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/strlist.h"
  39 #include "util/event.h"
  40 #include "util/debug.h"
  41 #include "util/debugfs.h"
  42 #include "util/symbol.h"
  43 #include "util/thread.h"
  44 #include "util/session.h"
  45 #include "util/parse-options.h"
  46 #include "util/parse-events.h"  /* For debugfs_path */
  47 #include "util/probe-finder.h"
  48 #include "util/probe-event.h"
  49
  50 #define MAX_PATH_LEN 256
  51 #define MAX_PROBES 128
  52
  53 /* Session management structure */
  54 static struct {
  55         bool need_dwarf;
  56         bool list_events;
  57         bool force_add;
  58         int nr_probe;
  59         struct probe_point probes[MAX_PROBES];
  60         struct strlist *dellist;
  61         struct perf_session *psession;
  62         struct map *kmap;
  63 } session;
  64
  65
  66 /* Parse an event definition. Note that any error must die. */
  67 static void parse_probe_event(const char *str)
  68 {
  69         struct probe_point *pp = &session.probes[session.nr_probe];
  70
  71         pr_debug("probe-definition(%d): %s\n", session.nr_probe, str);
  72         if (++session.nr_probe == MAX_PROBES)
  73                 die("Too many probes (> %d) are specified.", MAX_PROBES);
  74
  75         /* Parse perf-probe event into probe_point */
  76         parse_perf_probe_event(str, pp, &session.need_dwarf);
  77
  78         pr_debug("%d arguments\n", pp->nr_args);
  79 }
  80
  81 static void parse_probe_event_argv(int argc, const char **argv)
  82 {
  83         int i, len;
  84         char *buf;
  85
  86         /* Bind up rest arguments */
  87         len = 0;
  88         for (i = 0; i < argc; i++)
  89                 len += strlen(argv[i]) + 1;
  90         buf = zalloc(len + 1);
  91         if (!buf)
  92                 die("Failed to allocate memory for binding arguments.");
  93         len = 0;
  94         for (i = 0; i < argc; i++)
  95                 len += sprintf(&buf[len], "%s ", argv[i]);
  96         parse_probe_event(buf);
  97         free(buf);
  98 }
  99
 100 static int opt_add_probe_event(const struct option *opt __used,
 101                               const char *str, int unset __used)
 102 {
 103         if (str)
 104                 parse_probe_event(str);
 105         return 0;
 106 }
 107
 108 static int opt_del_probe_event(const struct option *opt __used,
 109                                const char *str, int unset __used)
 110 {
 111         if (str) {
 112                 if (!session.dellist)
 113                         session.dellist = strlist__new(true, NULL);
 114                 strlist__add(session.dellist, str);
 115         }
 116         return 0;
 117 }
 118
 119 /* Currently just checking function name from symbol map */
 120 static void evaluate_probe_point(struct probe_point *pp)
 121 {
 122         struct symbol *sym;
 123         sym = map__find_symbol_by_name(session.kmap, pp->function,
 124                                        session.psession, NULL);
 125         if (!sym)
 126                 die("Kernel symbol \'%s\' not found - probe not added.",
 127                     pp->function);
 128 }
 129
 130 #ifndef NO_LIBDWARF
 131 static int open_vmlinux(void)
 132 {
 133         if (map__load(session.kmap, session.psession, NULL) < 0) {
 134                 pr_debug("Failed to load kernel map.\n");
 135                 return -EINVAL;
 136         }
 137         pr_debug("Try to open %s\n", session.kmap->dso->long_name);
 138         return open(session.kmap->dso->long_name, O_RDONLY);
 139 }
 140 #endif
 141
 142 static const char * const probe_usage[] = {
 143         "perf probe [<options>] 'PROBEDEF' ['PROBEDEF' ...]",
 144         "perf probe [<options>] --add 'PROBEDEF' [--add 'PROBEDEF' ...]",
 145         "perf probe [<options>] --del '[GROUP:]EVENT' ...",
 146         "perf probe --list",
 147         NULL
 148 };
 149
 150 static const struct option options[] = {
 151         OPT_BOOLEAN('v', "verbose", &verbose,
 152                     "be more verbose (show parsed arguments, etc)"),
 153 #ifndef NO_LIBDWARF
 154         OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
 155                    "file", "vmlinux pathname"),
 156 #endif
 157         OPT_BOOLEAN('l', "list", &session.list_events,
 158                     "list up current probe events"),
 159         OPT_CALLBACK('d', "del", NULL, "[GROUP:]EVENT", "delete a probe event.",
 160                 opt_del_probe_event),
 161         OPT_CALLBACK('a', "add", NULL,
 162 #ifdef NO_LIBDWARF
 163                 "[EVENT=]FUNC[+OFFS|%return] [ARG ...]",
 164 #else
 165                 "[EVENT=]FUNC[+OFFS|%return|:RLN][@SRC]|SRC:ALN [ARG ...]",
 166 #endif
 167                 "probe point definition, where\n"
 168                 "\t\tGROUP:\tGroup name (optional)\n"
 169                 "\t\tEVENT:\tEvent name\n"
 170                 "\t\tFUNC:\tFunction name\n"
 171                 "\t\tOFFS:\tOffset from function entry (in byte)\n"
 172                 "\t\t%return:\tPut the probe at function return\n"
 173 #ifdef NO_LIBDWARF
 174                 "\t\tARG:\tProbe argument (only \n"
 175 #else
 176                 "\t\tSRC:\tSource code path\n"
 177                 "\t\tRLN:\tRelative line number from function entry.\n"
 178                 "\t\tALN:\tAbsolute line number in file.\n"
 179                 "\t\tARG:\tProbe argument (local variable name or\n"
 180 #endif
 181                 "\t\t\tkprobe-tracer argument format.)\n",
 182                 opt_add_probe_event),
 183         OPT_BOOLEAN('f', "force", &session.force_add, "forcibly add events"
 184                     " with existing name"),
 185         OPT_END()
 186 };
 187
 188 int cmd_probe(int argc, const char **argv, const char *prefix __used)
 189 {
 190         int i, ret;
 191 #ifndef NO_LIBDWARF
 192         int fd;
 193 #endif
 194         struct probe_point *pp;
 195
 196         argc = parse_options(argc, argv, options, probe_usage,
 197                              PARSE_OPT_STOP_AT_NON_OPTION);
 198         if (argc > 0) {
 199                 if (strcmp(argv[0], "-") == 0) {
 200                         pr_warning("  Error: '-' is not supported.\n");
 201                         usage_with_options(probe_usage, options);
 202                 }
 203                 parse_probe_event_argv(argc, argv);
 204         }
 205
 206         if ((!session.nr_probe && !session.dellist && !session.list_events))
 207                 usage_with_options(probe_usage, options);
 208
 209         if (debugfs_valid_mountpoint(debugfs_path) < 0)
 210                 die("Failed to find debugfs path.");
 211
 212         if (session.list_events) {
 213                 if (session.nr_probe != 0 || session.dellist) {
 214                         pr_warning("  Error: Don't use --list with"
 215                                    " --add/--del.\n");
 216                         usage_with_options(probe_usage, options);
 217                 }
 218                 show_perf_probe_events();
 219                 return 0;
 220         }
 221
 222         if (session.dellist) {
 223                 del_trace_kprobe_events(session.dellist);
 224                 strlist__delete(session.dellist);
 225                 if (session.nr_probe == 0)
 226                         return 0;
 227         }
 228
 229         /* Initialize symbol maps for vmlinux */
 230         symbol_conf.sort_by_name = true;
 231         if (symbol_conf.vmlinux_name == NULL)
 232                 symbol_conf.try_vmlinux_path = true;
 233         if (symbol__init() < 0)
 234                 die("Failed to init symbol map.");
 235         session.psession = perf_session__new(NULL, O_WRONLY, false);
 236         if (session.psession == NULL)
 237                 die("Failed to init perf_session.");
 238         session.kmap = map_groups__find_by_name(&session.psession->kmaps,
 239                                                 MAP__FUNCTION,
 240                                                 "[kernel.kallsyms]");
 241         if (!session.kmap)
 242                 die("Could not find kernel map.\n");
 243
 244         if (session.need_dwarf)
 245 #ifdef NO_LIBDWARF
 246                 die("Debuginfo-analysis is not supported");
 247 #else   /* !NO_LIBDWARF */
 248                 pr_debug("Some probes require debuginfo.\n");
 249
 250         fd = open_vmlinux();
 251         if (fd < 0) {
 252                 if (session.need_dwarf)
 253                         die("Could not open debuginfo file.");
 254
 255                 pr_debug("Could not open vmlinux/module file."
 256                          " Try to use symbols.\n");
 257                 goto end_dwarf;
 258         }
 259
 260         /* Searching probe points */
 261         for (i = 0; i < session.nr_probe; i++) {
 262                 pp = &session.probes[i];
 263                 if (pp->found)
 264                         continue;
 265
 266                 lseek(fd, SEEK_SET, 0);
 267                 ret = find_probepoint(fd, pp);
 268                 if (ret > 0)
 269                         continue;
 270                 if (ret == 0) { /* No error but failed to find probe point. */
 271                         synthesize_perf_probe_point(pp);
 272                         die("Probe point '%s' not found. - probe not added.",
 273                             pp->probes[0]);
 274                 }
 275                 /* Error path */
 276                 if (session.need_dwarf) {
 277                         if (ret == -ENOENT)
 278                                 pr_warning("No dwarf info found in the vmlinux - please rebuild with CONFIG_DEBUG_INFO=y.\n");
 279                         die("Could not analyze debuginfo.");
 280                 }
 281                 pr_debug("An error occurred in debuginfo analysis."
 282                          " Try to use symbols.\n");
 283                 break;
 284         }
 285         close(fd);
 286
 287 end_dwarf:
 288 #endif /* !NO_LIBDWARF */
 289
 290         /* Synthesize probes without dwarf */
 291         for (i = 0; i < session.nr_probe; i++) {
 292                 pp = &session.probes[i];
 293                 if (pp->found)  /* This probe is already found. */
 294                         continue;
 295
 296                 evaluate_probe_point(pp);
 297                 ret = synthesize_trace_kprobe_event(pp);
 298                 if (ret == -E2BIG)
 299                         die("probe point definition becomes too long.");
 300                 else if (ret < 0)
 301                         die("Failed to synthesize a probe point.");
 302         }
 303
 304         /* Settng up probe points */
 305         add_trace_kprobe_events(session.probes, session.nr_probe,
 306                                 session.force_add);
 307         return 0;
 308 }
 309