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