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/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 #include "util/probe-event.h"
  44
  45 /* Default vmlinux search paths */
  46 #define NR_SEARCH_PATH 3
  47 const char *default_search_path[NR_SEARCH_PATH] = {
  48 "/lib/modules/%s/build/vmlinux",                /* Custom build kernel */
  49 "/usr/lib/debug/lib/modules/%s/vmlinux",        /* Red Hat debuginfo */
  50 "/boot/vmlinux-debug-%s",                       /* Ubuntu */
  51 };
  52
  53 #define MAX_PATH_LEN 256
  54 #define MAX_PROBES 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 } session;
  64
  65 static bool listing;
  66
  67 /* Parse an event definition. Note that any error must die. */
  68 static void parse_probe_event(const char *str)
  69 {
  70         struct probe_point *pp = &session.probes[session.nr_probe];
  71
  72         pr_debug("probe-definition(%d): %s\n", session.nr_probe, str);
  73         if (++session.nr_probe == MAX_PROBES)
  74                 die("Too many probes (> %d) are specified.", MAX_PROBES);
  75
  76         /* Parse perf-probe event into probe_point */
  77         session.need_dwarf = parse_perf_probe_event(str, pp);
  78
  79         pr_debug("%d arguments\n", pp->nr_args);
  80 }
  81
  82 static int opt_add_probe_event(const struct option *opt __used,
  83                               const char *str, int unset __used)
  84 {
  85         if (str)
  86                 parse_probe_event(str);
  87         return 0;
  88 }
  89
  90 #ifndef NO_LIBDWARF
  91 static int open_default_vmlinux(void)
  92 {
  93         struct utsname uts;
  94         char fname[MAX_PATH_LEN];
  95         int fd, ret, i;
  96
  97         ret = uname(&uts);
  98         if (ret) {
  99                 pr_debug("uname() failed.\n");
 100                 return -errno;
 101         }
 102         session.release = uts.release;
 103         for (i = 0; i < NR_SEARCH_PATH; i++) {
 104                 ret = snprintf(fname, MAX_PATH_LEN,
 105                                default_search_path[i], session.release);
 106                 if (ret >= MAX_PATH_LEN || ret < 0) {
 107                         pr_debug("Filename(%d,%s) is too long.\n", i,
 108                                 uts.release);
 109                         errno = E2BIG;
 110                         return -E2BIG;
 111                 }
 112                 pr_debug("try to open %s\n", fname);
 113                 fd = open(fname, O_RDONLY);
 114                 if (fd >= 0)
 115                         break;
 116         }
 117         return fd;
 118 }
 119 #endif
 120
 121 static const char * const probe_usage[] = {
 122         "perf probe [<options>] 'PROBEDEF' ['PROBEDEF' ...]",
 123         "perf probe [<options>] --add 'PROBEDEF' [--add 'PROBEDEF' ...]",
 124         "perf probe --list",
 125         NULL
 126 };
 127
 128 static const struct option options[] = {
 129         OPT_BOOLEAN('v', "verbose", &verbose,
 130                     "be more verbose (show parsed arguments, etc)"),
 131 #ifndef NO_LIBDWARF
 132         OPT_STRING('k', "vmlinux", &session.vmlinux, "file",
 133                 "vmlinux/module pathname"),
 134 #endif
 135         OPT_BOOLEAN('l', "list", &listing, "list up current probes"),
 136         OPT_CALLBACK('a', "add", NULL,
 137 #ifdef NO_LIBDWARF
 138                 "FUNC[+OFFS|%return] [ARG ...]",
 139 #else
 140                 "FUNC[+OFFS|%return|:RLN][@SRC]|SRC:ALN [ARG ...]",
 141 #endif
 142                 "probe point definition, where\n"
 143                 "\t\tGRP:\tGroup name (optional)\n"
 144                 "\t\tNAME:\tEvent name\n"
 145                 "\t\tFUNC:\tFunction name\n"
 146                 "\t\tOFFS:\tOffset from function entry (in byte)\n"
 147                 "\t\t%return:\tPut the probe at function return\n"
 148 #ifdef NO_LIBDWARF
 149                 "\t\tARG:\tProbe argument (only \n"
 150 #else
 151                 "\t\tSRC:\tSource code path\n"
 152                 "\t\tRLN:\tRelative line number from function entry.\n"
 153                 "\t\tALN:\tAbsolute line number in file.\n"
 154                 "\t\tARG:\tProbe argument (local variable name or\n"
 155 #endif
 156                 "\t\t\tkprobe-tracer argument format.)\n",
 157                 opt_add_probe_event),
 158         OPT_END()
 159 };
 160
 161 int cmd_probe(int argc, const char **argv, const char *prefix __used)
 162 {
 163         int i, j, ret;
 164 #ifndef NO_LIBDWARF
 165         int fd;
 166 #endif
 167         struct probe_point *pp;
 168
 169         argc = parse_options(argc, argv, options, probe_usage,
 170                              PARSE_OPT_STOP_AT_NON_OPTION);
 171         for (i = 0; i < argc; i++)
 172                 parse_probe_event(argv[i]);
 173
 174         if ((session.nr_probe == 0 && !listing) ||
 175             (session.nr_probe != 0 && listing))
 176                 usage_with_options(probe_usage, options);
 177
 178         if (listing) {
 179                 show_perf_probe_events();
 180                 return 0;
 181         }
 182
 183         if (session.need_dwarf)
 184 #ifdef NO_LIBDWARF
 185                 die("Debuginfo-analysis is not supported");
 186 #else   /* !NO_LIBDWARF */
 187                 pr_debug("Some probes require debuginfo.\n");
 188
 189         if (session.vmlinux)
 190                 fd = open(session.vmlinux, O_RDONLY);
 191         else
 192                 fd = open_default_vmlinux();
 193         if (fd < 0) {
 194                 if (session.need_dwarf)
 195                         die("Could not open vmlinux/module file.");
 196
 197                 pr_warning("Could not open vmlinux/module file."
 198                            " Try to use symbols.\n");
 199                 goto end_dwarf;
 200         }
 201
 202         /* Searching probe points */
 203         for (j = 0; j < session.nr_probe; j++) {
 204                 pp = &session.probes[j];
 205                 if (pp->found)
 206                         continue;
 207
 208                 lseek(fd, SEEK_SET, 0);
 209                 ret = find_probepoint(fd, pp);
 210                 if (ret < 0) {
 211                         if (session.need_dwarf)
 212                                 die("Could not analyze debuginfo.");
 213
 214                         pr_warning("An error occurred in debuginfo analysis. Try to use symbols.\n");
 215                         break;
 216                 }
 217                 if (ret == 0)   /* No error but failed to find probe point. */
 218                         die("No probe point found.");
 219         }
 220         close(fd);
 221
 222 end_dwarf:
 223 #endif /* !NO_LIBDWARF */
 224
 225         /* Synthesize probes without dwarf */
 226         for (j = 0; j < session.nr_probe; j++) {
 227                 pp = &session.probes[j];
 228                 if (pp->found)  /* This probe is already found. */
 229                         continue;
 230
 231                 ret = synthesize_trace_kprobe_event(pp);
 232                 if (ret == -E2BIG)
 233                         die("probe point definition becomes too long.");
 234                 else if (ret < 0)
 235                         die("Failed to synthesize a probe point.");
 236         }
 237
 238         /* Settng up probe points */
 239         add_trace_kprobe_events(session.probes, session.nr_probe);
 240         return 0;
 241 }
 242