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         /*
  44          * On the ARM architecture gd is mapped to a fixed register (r9 or x18).
  45          * As this register may be overwritten by an EFI payload we save it here
  46          * and restore it on every callback entered.
  47          */
  48         efi_save_gd();
  49
  50         /* Initialize once only */
  51         if (efi_obj_list_initialized != OBJ_LIST_NOT_INITIALIZED)
  52                 return efi_obj_list_initialized;
  53
  54         /* Initialize system table */
  55         ret = efi_initialize_system_table();
  56         if (ret != EFI_SUCCESS)
  57                 goto out;
  58
  59         /* Initialize root node */
  60         ret = efi_root_node_register();
  61         if (ret != EFI_SUCCESS)
  62                 goto out;
  63
  64         /* Initialize EFI driver uclass */
  65         ret = efi_driver_init();
  66         if (ret != EFI_SUCCESS)
  67                 goto out;
  68
  69         ret = efi_console_register();
  70         if (ret != EFI_SUCCESS)
  71                 goto out;
  72 #ifdef CONFIG_PARTITIONS
  73         ret = efi_disk_register();
  74         if (ret != EFI_SUCCESS)
  75                 goto out;
  76 #endif
  77 #if defined(CONFIG_LCD) || defined(CONFIG_DM_VIDEO)
  78         ret = efi_gop_register();
  79         if (ret != EFI_SUCCESS)
  80                 goto out;
  81 #endif
  82 #ifdef CONFIG_NET
  83         ret = efi_net_register();
  84         if (ret != EFI_SUCCESS)
  85                 goto out;
  86 #endif
  87 #ifdef CONFIG_GENERATE_ACPI_TABLE
  88         ret = efi_acpi_register();
  89         if (ret != EFI_SUCCESS)
  90                 goto out;
  91 #endif
  92 #ifdef CONFIG_GENERATE_SMBIOS_TABLE
  93         ret = efi_smbios_register();
  94         if (ret != EFI_SUCCESS)
  95                 goto out;
  96 #endif
  97         ret = efi_watchdog_register();
  98         if (ret != EFI_SUCCESS)
  99                 goto out;
 100
 101         /* Initialize EFI runtime services */
 102         ret = efi_reset_system_init();
 103         if (ret != EFI_SUCCESS)
 104                 goto out;
 105
 106 out:
 107         efi_obj_list_initialized = ret;
 108         return ret;
 109 }
 110
 111 /*
 112  * Allow unaligned memory access.
 113  *
 114  * This routine is overridden by architectures providing this feature.
 115  */
 116 void __weak allow_unaligned(void)
 117 {
 118 }
 119
 120 /*
 121  * Set the load options of an image from an environment variable.
 122  *
 123  * @loaded_image_info:  the image
 124  * @env_var:            name of the environment variable
 125  */
 126 static void set_load_options(struct efi_loaded_image *loaded_image_info,
 127                              const char *env_var)
 128 {
 129         size_t size;
 130         const char *env = env_get(env_var);
 131         u16 *pos;
 132
 133         loaded_image_info->load_options = NULL;
 134         loaded_image_info->load_options_size = 0;
 135         if (!env)
 136                 return;
 137         size = utf8_utf16_strlen(env) + 1;
 138         loaded_image_info->load_options = calloc(size, sizeof(u16));
 139         if (!loaded_image_info->load_options) {
 140                 printf("ERROR: Out of memory\n");
 141                 return;
 142         }
 143         pos = loaded_image_info->load_options;
 144         utf8_utf16_strcpy(&pos, env);
 145         loaded_image_info->load_options_size = size * 2;
 146 }
 147
 148 /**
 149  * copy_fdt() - Copy the device tree to a new location available to EFI
 150  *
 151  * The FDT is relocated into a suitable location within the EFI memory map.
 152  * An additional 12KB is added to the space in case the device tree needs to be
 153  * expanded later with fdt_open_into().
 154  *
 155  * @fdt_addr: On entry, address of start of FDT. On exit, address of relocated
 156  *      FDT start
 157  * @fdt_sizep: Returns new size of FDT, including
 158  * @return new relocated address of FDT
 159  */
 160 static efi_status_t copy_fdt(ulong *fdt_addrp, ulong *fdt_sizep)
 161 {
 162         unsigned long fdt_ram_start = -1L, fdt_pages;
 163         efi_status_t ret = 0;
 164         void *fdt, *new_fdt;
 165         u64 new_fdt_addr;
 166         uint fdt_size;
 167         int i;
 168
 169         for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
 170                 u64 ram_start = gd->bd->bi_dram[i].start;
 171                 u64 ram_size = gd->bd->bi_dram[i].size;
 172
 173                 if (!ram_size)
 174                         continue;
 175
 176                 if (ram_start < fdt_ram_start)
 177                         fdt_ram_start = ram_start;
 178         }
 179
 180         /*
 181          * Give us at least 4KB of breathing room in case the device tree needs
 182          * to be expanded later. Round up to the nearest EFI page boundary.
 183          */
 184         fdt = map_sysmem(*fdt_addrp, 0);
 185         fdt_size = fdt_totalsize(fdt);
 186         fdt_size += 4096 * 3;
 187         fdt_size = ALIGN(fdt_size + EFI_PAGE_SIZE - 1, EFI_PAGE_SIZE);
 188         fdt_pages = fdt_size >> EFI_PAGE_SHIFT;
 189
 190         /* Safe fdt location is at 127MB */
 191         new_fdt_addr = fdt_ram_start + (127 * 1024 * 1024) + fdt_size;
 192         ret = efi_allocate_pages(EFI_ALLOCATE_MAX_ADDRESS,
 193                                  EFI_RUNTIME_SERVICES_DATA, fdt_pages,
 194                                  &new_fdt_addr);
 195         if (ret != EFI_SUCCESS) {
 196                 /* If we can't put it there, put it somewhere */
 197                 new_fdt_addr = (ulong)memalign(EFI_PAGE_SIZE, fdt_size);
 198                 ret = efi_allocate_pages(EFI_ALLOCATE_MAX_ADDRESS,
 199                                          EFI_RUNTIME_SERVICES_DATA, fdt_pages,
 200                                          &new_fdt_addr);
 201                 if (ret != EFI_SUCCESS) {
 202                         printf("ERROR: Failed to reserve space for FDT\n");
 203                         goto done;
 204                 }
 205         }
 206
 207         new_fdt = map_sysmem(new_fdt_addr, fdt_size);
 208         memcpy(new_fdt, fdt, fdt_totalsize(fdt));
 209         fdt_set_totalsize(new_fdt, fdt_size);
 210
 211         *fdt_addrp = new_fdt_addr;
 212         *fdt_sizep = fdt_size;
 213 done:
 214         return ret;
 215 }
 216
 217 static efi_status_t efi_do_enter(
 218                         efi_handle_t image_handle, struct efi_system_table *st,
 219                         EFIAPI efi_status_t (*entry)(
 220                                 efi_handle_t image_handle,
 221                                 struct efi_system_table *st))
 222 {
 223         efi_status_t ret = EFI_LOAD_ERROR;
 224
 225         if (entry)
 226                 ret = entry(image_handle, st);
 227         st->boottime->exit(image_handle, ret, 0, NULL);
 228         return ret;
 229 }
 230
 231 #ifdef CONFIG_ARM64
 232 static efi_status_t efi_run_in_el2(EFIAPI efi_status_t (*entry)(
 233                         efi_handle_t image_handle, struct efi_system_table *st),
 234                         efi_handle_t image_handle, struct efi_system_table *st)
 235 {
 236         /* Enable caches again */
 237         dcache_enable();
 238
 239         return efi_do_enter(image_handle, st, entry);
 240 }
 241 #endif
 242
 243 #ifdef CONFIG_ARMV7_NONSEC
 244 static bool is_nonsec;
 245
 246 static efi_status_t efi_run_in_hyp(EFIAPI efi_status_t (*entry)(
 247                         efi_handle_t image_handle, struct efi_system_table *st),
 248                         efi_handle_t image_handle, struct efi_system_table *st)
 249 {
 250         /* Enable caches again */
 251         dcache_enable();
 252
 253         is_nonsec = true;
 254
 255         return efi_do_enter(image_handle, st, entry);
 256 }
 257 #endif
 258
 259 /*
 260  * efi_carve_out_dt_rsv() - Carve out DT reserved memory ranges
 261  *
 262  * The mem_rsv entries of the FDT are added to the memory map. Any failures are
 263  * ignored because this is not critical and we would rather continue to try to
 264  * boot.
 265  *
 266  * @fdt: Pointer to device tree
 267  */
 268 static void efi_carve_out_dt_rsv(void *fdt)
 269 {
 270         int nr_rsv, i;
 271         uint64_t addr, size, pages;
 272
 273         nr_rsv = fdt_num_mem_rsv(fdt);
 274
 275         /* Look for an existing entry and add it to the efi mem map. */
 276         for (i = 0; i < nr_rsv; i++) {
 277                 if (fdt_get_mem_rsv(fdt, i, &addr, &size) != 0)
 278                         continue;
 279
 280                 pages = ALIGN(size, EFI_PAGE_SIZE) >> EFI_PAGE_SHIFT;
 281                 if (!efi_add_memory_map(addr, pages, EFI_RESERVED_MEMORY_TYPE,
 282                                         false))
 283                         printf("FDT memrsv map %d: Failed to add to map\n", i);
 284         }
 285 }
 286
 287 static efi_status_t efi_install_fdt(ulong fdt_addr)
 288 {
 289         bootm_headers_t img = { 0 };
 290         ulong fdt_pages, fdt_size, fdt_start;
 291         efi_status_t ret;
 292         void *fdt;
 293
 294         fdt = map_sysmem(fdt_addr, 0);
 295         if (fdt_check_header(fdt)) {
 296                 printf("ERROR: invalid device tree\n");
 297                 return EFI_INVALID_PARAMETER;
 298         }
 299
 300         /* Prepare fdt for payload */
 301         ret = copy_fdt(&fdt_addr, &fdt_size);
 302         if (ret)
 303                 return ret;
 304
 305         unmap_sysmem(fdt);
 306         fdt = map_sysmem(fdt_addr, 0);
 307         fdt_size = fdt_totalsize(fdt);
 308         if (image_setup_libfdt(&img, fdt, 0, NULL)) {
 309                 printf("ERROR: failed to process device tree\n");
 310                 return EFI_LOAD_ERROR;
 311         }
 312
 313         efi_carve_out_dt_rsv(fdt);
 314
 315         /* Link to it in the efi tables */
 316         ret = efi_install_configuration_table(&efi_guid_fdt, fdt);
 317         if (ret != EFI_SUCCESS)
 318                 return EFI_OUT_OF_RESOURCES;
 319
 320         /* And reserve the space in the memory map */
 321         fdt_start = fdt_addr;
 322         fdt_pages = fdt_size >> EFI_PAGE_SHIFT;
 323
 324         ret = efi_add_memory_map(fdt_start, fdt_pages,
 325                                  EFI_BOOT_SERVICES_DATA, true);
 326
 327         return ret;
 328 }
 329
 330 /**
 331  * do_bootefi_exec() - execute EFI binary
 332  *
 333  * @efi:                address of the binary
 334  * @device_path:        path of the device from which the binary was loaded
 335  * @image_path:         device path of the binary
 336  * Return:              status code
 337  *
 338  * Load the EFI binary into a newly assigned memory unwinding the relocation
 339  * information, install the loaded image protocol, and call the binary.
 340  */
 341 static efi_status_t do_bootefi_exec(void *efi,
 342                                     struct efi_device_path *device_path,
 343                                     struct efi_device_path *image_path)
 344 {
 345         efi_handle_t mem_handle = NULL;
 346         struct efi_device_path *memdp = NULL;
 347         efi_status_t ret;
 348         struct efi_loaded_image_obj *image_handle = NULL;
 349         struct efi_loaded_image *loaded_image_info = NULL;
 350
 351         EFIAPI efi_status_t (*entry)(efi_handle_t image_handle,
 352                                      struct efi_system_table *st);
 353
 354         /*
 355          * Special case for efi payload not loaded from disk, such as
 356          * 'bootefi hello' or for example payload loaded directly into
 357          * memory via jtag, etc:
 358          */
 359         if (!device_path && !image_path) {
 360                 printf("WARNING: using memory device/image path, this may confuse some payloads!\n");
 361                 /* actual addresses filled in after efi_load_pe() */
 362                 memdp = efi_dp_from_mem(0, 0, 0);
 363                 device_path = image_path = memdp;
 364                 /*
 365                  * Grub expects that the device path of the loaded image is
 366                  * installed on a handle.
 367                  */
 368                 ret = efi_create_handle(&mem_handle);
 369                 if (ret != EFI_SUCCESS)
 370                         goto exit;
 371                 ret = efi_add_protocol(mem_handle, &efi_guid_device_path,
 372                                        device_path);
 373                 if (ret != EFI_SUCCESS)
 374                         goto exit;
 375         } else {
 376                 assert(device_path && image_path);
 377         }
 378
 379         ret = efi_setup_loaded_image(device_path, image_path, &image_handle,
 380                                      &loaded_image_info);
 381         if (ret != EFI_SUCCESS)
 382                 goto exit;
 383
 384         /* Transfer environment variable bootargs as load options */
 385         set_load_options(loaded_image_info, "bootargs");
 386         /* Load the EFI payload */
 387         entry = efi_load_pe(image_handle, efi, loaded_image_info);
 388         if (!entry) {
 389                 ret = EFI_LOAD_ERROR;
 390                 goto exit;
 391         }
 392
 393         if (memdp) {
 394                 struct efi_device_path_memory *mdp = (void *)memdp;
 395                 mdp->memory_type = loaded_image_info->image_code_type;
 396                 mdp->start_address = (uintptr_t)loaded_image_info->image_base;
 397                 mdp->end_address = mdp->start_address +
 398                                 loaded_image_info->image_size;
 399         }
 400
 401         /* we don't support much: */
 402         env_set("efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_OsIndicationsSupported",
 403                 "{ro,boot}(blob)0000000000000000");
 404
 405         /* Call our payload! */
 406         debug("%s:%d Jumping to 0x%lx\n", __func__, __LINE__, (long)entry);
 407
 408         if (setjmp(&image_handle->exit_jmp)) {
 409                 ret = image_handle->exit_status;
 410                 goto exit;
 411         }
 412
 413 #ifdef CONFIG_ARM64
 414         /* On AArch64 we need to make sure we call our payload in < EL3 */
 415         if (current_el() == 3) {
 416                 smp_kick_all_cpus();
 417                 dcache_disable();       /* flush cache before switch to EL2 */
 418
 419                 /* Move into EL2 and keep running there */
 420                 armv8_switch_to_el2((ulong)entry,
 421                                     (ulong)image_handle,
 422                                     (ulong)&systab, 0, (ulong)efi_run_in_el2,
 423                                     ES_TO_AARCH64);
 424
 425                 /* Should never reach here, efi exits with longjmp */
 426                 while (1) { }
 427         }
 428 #endif
 429
 430 #ifdef CONFIG_ARMV7_NONSEC
 431         if (armv7_boot_nonsec() && !is_nonsec) {
 432                 dcache_disable();       /* flush cache before switch to HYP */
 433
 434                 armv7_init_nonsec();
 435                 secure_ram_addr(_do_nonsec_entry)(
 436                                         efi_run_in_hyp,
 437                                         (uintptr_t)entry,
 438                                         (uintptr_t)image_handle,
 439                                         (uintptr_t)&systab);
 440
 441                 /* Should never reach here, efi exits with longjmp */
 442                 while (1) { }
 443         }
 444 #endif
 445
 446         ret = efi_do_enter(image_handle, &systab, entry);
 447
 448 exit:
 449         /* image has returned, loaded-image obj goes *poof*: */
 450         if (image_handle)
 451                 efi_delete_handle(&image_handle->parent);
 452         if (mem_handle)
 453                 efi_delete_handle(mem_handle);
 454
 455         return ret;
 456 }
 457
 458 static int do_bootefi_bootmgr_exec(void)
 459 {
 460         struct efi_device_path *device_path, *file_path;
 461         void *addr;
 462         efi_status_t r;
 463
 464         addr = efi_bootmgr_load(&device_path, &file_path);
 465         if (!addr)
 466                 return 1;
 467
 468         printf("## Starting EFI application at %p ...\n", addr);
 469         r = do_bootefi_exec(addr, device_path, file_path);
 470         printf("## Application terminated, r = %lu\n",
 471                r & ~EFI_ERROR_MASK);
 472
 473         if (r != EFI_SUCCESS)
 474                 return 1;
 475
 476         return 0;
 477 }
 478
 479 /* Interpreter command to boot an arbitrary EFI image from memory */
 480 static int do_bootefi(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 481 {
 482         unsigned long addr;
 483         char *saddr;
 484         efi_status_t r;
 485         unsigned long fdt_addr;
 486
 487         /* Allow unaligned memory access */
 488         allow_unaligned();
 489
 490         /* Initialize EFI drivers */
 491         r = efi_init_obj_list();
 492         if (r != EFI_SUCCESS) {
 493                 printf("Error: Cannot set up EFI drivers, r = %lu\n",
 494                        r & ~EFI_ERROR_MASK);
 495                 return CMD_RET_FAILURE;
 496         }
 497
 498         if (argc < 2)
 499                 return CMD_RET_USAGE;
 500
 501         if (argc > 2) {
 502                 fdt_addr = simple_strtoul(argv[2], NULL, 16);
 503                 if (!fdt_addr && *argv[2] != '0')
 504                         return CMD_RET_USAGE;
 505                 /* Install device tree */
 506                 r = efi_install_fdt(fdt_addr);
 507                 if (r != EFI_SUCCESS) {
 508                         printf("ERROR: failed to install device tree\n");
 509                         return CMD_RET_FAILURE;
 510                 }
 511         } else {
 512                 /* Remove device tree. EFI_NOT_FOUND can be ignored here */
 513                 efi_install_configuration_table(&efi_guid_fdt, NULL);
 514                 printf("WARNING: booting without device tree\n");
 515         }
 516 #ifdef CONFIG_CMD_BOOTEFI_HELLO
 517         if (!strcmp(argv[1], "hello")) {
 518                 ulong size = __efi_helloworld_end - __efi_helloworld_begin;
 519
 520                 saddr = env_get("loadaddr");
 521                 if (saddr)
 522                         addr = simple_strtoul(saddr, NULL, 16);
 523                 else
 524                         addr = CONFIG_SYS_LOAD_ADDR;
 525                 memcpy(map_sysmem(addr, size), __efi_helloworld_begin, size);
 526         } else
 527 #endif
 528 #ifdef CONFIG_CMD_BOOTEFI_SELFTEST
 529         if (!strcmp(argv[1], "selftest")) {
 530                 struct efi_loaded_image_obj *image_handle;
 531                 struct efi_loaded_image *loaded_image_info;
 532
 533                 /* Construct a dummy device path. */
 534                 bootefi_device_path = efi_dp_from_mem(EFI_RESERVED_MEMORY_TYPE,
 535                                                       (uintptr_t)&efi_selftest,
 536                                                       (uintptr_t)&efi_selftest);
 537                 bootefi_image_path = efi_dp_from_file(NULL, 0, "\\selftest");
 538
 539                 r = efi_setup_loaded_image(bootefi_device_path,
 540                                            bootefi_image_path, &image_handle,
 541                                            &loaded_image_info);
 542                 if (r != EFI_SUCCESS)
 543                         return CMD_RET_FAILURE;
 544
 545                 efi_save_gd();
 546                 /* Transfer environment variable efi_selftest as load options */
 547                 set_load_options(loaded_image_info, "efi_selftest");
 548                 /* Execute the test */
 549                 r = efi_selftest(image_handle, &systab);
 550                 efi_restore_gd();
 551                 free(loaded_image_info->load_options);
 552                 efi_delete_handle(&image_handle->parent);
 553                 return r != EFI_SUCCESS;
 554         } else
 555 #endif
 556         if (!strcmp(argv[1], "bootmgr")) {
 557                 return do_bootefi_bootmgr_exec();
 558         } else {
 559                 saddr = argv[1];
 560
 561                 addr = simple_strtoul(saddr, NULL, 16);
 562                 /* Check that a numeric value was passed */
 563                 if (!addr && *saddr != '0')
 564                         return CMD_RET_USAGE;
 565
 566         }
 567
 568         printf("## Starting EFI application at %08lx ...\n", addr);
 569         r = do_bootefi_exec(map_sysmem(addr, 0), bootefi_device_path,
 570                             bootefi_image_path);
 571         printf("## Application terminated, r = %lu\n",
 572                r & ~EFI_ERROR_MASK);
 573
 574         if (r != EFI_SUCCESS)
 575                 return 1;
 576         else
 577                 return 0;
 578 }
 579
 580 #ifdef CONFIG_SYS_LONGHELP
 581 static char bootefi_help_text[] =
 582         "<image address> [fdt address]\n"
 583         "  - boot EFI payload stored at address <image address>.\n"
 584         "    If specified, the device tree located at <fdt address> gets\n"
 585         "    exposed as EFI configuration table.\n"
 586 #ifdef CONFIG_CMD_BOOTEFI_HELLO
 587         "bootefi hello\n"
 588         "  - boot a sample Hello World application stored within U-Boot\n"
 589 #endif
 590 #ifdef CONFIG_CMD_BOOTEFI_SELFTEST
 591         "bootefi selftest [fdt address]\n"
 592         "  - boot an EFI selftest application stored within U-Boot\n"
 593         "    Use environment variable efi_selftest to select a single test.\n"
 594         "    Use 'setenv efi_selftest list' to enumerate all tests.\n"
 595 #endif
 596         "bootefi bootmgr [fdt addr]\n"
 597         "  - load and boot EFI payload based on BootOrder/BootXXXX variables.\n"
 598         "\n"
 599         "    If specified, the device tree located at <fdt address> gets\n"
 600         "    exposed as EFI configuration table.\n";
 601 #endif
 602
 603 U_BOOT_CMD(
 604         bootefi, 3, 0, do_bootefi,
 605         "Boots an EFI payload from memory",
 606         bootefi_help_text
 607 );
 608
 609 void efi_set_bootdev(const char *dev, const char *devnr, const char *path)
 610 {
 611         char filename[32] = { 0 }; /* dp->str is u16[32] long */
 612         char *s;
 613
 614         /* efi_set_bootdev is typically called repeatedly, recover memory */
 615         efi_free_pool(bootefi_device_path);
 616         efi_free_pool(bootefi_image_path);
 617         /* If blk_get_device_part_str fails, avoid duplicate free. */
 618         bootefi_device_path = NULL;
 619         bootefi_image_path = NULL;
 620
 621         if (strcmp(dev, "Net")) {
 622                 struct blk_desc *desc;
 623                 disk_partition_t fs_partition;
 624                 int part;
 625
 626                 part = blk_get_device_part_str(dev, devnr, &desc, &fs_partition,
 627                                                1);
 628                 if (part < 0)
 629                         return;
 630
 631                 bootefi_device_path = efi_dp_from_part(desc, part);
 632         } else {
 633 #ifdef CONFIG_NET
 634                 bootefi_device_path = efi_dp_from_eth();
 635 #endif
 636         }
 637
 638         if (!path)
 639                 return;
 640
 641         if (strcmp(dev, "Net")) {
 642                 /* Add leading / to fs paths, because they're absolute */
 643                 snprintf(filename, sizeof(filename), "/%s", path);
 644         } else {
 645                 snprintf(filename, sizeof(filename), "%s", path);
 646         }
 647         /* DOS style file path: */
 648         s = filename;
 649         while ((s = strchr(s, '/')))
 650                 *s++ = '\\';
 651         bootefi_image_path = efi_dp_from_file(NULL, 0, filename);
 652 }