src/drm-shim/drm_shim.c

   1 /*
   2  * Copyright © 2018 Broadcom
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 /**
  25  * @file
  26  *
  27  * Implements wrappers of libc functions to fake having a DRM device that
  28  * isn't actually present in the kernel.
  29  */
  30
  31 /* Prevent glibc from defining open64 when we want to alias it. */
  32 #undef _FILE_OFFSET_BITS
  33 #define _LARGEFILE64_SOURCE
  34
  35 #include <stdbool.h>
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39 #include <unistd.h>
  40 #include <sys/ioctl.h>
  41 #include <sys/mman.h>
  42 #include <sys/stat.h>
  43 #include <sys/sysmacros.h>
  44 #include <stdarg.h>
  45 #include <fcntl.h>
  46 #include <dlfcn.h>
  47 #include <dirent.h>
  48 #include <c11/threads.h>
  49 #include <drm-uapi/drm.h>
  50
  51 #include "util/set.h"
  52 #include "util/u_debug.h"
  53 #include "drm_shim.h"
  54
  55 #define REAL_FUNCTION_POINTER(x) typeof(x) *real_##x
  56
  57 static mtx_t shim_lock = _MTX_INITIALIZER_NP;
  58 struct set *opendir_set;
  59 bool drm_shim_debug;
  60
  61 /* If /dev/dri doesn't exist, we'll need an arbitrary pointer that wouldn't be
  62  * returned by any other opendir() call so we can return just our fake node.
  63  */
  64 DIR *fake_dev_dri = (void *)&opendir_set;
  65
  66 /* XXX: implement REAL_FUNCTION_POINTER(close); */
  67 REAL_FUNCTION_POINTER(closedir);
  68 REAL_FUNCTION_POINTER(dup);
  69 REAL_FUNCTION_POINTER(fcntl);
  70 REAL_FUNCTION_POINTER(fopen);
  71 REAL_FUNCTION_POINTER(ioctl);
  72 REAL_FUNCTION_POINTER(mmap);
  73 REAL_FUNCTION_POINTER(open);
  74 REAL_FUNCTION_POINTER(opendir);
  75 REAL_FUNCTION_POINTER(readdir);
  76 REAL_FUNCTION_POINTER(readdir64);
  77 REAL_FUNCTION_POINTER(readlink);
  78 REAL_FUNCTION_POINTER(realpath);
  79 REAL_FUNCTION_POINTER(__xstat);
  80 REAL_FUNCTION_POINTER(__xstat64);
  81 REAL_FUNCTION_POINTER(__fxstat);
  82 REAL_FUNCTION_POINTER(__fxstat64);
  83
  84 /* Full path of /dev/dri/renderD* */
  85 static char *render_node_path;
  86 /* renderD* */
  87 static char *render_node_dirent_name;
  88 /* /sys/dev/char/major:minor/device */
  89 static char *device_path;
  90 /* /sys/dev/char/major:minor/device/subsystem */
  91 static char *subsystem_path;
  92 int render_node_minor = -1;
  93
  94 struct file_override {
  95    const char *path;
  96    char *contents;
  97 };
  98 static struct file_override file_overrides[10];
  99 static int file_overrides_count;
 100
 101 /* Come up with a filename for a render node that doesn't actually exist on
 102  * the system.
 103  */
 104 static void
 105 get_dri_render_node_minor(void)
 106 {
 107    for (int i = 0; i < 10; i++) {
 108       int minor = 128 + i;
 109       asprintf(&render_node_dirent_name, "renderD%d", minor);
 110       asprintf(&render_node_path, "/dev/dri/%s",
 111                render_node_dirent_name);
 112       struct stat st;
 113       if (stat(render_node_path, &st) == -1) {
 114
 115          render_node_minor = minor;
 116          return;
 117       }
 118    }
 119
 120    fprintf(stderr, "Couldn't find a spare render node slot\n");
 121 }
 122
 123 static void *get_function_pointer(const char *name)
 124 {
 125    void *func = dlsym(RTLD_NEXT, name);
 126    if (!func) {
 127       fprintf(stderr, "Failed to resolve %s\n", name);
 128       abort();
 129    }
 130    return func;
 131 }
 132
 133 #define GET_FUNCTION_POINTER(x) real_##x = get_function_pointer(#x)
 134
 135 void
 136 drm_shim_override_file(const char *contents, const char *path_format, ...)
 137 {
 138    assert(file_overrides_count < ARRAY_SIZE(file_overrides));
 139
 140    char *path;
 141    va_list ap;
 142    va_start(ap, path_format);
 143    vasprintf(&path, path_format, ap);
 144    va_end(ap);
 145
 146    struct file_override *override = &file_overrides[file_overrides_count++];
 147    override->path = path;
 148    override->contents = strdup(contents);
 149 }
 150
 151 static void
 152 destroy_shim(void)
 153 {
 154    _mesa_set_destroy(opendir_set, NULL);
 155    free(render_node_path);
 156    free(render_node_dirent_name);
 157    free(subsystem_path);
 158 }
 159
 160 /* Initialization, which will be called from the first general library call
 161  * that might need to be wrapped with the shim.
 162  */
 163 static void
 164 init_shim(void)
 165 {
 166    static bool inited = false;
 167    drm_shim_debug = debug_get_bool_option("DRM_SHIM_DEBUG", false);
 168
 169    /* We can't lock this, because we recurse during initialization. */
 170    if (inited)
 171       return;
 172
 173    /* This comes first (and we're locked), to make sure we don't recurse
 174     * during initialization.
 175     */
 176    inited = true;
 177
 178    opendir_set = _mesa_set_create(NULL,
 179                                   _mesa_hash_string,
 180                                   _mesa_key_string_equal);
 181
 182    GET_FUNCTION_POINTER(closedir);
 183    GET_FUNCTION_POINTER(dup);
 184    GET_FUNCTION_POINTER(fcntl);
 185    GET_FUNCTION_POINTER(fopen);
 186    GET_FUNCTION_POINTER(ioctl);
 187    GET_FUNCTION_POINTER(mmap);
 188    GET_FUNCTION_POINTER(open);
 189    GET_FUNCTION_POINTER(opendir);
 190    GET_FUNCTION_POINTER(readdir);
 191    GET_FUNCTION_POINTER(readdir64);
 192    GET_FUNCTION_POINTER(readlink);
 193    GET_FUNCTION_POINTER(realpath);
 194    GET_FUNCTION_POINTER(__xstat);
 195    GET_FUNCTION_POINTER(__xstat64);
 196    GET_FUNCTION_POINTER(__fxstat);
 197    GET_FUNCTION_POINTER(__fxstat64);
 198
 199    get_dri_render_node_minor();
 200
 201    if (drm_shim_debug) {
 202       fprintf(stderr, "Initializing DRM shim on %s\n",
 203               render_node_path);
 204    }
 205
 206    asprintf(&device_path,
 207             "/sys/dev/char/%d:%d/device",
 208             DRM_MAJOR, render_node_minor);
 209
 210    asprintf(&subsystem_path,
 211             "/sys/dev/char/%d:%d/device/subsystem",
 212             DRM_MAJOR, render_node_minor);
 213
 214    drm_shim_device_init();
 215
 216    atexit(destroy_shim);
 217 }
 218
 219 /* Override libdrm's reading of various sysfs files for device enumeration. */
 220 PUBLIC FILE *fopen(const char *path, const char *mode)
 221 {
 222    init_shim();
 223
 224    for (int i = 0; i < file_overrides_count; i++) {
 225       if (strcmp(file_overrides[i].path, path) == 0) {
 226          int fds[2];
 227          pipe(fds);
 228          write(fds[1], file_overrides[i].contents,
 229                strlen(file_overrides[i].contents));
 230          close(fds[1]);
 231          return fdopen(fds[0], "r");
 232       }
 233    }
 234
 235    return real_fopen(path, mode);
 236 }
 237 PUBLIC FILE *fopen64(const char *path, const char *mode)
 238    __attribute__((alias("fopen")));
 239
 240 /* Intercepts open(render_node_path) to redirect it to the simulator. */
 241 PUBLIC int open(const char *path, int flags, ...)
 242 {
 243    init_shim();
 244
 245    va_list ap;
 246    va_start(ap, flags);
 247    mode_t mode = va_arg(ap, mode_t);
 248    va_end(ap);
 249
 250    if (strcmp(path, render_node_path) != 0)
 251       return real_open(path, flags, mode);
 252
 253    int fd = real_open("/dev/null", O_RDWR, 0);
 254
 255    drm_shim_fd_register(fd, NULL);
 256
 257    return fd;
 258 }
 259 PUBLIC int open64(const char*, int, ...) __attribute__((alias("open")));
 260
 261 /* Fakes stat to return character device stuff for our fake render node. */
 262 PUBLIC int __xstat(int ver, const char *path, struct stat *st)
 263 {
 264    init_shim();
 265
 266    /* Note: call real stat if we're in the process of probing for a free
 267     * render node!
 268     */
 269    if (render_node_minor == -1)
 270       return real___xstat(ver, path, st);
 271
 272    /* Fool libdrm's probe of whether the /sys dir for this char dev is
 273     * there.
 274     */
 275    char *sys_dev_drm_dir;
 276    asprintf(&sys_dev_drm_dir, "/sys/dev/char/%d:%d/device/drm",
 277             DRM_MAJOR, render_node_minor);
 278    if (strcmp(path, sys_dev_drm_dir) == 0) {
 279       free(sys_dev_drm_dir);
 280       return 0;
 281    }
 282    free(sys_dev_drm_dir);
 283
 284    if (strcmp(path, render_node_path) != 0)
 285       return real___xstat(ver, path, st);
 286
 287    memset(st, 0, sizeof(*st));
 288    st->st_rdev = makedev(DRM_MAJOR, render_node_minor);
 289    st->st_mode = S_IFCHR;
 290
 291    return 0;
 292 }
 293
 294 /* Fakes stat to return character device stuff for our fake render node. */
 295 PUBLIC int __xstat64(int ver, const char *path, struct stat64 *st)
 296 {
 297    init_shim();
 298
 299    /* Note: call real stat if we're in the process of probing for a free
 300     * render node!
 301     */
 302    if (render_node_minor == -1)
 303       return real___xstat64(ver, path, st);
 304
 305    /* Fool libdrm's probe of whether the /sys dir for this char dev is
 306     * there.
 307     */
 308    char *sys_dev_drm_dir;
 309    asprintf(&sys_dev_drm_dir, "/sys/dev/char/%d:%d/device/drm",
 310             DRM_MAJOR, render_node_minor);
 311    if (strcmp(path, sys_dev_drm_dir) == 0) {
 312       free(sys_dev_drm_dir);
 313       return 0;
 314    }
 315    free(sys_dev_drm_dir);
 316
 317    if (strcmp(path, render_node_path) != 0)
 318       return real___xstat64(ver, path, st);
 319
 320    memset(st, 0, sizeof(*st));
 321    st->st_rdev = makedev(DRM_MAJOR, render_node_minor);
 322    st->st_mode = S_IFCHR;
 323
 324    return 0;
 325 }
 326
 327 /* Fakes fstat to return character device stuff for our fake render node. */
 328 PUBLIC int __fxstat(int ver, int fd, struct stat *st)
 329 {
 330    init_shim();
 331
 332    struct shim_fd *shim_fd = drm_shim_fd_lookup(fd);
 333
 334    if (!shim_fd)
 335       return real___fxstat(ver, fd, st);
 336
 337    memset(st, 0, sizeof(*st));
 338    st->st_rdev = makedev(DRM_MAJOR, render_node_minor);
 339    st->st_mode = S_IFCHR;
 340
 341    return 0;
 342 }
 343
 344 PUBLIC int __fxstat64(int ver, int fd, struct stat64 *st)
 345 {
 346    init_shim();
 347
 348    struct shim_fd *shim_fd = drm_shim_fd_lookup(fd);
 349
 350    if (!shim_fd)
 351       return real___fxstat64(ver, fd, st);
 352
 353    memset(st, 0, sizeof(*st));
 354    st->st_rdev = makedev(DRM_MAJOR, render_node_minor);
 355    st->st_mode = S_IFCHR;
 356
 357    return 0;
 358 }
 359
 360 /* Tracks if the opendir was on /dev/dri. */
 361 PUBLIC DIR *
 362 opendir(const char *name)
 363 {
 364    init_shim();
 365
 366    DIR *dir = real_opendir(name);
 367    if (strcmp(name, "/dev/dri") == 0) {
 368       if (!dir) {
 369          /* If /dev/dri didn't exist, we still want to be able to return our
 370           * fake /dev/dri/render* even though we probably can't
 371           * mkdir("/dev/dri").  Return a fake DIR pointer for that.
 372           */
 373          dir = fake_dev_dri;
 374       }
 375
 376       mtx_lock(&shim_lock);
 377       _mesa_set_add(opendir_set, dir);
 378       mtx_unlock(&shim_lock);
 379    }
 380
 381    return dir;
 382 }
 383
 384 /* If we've reached the end of the real directory list and we're
 385  * looking at /dev/dri, add our render node to the list.
 386  */
 387 PUBLIC struct dirent *
 388 readdir(DIR *dir)
 389 {
 390    init_shim();
 391
 392    struct dirent *ent = NULL;
 393
 394    if (dir != fake_dev_dri)
 395       ent = real_readdir(dir);
 396    static struct dirent render_node_dirent = { 0 };
 397
 398    if (!ent) {
 399       mtx_lock(&shim_lock);
 400       if (_mesa_set_search(opendir_set, dir)) {
 401          strcpy(render_node_dirent.d_name,
 402                 render_node_dirent_name);
 403          ent = &render_node_dirent;
 404          _mesa_set_remove_key(opendir_set, dir);
 405       }
 406       mtx_unlock(&shim_lock);
 407    }
 408
 409    return ent;
 410 }
 411
 412 /* If we've reached the end of the real directory list and we're
 413  * looking at /dev/dri, add our render node to the list.
 414  */
 415 PUBLIC struct dirent64 *
 416 readdir64(DIR *dir)
 417 {
 418    init_shim();
 419
 420    struct dirent64 *ent = NULL;
 421    if (dir != fake_dev_dri)
 422       ent = real_readdir64(dir);
 423    static struct dirent64 render_node_dirent = { 0 };
 424
 425    if (!ent) {
 426       mtx_lock(&shim_lock);
 427       if (_mesa_set_search(opendir_set, dir)) {
 428          strcpy(render_node_dirent.d_name,
 429                 render_node_dirent_name);
 430          ent = &render_node_dirent;
 431          _mesa_set_remove_key(opendir_set, dir);
 432       }
 433       mtx_unlock(&shim_lock);
 434    }
 435
 436    return ent;
 437 }
 438
 439 /* Cleans up tracking of opendir("/dev/dri") */
 440 PUBLIC int
 441 closedir(DIR *dir)
 442 {
 443    init_shim();
 444
 445    mtx_lock(&shim_lock);
 446    _mesa_set_remove_key(opendir_set, dir);
 447    mtx_unlock(&shim_lock);
 448
 449    if (dir != fake_dev_dri)
 450       return real_closedir(dir);
 451    else
 452       return 0;
 453 }
 454
 455 /* Handles libdrm's readlink to figure out what kind of device we have. */
 456 PUBLIC ssize_t
 457 readlink(const char *path, char *buf, size_t size)
 458 {
 459    init_shim();
 460
 461    if (strcmp(path, subsystem_path) != 0)
 462       return real_readlink(path, buf, size);
 463
 464    static const struct {
 465       const char *name;
 466       int bus_type;
 467    } bus_types[] = {
 468       { "/pci", DRM_BUS_PCI },
 469       { "/usb", DRM_BUS_USB },
 470       { "/platform", DRM_BUS_PLATFORM },
 471       { "/spi", DRM_BUS_PLATFORM },
 472       { "/host1x", DRM_BUS_HOST1X },
 473    };
 474
 475    for (uint32_t i = 0; i < ARRAY_SIZE(bus_types); i++) {
 476       if (bus_types[i].bus_type != shim_device.bus_type)
 477          continue;
 478
 479       strncpy(buf, bus_types[i].name, size);
 480       buf[size - 1] = 0;
 481       break;
 482    }
 483
 484    return strlen(buf) + 1;
 485 }
 486
 487 /* Handles libdrm's realpath to figure out what kind of device we have. */
 488 PUBLIC char *
 489 realpath(const char *path, char *resolved_path)
 490 {
 491    init_shim();
 492
 493    if (strcmp(path, device_path) != 0)
 494       return real_realpath(path, resolved_path);
 495
 496    strcpy(resolved_path, path);
 497
 498    return resolved_path;
 499 }
 500
 501 /* Main entrypoint to DRM drivers: the ioctl syscall.  We send all ioctls on
 502  * our DRM fd to drm_shim_ioctl().
 503  */
 504 PUBLIC int
 505 ioctl(int fd, unsigned long request, ...)
 506 {
 507    init_shim();
 508
 509    va_list ap;
 510    va_start(ap, request);
 511    void *arg = va_arg(ap, void *);
 512    va_end(ap);
 513
 514    struct shim_fd *shim_fd = drm_shim_fd_lookup(fd);
 515    if (!shim_fd)
 516       return real_ioctl(fd, request, arg);
 517
 518    return drm_shim_ioctl(fd, request, arg);
 519 }
 520
 521 /* Gallium uses this to dup the incoming fd on gbm screen creation */
 522 PUBLIC int
 523 fcntl(int fd, int cmd, ...)
 524 {
 525    init_shim();
 526
 527    struct shim_fd *shim_fd = drm_shim_fd_lookup(fd);
 528
 529    va_list ap;
 530    va_start(ap, cmd);
 531    void *arg = va_arg(ap, void *);
 532    va_end(ap);
 533
 534    int ret = real_fcntl(fd, cmd, arg);
 535
 536    if (shim_fd && (cmd == F_DUPFD || cmd == F_DUPFD_CLOEXEC))
 537       drm_shim_fd_register(ret, shim_fd);
 538
 539    return ret;
 540 }
 541 PUBLIC int fcntl64(int, int, ...)
 542    __attribute__((alias("fcntl")));
 543
 544 /* I wrote this when trying to fix gallium screen creation, leaving it around
 545  * since it's probably good to have.
 546  */
 547 PUBLIC int
 548 dup(int fd)
 549 {
 550    init_shim();
 551
 552    int ret = real_dup(fd);
 553
 554    struct shim_fd *shim_fd = drm_shim_fd_lookup(fd);
 555    if (shim_fd && ret >= 0)
 556       drm_shim_fd_register(ret, shim_fd);
 557
 558    return ret;
 559 }
 560
 561 PUBLIC void *
 562 mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
 563 {
 564    init_shim();
 565
 566    struct shim_fd *shim_fd = drm_shim_fd_lookup(fd);
 567    if (shim_fd)
 568       return drm_shim_mmap(shim_fd, length, prot, flags, fd, offset);
 569
 570    return real_mmap(addr, length, prot, flags, fd, offset);
 571 }
 572 PUBLIC void *mmap64(void*, size_t, int, int, int, off_t)
 573    __attribute__((alias("mmap")));