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 "dso.h"
  14 #include <internal/lib.h>
  15 #include "map.h"
  16 #include "symbol.h"
  17 #include "machine.h"
  18 #include "thread.h"
  19 #include "linux/string.h"
  20 #include <linux/zalloc.h>
  21 #include "debug.h"
  22
  23 /*
  24  * Include definition of find_map() also used in perf-read-vdso.c for
  25  * building perf-read-vdso32 and perf-read-vdsox32.
  26  */
  27 #include "find-map.c"
  28
  29 #define VDSO__TEMP_FILE_NAME "/tmp/perf-vdso.so-XXXXXX"
  30
  31 struct vdso_file {
  32         bool found;
  33         bool error;
  34         char temp_file_name[sizeof(VDSO__TEMP_FILE_NAME)];
  35         const char *dso_name;
  36         const char *read_prog;
  37 };
  38
  39 struct vdso_info {
  40         struct vdso_file vdso;
  41 #if BITS_PER_LONG == 64
  42         struct vdso_file vdso32;
  43         struct vdso_file vdsox32;
  44 #endif
  45 };
  46
  47 static struct vdso_info *vdso_info__new(void)
  48 {
  49         static const struct vdso_info vdso_info_init = {
  50                 .vdso    = {
  51                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  52                         .dso_name = DSO__NAME_VDSO,
  53                 },
  54 #if BITS_PER_LONG == 64
  55                 .vdso32  = {
  56                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  57                         .dso_name = DSO__NAME_VDSO32,
  58                         .read_prog = "perf-read-vdso32",
  59                 },
  60                 .vdsox32  = {
  61                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  62                         .dso_name = DSO__NAME_VDSOX32,
  63                         .read_prog = "perf-read-vdsox32",
  64                 },
  65 #endif
  66         };
  67
  68         return memdup(&vdso_info_init, sizeof(vdso_info_init));
  69 }
  70
  71 static char *get_file(struct vdso_file *vdso_file)
  72 {
  73         char *vdso = NULL;
  74         char *buf = NULL;
  75         void *start, *end;
  76         size_t size;
  77         int fd;
  78
  79         if (vdso_file->found)
  80                 return vdso_file->temp_file_name;
  81
  82         if (vdso_file->error || find_map(&start, &end, VDSO__MAP_NAME))
  83                 return NULL;
  84
  85         size = end - start;
  86
  87         buf = memdup(start, size);
  88         if (!buf)
  89                 return NULL;
  90
  91         fd = mkstemp(vdso_file->temp_file_name);
  92         if (fd < 0)
  93                 goto out;
  94
  95         if (size == (size_t) write(fd, buf, size))
  96                 vdso = vdso_file->temp_file_name;
  97
  98         close(fd);
  99
 100  out:
 101         free(buf);
 102
 103         vdso_file->found = (vdso != NULL);
 104         vdso_file->error = !vdso_file->found;
 105         return vdso;
 106 }
 107
 108 void machine__exit_vdso(struct machine *machine)
 109 {
 110         struct vdso_info *vdso_info = machine->vdso_info;
 111
 112         if (!vdso_info)
 113                 return;
 114
 115         if (vdso_info->vdso.found)
 116                 unlink(vdso_info->vdso.temp_file_name);
 117 #if BITS_PER_LONG == 64
 118         if (vdso_info->vdso32.found)
 119                 unlink(vdso_info->vdso32.temp_file_name);
 120         if (vdso_info->vdsox32.found)
 121                 unlink(vdso_info->vdsox32.temp_file_name);
 122 #endif
 123
 124         zfree(&machine->vdso_info);
 125 }
 126
 127 static struct dso *__machine__addnew_vdso(struct machine *machine, const char *short_name,
 128                                           const char *long_name)
 129 {
 130         struct dso *dso;
 131
 132         dso = dso__new(short_name);
 133         if (dso != NULL) {
 134                 __dsos__add(&machine->dsos, dso);
 135                 dso__set_long_name(dso, long_name, false);
 136         }
 137
 138         return dso;
 139 }
 140
 141 struct machine__thread_dso_type_maps_cb_args {
 142         struct machine *machine;
 143         enum dso_type dso_type;
 144 };
 145
 146 static int machine__thread_dso_type_maps_cb(struct map *map, void *data)
 147 {
 148         struct machine__thread_dso_type_maps_cb_args *args = data;
 149         struct dso *dso = map__dso(map);
 150
 151         if (!dso || dso__long_name(dso)[0] != '/')
 152                 return 0;
 153
 154         args->dso_type = dso__type(dso, args->machine);
 155         return (args->dso_type != DSO__TYPE_UNKNOWN) ? 1 : 0;
 156 }
 157
 158 static enum dso_type machine__thread_dso_type(struct machine *machine,
 159                                               struct thread *thread)
 160 {
 161         struct machine__thread_dso_type_maps_cb_args args = {
 162                 .machine = machine,
 163                 .dso_type = DSO__TYPE_UNKNOWN,
 164         };
 165
 166         maps__for_each_map(thread__maps(thread), machine__thread_dso_type_maps_cb, &args);
 167
 168         return args.dso_type;
 169 }
 170
 171 #if BITS_PER_LONG == 64
 172
 173 static int vdso__do_copy_compat(FILE *f, int fd)
 174 {
 175         char buf[4096];
 176         size_t count;
 177
 178         while (1) {
 179                 count = fread(buf, 1, sizeof(buf), f);
 180                 if (ferror(f))
 181                         return -errno;
 182                 if (feof(f))
 183                         break;
 184                 if (count && writen(fd, buf, count) != (ssize_t)count)
 185                         return -errno;
 186         }
 187
 188         return 0;
 189 }
 190
 191 static int vdso__copy_compat(const char *prog, int fd)
 192 {
 193         FILE *f;
 194         int err;
 195
 196         f = popen(prog, "r");
 197         if (!f)
 198                 return -errno;
 199
 200         err = vdso__do_copy_compat(f, fd);
 201
 202         if (pclose(f) == -1)
 203                 return -errno;
 204
 205         return err;
 206 }
 207
 208 static int vdso__create_compat_file(const char *prog, char *temp_name)
 209 {
 210         int fd, err;
 211
 212         fd = mkstemp(temp_name);
 213         if (fd < 0)
 214                 return -errno;
 215
 216         err = vdso__copy_compat(prog, fd);
 217
 218         if (close(fd) == -1)
 219                 return -errno;
 220
 221         return err;
 222 }
 223
 224 static const char *vdso__get_compat_file(struct vdso_file *vdso_file)
 225 {
 226         int err;
 227
 228         if (vdso_file->found)
 229                 return vdso_file->temp_file_name;
 230
 231         if (vdso_file->error)
 232                 return NULL;
 233
 234         err = vdso__create_compat_file(vdso_file->read_prog,
 235                                        vdso_file->temp_file_name);
 236         if (err) {
 237                 pr_err("%s failed, error %d\n", vdso_file->read_prog, err);
 238                 vdso_file->error = true;
 239                 return NULL;
 240         }
 241
 242         vdso_file->found = true;
 243
 244         return vdso_file->temp_file_name;
 245 }
 246
 247 static struct dso *__machine__findnew_compat(struct machine *machine,
 248                                              struct vdso_file *vdso_file)
 249 {
 250         const char *file_name;
 251         struct dso *dso;
 252
 253         dso = dsos__find(&machine->dsos, vdso_file->dso_name, true);
 254         if (dso)
 255                 return dso;
 256
 257         file_name = vdso__get_compat_file(vdso_file);
 258         if (!file_name)
 259                 return NULL;
 260
 261         return __machine__addnew_vdso(machine, vdso_file->dso_name, file_name);
 262 }
 263
 264 static int __machine__findnew_vdso_compat(struct machine *machine,
 265                                           struct thread *thread,
 266                                           struct vdso_info *vdso_info,
 267                                           struct dso **dso)
 268 {
 269         enum dso_type dso_type;
 270
 271         dso_type = machine__thread_dso_type(machine, thread);
 272
 273 #ifndef HAVE_PERF_READ_VDSO32
 274         if (dso_type == DSO__TYPE_32BIT)
 275                 return 0;
 276 #endif
 277 #ifndef HAVE_PERF_READ_VDSOX32
 278         if (dso_type == DSO__TYPE_X32BIT)
 279                 return 0;
 280 #endif
 281
 282         switch (dso_type) {
 283         case DSO__TYPE_32BIT:
 284                 *dso = __machine__findnew_compat(machine, &vdso_info->vdso32);
 285                 return 1;
 286         case DSO__TYPE_X32BIT:
 287                 *dso = __machine__findnew_compat(machine, &vdso_info->vdsox32);
 288                 return 1;
 289         case DSO__TYPE_UNKNOWN:
 290         case DSO__TYPE_64BIT:
 291         default:
 292                 return 0;
 293         }
 294 }
 295
 296 #endif
 297
 298 static struct dso *machine__find_vdso(struct machine *machine,
 299                                       struct thread *thread)
 300 {
 301         struct dso *dso = NULL;
 302         enum dso_type dso_type;
 303
 304         dso_type = machine__thread_dso_type(machine, thread);
 305         switch (dso_type) {
 306         case DSO__TYPE_32BIT:
 307                 dso = dsos__find(&machine->dsos, DSO__NAME_VDSO32, true);
 308                 if (!dso) {
 309                         dso = dsos__find(&machine->dsos, DSO__NAME_VDSO,
 310                                          true);
 311                         if (dso && dso_type != dso__type(dso, machine))
 312                                 dso = NULL;
 313                 }
 314                 break;
 315         case DSO__TYPE_X32BIT:
 316                 dso = dsos__find(&machine->dsos, DSO__NAME_VDSOX32, true);
 317                 break;
 318         case DSO__TYPE_64BIT:
 319         case DSO__TYPE_UNKNOWN:
 320         default:
 321                 dso = dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 322                 break;
 323         }
 324
 325         return dso;
 326 }
 327
 328 struct dso *machine__findnew_vdso(struct machine *machine,
 329                                   struct thread *thread)
 330 {
 331         struct vdso_info *vdso_info;
 332         struct dso *dso = NULL;
 333         char *file;
 334
 335         if (!machine->vdso_info)
 336                 machine->vdso_info = vdso_info__new();
 337
 338         vdso_info = machine->vdso_info;
 339         if (!vdso_info)
 340                 return NULL;
 341
 342         dso = machine__find_vdso(machine, thread);
 343         if (dso)
 344                 return dso;
 345
 346 #if BITS_PER_LONG == 64
 347         if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
 348                 return dso;
 349 #endif
 350
 351         dso = dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 352         if (dso)
 353                 return dso;
 354
 355         file = get_file(&vdso_info->vdso);
 356         if (!file)
 357                 return NULL;
 358
 359         return __machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
 360 }
 361
 362 bool dso__is_vdso(struct dso *dso)
 363 {
 364         return !strcmp(dso__short_name(dso), DSO__NAME_VDSO) ||
 365                !strcmp(dso__short_name(dso), DSO__NAME_VDSO32) ||
 366                !strcmp(dso__short_name(dso), DSO__NAME_VDSOX32);
 367 }