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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * EFI stub implementation that is shared by arm and arm64 architectures.
   4  * This should be #included by the EFI stub implementation files.
   5  *
   6  * Copyright (C) 2013,2014 Linaro Limited
   7  *     Roy Franz <roy.franz@linaro.org
   8  * Copyright (C) 2013 Red Hat, Inc.
   9  *     Mark Salter <msalter@redhat.com>
  10  */
  11
  12 #include <linux/efi.h>
  13 #include <linux/libfdt.h>
  14 #include <asm/efi.h>
  15
  16 #include "efistub.h"
  17
  18 /*
  19  * This is the base address at which to start allocating virtual memory ranges
  20  * for UEFI Runtime Services. This is in the low TTBR0 range so that we can use
  21  * any allocation we choose, and eliminate the risk of a conflict after kexec.
  22  * The value chosen is the largest non-zero power of 2 suitable for this purpose
  23  * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
  24  * be mapped efficiently.
  25  * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
  26  * map everything below 1 GB. (512 MB is a reasonable upper bound for the
  27  * entire footprint of the UEFI runtime services memory regions)
  28  */
  29 #define EFI_RT_VIRTUAL_BASE     SZ_512M
  30 #define EFI_RT_VIRTUAL_SIZE     SZ_512M
  31
  32 #ifdef CONFIG_ARM64
  33 # define EFI_RT_VIRTUAL_LIMIT   DEFAULT_MAP_WINDOW_64
  34 #else
  35 # define EFI_RT_VIRTUAL_LIMIT   TASK_SIZE
  36 #endif
  37
  38 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
  39 static bool flat_va_mapping;
  40
  41 const efi_system_table_t *efi_system_table;
  42
  43 static struct screen_info *setup_graphics(void)
  44 {
  45         efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
  46         efi_status_t status;
  47         unsigned long size;
  48         void **gop_handle = NULL;
  49         struct screen_info *si = NULL;
  50
  51         size = 0;
  52         status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
  53                              &gop_proto, NULL, &size, gop_handle);
  54         if (status == EFI_BUFFER_TOO_SMALL) {
  55                 si = alloc_screen_info();
  56                 if (!si)
  57                         return NULL;
  58                 status = efi_setup_gop(si, &gop_proto, size);
  59                 if (status != EFI_SUCCESS) {
  60                         free_screen_info(si);
  61                         return NULL;
  62                 }
  63         }
  64         return si;
  65 }
  66
  67 static void install_memreserve_table(void)
  68 {
  69         struct linux_efi_memreserve *rsv;
  70         efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
  71         efi_status_t status;
  72
  73         status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
  74                              (void **)&rsv);
  75         if (status != EFI_SUCCESS) {
  76                 efi_err("Failed to allocate memreserve entry!\n");
  77                 return;
  78         }
  79
  80         rsv->next = 0;
  81         rsv->size = 0;
  82         atomic_set(&rsv->count, 0);
  83
  84         status = efi_bs_call(install_configuration_table,
  85                              &memreserve_table_guid, rsv);
  86         if (status != EFI_SUCCESS)
  87                 efi_err("Failed to install memreserve config table!\n");
  88 }
  89
  90 static unsigned long get_dram_base(void)
  91 {
  92         efi_status_t status;
  93         unsigned long map_size, buff_size;
  94         unsigned long membase  = EFI_ERROR;
  95         struct efi_memory_map map;
  96         efi_memory_desc_t *md;
  97         struct efi_boot_memmap boot_map;
  98
  99         boot_map.map            = (efi_memory_desc_t **)&map.map;
 100         boot_map.map_size       = &map_size;
 101         boot_map.desc_size      = &map.desc_size;
 102         boot_map.desc_ver       = NULL;
 103         boot_map.key_ptr        = NULL;
 104         boot_map.buff_size      = &buff_size;
 105
 106         status = efi_get_memory_map(&boot_map);
 107         if (status != EFI_SUCCESS)
 108                 return membase;
 109
 110         map.map_end = map.map + map_size;
 111
 112         for_each_efi_memory_desc_in_map(&map, md) {
 113                 if (md->attribute & EFI_MEMORY_WB) {
 114                         if (membase > md->phys_addr)
 115                                 membase = md->phys_addr;
 116                 }
 117         }
 118
 119         efi_bs_call(free_pool, map.map);
 120
 121         return membase;
 122 }
 123
 124 /*
 125  * This function handles the architcture specific differences between arm and
 126  * arm64 regarding where the kernel image must be loaded and any memory that
 127  * must be reserved. On failure it is required to free all
 128  * all allocations it has made.
 129  */
 130 efi_status_t handle_kernel_image(unsigned long *image_addr,
 131                                  unsigned long *image_size,
 132                                  unsigned long *reserve_addr,
 133                                  unsigned long *reserve_size,
 134                                  unsigned long dram_base,
 135                                  efi_loaded_image_t *image);
 136
 137 asmlinkage void __noreturn efi_enter_kernel(unsigned long entrypoint,
 138                                             unsigned long fdt_addr,
 139                                             unsigned long fdt_size);
 140
 141 /*
 142  * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
 143  * that is described in the PE/COFF header.  Most of the code is the same
 144  * for both archictectures, with the arch-specific code provided in the
 145  * handle_kernel_image() function.
 146  */
 147 efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
 148                                    efi_system_table_t *sys_table_arg)
 149 {
 150         efi_loaded_image_t *image;
 151         efi_status_t status;
 152         unsigned long image_addr;
 153         unsigned long image_size = 0;
 154         unsigned long dram_base;
 155         /* addr/point and size pairs for memory management*/
 156         unsigned long initrd_addr = 0;
 157         unsigned long initrd_size = 0;
 158         unsigned long fdt_addr = 0;  /* Original DTB */
 159         unsigned long fdt_size = 0;
 160         char *cmdline_ptr = NULL;
 161         int cmdline_size = 0;
 162         efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
 163         unsigned long reserve_addr = 0;
 164         unsigned long reserve_size = 0;
 165         enum efi_secureboot_mode secure_boot;
 166         struct screen_info *si;
 167         efi_properties_table_t *prop_tbl;
 168         unsigned long max_addr;
 169
 170         efi_system_table = sys_table_arg;
 171
 172         /* Check if we were booted by the EFI firmware */
 173         if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
 174                 status = EFI_INVALID_PARAMETER;
 175                 goto fail;
 176         }
 177
 178         status = check_platform_features();
 179         if (status != EFI_SUCCESS)
 180                 goto fail;
 181
 182         /*
 183          * Get a handle to the loaded image protocol.  This is used to get
 184          * information about the running image, such as size and the command
 185          * line.
 186          */
 187         status = efi_system_table->boottime->handle_protocol(handle,
 188                                         &loaded_image_proto, (void *)&image);
 189         if (status != EFI_SUCCESS) {
 190                 efi_err("Failed to get loaded image protocol\n");
 191                 goto fail;
 192         }
 193
 194         dram_base = get_dram_base();
 195         if (dram_base == EFI_ERROR) {
 196                 efi_err("Failed to find DRAM base\n");
 197                 status = EFI_LOAD_ERROR;
 198                 goto fail;
 199         }
 200
 201         /*
 202          * Get the command line from EFI, using the LOADED_IMAGE
 203          * protocol. We are going to copy the command line into the
 204          * device tree, so this can be allocated anywhere.
 205          */
 206         cmdline_ptr = efi_convert_cmdline(image, &cmdline_size);
 207         if (!cmdline_ptr) {
 208                 efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
 209                 status = EFI_OUT_OF_RESOURCES;
 210                 goto fail;
 211         }
 212
 213         if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
 214             IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
 215             cmdline_size == 0) {
 216                 status = efi_parse_options(CONFIG_CMDLINE);
 217                 if (status != EFI_SUCCESS) {
 218                         efi_err("Failed to parse options\n");
 219                         goto fail_free_cmdline;
 220                 }
 221         }
 222
 223         if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
 224                 status = efi_parse_options(cmdline_ptr);
 225                 if (status != EFI_SUCCESS) {
 226                         efi_err("Failed to parse options\n");
 227                         goto fail_free_cmdline;
 228                 }
 229         }
 230
 231         efi_info("Booting Linux Kernel...\n");
 232
 233         si = setup_graphics();
 234
 235         status = handle_kernel_image(&image_addr, &image_size,
 236                                      &reserve_addr,
 237                                      &reserve_size,
 238                                      dram_base, image);
 239         if (status != EFI_SUCCESS) {
 240                 efi_err("Failed to relocate kernel\n");
 241                 goto fail_free_screeninfo;
 242         }
 243
 244         efi_retrieve_tpm2_eventlog();
 245
 246         /* Ask the firmware to clear memory on unclean shutdown */
 247         efi_enable_reset_attack_mitigation();
 248
 249         secure_boot = efi_get_secureboot();
 250
 251         /*
 252          * Unauthenticated device tree data is a security hazard, so ignore
 253          * 'dtb=' unless UEFI Secure Boot is disabled.  We assume that secure
 254          * boot is enabled if we can't determine its state.
 255          */
 256         if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
 257              secure_boot != efi_secureboot_mode_disabled) {
 258                 if (strstr(cmdline_ptr, "dtb="))
 259                         efi_err("Ignoring DTB from command line.\n");
 260         } else {
 261                 status = efi_load_dtb(image, &fdt_addr, &fdt_size);
 262
 263                 if (status != EFI_SUCCESS) {
 264                         efi_err("Failed to load device tree!\n");
 265                         goto fail_free_image;
 266                 }
 267         }
 268
 269         if (fdt_addr) {
 270                 efi_info("Using DTB from command line\n");
 271         } else {
 272                 /* Look for a device tree configuration table entry. */
 273                 fdt_addr = (uintptr_t)get_fdt(&fdt_size);
 274                 if (fdt_addr)
 275                         efi_info("Using DTB from configuration table\n");
 276         }
 277
 278         if (!fdt_addr)
 279                 efi_info("Generating empty DTB\n");
 280
 281         if (!efi_noinitrd) {
 282                 max_addr = efi_get_max_initrd_addr(dram_base, image_addr);
 283                 status = efi_load_initrd(image, &initrd_addr, &initrd_size,
 284                                          ULONG_MAX, max_addr);
 285                 if (status != EFI_SUCCESS)
 286                         efi_err("Failed to load initrd!\n");
 287         }
 288
 289         efi_random_get_seed();
 290
 291         /*
 292          * If the NX PE data feature is enabled in the properties table, we
 293          * should take care not to create a virtual mapping that changes the
 294          * relative placement of runtime services code and data regions, as
 295          * they may belong to the same PE/COFF executable image in memory.
 296          * The easiest way to achieve that is to simply use a 1:1 mapping.
 297          */
 298         prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID);
 299         flat_va_mapping = prop_tbl &&
 300                           (prop_tbl->memory_protection_attribute &
 301                            EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);
 302
 303         /* hibernation expects the runtime regions to stay in the same place */
 304         if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) {
 305                 /*
 306                  * Randomize the base of the UEFI runtime services region.
 307                  * Preserve the 2 MB alignment of the region by taking a
 308                  * shift of 21 bit positions into account when scaling
 309                  * the headroom value using a 32-bit random value.
 310                  */
 311                 static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
 312                                             EFI_RT_VIRTUAL_BASE -
 313                                             EFI_RT_VIRTUAL_SIZE;
 314                 u32 rnd;
 315
 316                 status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd);
 317                 if (status == EFI_SUCCESS) {
 318                         virtmap_base = EFI_RT_VIRTUAL_BASE +
 319                                        (((headroom >> 21) * rnd) >> (32 - 21));
 320                 }
 321         }
 322
 323         install_memreserve_table();
 324
 325         status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr,
 326                                                 efi_get_max_fdt_addr(dram_base),
 327                                                 initrd_addr, initrd_size,
 328                                                 cmdline_ptr, fdt_addr, fdt_size);
 329         if (status != EFI_SUCCESS)
 330                 goto fail_free_initrd;
 331
 332         efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));
 333         /* not reached */
 334
 335 fail_free_initrd:
 336         efi_err("Failed to update FDT and exit boot services\n");
 337
 338         efi_free(initrd_size, initrd_addr);
 339         efi_free(fdt_size, fdt_addr);
 340
 341 fail_free_image:
 342         efi_free(image_size, image_addr);
 343         efi_free(reserve_size, reserve_addr);
 344 fail_free_screeninfo:
 345         free_screen_info(si);
 346 fail_free_cmdline:
 347         efi_bs_call(free_pool, cmdline_ptr);
 348 fail:
 349         return status;
 350 }
 351
 352 /*
 353  * efi_get_virtmap() - create a virtual mapping for the EFI memory map
 354  *
 355  * This function populates the virt_addr fields of all memory region descriptors
 356  * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
 357  * are also copied to @runtime_map, and their total count is returned in @count.
 358  */
 359 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
 360                      unsigned long desc_size, efi_memory_desc_t *runtime_map,
 361                      int *count)
 362 {
 363         u64 efi_virt_base = virtmap_base;
 364         efi_memory_desc_t *in, *out = runtime_map;
 365         int l;
 366
 367         for (l = 0; l < map_size; l += desc_size) {
 368                 u64 paddr, size;
 369
 370                 in = (void *)memory_map + l;
 371                 if (!(in->attribute & EFI_MEMORY_RUNTIME))
 372                         continue;
 373
 374                 paddr = in->phys_addr;
 375                 size = in->num_pages * EFI_PAGE_SIZE;
 376
 377                 in->virt_addr = in->phys_addr;
 378                 if (efi_novamap) {
 379                         continue;
 380                 }
 381
 382                 /*
 383                  * Make the mapping compatible with 64k pages: this allows
 384                  * a 4k page size kernel to kexec a 64k page size kernel and
 385                  * vice versa.
 386                  */
 387                 if (!flat_va_mapping) {
 388
 389                         paddr = round_down(in->phys_addr, SZ_64K);
 390                         size += in->phys_addr - paddr;
 391
 392                         /*
 393                          * Avoid wasting memory on PTEs by choosing a virtual
 394                          * base that is compatible with section mappings if this
 395                          * region has the appropriate size and physical
 396                          * alignment. (Sections are 2 MB on 4k granule kernels)
 397                          */
 398                         if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
 399                                 efi_virt_base = round_up(efi_virt_base, SZ_2M);
 400                         else
 401                                 efi_virt_base = round_up(efi_virt_base, SZ_64K);
 402
 403                         in->virt_addr += efi_virt_base - paddr;
 404                         efi_virt_base += size;
 405                 }
 406
 407                 memcpy(out, in, desc_size);
 408                 out = (void *)out + desc_size;
 409                 ++*count;
 410         }
 411 }