cmd/bootefi.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *  EFI application loader
   4  *
   5  *  Copyright (c) 2016 Alexander Graf
   6  */
   7
   8 #include <charset.h>
   9 #include <common.h>
  10 #include <command.h>
  11 #include <dm.h>
  12 #include <efi_loader.h>
  13 #include <efi_selftest.h>
  14 #include <errno.h>
  15 #include <linux/libfdt.h>
  16 #include <linux/libfdt_env.h>
  17 #include <mapmem.h>
  18 #include <memalign.h>
  19 #include <asm/global_data.h>
  20 #include <asm-generic/sections.h>
  21 #include <asm-generic/unaligned.h>
  22 #include <linux/linkage.h>
  23
  24 #ifdef CONFIG_ARMV7_NONSEC
  25 #include <asm/armv7.h>
  26 #include <asm/secure.h>
  27 #endif
  28
  29 DECLARE_GLOBAL_DATA_PTR;
  30
  31 #define OBJ_LIST_NOT_INITIALIZED 1
  32
  33 static efi_status_t efi_obj_list_initialized = OBJ_LIST_NOT_INITIALIZED;
  34
  35 static struct efi_device_path *bootefi_image_path;
  36 static struct efi_device_path *bootefi_device_path;
  37
  38 /* Initialize and populate EFI object list */
  39 efi_status_t efi_init_obj_list(void)
  40 {
  41         efi_status_t ret = EFI_SUCCESS;
  42
  43         /* Initialize once only */
  44         if (efi_obj_list_initialized != OBJ_LIST_NOT_INITIALIZED)
  45                 return efi_obj_list_initialized;
  46
  47         /* Initialize system table */
  48         ret = efi_initialize_system_table();
  49         if (ret != EFI_SUCCESS)
  50                 goto out;
  51
  52         /* Initialize root node */
  53         ret = efi_root_node_register();
  54         if (ret != EFI_SUCCESS)
  55                 goto out;
  56
  57         /* Initialize EFI driver uclass */
  58         ret = efi_driver_init();
  59         if (ret != EFI_SUCCESS)
  60                 goto out;
  61
  62         ret = efi_console_register();
  63         if (ret != EFI_SUCCESS)
  64                 goto out;
  65 #ifdef CONFIG_PARTITIONS
  66         ret = efi_disk_register();
  67         if (ret != EFI_SUCCESS)
  68                 goto out;
  69 #endif
  70 #if defined(CONFIG_LCD) || defined(CONFIG_DM_VIDEO)
  71         ret = efi_gop_register();
  72         if (ret != EFI_SUCCESS)
  73                 goto out;
  74 #endif
  75 #ifdef CONFIG_NET
  76         ret = efi_net_register();
  77         if (ret != EFI_SUCCESS)
  78                 goto out;
  79 #endif
  80 #ifdef CONFIG_GENERATE_ACPI_TABLE
  81         ret = efi_acpi_register();
  82         if (ret != EFI_SUCCESS)
  83                 goto out;
  84 #endif
  85 #ifdef CONFIG_GENERATE_SMBIOS_TABLE
  86         ret = efi_smbios_register();
  87         if (ret != EFI_SUCCESS)
  88                 goto out;
  89 #endif
  90         ret = efi_watchdog_register();
  91         if (ret != EFI_SUCCESS)
  92                 goto out;
  93
  94         /* Initialize EFI runtime services */
  95         ret = efi_reset_system_init();
  96         if (ret != EFI_SUCCESS)
  97                 goto out;
  98
  99 out:
 100         efi_obj_list_initialized = ret;
 101         return ret;
 102 }
 103
 104 /*
 105  * Allow unaligned memory access.
 106  *
 107  * This routine is overridden by architectures providing this feature.
 108  */
 109 void __weak allow_unaligned(void)
 110 {
 111 }
 112
 113 /*
 114  * Set the load options of an image from an environment variable.
 115  *
 116  * @loaded_image_info:  the image
 117  * @env_var:            name of the environment variable
 118  */
 119 static void set_load_options(struct efi_loaded_image *loaded_image_info,
 120                              const char *env_var)
 121 {
 122         size_t size;
 123         const char *env = env_get(env_var);
 124         u16 *pos;
 125
 126         loaded_image_info->load_options = NULL;
 127         loaded_image_info->load_options_size = 0;
 128         if (!env)
 129                 return;
 130         size = utf8_utf16_strlen(env) + 1;
 131         loaded_image_info->load_options = calloc(size, sizeof(u16));
 132         if (!loaded_image_info->load_options) {
 133                 printf("ERROR: Out of memory\n");
 134                 return;
 135         }
 136         pos = loaded_image_info->load_options;
 137         utf8_utf16_strcpy(&pos, env);
 138         loaded_image_info->load_options_size = size * 2;
 139 }
 140
 141 /**
 142  * copy_fdt() - Copy the device tree to a new location available to EFI
 143  *
 144  * The FDT is relocated into a suitable location within the EFI memory map.
 145  * An additional 12KB is added to the space in case the device tree needs to be
 146  * expanded later with fdt_open_into().
 147  *
 148  * @fdt_addr: On entry, address of start of FDT. On exit, address of relocated
 149  *      FDT start
 150  * @fdt_sizep: Returns new size of FDT, including
 151  * @return new relocated address of FDT
 152  */
 153 static efi_status_t copy_fdt(ulong *fdt_addrp, ulong *fdt_sizep)
 154 {
 155         unsigned long fdt_ram_start = -1L, fdt_pages;
 156         efi_status_t ret = 0;
 157         void *fdt, *new_fdt;
 158         u64 new_fdt_addr;
 159         uint fdt_size;
 160         int i;
 161
 162         for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
 163                 u64 ram_start = gd->bd->bi_dram[i].start;
 164                 u64 ram_size = gd->bd->bi_dram[i].size;
 165
 166                 if (!ram_size)
 167                         continue;
 168
 169                 if (ram_start < fdt_ram_start)
 170                         fdt_ram_start = ram_start;
 171         }
 172
 173         /*
 174          * Give us at least 4KB of breathing room in case the device tree needs
 175          * to be expanded later. Round up to the nearest EFI page boundary.
 176          */
 177         fdt = map_sysmem(*fdt_addrp, 0);
 178         fdt_size = fdt_totalsize(fdt);
 179         fdt_size += 4096 * 3;
 180         fdt_size = ALIGN(fdt_size + EFI_PAGE_SIZE - 1, EFI_PAGE_SIZE);
 181         fdt_pages = fdt_size >> EFI_PAGE_SHIFT;
 182
 183         /* Safe fdt location is at 127MB */
 184         new_fdt_addr = fdt_ram_start + (127 * 1024 * 1024) + fdt_size;
 185         ret = efi_allocate_pages(EFI_ALLOCATE_MAX_ADDRESS,
 186                                  EFI_RUNTIME_SERVICES_DATA, fdt_pages,
 187                                  &new_fdt_addr);
 188         if (ret != EFI_SUCCESS) {
 189                 /* If we can't put it there, put it somewhere */
 190                 new_fdt_addr = (ulong)memalign(EFI_PAGE_SIZE, fdt_size);
 191                 ret = efi_allocate_pages(EFI_ALLOCATE_MAX_ADDRESS,
 192                                          EFI_RUNTIME_SERVICES_DATA, fdt_pages,
 193                                          &new_fdt_addr);
 194                 if (ret != EFI_SUCCESS) {
 195                         printf("ERROR: Failed to reserve space for FDT\n");
 196                         goto done;
 197                 }
 198         }
 199
 200         new_fdt = map_sysmem(new_fdt_addr, fdt_size);
 201         memcpy(new_fdt, fdt, fdt_totalsize(fdt));
 202         fdt_set_totalsize(new_fdt, fdt_size);
 203
 204         *fdt_addrp = new_fdt_addr;
 205         *fdt_sizep = fdt_size;
 206 done:
 207         return ret;
 208 }
 209
 210 static efi_status_t efi_do_enter(
 211                         efi_handle_t image_handle, struct efi_system_table *st,
 212                         EFIAPI efi_status_t (*entry)(
 213                                 efi_handle_t image_handle,
 214                                 struct efi_system_table *st))
 215 {
 216         efi_status_t ret = EFI_LOAD_ERROR;
 217
 218         if (entry)
 219                 ret = entry(image_handle, st);
 220         st->boottime->exit(image_handle, ret, 0, NULL);
 221         return ret;
 222 }
 223
 224 #ifdef CONFIG_ARM64
 225 static efi_status_t efi_run_in_el2(EFIAPI efi_status_t (*entry)(
 226                         efi_handle_t image_handle, struct efi_system_table *st),
 227                         efi_handle_t image_handle, struct efi_system_table *st)
 228 {
 229         /* Enable caches again */
 230         dcache_enable();
 231
 232         return efi_do_enter(image_handle, st, entry);
 233 }
 234 #endif
 235
 236 #ifdef CONFIG_ARMV7_NONSEC
 237 static bool is_nonsec;
 238
 239 static efi_status_t efi_run_in_hyp(EFIAPI efi_status_t (*entry)(
 240                         efi_handle_t image_handle, struct efi_system_table *st),
 241                         efi_handle_t image_handle, struct efi_system_table *st)
 242 {
 243         /* Enable caches again */
 244         dcache_enable();
 245
 246         is_nonsec = true;
 247
 248         return efi_do_enter(image_handle, st, entry);
 249 }
 250 #endif
 251
 252 /*
 253  * efi_carve_out_dt_rsv() - Carve out DT reserved memory ranges
 254  *
 255  * The mem_rsv entries of the FDT are added to the memory map. Any failures are
 256  * ignored because this is not critical and we would rather continue to try to
 257  * boot.
 258  *
 259  * @fdt: Pointer to device tree
 260  */
 261 static void efi_carve_out_dt_rsv(void *fdt)
 262 {
 263         int nr_rsv, i;
 264         uint64_t addr, size, pages;
 265
 266         nr_rsv = fdt_num_mem_rsv(fdt);
 267
 268         /* Look for an existing entry and add it to the efi mem map. */
 269         for (i = 0; i < nr_rsv; i++) {
 270                 if (fdt_get_mem_rsv(fdt, i, &addr, &size) != 0)
 271                         continue;
 272
 273                 pages = ALIGN(size, EFI_PAGE_SIZE) >> EFI_PAGE_SHIFT;
 274                 if (!efi_add_memory_map(addr, pages, EFI_RESERVED_MEMORY_TYPE,
 275                                         false))
 276                         printf("FDT memrsv map %d: Failed to add to map\n", i);
 277         }
 278 }
 279
 280 static efi_status_t efi_install_fdt(ulong fdt_addr)
 281 {
 282         bootm_headers_t img = { 0 };
 283         ulong fdt_pages, fdt_size, fdt_start;
 284         efi_status_t ret;
 285         void *fdt;
 286
 287         fdt = map_sysmem(fdt_addr, 0);
 288         if (fdt_check_header(fdt)) {
 289                 printf("ERROR: invalid device tree\n");
 290                 return EFI_INVALID_PARAMETER;
 291         }
 292
 293         /* Prepare fdt for payload */
 294         ret = copy_fdt(&fdt_addr, &fdt_size);
 295         if (ret)
 296                 return ret;
 297
 298         unmap_sysmem(fdt);
 299         fdt = map_sysmem(fdt_addr, 0);
 300         fdt_size = fdt_totalsize(fdt);
 301         if (image_setup_libfdt(&img, fdt, 0, NULL)) {
 302                 printf("ERROR: failed to process device tree\n");
 303                 return EFI_LOAD_ERROR;
 304         }
 305
 306         efi_carve_out_dt_rsv(fdt);
 307
 308         /* Link to it in the efi tables */
 309         ret = efi_install_configuration_table(&efi_guid_fdt, fdt);
 310         if (ret != EFI_SUCCESS)
 311                 return EFI_OUT_OF_RESOURCES;
 312
 313         /* And reserve the space in the memory map */
 314         fdt_start = fdt_addr;
 315         fdt_pages = fdt_size >> EFI_PAGE_SHIFT;
 316
 317         ret = efi_add_memory_map(fdt_start, fdt_pages,
 318                                  EFI_BOOT_SERVICES_DATA, true);
 319
 320         return ret;
 321 }
 322
 323 /*
 324  * Load an EFI payload into a newly allocated piece of memory, register all
 325  * EFI objects it would want to access and jump to it.
 326  */
 327 static efi_status_t do_bootefi_exec(void *efi,
 328                                     struct efi_device_path *device_path,
 329                                     struct efi_device_path *image_path)
 330 {
 331         struct efi_loaded_image loaded_image_info = {};
 332         struct efi_object loaded_image_info_obj = {};
 333         efi_handle_t mem_handle = NULL;
 334         struct efi_device_path *memdp = NULL;
 335         efi_status_t ret;
 336
 337         EFIAPI efi_status_t (*entry)(efi_handle_t image_handle,
 338                                      struct efi_system_table *st);
 339
 340         /*
 341          * Special case for efi payload not loaded from disk, such as
 342          * 'bootefi hello' or for example payload loaded directly into
 343          * memory via jtag, etc:
 344          */
 345         if (!device_path && !image_path) {
 346                 printf("WARNING: using memory device/image path, this may confuse some payloads!\n");
 347                 /* actual addresses filled in after efi_load_pe() */
 348                 memdp = efi_dp_from_mem(0, 0, 0);
 349                 device_path = image_path = memdp;
 350                 /*
 351                  * Grub expects that the device path of the loaded image is
 352                  * installed on a handle.
 353                  */
 354                 ret = efi_create_handle(&mem_handle);
 355                 if (ret != EFI_SUCCESS)
 356                         goto exit;
 357                 ret = efi_add_protocol(mem_handle, &efi_guid_device_path,
 358                                        device_path);
 359                 if (ret != EFI_SUCCESS)
 360                         goto exit;
 361         } else {
 362                 assert(device_path && image_path);
 363         }
 364
 365         efi_setup_loaded_image(&loaded_image_info, &loaded_image_info_obj,
 366                                device_path, image_path);
 367
 368         /*
 369          * gd lives in a fixed register which may get clobbered while we execute
 370          * the payload. So save it here and restore it on every callback entry
 371          */
 372         efi_save_gd();
 373
 374         /* Transfer environment variable bootargs as load options */
 375         set_load_options(&loaded_image_info, "bootargs");
 376         /* Load the EFI payload */
 377         entry = efi_load_pe(efi, &loaded_image_info);
 378         if (!entry) {
 379                 ret = EFI_LOAD_ERROR;
 380                 goto exit;
 381         }
 382
 383         if (memdp) {
 384                 struct efi_device_path_memory *mdp = (void *)memdp;
 385                 mdp->memory_type = loaded_image_info.image_code_type;
 386                 mdp->start_address = (uintptr_t)loaded_image_info.image_base;
 387                 mdp->end_address = mdp->start_address +
 388                                 loaded_image_info.image_size;
 389         }
 390
 391         /* we don't support much: */
 392         env_set("efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_OsIndicationsSupported",
 393                 "{ro,boot}(blob)0000000000000000");
 394
 395         /* Call our payload! */
 396         debug("%s:%d Jumping to 0x%lx\n", __func__, __LINE__, (long)entry);
 397
 398         if (setjmp(&loaded_image_info.exit_jmp)) {
 399                 ret = loaded_image_info.exit_status;
 400                 goto exit;
 401         }
 402
 403 #ifdef CONFIG_ARM64
 404         /* On AArch64 we need to make sure we call our payload in < EL3 */
 405         if (current_el() == 3) {
 406                 smp_kick_all_cpus();
 407                 dcache_disable();       /* flush cache before switch to EL2 */
 408
 409                 /* Move into EL2 and keep running there */
 410                 armv8_switch_to_el2((ulong)entry,
 411                                     (ulong)loaded_image_info_obj.handle,
 412                                     (ulong)&systab, 0, (ulong)efi_run_in_el2,
 413                                     ES_TO_AARCH64);
 414
 415                 /* Should never reach here, efi exits with longjmp */
 416                 while (1) { }
 417         }
 418 #endif
 419
 420 #ifdef CONFIG_ARMV7_NONSEC
 421         if (armv7_boot_nonsec() && !is_nonsec) {
 422                 dcache_disable();       /* flush cache before switch to HYP */
 423
 424                 armv7_init_nonsec();
 425                 secure_ram_addr(_do_nonsec_entry)(
 426                                         efi_run_in_hyp,
 427                                         (uintptr_t)entry,
 428                                         (uintptr_t)loaded_image_info_obj.handle,
 429                                         (uintptr_t)&systab);
 430
 431                 /* Should never reach here, efi exits with longjmp */
 432                 while (1) { }
 433         }
 434 #endif
 435
 436         ret = efi_do_enter(loaded_image_info_obj.handle, &systab, entry);
 437
 438 exit:
 439         /* image has returned, loaded-image obj goes *poof*: */
 440         list_del(&loaded_image_info_obj.link);
 441         if (mem_handle)
 442                 efi_delete_handle(mem_handle);
 443
 444         return ret;
 445 }
 446
 447 static int do_bootefi_bootmgr_exec(void)
 448 {
 449         struct efi_device_path *device_path, *file_path;
 450         void *addr;
 451         efi_status_t r;
 452
 453         /*
 454          * gd lives in a fixed register which may get clobbered while we execute
 455          * the payload. So save it here and restore it on every callback entry
 456          */
 457         efi_save_gd();
 458
 459         addr = efi_bootmgr_load(&device_path, &file_path);
 460         if (!addr)
 461                 return 1;
 462
 463         printf("## Starting EFI application at %p ...\n", addr);
 464         r = do_bootefi_exec(addr, device_path, file_path);
 465         printf("## Application terminated, r = %lu\n",
 466                r & ~EFI_ERROR_MASK);
 467
 468         if (r != EFI_SUCCESS)
 469                 return 1;
 470
 471         return 0;
 472 }
 473
 474 /* Interpreter command to boot an arbitrary EFI image from memory */
 475 static int do_bootefi(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 476 {
 477         unsigned long addr;
 478         char *saddr;
 479         efi_status_t r;
 480         unsigned long fdt_addr;
 481
 482         /* Allow unaligned memory access */
 483         allow_unaligned();
 484
 485         /* Initialize EFI drivers */
 486         r = efi_init_obj_list();
 487         if (r != EFI_SUCCESS) {
 488                 printf("Error: Cannot set up EFI drivers, r = %lu\n",
 489                        r & ~EFI_ERROR_MASK);
 490                 return CMD_RET_FAILURE;
 491         }
 492
 493         if (argc < 2)
 494                 return CMD_RET_USAGE;
 495
 496         if (argc > 2) {
 497                 fdt_addr = simple_strtoul(argv[2], NULL, 16);
 498                 if (!fdt_addr && *argv[2] != '0')
 499                         return CMD_RET_USAGE;
 500                 /* Install device tree */
 501                 r = efi_install_fdt(fdt_addr);
 502                 if (r != EFI_SUCCESS) {
 503                         printf("ERROR: failed to install device tree\n");
 504                         return CMD_RET_FAILURE;
 505                 }
 506         } else {
 507                 /* Remove device tree. EFI_NOT_FOUND can be ignored here */
 508                 efi_install_configuration_table(&efi_guid_fdt, NULL);
 509                 printf("WARNING: booting without device tree\n");
 510         }
 511 #ifdef CONFIG_CMD_BOOTEFI_HELLO
 512         if (!strcmp(argv[1], "hello")) {
 513                 ulong size = __efi_helloworld_end - __efi_helloworld_begin;
 514
 515                 saddr = env_get("loadaddr");
 516                 if (saddr)
 517                         addr = simple_strtoul(saddr, NULL, 16);
 518                 else
 519                         addr = CONFIG_SYS_LOAD_ADDR;
 520                 memcpy(map_sysmem(addr, size), __efi_helloworld_begin, size);
 521         } else
 522 #endif
 523 #ifdef CONFIG_CMD_BOOTEFI_SELFTEST
 524         if (!strcmp(argv[1], "selftest")) {
 525                 struct efi_loaded_image loaded_image_info = {};
 526                 struct efi_object loaded_image_info_obj = {};
 527
 528                 /* Construct a dummy device path. */
 529                 bootefi_device_path = efi_dp_from_mem(EFI_RESERVED_MEMORY_TYPE,
 530                                                       (uintptr_t)&efi_selftest,
 531                                                       (uintptr_t)&efi_selftest);
 532                 bootefi_image_path = efi_dp_from_file(NULL, 0, "\\selftest");
 533
 534                 efi_setup_loaded_image(&loaded_image_info,
 535                                        &loaded_image_info_obj,
 536                                        bootefi_device_path, bootefi_image_path);
 537                 /*
 538                  * gd lives in a fixed register which may get clobbered while we
 539                  * execute the payload. So save it here and restore it on every
 540                  * callback entry
 541                  */
 542                 efi_save_gd();
 543                 /* Transfer environment variable efi_selftest as load options */
 544                 set_load_options(&loaded_image_info, "efi_selftest");
 545                 /* Execute the test */
 546                 r = efi_selftest(loaded_image_info_obj.handle, &systab);
 547                 efi_restore_gd();
 548                 free(loaded_image_info.load_options);
 549                 list_del(&loaded_image_info_obj.link);
 550                 return r != EFI_SUCCESS;
 551         } else
 552 #endif
 553         if (!strcmp(argv[1], "bootmgr")) {
 554                 return do_bootefi_bootmgr_exec();
 555         } else {
 556                 saddr = argv[1];
 557
 558                 addr = simple_strtoul(saddr, NULL, 16);
 559                 /* Check that a numeric value was passed */
 560                 if (!addr && *saddr != '0')
 561                         return CMD_RET_USAGE;
 562
 563         }
 564
 565         printf("## Starting EFI application at %08lx ...\n", addr);
 566         r = do_bootefi_exec(map_sysmem(addr, 0), bootefi_device_path,
 567                             bootefi_image_path);
 568         printf("## Application terminated, r = %lu\n",
 569                r & ~EFI_ERROR_MASK);
 570
 571         if (r != EFI_SUCCESS)
 572                 return 1;
 573         else
 574                 return 0;
 575 }
 576
 577 #ifdef CONFIG_SYS_LONGHELP
 578 static char bootefi_help_text[] =
 579         "<image address> [fdt address]\n"
 580         "  - boot EFI payload stored at address <image address>.\n"
 581         "    If specified, the device tree located at <fdt address> gets\n"
 582         "    exposed as EFI configuration table.\n"
 583 #ifdef CONFIG_CMD_BOOTEFI_HELLO
 584         "bootefi hello\n"
 585         "  - boot a sample Hello World application stored within U-Boot\n"
 586 #endif
 587 #ifdef CONFIG_CMD_BOOTEFI_SELFTEST
 588         "bootefi selftest [fdt address]\n"
 589         "  - boot an EFI selftest application stored within U-Boot\n"
 590         "    Use environment variable efi_selftest to select a single test.\n"
 591         "    Use 'setenv efi_selftest list' to enumerate all tests.\n"
 592 #endif
 593         "bootefi bootmgr [fdt addr]\n"
 594         "  - load and boot EFI payload based on BootOrder/BootXXXX variables.\n"
 595         "\n"
 596         "    If specified, the device tree located at <fdt address> gets\n"
 597         "    exposed as EFI configuration table.\n";
 598 #endif
 599
 600 U_BOOT_CMD(
 601         bootefi, 3, 0, do_bootefi,
 602         "Boots an EFI payload from memory",
 603         bootefi_help_text
 604 );
 605
 606 void efi_set_bootdev(const char *dev, const char *devnr, const char *path)
 607 {
 608         char filename[32] = { 0 }; /* dp->str is u16[32] long */
 609         char *s;
 610
 611         /* efi_set_bootdev is typically called repeatedly, recover memory */
 612         efi_free_pool(bootefi_device_path);
 613         efi_free_pool(bootefi_image_path);
 614         /* If blk_get_device_part_str fails, avoid duplicate free. */
 615         bootefi_device_path = NULL;
 616         bootefi_image_path = NULL;
 617
 618         if (strcmp(dev, "Net")) {
 619                 struct blk_desc *desc;
 620                 disk_partition_t fs_partition;
 621                 int part;
 622
 623                 part = blk_get_device_part_str(dev, devnr, &desc, &fs_partition,
 624                                                1);
 625                 if (part < 0)
 626                         return;
 627
 628                 bootefi_device_path = efi_dp_from_part(desc, part);
 629         } else {
 630 #ifdef CONFIG_NET
 631                 bootefi_device_path = efi_dp_from_eth();
 632 #endif
 633         }
 634
 635         if (!path)
 636                 return;
 637
 638         if (strcmp(dev, "Net")) {
 639                 /* Add leading / to fs paths, because they're absolute */
 640                 snprintf(filename, sizeof(filename), "/%s", path);
 641         } else {
 642                 snprintf(filename, sizeof(filename), "%s", path);
 643         }
 644         /* DOS style file path: */
 645         s = filename;
 646         while ((s = strchr(s, '/')))
 647                 *s++ = '\\';
 648         bootefi_image_path = efi_dp_from_file(NULL, 0, filename);
 649 }