tools/perf/util/vdso.c

   1
   2 #include <unistd.h>
   3 #include <stdio.h>
   4 #include <string.h>
   5 #include <sys/types.h>
   6 #include <sys/stat.h>
   7 #include <fcntl.h>
   8 #include <stdlib.h>
   9 #include <linux/kernel.h>
  10
  11 #include "vdso.h"
  12 #include "util.h"
  13 #include "symbol.h"
  14 #include "machine.h"
  15 #include "thread.h"
  16 #include "linux/string.h"
  17 #include "debug.h"
  18
  19 /*
  20  * Include definition of find_vdso_map() also used in perf-read-vdso.c for
  21  * building perf-read-vdso32 and perf-read-vdsox32.
  22  */
  23 #include "find-vdso-map.c"
  24
  25 #define VDSO__TEMP_FILE_NAME "/tmp/perf-vdso.so-XXXXXX"
  26
  27 struct vdso_file {
  28         bool found;
  29         bool error;
  30         char temp_file_name[sizeof(VDSO__TEMP_FILE_NAME)];
  31         const char *dso_name;
  32         const char *read_prog;
  33 };
  34
  35 struct vdso_info {
  36         struct vdso_file vdso;
  37 #if BITS_PER_LONG == 64
  38         struct vdso_file vdso32;
  39         struct vdso_file vdsox32;
  40 #endif
  41 };
  42
  43 static struct vdso_info *vdso_info__new(void)
  44 {
  45         static const struct vdso_info vdso_info_init = {
  46                 .vdso    = {
  47                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  48                         .dso_name = DSO__NAME_VDSO,
  49                 },
  50 #if BITS_PER_LONG == 64
  51                 .vdso32  = {
  52                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  53                         .dso_name = DSO__NAME_VDSO32,
  54                         .read_prog = "perf-read-vdso32",
  55                 },
  56                 .vdsox32  = {
  57                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  58                         .dso_name = DSO__NAME_VDSOX32,
  59                         .read_prog = "perf-read-vdsox32",
  60                 },
  61 #endif
  62         };
  63
  64         return memdup(&vdso_info_init, sizeof(vdso_info_init));
  65 }
  66
  67 static char *get_file(struct vdso_file *vdso_file)
  68 {
  69         char *vdso = NULL;
  70         char *buf = NULL;
  71         void *start, *end;
  72         size_t size;
  73         int fd;
  74
  75         if (vdso_file->found)
  76                 return vdso_file->temp_file_name;
  77
  78         if (vdso_file->error || find_vdso_map(&start, &end))
  79                 return NULL;
  80
  81         size = end - start;
  82
  83         buf = memdup(start, size);
  84         if (!buf)
  85                 return NULL;
  86
  87         fd = mkstemp(vdso_file->temp_file_name);
  88         if (fd < 0)
  89                 goto out;
  90
  91         if (size == (size_t) write(fd, buf, size))
  92                 vdso = vdso_file->temp_file_name;
  93
  94         close(fd);
  95
  96  out:
  97         free(buf);
  98
  99         vdso_file->found = (vdso != NULL);
 100         vdso_file->error = !vdso_file->found;
 101         return vdso;
 102 }
 103
 104 void machine__exit_vdso(struct machine *machine)
 105 {
 106         struct vdso_info *vdso_info = machine->vdso_info;
 107
 108         if (!vdso_info)
 109                 return;
 110
 111         if (vdso_info->vdso.found)
 112                 unlink(vdso_info->vdso.temp_file_name);
 113 #if BITS_PER_LONG == 64
 114         if (vdso_info->vdso32.found)
 115                 unlink(vdso_info->vdso32.temp_file_name);
 116         if (vdso_info->vdsox32.found)
 117                 unlink(vdso_info->vdsox32.temp_file_name);
 118 #endif
 119
 120         zfree(&machine->vdso_info);
 121 }
 122
 123 static struct dso *__machine__addnew_vdso(struct machine *machine, const char *short_name,
 124                                           const char *long_name)
 125 {
 126         struct dso *dso;
 127
 128         dso = dso__new(short_name);
 129         if (dso != NULL) {
 130                 __dsos__add(&machine->dsos, dso);
 131                 dso__set_long_name(dso, long_name, false);
 132         }
 133
 134         return dso;
 135 }
 136
 137 #if BITS_PER_LONG == 64
 138
 139 static enum dso_type machine__thread_dso_type(struct machine *machine,
 140                                               struct thread *thread)
 141 {
 142         enum dso_type dso_type = DSO__TYPE_UNKNOWN;
 143         struct map *map;
 144         struct dso *dso;
 145
 146         map = map_groups__first(thread->mg, MAP__FUNCTION);
 147         for (; map ; map = map_groups__next(map)) {
 148                 dso = map->dso;
 149                 if (!dso || dso->long_name[0] != '/')
 150                         continue;
 151                 dso_type = dso__type(dso, machine);
 152                 if (dso_type != DSO__TYPE_UNKNOWN)
 153                         break;
 154         }
 155
 156         return dso_type;
 157 }
 158
 159 static int vdso__do_copy_compat(FILE *f, int fd)
 160 {
 161         char buf[4096];
 162         size_t count;
 163
 164         while (1) {
 165                 count = fread(buf, 1, sizeof(buf), f);
 166                 if (ferror(f))
 167                         return -errno;
 168                 if (feof(f))
 169                         break;
 170                 if (count && writen(fd, buf, count) != (ssize_t)count)
 171                         return -errno;
 172         }
 173
 174         return 0;
 175 }
 176
 177 static int vdso__copy_compat(const char *prog, int fd)
 178 {
 179         FILE *f;
 180         int err;
 181
 182         f = popen(prog, "r");
 183         if (!f)
 184                 return -errno;
 185
 186         err = vdso__do_copy_compat(f, fd);
 187
 188         if (pclose(f) == -1)
 189                 return -errno;
 190
 191         return err;
 192 }
 193
 194 static int vdso__create_compat_file(const char *prog, char *temp_name)
 195 {
 196         int fd, err;
 197
 198         fd = mkstemp(temp_name);
 199         if (fd < 0)
 200                 return -errno;
 201
 202         err = vdso__copy_compat(prog, fd);
 203
 204         if (close(fd) == -1)
 205                 return -errno;
 206
 207         return err;
 208 }
 209
 210 static const char *vdso__get_compat_file(struct vdso_file *vdso_file)
 211 {
 212         int err;
 213
 214         if (vdso_file->found)
 215                 return vdso_file->temp_file_name;
 216
 217         if (vdso_file->error)
 218                 return NULL;
 219
 220         err = vdso__create_compat_file(vdso_file->read_prog,
 221                                        vdso_file->temp_file_name);
 222         if (err) {
 223                 pr_err("%s failed, error %d\n", vdso_file->read_prog, err);
 224                 vdso_file->error = true;
 225                 return NULL;
 226         }
 227
 228         vdso_file->found = true;
 229
 230         return vdso_file->temp_file_name;
 231 }
 232
 233 static struct dso *__machine__findnew_compat(struct machine *machine,
 234                                              struct vdso_file *vdso_file)
 235 {
 236         const char *file_name;
 237         struct dso *dso;
 238
 239         dso = __dsos__find(&machine->dsos, vdso_file->dso_name, true);
 240         if (dso)
 241                 goto out;
 242
 243         file_name = vdso__get_compat_file(vdso_file);
 244         if (!file_name)
 245                 goto out;
 246
 247         dso = __machine__addnew_vdso(machine, vdso_file->dso_name, file_name);
 248 out:
 249         return dso;
 250 }
 251
 252 static int __machine__findnew_vdso_compat(struct machine *machine,
 253                                           struct thread *thread,
 254                                           struct vdso_info *vdso_info,
 255                                           struct dso **dso)
 256 {
 257         enum dso_type dso_type;
 258
 259         dso_type = machine__thread_dso_type(machine, thread);
 260
 261 #ifndef HAVE_PERF_READ_VDSO32
 262         if (dso_type == DSO__TYPE_32BIT)
 263                 return 0;
 264 #endif
 265 #ifndef HAVE_PERF_READ_VDSOX32
 266         if (dso_type == DSO__TYPE_X32BIT)
 267                 return 0;
 268 #endif
 269
 270         switch (dso_type) {
 271         case DSO__TYPE_32BIT:
 272                 *dso = __machine__findnew_compat(machine, &vdso_info->vdso32);
 273                 return 1;
 274         case DSO__TYPE_X32BIT:
 275                 *dso = __machine__findnew_compat(machine, &vdso_info->vdsox32);
 276                 return 1;
 277         case DSO__TYPE_UNKNOWN:
 278         case DSO__TYPE_64BIT:
 279         default:
 280                 return 0;
 281         }
 282 }
 283
 284 #endif
 285
 286 struct dso *machine__findnew_vdso(struct machine *machine,
 287                                   struct thread *thread __maybe_unused)
 288 {
 289         struct vdso_info *vdso_info;
 290         struct dso *dso = NULL;
 291
 292         pthread_rwlock_wrlock(&machine->dsos.lock);
 293         if (!machine->vdso_info)
 294                 machine->vdso_info = vdso_info__new();
 295
 296         vdso_info = machine->vdso_info;
 297         if (!vdso_info)
 298                 goto out_unlock;
 299
 300 #if BITS_PER_LONG == 64
 301         if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
 302                 goto out_unlock;
 303 #endif
 304
 305         dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 306         if (!dso) {
 307                 char *file;
 308
 309                 file = get_file(&vdso_info->vdso);
 310                 if (file)
 311                         dso = __machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
 312         }
 313
 314 out_unlock:
 315         dso__get(dso);
 316         pthread_rwlock_unlock(&machine->dsos.lock);
 317         return dso;
 318 }
 319
 320 bool dso__is_vdso(struct dso *dso)
 321 {
 322         return !strcmp(dso->short_name, DSO__NAME_VDSO) ||
 323                !strcmp(dso->short_name, DSO__NAME_VDSO32) ||
 324                !strcmp(dso->short_name, DSO__NAME_VDSOX32);
 325 }