tools/perf/util/vdso.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <errno.h>
   3 #include <unistd.h>
   4 #include <stdio.h>
   5 #include <string.h>
   6 #include <sys/types.h>
   7 #include <sys/stat.h>
   8 #include <fcntl.h>
   9 #include <stdlib.h>
  10 #include <linux/kernel.h>
  11
  12 #include "vdso.h"
  13 #include "util.h"
  14 #include "map.h"
  15 #include "symbol.h"
  16 #include "machine.h"
  17 #include "thread.h"
  18 #include "linux/string.h"
  19 #include "debug.h"
  20
  21 /*
  22  * Include definition of find_map() also used in perf-read-vdso.c for
  23  * building perf-read-vdso32 and perf-read-vdsox32.
  24  */
  25 #include "find-map.c"
  26
  27 #define VDSO__TEMP_FILE_NAME "/tmp/perf-vdso.so-XXXXXX"
  28
  29 struct vdso_file {
  30         bool found;
  31         bool error;
  32         char temp_file_name[sizeof(VDSO__TEMP_FILE_NAME)];
  33         const char *dso_name;
  34         const char *read_prog;
  35 };
  36
  37 struct vdso_info {
  38         struct vdso_file vdso;
  39 #if BITS_PER_LONG == 64
  40         struct vdso_file vdso32;
  41         struct vdso_file vdsox32;
  42 #endif
  43 };
  44
  45 static struct vdso_info *vdso_info__new(void)
  46 {
  47         static const struct vdso_info vdso_info_init = {
  48                 .vdso    = {
  49                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  50                         .dso_name = DSO__NAME_VDSO,
  51                 },
  52 #if BITS_PER_LONG == 64
  53                 .vdso32  = {
  54                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  55                         .dso_name = DSO__NAME_VDSO32,
  56                         .read_prog = "perf-read-vdso32",
  57                 },
  58                 .vdsox32  = {
  59                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  60                         .dso_name = DSO__NAME_VDSOX32,
  61                         .read_prog = "perf-read-vdsox32",
  62                 },
  63 #endif
  64         };
  65
  66         return memdup(&vdso_info_init, sizeof(vdso_info_init));
  67 }
  68
  69 static char *get_file(struct vdso_file *vdso_file)
  70 {
  71         char *vdso = NULL;
  72         char *buf = NULL;
  73         void *start, *end;
  74         size_t size;
  75         int fd;
  76
  77         if (vdso_file->found)
  78                 return vdso_file->temp_file_name;
  79
  80         if (vdso_file->error || find_map(&start, &end, VDSO__MAP_NAME))
  81                 return NULL;
  82
  83         size = end - start;
  84
  85         buf = memdup(start, size);
  86         if (!buf)
  87                 return NULL;
  88
  89         fd = mkstemp(vdso_file->temp_file_name);
  90         if (fd < 0)
  91                 goto out;
  92
  93         if (size == (size_t) write(fd, buf, size))
  94                 vdso = vdso_file->temp_file_name;
  95
  96         close(fd);
  97
  98  out:
  99         free(buf);
 100
 101         vdso_file->found = (vdso != NULL);
 102         vdso_file->error = !vdso_file->found;
 103         return vdso;
 104 }
 105
 106 void machine__exit_vdso(struct machine *machine)
 107 {
 108         struct vdso_info *vdso_info = machine->vdso_info;
 109
 110         if (!vdso_info)
 111                 return;
 112
 113         if (vdso_info->vdso.found)
 114                 unlink(vdso_info->vdso.temp_file_name);
 115 #if BITS_PER_LONG == 64
 116         if (vdso_info->vdso32.found)
 117                 unlink(vdso_info->vdso32.temp_file_name);
 118         if (vdso_info->vdsox32.found)
 119                 unlink(vdso_info->vdsox32.temp_file_name);
 120 #endif
 121
 122         zfree(&machine->vdso_info);
 123 }
 124
 125 static struct dso *__machine__addnew_vdso(struct machine *machine, const char *short_name,
 126                                           const char *long_name)
 127 {
 128         struct dso *dso;
 129
 130         dso = dso__new(short_name);
 131         if (dso != NULL) {
 132                 __dsos__add(&machine->dsos, dso);
 133                 dso__set_long_name(dso, long_name, false);
 134         }
 135
 136         return dso;
 137 }
 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 = map_groups__first(thread->mg);
 144
 145         for (; map ; map = map_groups__next(map)) {
 146                 struct dso *dso = map->dso;
 147                 if (!dso || dso->long_name[0] != '/')
 148                         continue;
 149                 dso_type = dso__type(dso, machine);
 150                 if (dso_type != DSO__TYPE_UNKNOWN)
 151                         break;
 152         }
 153
 154         return dso_type;
 155 }
 156
 157 #if BITS_PER_LONG == 64
 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 static struct dso *machine__find_vdso(struct machine *machine,
 287                                       struct thread *thread)
 288 {
 289         struct dso *dso = NULL;
 290         enum dso_type dso_type;
 291
 292         dso_type = machine__thread_dso_type(machine, thread);
 293         switch (dso_type) {
 294         case DSO__TYPE_32BIT:
 295                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO32, true);
 296                 if (!dso) {
 297                         dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
 298                                            true);
 299                         if (dso && dso_type != dso__type(dso, machine))
 300                                 dso = NULL;
 301                 }
 302                 break;
 303         case DSO__TYPE_X32BIT:
 304                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSOX32, true);
 305                 break;
 306         case DSO__TYPE_64BIT:
 307         case DSO__TYPE_UNKNOWN:
 308         default:
 309                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 310                 break;
 311         }
 312
 313         return dso;
 314 }
 315
 316 struct dso *machine__findnew_vdso(struct machine *machine,
 317                                   struct thread *thread)
 318 {
 319         struct vdso_info *vdso_info;
 320         struct dso *dso = NULL;
 321
 322         down_write(&machine->dsos.lock);
 323         if (!machine->vdso_info)
 324                 machine->vdso_info = vdso_info__new();
 325
 326         vdso_info = machine->vdso_info;
 327         if (!vdso_info)
 328                 goto out_unlock;
 329
 330         dso = machine__find_vdso(machine, thread);
 331         if (dso)
 332                 goto out_unlock;
 333
 334 #if BITS_PER_LONG == 64
 335         if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
 336                 goto out_unlock;
 337 #endif
 338
 339         dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 340         if (!dso) {
 341                 char *file;
 342
 343                 file = get_file(&vdso_info->vdso);
 344                 if (file)
 345                         dso = __machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
 346         }
 347
 348 out_unlock:
 349         dso__get(dso);
 350         up_write(&machine->dsos.lock);
 351         return dso;
 352 }
 353
 354 bool dso__is_vdso(struct dso *dso)
 355 {
 356         return !strcmp(dso->short_name, DSO__NAME_VDSO) ||
 357                !strcmp(dso->short_name, DSO__NAME_VDSO32) ||
 358                !strcmp(dso->short_name, DSO__NAME_VDSOX32);
 359 }