drivers/firmware/efi/libstub/x86-stub.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2
   3 /* -----------------------------------------------------------------------
   4  *
   5  *   Copyright 2011 Intel Corporation; author Matt Fleming
   6  *
   7  * ----------------------------------------------------------------------- */
   8
   9 #include <linux/efi.h>
  10 #include <linux/pci.h>
  11 #include <linux/stddef.h>
  12
  13 #include <asm/efi.h>
  14 #include <asm/e820/types.h>
  15 #include <asm/setup.h>
  16 #include <asm/desc.h>
  17 #include <asm/boot.h>
  18
  19 #include "efistub.h"
  20
  21 /* Maximum physical address for 64-bit kernel with 4-level paging */
  22 #define MAXMEM_X86_64_4LEVEL (1ull << 46)
  23
  24 const efi_system_table_t *efi_system_table;
  25 const efi_dxe_services_table_t *efi_dxe_table;
  26 extern u32 image_offset;
  27 static efi_loaded_image_t *image = NULL;
  28
  29 static efi_status_t
  30 preserve_pci_rom_image(efi_pci_io_protocol_t *pci, struct pci_setup_rom **__rom)
  31 {
  32         struct pci_setup_rom *rom = NULL;
  33         efi_status_t status;
  34         unsigned long size;
  35         uint64_t romsize;
  36         void *romimage;
  37
  38         /*
  39          * Some firmware images contain EFI function pointers at the place where
  40          * the romimage and romsize fields are supposed to be. Typically the EFI
  41          * code is mapped at high addresses, translating to an unrealistically
  42          * large romsize. The UEFI spec limits the size of option ROMs to 16
  43          * MiB so we reject any ROMs over 16 MiB in size to catch this.
  44          */
  45         romimage = efi_table_attr(pci, romimage);
  46         romsize = efi_table_attr(pci, romsize);
  47         if (!romimage || !romsize || romsize > SZ_16M)
  48                 return EFI_INVALID_PARAMETER;
  49
  50         size = romsize + sizeof(*rom);
  51
  52         status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
  53                              (void **)&rom);
  54         if (status != EFI_SUCCESS) {
  55                 efi_err("Failed to allocate memory for 'rom'\n");
  56                 return status;
  57         }
  58
  59         memset(rom, 0, sizeof(*rom));
  60
  61         rom->data.type  = SETUP_PCI;
  62         rom->data.len   = size - sizeof(struct setup_data);
  63         rom->data.next  = 0;
  64         rom->pcilen     = pci->romsize;
  65         *__rom = rom;
  66
  67         status = efi_call_proto(pci, pci.read, EfiPciIoWidthUint16,
  68                                 PCI_VENDOR_ID, 1, &rom->vendor);
  69
  70         if (status != EFI_SUCCESS) {
  71                 efi_err("Failed to read rom->vendor\n");
  72                 goto free_struct;
  73         }
  74
  75         status = efi_call_proto(pci, pci.read, EfiPciIoWidthUint16,
  76                                 PCI_DEVICE_ID, 1, &rom->devid);
  77
  78         if (status != EFI_SUCCESS) {
  79                 efi_err("Failed to read rom->devid\n");
  80                 goto free_struct;
  81         }
  82
  83         status = efi_call_proto(pci, get_location, &rom->segment, &rom->bus,
  84                                 &rom->device, &rom->function);
  85
  86         if (status != EFI_SUCCESS)
  87                 goto free_struct;
  88
  89         memcpy(rom->romdata, romimage, romsize);
  90         return status;
  91
  92 free_struct:
  93         efi_bs_call(free_pool, rom);
  94         return status;
  95 }
  96
  97 /*
  98  * There's no way to return an informative status from this function,
  99  * because any analysis (and printing of error messages) needs to be
 100  * done directly at the EFI function call-site.
 101  *
 102  * For example, EFI_INVALID_PARAMETER could indicate a bug or maybe we
 103  * just didn't find any PCI devices, but there's no way to tell outside
 104  * the context of the call.
 105  */
 106 static void setup_efi_pci(struct boot_params *params)
 107 {
 108         efi_status_t status;
 109         void **pci_handle = NULL;
 110         efi_guid_t pci_proto = EFI_PCI_IO_PROTOCOL_GUID;
 111         unsigned long size = 0;
 112         struct setup_data *data;
 113         efi_handle_t h;
 114         int i;
 115
 116         status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
 117                              &pci_proto, NULL, &size, pci_handle);
 118
 119         if (status == EFI_BUFFER_TOO_SMALL) {
 120                 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
 121                                      (void **)&pci_handle);
 122
 123                 if (status != EFI_SUCCESS) {
 124                         efi_err("Failed to allocate memory for 'pci_handle'\n");
 125                         return;
 126                 }
 127
 128                 status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
 129                                      &pci_proto, NULL, &size, pci_handle);
 130         }
 131
 132         if (status != EFI_SUCCESS)
 133                 goto free_handle;
 134
 135         data = (struct setup_data *)(unsigned long)params->hdr.setup_data;
 136
 137         while (data && data->next)
 138                 data = (struct setup_data *)(unsigned long)data->next;
 139
 140         for_each_efi_handle(h, pci_handle, size, i) {
 141                 efi_pci_io_protocol_t *pci = NULL;
 142                 struct pci_setup_rom *rom;
 143
 144                 status = efi_bs_call(handle_protocol, h, &pci_proto,
 145                                      (void **)&pci);
 146                 if (status != EFI_SUCCESS || !pci)
 147                         continue;
 148
 149                 status = preserve_pci_rom_image(pci, &rom);
 150                 if (status != EFI_SUCCESS)
 151                         continue;
 152
 153                 if (data)
 154                         data->next = (unsigned long)rom;
 155                 else
 156                         params->hdr.setup_data = (unsigned long)rom;
 157
 158                 data = (struct setup_data *)rom;
 159         }
 160
 161 free_handle:
 162         efi_bs_call(free_pool, pci_handle);
 163 }
 164
 165 static void retrieve_apple_device_properties(struct boot_params *boot_params)
 166 {
 167         efi_guid_t guid = APPLE_PROPERTIES_PROTOCOL_GUID;
 168         struct setup_data *data, *new;
 169         efi_status_t status;
 170         u32 size = 0;
 171         apple_properties_protocol_t *p;
 172
 173         status = efi_bs_call(locate_protocol, &guid, NULL, (void **)&p);
 174         if (status != EFI_SUCCESS)
 175                 return;
 176
 177         if (efi_table_attr(p, version) != 0x10000) {
 178                 efi_err("Unsupported properties proto version\n");
 179                 return;
 180         }
 181
 182         efi_call_proto(p, get_all, NULL, &size);
 183         if (!size)
 184                 return;
 185
 186         do {
 187                 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA,
 188                                      size + sizeof(struct setup_data),
 189                                      (void **)&new);
 190                 if (status != EFI_SUCCESS) {
 191                         efi_err("Failed to allocate memory for 'properties'\n");
 192                         return;
 193                 }
 194
 195                 status = efi_call_proto(p, get_all, new->data, &size);
 196
 197                 if (status == EFI_BUFFER_TOO_SMALL)
 198                         efi_bs_call(free_pool, new);
 199         } while (status == EFI_BUFFER_TOO_SMALL);
 200
 201         new->type = SETUP_APPLE_PROPERTIES;
 202         new->len  = size;
 203         new->next = 0;
 204
 205         data = (struct setup_data *)(unsigned long)boot_params->hdr.setup_data;
 206         if (!data) {
 207                 boot_params->hdr.setup_data = (unsigned long)new;
 208         } else {
 209                 while (data->next)
 210                         data = (struct setup_data *)(unsigned long)data->next;
 211                 data->next = (unsigned long)new;
 212         }
 213 }
 214
 215 static void
 216 adjust_memory_range_protection(unsigned long start, unsigned long size)
 217 {
 218         efi_status_t status;
 219         efi_gcd_memory_space_desc_t desc;
 220         unsigned long end, next;
 221         unsigned long rounded_start, rounded_end;
 222         unsigned long unprotect_start, unprotect_size;
 223
 224         if (efi_dxe_table == NULL)
 225                 return;
 226
 227         rounded_start = rounddown(start, EFI_PAGE_SIZE);
 228         rounded_end = roundup(start + size, EFI_PAGE_SIZE);
 229
 230         /*
 231          * Don't modify memory region attributes, they are
 232          * already suitable, to lower the possibility to
 233          * encounter firmware bugs.
 234          */
 235
 236         for (end = start + size; start < end; start = next) {
 237
 238                 status = efi_dxe_call(get_memory_space_descriptor, start, &desc);
 239
 240                 if (status != EFI_SUCCESS)
 241                         return;
 242
 243                 next = desc.base_address + desc.length;
 244
 245                 /*
 246                  * Only system memory is suitable for trampoline/kernel image placement,
 247                  * so only this type of memory needs its attributes to be modified.
 248                  */
 249
 250                 if (desc.gcd_memory_type != EfiGcdMemoryTypeSystemMemory ||
 251                     (desc.attributes & (EFI_MEMORY_RO | EFI_MEMORY_XP)) == 0)
 252                         continue;
 253
 254                 unprotect_start = max(rounded_start, (unsigned long)desc.base_address);
 255                 unprotect_size = min(rounded_end, next) - unprotect_start;
 256
 257                 status = efi_dxe_call(set_memory_space_attributes,
 258                                       unprotect_start, unprotect_size,
 259                                       EFI_MEMORY_WB);
 260
 261                 if (status != EFI_SUCCESS) {
 262                         efi_warn("Unable to unprotect memory range [%08lx,%08lx]: %lx\n",
 263                                  unprotect_start,
 264                                  unprotect_start + unprotect_size,
 265                                  status);
 266                 }
 267         }
 268 }
 269
 270 /*
 271  * Trampoline takes 2 pages and can be loaded in first megabyte of memory
 272  * with its end placed between 128k and 640k where BIOS might start.
 273  * (see arch/x86/boot/compressed/pgtable_64.c)
 274  *
 275  * We cannot find exact trampoline placement since memory map
 276  * can be modified by UEFI, and it can alter the computed address.
 277  */
 278
 279 #define TRAMPOLINE_PLACEMENT_BASE ((128 - 8)*1024)
 280 #define TRAMPOLINE_PLACEMENT_SIZE (640*1024 - (128 - 8)*1024)
 281
 282 void startup_32(struct boot_params *boot_params);
 283
 284 static void
 285 setup_memory_protection(unsigned long image_base, unsigned long image_size)
 286 {
 287         /*
 288          * Allow execution of possible trampoline used
 289          * for switching between 4- and 5-level page tables
 290          * and relocated kernel image.
 291          */
 292
 293         adjust_memory_range_protection(TRAMPOLINE_PLACEMENT_BASE,
 294                                        TRAMPOLINE_PLACEMENT_SIZE);
 295
 296 #ifdef CONFIG_64BIT
 297         if (image_base != (unsigned long)startup_32)
 298                 adjust_memory_range_protection(image_base, image_size);
 299 #else
 300         /*
 301          * Clear protection flags on a whole range of possible
 302          * addresses used for KASLR. We don't need to do that
 303          * on x86_64, since KASLR/extraction is performed after
 304          * dedicated identity page tables are built and we only
 305          * need to remove possible protection on relocated image
 306          * itself disregarding further relocations.
 307          */
 308         adjust_memory_range_protection(LOAD_PHYSICAL_ADDR,
 309                                        KERNEL_IMAGE_SIZE - LOAD_PHYSICAL_ADDR);
 310 #endif
 311 }
 312
 313 static const efi_char16_t apple[] = L"Apple";
 314
 315 static void setup_quirks(struct boot_params *boot_params,
 316                          unsigned long image_base,
 317                          unsigned long image_size)
 318 {
 319         efi_char16_t *fw_vendor = (efi_char16_t *)(unsigned long)
 320                 efi_table_attr(efi_system_table, fw_vendor);
 321
 322         if (!memcmp(fw_vendor, apple, sizeof(apple))) {
 323                 if (IS_ENABLED(CONFIG_APPLE_PROPERTIES))
 324                         retrieve_apple_device_properties(boot_params);
 325         }
 326
 327         if (IS_ENABLED(CONFIG_EFI_DXE_MEM_ATTRIBUTES))
 328                 setup_memory_protection(image_base, image_size);
 329 }
 330
 331 /*
 332  * See if we have Universal Graphics Adapter (UGA) protocol
 333  */
 334 static efi_status_t
 335 setup_uga(struct screen_info *si, efi_guid_t *uga_proto, unsigned long size)
 336 {
 337         efi_status_t status;
 338         u32 width, height;
 339         void **uga_handle = NULL;
 340         efi_uga_draw_protocol_t *uga = NULL, *first_uga;
 341         efi_handle_t handle;
 342         int i;
 343
 344         status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
 345                              (void **)&uga_handle);
 346         if (status != EFI_SUCCESS)
 347                 return status;
 348
 349         status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
 350                              uga_proto, NULL, &size, uga_handle);
 351         if (status != EFI_SUCCESS)
 352                 goto free_handle;
 353
 354         height = 0;
 355         width = 0;
 356
 357         first_uga = NULL;
 358         for_each_efi_handle(handle, uga_handle, size, i) {
 359                 efi_guid_t pciio_proto = EFI_PCI_IO_PROTOCOL_GUID;
 360                 u32 w, h, depth, refresh;
 361                 void *pciio;
 362
 363                 status = efi_bs_call(handle_protocol, handle, uga_proto,
 364                                      (void **)&uga);
 365                 if (status != EFI_SUCCESS)
 366                         continue;
 367
 368                 pciio = NULL;
 369                 efi_bs_call(handle_protocol, handle, &pciio_proto, &pciio);
 370
 371                 status = efi_call_proto(uga, get_mode, &w, &h, &depth, &refresh);
 372                 if (status == EFI_SUCCESS && (!first_uga || pciio)) {
 373                         width = w;
 374                         height = h;
 375
 376                         /*
 377                          * Once we've found a UGA supporting PCIIO,
 378                          * don't bother looking any further.
 379                          */
 380                         if (pciio)
 381                                 break;
 382
 383                         first_uga = uga;
 384                 }
 385         }
 386
 387         if (!width && !height)
 388                 goto free_handle;
 389
 390         /* EFI framebuffer */
 391         si->orig_video_isVGA    = VIDEO_TYPE_EFI;
 392
 393         si->lfb_depth           = 32;
 394         si->lfb_width           = width;
 395         si->lfb_height          = height;
 396
 397         si->red_size            = 8;
 398         si->red_pos             = 16;
 399         si->green_size          = 8;
 400         si->green_pos           = 8;
 401         si->blue_size           = 8;
 402         si->blue_pos            = 0;
 403         si->rsvd_size           = 8;
 404         si->rsvd_pos            = 24;
 405
 406 free_handle:
 407         efi_bs_call(free_pool, uga_handle);
 408
 409         return status;
 410 }
 411
 412 static void setup_graphics(struct boot_params *boot_params)
 413 {
 414         efi_guid_t graphics_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
 415         struct screen_info *si;
 416         efi_guid_t uga_proto = EFI_UGA_PROTOCOL_GUID;
 417         efi_status_t status;
 418         unsigned long size;
 419         void **gop_handle = NULL;
 420         void **uga_handle = NULL;
 421
 422         si = &boot_params->screen_info;
 423         memset(si, 0, sizeof(*si));
 424
 425         size = 0;
 426         status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
 427                              &graphics_proto, NULL, &size, gop_handle);
 428         if (status == EFI_BUFFER_TOO_SMALL)
 429                 status = efi_setup_gop(si, &graphics_proto, size);
 430
 431         if (status != EFI_SUCCESS) {
 432                 size = 0;
 433                 status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
 434                                      &uga_proto, NULL, &size, uga_handle);
 435                 if (status == EFI_BUFFER_TOO_SMALL)
 436                         setup_uga(si, &uga_proto, size);
 437         }
 438 }
 439
 440
 441 static void __noreturn efi_exit(efi_handle_t handle, efi_status_t status)
 442 {
 443         efi_bs_call(exit, handle, status, 0, NULL);
 444         for(;;)
 445                 asm("hlt");
 446 }
 447
 448 void __noreturn efi_stub_entry(efi_handle_t handle,
 449                                efi_system_table_t *sys_table_arg,
 450                                struct boot_params *boot_params);
 451
 452 /*
 453  * Because the x86 boot code expects to be passed a boot_params we
 454  * need to create one ourselves (usually the bootloader would create
 455  * one for us).
 456  */
 457 efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
 458                                    efi_system_table_t *sys_table_arg)
 459 {
 460         struct boot_params *boot_params;
 461         struct setup_header *hdr;
 462         void *image_base;
 463         efi_guid_t proto = LOADED_IMAGE_PROTOCOL_GUID;
 464         int options_size = 0;
 465         efi_status_t status;
 466         char *cmdline_ptr;
 467
 468         efi_system_table = sys_table_arg;
 469
 470         /* Check if we were booted by the EFI firmware */
 471         if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
 472                 efi_exit(handle, EFI_INVALID_PARAMETER);
 473
 474         status = efi_bs_call(handle_protocol, handle, &proto, (void **)&image);
 475         if (status != EFI_SUCCESS) {
 476                 efi_err("Failed to get handle for LOADED_IMAGE_PROTOCOL\n");
 477                 efi_exit(handle, status);
 478         }
 479
 480         image_base = efi_table_attr(image, image_base);
 481         image_offset = (void *)startup_32 - image_base;
 482
 483         status = efi_allocate_pages(sizeof(struct boot_params),
 484                                     (unsigned long *)&boot_params, ULONG_MAX);
 485         if (status != EFI_SUCCESS) {
 486                 efi_err("Failed to allocate lowmem for boot params\n");
 487                 efi_exit(handle, status);
 488         }
 489
 490         memset(boot_params, 0x0, sizeof(struct boot_params));
 491
 492         hdr = &boot_params->hdr;
 493
 494         /* Copy the setup header from the second sector to boot_params */
 495         memcpy(&hdr->jump, image_base + 512,
 496                sizeof(struct setup_header) - offsetof(struct setup_header, jump));
 497
 498         /*
 499          * Fill out some of the header fields ourselves because the
 500          * EFI firmware loader doesn't load the first sector.
 501          */
 502         hdr->root_flags = 1;
 503         hdr->vid_mode   = 0xffff;
 504         hdr->boot_flag  = 0xAA55;
 505
 506         hdr->type_of_loader = 0x21;
 507
 508         /* Convert unicode cmdline to ascii */
 509         cmdline_ptr = efi_convert_cmdline(image, &options_size);
 510         if (!cmdline_ptr)
 511                 goto fail;
 512
 513         efi_set_u64_split((unsigned long)cmdline_ptr,
 514                           &hdr->cmd_line_ptr, &boot_params->ext_cmd_line_ptr);
 515
 516         hdr->ramdisk_image = 0;
 517         hdr->ramdisk_size = 0;
 518
 519         efi_stub_entry(handle, sys_table_arg, boot_params);
 520         /* not reached */
 521
 522 fail:
 523         efi_free(sizeof(struct boot_params), (unsigned long)boot_params);
 524
 525         efi_exit(handle, status);
 526 }
 527
 528 static void add_e820ext(struct boot_params *params,
 529                         struct setup_data *e820ext, u32 nr_entries)
 530 {
 531         struct setup_data *data;
 532
 533         e820ext->type = SETUP_E820_EXT;
 534         e820ext->len  = nr_entries * sizeof(struct boot_e820_entry);
 535         e820ext->next = 0;
 536
 537         data = (struct setup_data *)(unsigned long)params->hdr.setup_data;
 538
 539         while (data && data->next)
 540                 data = (struct setup_data *)(unsigned long)data->next;
 541
 542         if (data)
 543                 data->next = (unsigned long)e820ext;
 544         else
 545                 params->hdr.setup_data = (unsigned long)e820ext;
 546 }
 547
 548 static efi_status_t
 549 setup_e820(struct boot_params *params, struct setup_data *e820ext, u32 e820ext_size)
 550 {
 551         struct boot_e820_entry *entry = params->e820_table;
 552         struct efi_info *efi = &params->efi_info;
 553         struct boot_e820_entry *prev = NULL;
 554         u32 nr_entries;
 555         u32 nr_desc;
 556         int i;
 557
 558         nr_entries = 0;
 559         nr_desc = efi->efi_memmap_size / efi->efi_memdesc_size;
 560
 561         for (i = 0; i < nr_desc; i++) {
 562                 efi_memory_desc_t *d;
 563                 unsigned int e820_type = 0;
 564                 unsigned long m = efi->efi_memmap;
 565
 566 #ifdef CONFIG_X86_64
 567                 m |= (u64)efi->efi_memmap_hi << 32;
 568 #endif
 569
 570                 d = efi_early_memdesc_ptr(m, efi->efi_memdesc_size, i);
 571                 switch (d->type) {
 572                 case EFI_RESERVED_TYPE:
 573                 case EFI_RUNTIME_SERVICES_CODE:
 574                 case EFI_RUNTIME_SERVICES_DATA:
 575                 case EFI_MEMORY_MAPPED_IO:
 576                 case EFI_MEMORY_MAPPED_IO_PORT_SPACE:
 577                 case EFI_PAL_CODE:
 578                         e820_type = E820_TYPE_RESERVED;
 579                         break;
 580
 581                 case EFI_UNUSABLE_MEMORY:
 582                         e820_type = E820_TYPE_UNUSABLE;
 583                         break;
 584
 585                 case EFI_ACPI_RECLAIM_MEMORY:
 586                         e820_type = E820_TYPE_ACPI;
 587                         break;
 588
 589                 case EFI_LOADER_CODE:
 590                 case EFI_LOADER_DATA:
 591                 case EFI_BOOT_SERVICES_CODE:
 592                 case EFI_BOOT_SERVICES_DATA:
 593                 case EFI_CONVENTIONAL_MEMORY:
 594                         if (efi_soft_reserve_enabled() &&
 595                             (d->attribute & EFI_MEMORY_SP))
 596                                 e820_type = E820_TYPE_SOFT_RESERVED;
 597                         else
 598                                 e820_type = E820_TYPE_RAM;
 599                         break;
 600
 601                 case EFI_ACPI_MEMORY_NVS:
 602                         e820_type = E820_TYPE_NVS;
 603                         break;
 604
 605                 case EFI_PERSISTENT_MEMORY:
 606                         e820_type = E820_TYPE_PMEM;
 607                         break;
 608
 609                 default:
 610                         continue;
 611                 }
 612
 613                 /* Merge adjacent mappings */
 614                 if (prev && prev->type == e820_type &&
 615                     (prev->addr + prev->size) == d->phys_addr) {
 616                         prev->size += d->num_pages << 12;
 617                         continue;
 618                 }
 619
 620                 if (nr_entries == ARRAY_SIZE(params->e820_table)) {
 621                         u32 need = (nr_desc - i) * sizeof(struct e820_entry) +
 622                                    sizeof(struct setup_data);
 623
 624                         if (!e820ext || e820ext_size < need)
 625                                 return EFI_BUFFER_TOO_SMALL;
 626
 627                         /* boot_params map full, switch to e820 extended */
 628                         entry = (struct boot_e820_entry *)e820ext->data;
 629                 }
 630
 631                 entry->addr = d->phys_addr;
 632                 entry->size = d->num_pages << PAGE_SHIFT;
 633                 entry->type = e820_type;
 634                 prev = entry++;
 635                 nr_entries++;
 636         }
 637
 638         if (nr_entries > ARRAY_SIZE(params->e820_table)) {
 639                 u32 nr_e820ext = nr_entries - ARRAY_SIZE(params->e820_table);
 640
 641                 add_e820ext(params, e820ext, nr_e820ext);
 642                 nr_entries -= nr_e820ext;
 643         }
 644
 645         params->e820_entries = (u8)nr_entries;
 646
 647         return EFI_SUCCESS;
 648 }
 649
 650 static efi_status_t alloc_e820ext(u32 nr_desc, struct setup_data **e820ext,
 651                                   u32 *e820ext_size)
 652 {
 653         efi_status_t status;
 654         unsigned long size;
 655
 656         size = sizeof(struct setup_data) +
 657                 sizeof(struct e820_entry) * nr_desc;
 658
 659         if (*e820ext) {
 660                 efi_bs_call(free_pool, *e820ext);
 661                 *e820ext = NULL;
 662                 *e820ext_size = 0;
 663         }
 664
 665         status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
 666                              (void **)e820ext);
 667         if (status == EFI_SUCCESS)
 668                 *e820ext_size = size;
 669
 670         return status;
 671 }
 672
 673 static efi_status_t allocate_e820(struct boot_params *params,
 674                                   struct setup_data **e820ext,
 675                                   u32 *e820ext_size)
 676 {
 677         unsigned long map_size, desc_size, map_key;
 678         efi_status_t status;
 679         __u32 nr_desc, desc_version;
 680
 681         /* Only need the size of the mem map and size of each mem descriptor */
 682         map_size = 0;
 683         status = efi_bs_call(get_memory_map, &map_size, NULL, &map_key,
 684                              &desc_size, &desc_version);
 685         if (status != EFI_BUFFER_TOO_SMALL)
 686                 return (status != EFI_SUCCESS) ? status : EFI_UNSUPPORTED;
 687
 688         nr_desc = map_size / desc_size + EFI_MMAP_NR_SLACK_SLOTS;
 689
 690         if (nr_desc > ARRAY_SIZE(params->e820_table)) {
 691                 u32 nr_e820ext = nr_desc - ARRAY_SIZE(params->e820_table);
 692
 693                 status = alloc_e820ext(nr_e820ext, e820ext, e820ext_size);
 694                 if (status != EFI_SUCCESS)
 695                         return status;
 696         }
 697
 698         return EFI_SUCCESS;
 699 }
 700
 701 struct exit_boot_struct {
 702         struct boot_params      *boot_params;
 703         struct efi_info         *efi;
 704 };
 705
 706 static efi_status_t exit_boot_func(struct efi_boot_memmap *map,
 707                                    void *priv)
 708 {
 709         const char *signature;
 710         struct exit_boot_struct *p = priv;
 711
 712         signature = efi_is_64bit() ? EFI64_LOADER_SIGNATURE
 713                                    : EFI32_LOADER_SIGNATURE;
 714         memcpy(&p->efi->efi_loader_signature, signature, sizeof(__u32));
 715
 716         efi_set_u64_split((unsigned long)efi_system_table,
 717                           &p->efi->efi_systab, &p->efi->efi_systab_hi);
 718         p->efi->efi_memdesc_size        = *map->desc_size;
 719         p->efi->efi_memdesc_version     = *map->desc_ver;
 720         efi_set_u64_split((unsigned long)*map->map,
 721                           &p->efi->efi_memmap, &p->efi->efi_memmap_hi);
 722         p->efi->efi_memmap_size         = *map->map_size;
 723
 724         return EFI_SUCCESS;
 725 }
 726
 727 static efi_status_t exit_boot(struct boot_params *boot_params, void *handle)
 728 {
 729         unsigned long map_sz, key, desc_size, buff_size;
 730         efi_memory_desc_t *mem_map;
 731         struct setup_data *e820ext = NULL;
 732         __u32 e820ext_size = 0;
 733         efi_status_t status;
 734         __u32 desc_version;
 735         struct efi_boot_memmap map;
 736         struct exit_boot_struct priv;
 737
 738         map.map                 = &mem_map;
 739         map.map_size            = &map_sz;
 740         map.desc_size           = &desc_size;
 741         map.desc_ver            = &desc_version;
 742         map.key_ptr             = &key;
 743         map.buff_size           = &buff_size;
 744         priv.boot_params        = boot_params;
 745         priv.efi                = &boot_params->efi_info;
 746
 747         status = allocate_e820(boot_params, &e820ext, &e820ext_size);
 748         if (status != EFI_SUCCESS)
 749                 return status;
 750
 751         /* Might as well exit boot services now */
 752         status = efi_exit_boot_services(handle, &map, &priv, exit_boot_func);
 753         if (status != EFI_SUCCESS)
 754                 return status;
 755
 756         /* Historic? */
 757         boot_params->alt_mem_k  = 32 * 1024;
 758
 759         status = setup_e820(boot_params, e820ext, e820ext_size);
 760         if (status != EFI_SUCCESS)
 761                 return status;
 762
 763         return EFI_SUCCESS;
 764 }
 765
 766 /*
 767  * On success, we return the address of startup_32, which has potentially been
 768  * relocated by efi_relocate_kernel.
 769  * On failure, we exit to the firmware via efi_exit instead of returning.
 770  */
 771 unsigned long efi_main(efi_handle_t handle,
 772                              efi_system_table_t *sys_table_arg,
 773                              struct boot_params *boot_params)
 774 {
 775         unsigned long bzimage_addr = (unsigned long)startup_32;
 776         unsigned long buffer_start, buffer_end;
 777         struct setup_header *hdr = &boot_params->hdr;
 778         unsigned long addr, size;
 779         efi_status_t status;
 780
 781         efi_system_table = sys_table_arg;
 782         /* Check if we were booted by the EFI firmware */
 783         if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
 784                 efi_exit(handle, EFI_INVALID_PARAMETER);
 785
 786         efi_dxe_table = get_efi_config_table(EFI_DXE_SERVICES_TABLE_GUID);
 787         if (efi_dxe_table &&
 788             efi_dxe_table->hdr.signature != EFI_DXE_SERVICES_TABLE_SIGNATURE) {
 789                 efi_warn("Ignoring DXE services table: invalid signature\n");
 790                 efi_dxe_table = NULL;
 791         }
 792
 793         /*
 794          * If the kernel isn't already loaded at a suitable address,
 795          * relocate it.
 796          *
 797          * It must be loaded above LOAD_PHYSICAL_ADDR.
 798          *
 799          * The maximum address for 64-bit is 1 << 46 for 4-level paging. This
 800          * is defined as the macro MAXMEM, but unfortunately that is not a
 801          * compile-time constant if 5-level paging is configured, so we instead
 802          * define our own macro for use here.
 803          *
 804          * For 32-bit, the maximum address is complicated to figure out, for
 805          * now use KERNEL_IMAGE_SIZE, which will be 512MiB, the same as what
 806          * KASLR uses.
 807          *
 808          * Also relocate it if image_offset is zero, i.e. the kernel wasn't
 809          * loaded by LoadImage, but rather by a bootloader that called the
 810          * handover entry. The reason we must always relocate in this case is
 811          * to handle the case of systemd-boot booting a unified kernel image,
 812          * which is a PE executable that contains the bzImage and an initrd as
 813          * COFF sections. The initrd section is placed after the bzImage
 814          * without ensuring that there are at least init_size bytes available
 815          * for the bzImage, and thus the compressed kernel's startup code may
 816          * overwrite the initrd unless it is moved out of the way.
 817          */
 818
 819         buffer_start = ALIGN(bzimage_addr - image_offset,
 820                              hdr->kernel_alignment);
 821         buffer_end = buffer_start + hdr->init_size;
 822
 823         if ((buffer_start < LOAD_PHYSICAL_ADDR)                              ||
 824             (IS_ENABLED(CONFIG_X86_32) && buffer_end > KERNEL_IMAGE_SIZE)    ||
 825             (IS_ENABLED(CONFIG_X86_64) && buffer_end > MAXMEM_X86_64_4LEVEL) ||
 826             (image_offset == 0)) {
 827                 extern char _bss[];
 828
 829                 status = efi_relocate_kernel(&bzimage_addr,
 830                                              (unsigned long)_bss - bzimage_addr,
 831                                              hdr->init_size,
 832                                              hdr->pref_address,
 833                                              hdr->kernel_alignment,
 834                                              LOAD_PHYSICAL_ADDR);
 835                 if (status != EFI_SUCCESS) {
 836                         efi_err("efi_relocate_kernel() failed!\n");
 837                         goto fail;
 838                 }
 839                 /*
 840                  * Now that we've copied the kernel elsewhere, we no longer
 841                  * have a set up block before startup_32(), so reset image_offset
 842                  * to zero in case it was set earlier.
 843                  */
 844                 image_offset = 0;
 845         }
 846
 847 #ifdef CONFIG_CMDLINE_BOOL
 848         status = efi_parse_options(CONFIG_CMDLINE);
 849         if (status != EFI_SUCCESS) {
 850                 efi_err("Failed to parse options\n");
 851                 goto fail;
 852         }
 853 #endif
 854         if (!IS_ENABLED(CONFIG_CMDLINE_OVERRIDE)) {
 855                 unsigned long cmdline_paddr = ((u64)hdr->cmd_line_ptr |
 856                                                ((u64)boot_params->ext_cmd_line_ptr << 32));
 857                 status = efi_parse_options((char *)cmdline_paddr);
 858                 if (status != EFI_SUCCESS) {
 859                         efi_err("Failed to parse options\n");
 860                         goto fail;
 861                 }
 862         }
 863
 864         /*
 865          * At this point, an initrd may already have been loaded by the
 866          * bootloader and passed via bootparams. We permit an initrd loaded
 867          * from the LINUX_EFI_INITRD_MEDIA_GUID device path to supersede it.
 868          *
 869          * If the device path is not present, any command-line initrd=
 870          * arguments will be processed only if image is not NULL, which will be
 871          * the case only if we were loaded via the PE entry point.
 872          */
 873         status = efi_load_initrd(image, &addr, &size, hdr->initrd_addr_max,
 874                                  ULONG_MAX);
 875         if (status != EFI_SUCCESS)
 876                 goto fail;
 877         if (size > 0) {
 878                 efi_set_u64_split(addr, &hdr->ramdisk_image,
 879                                   &boot_params->ext_ramdisk_image);
 880                 efi_set_u64_split(size, &hdr->ramdisk_size,
 881                                   &boot_params->ext_ramdisk_size);
 882         }
 883
 884         /*
 885          * If the boot loader gave us a value for secure_boot then we use that,
 886          * otherwise we ask the BIOS.
 887          */
 888         if (boot_params->secure_boot == efi_secureboot_mode_unset)
 889                 boot_params->secure_boot = efi_get_secureboot();
 890
 891         /* Ask the firmware to clear memory on unclean shutdown */
 892         efi_enable_reset_attack_mitigation();
 893
 894         efi_random_get_seed();
 895
 896         efi_retrieve_tpm2_eventlog();
 897
 898         setup_graphics(boot_params);
 899
 900         setup_efi_pci(boot_params);
 901
 902         setup_quirks(boot_params, bzimage_addr, buffer_end - buffer_start);
 903
 904         status = exit_boot(boot_params, handle);
 905         if (status != EFI_SUCCESS) {
 906                 efi_err("exit_boot() failed!\n");
 907                 goto fail;
 908         }
 909
 910         return bzimage_addr;
 911 fail:
 912         efi_err("efi_main() failed!\n");
 913
 914         efi_exit(handle, status);
 915 }