                                         PERFPROBE_GROUP,
 242                                         pp->function, pp->offset, i,
 243                                         pp->probes[i]);
 244                                 write_trace_kprobe_event(fd, buf);
 245                         }
 246         }
 247         close(fd);
 248 }