drivers/firmware/efi/libstub/arm-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 __efistub_global flat_va_mapping;
  40
  41 static efi_system_table_t *__efistub_global sys_table;
  42
  43 __pure efi_system_table_t *efi_system_table(void)
  44 {
  45         return sys_table;
  46 }
  47
  48 static struct screen_info *setup_graphics(void)
  49 {
  50         efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
  51         efi_status_t status;
  52         unsigned long size;
  53         void **gop_handle = NULL;
  54         struct screen_info *si = NULL;
  55
  56         size = 0;
  57         status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
  58                              &gop_proto, NULL, &size, gop_handle);
  59         if (status == EFI_BUFFER_TOO_SMALL) {
  60                 si = alloc_screen_info();
  61                 if (!si)
  62                         return NULL;
  63                 status = efi_setup_gop(si, &gop_proto, size);
  64                 if (status != EFI_SUCCESS) {
  65                         free_screen_info(si);
  66                         return NULL;
  67                 }
  68         }
  69         return si;
  70 }
  71
  72 void install_memreserve_table(void)
  73 {
  74         struct linux_efi_memreserve *rsv;
  75         efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
  76         efi_status_t status;
  77
  78         status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
  79                              (void **)&rsv);
  80         if (status != EFI_SUCCESS) {
  81                 pr_efi_err("Failed to allocate memreserve entry!\n");
  82                 return;
  83         }
  84
  85         rsv->next = 0;
  86         rsv->size = 0;
  87         atomic_set(&rsv->count, 0);
  88
  89         status = efi_bs_call(install_configuration_table,
  90                              &memreserve_table_guid, rsv);
  91         if (status != EFI_SUCCESS)
  92                 pr_efi_err("Failed to install memreserve config table!\n");
  93 }
  94
  95 static unsigned long get_dram_base(void)
  96 {
  97         efi_status_t status;
  98         unsigned long map_size, buff_size;
  99         unsigned long membase  = EFI_ERROR;
 100         struct efi_memory_map map;
 101         efi_memory_desc_t *md;
 102         struct efi_boot_memmap boot_map;
 103
 104         boot_map.map            = (efi_memory_desc_t **)&map.map;
 105         boot_map.map_size       = &map_size;
 106         boot_map.desc_size      = &map.desc_size;
 107         boot_map.desc_ver       = NULL;
 108         boot_map.key_ptr        = NULL;
 109         boot_map.buff_size      = &buff_size;
 110
 111         status = efi_get_memory_map(&boot_map);
 112         if (status != EFI_SUCCESS)
 113                 return membase;
 114
 115         map.map_end = map.map + map_size;
 116
 117         for_each_efi_memory_desc_in_map(&map, md) {
 118                 if (md->attribute & EFI_MEMORY_WB) {
 119                         if (membase > md->phys_addr)
 120                                 membase = md->phys_addr;
 121                 }
 122         }
 123
 124         efi_bs_call(free_pool, map.map);
 125
 126         return membase;
 127 }
 128
 129 /*
 130  * This function handles the architcture specific differences between arm and
 131  * arm64 regarding where the kernel image must be loaded and any memory that
 132  * must be reserved. On failure it is required to free all
 133  * all allocations it has made.
 134  */
 135 efi_status_t handle_kernel_image(unsigned long *image_addr,
 136                                  unsigned long *image_size,
 137                                  unsigned long *reserve_addr,
 138                                  unsigned long *reserve_size,
 139                                  unsigned long dram_base,
 140                                  efi_loaded_image_t *image);
 141
 142 asmlinkage void __noreturn efi_enter_kernel(unsigned long entrypoint,
 143                                             unsigned long fdt_addr,
 144                                             unsigned long fdt_size);
 145
 146 /*
 147  * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
 148  * that is described in the PE/COFF header.  Most of the code is the same
 149  * for both archictectures, with the arch-specific code provided in the
 150  * handle_kernel_image() function.
 151  */
 152 efi_status_t efi_entry(efi_handle_t handle, efi_system_table_t *sys_table_arg)
 153 {
 154         efi_loaded_image_t *image;
 155         efi_status_t status;
 156         unsigned long image_addr;
 157         unsigned long image_size = 0;
 158         unsigned long dram_base;
 159         /* addr/point and size pairs for memory management*/
 160         unsigned long initrd_addr = 0;
 161         unsigned long initrd_size = 0;
 162         unsigned long fdt_addr = 0;  /* Original DTB */
 163         unsigned long fdt_size = 0;
 164         char *cmdline_ptr = NULL;
 165         int cmdline_size = 0;
 166         efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
 167         unsigned long reserve_addr = 0;
 168         unsigned long reserve_size = 0;
 169         enum efi_secureboot_mode secure_boot;
 170         struct screen_info *si;
 171         efi_properties_table_t *prop_tbl;
 172         unsigned long max_addr;
 173
 174         sys_table = sys_table_arg;
 175
 176         /* Check if we were booted by the EFI firmware */
 177         if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
 178                 status = EFI_INVALID_PARAMETER;
 179                 goto fail;
 180         }
 181
 182         status = check_platform_features();
 183         if (status != EFI_SUCCESS)
 184                 goto fail;
 185
 186         /*
 187          * Get a handle to the loaded image protocol.  This is used to get
 188          * information about the running image, such as size and the command
 189          * line.
 190          */
 191         status = sys_table->boottime->handle_protocol(handle,
 192                                         &loaded_image_proto, (void *)&image);
 193         if (status != EFI_SUCCESS) {
 194                 pr_efi_err("Failed to get loaded image protocol\n");
 195                 goto fail;
 196         }
 197
 198         dram_base = get_dram_base();
 199         if (dram_base == EFI_ERROR) {
 200                 pr_efi_err("Failed to find DRAM base\n");
 201                 status = EFI_LOAD_ERROR;
 202                 goto fail;
 203         }
 204
 205         /*
 206          * Get the command line from EFI, using the LOADED_IMAGE
 207          * protocol. We are going to copy the command line into the
 208          * device tree, so this can be allocated anywhere.
 209          */
 210         cmdline_ptr = efi_convert_cmdline(image, &cmdline_size, ULONG_MAX);
 211         if (!cmdline_ptr) {
 212                 pr_efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
 213                 status = EFI_OUT_OF_RESOURCES;
 214                 goto fail;
 215         }
 216
 217         if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
 218             IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
 219             cmdline_size == 0)
 220                 efi_parse_options(CONFIG_CMDLINE);
 221
 222         if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0)
 223                 efi_parse_options(cmdline_ptr);
 224
 225         pr_efi("Booting Linux Kernel...\n");
 226
 227         si = setup_graphics();
 228
 229         status = handle_kernel_image(&image_addr, &image_size,
 230                                      &reserve_addr,
 231                                      &reserve_size,
 232                                      dram_base, image);
 233         if (status != EFI_SUCCESS) {
 234                 pr_efi_err("Failed to relocate kernel\n");
 235                 goto fail_free_cmdline;
 236         }
 237
 238         efi_retrieve_tpm2_eventlog();
 239
 240         /* Ask the firmware to clear memory on unclean shutdown */
 241         efi_enable_reset_attack_mitigation();
 242
 243         secure_boot = efi_get_secureboot();
 244
 245         /*
 246          * Unauthenticated device tree data is a security hazard, so ignore
 247          * 'dtb=' unless UEFI Secure Boot is disabled.  We assume that secure
 248          * boot is enabled if we can't determine its state.
 249          */
 250         if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
 251              secure_boot != efi_secureboot_mode_disabled) {
 252                 if (strstr(cmdline_ptr, "dtb="))
 253                         pr_efi("Ignoring DTB from command line.\n");
 254         } else {
 255                 status = efi_load_dtb(image, &fdt_addr, &fdt_size);
 256
 257                 if (status != EFI_SUCCESS) {
 258                         pr_efi_err("Failed to load device tree!\n");
 259                         goto fail_free_image;
 260                 }
 261         }
 262
 263         if (fdt_addr) {
 264                 pr_efi("Using DTB from command line\n");
 265         } else {
 266                 /* Look for a device tree configuration table entry. */
 267                 fdt_addr = (uintptr_t)get_fdt(&fdt_size);
 268                 if (fdt_addr)
 269                         pr_efi("Using DTB from configuration table\n");
 270         }
 271
 272         if (!fdt_addr)
 273                 pr_efi("Generating empty DTB\n");
 274
 275         if (!noinitrd()) {
 276                 max_addr = efi_get_max_initrd_addr(dram_base, image_addr);
 277                 status = efi_load_initrd_dev_path(&initrd_addr, &initrd_size,
 278                                                   max_addr);
 279                 if (status == EFI_SUCCESS) {
 280                         pr_efi("Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path\n");
 281                 } else if (status == EFI_NOT_FOUND) {
 282                         status = efi_load_initrd(image, &initrd_addr, &initrd_size,
 283                                                  ULONG_MAX, max_addr);
 284                         if (status == EFI_SUCCESS && initrd_size > 0)
 285                                 pr_efi("Loaded initrd from command line option\n");
 286                 }
 287                 if (status != EFI_SUCCESS)
 288                         pr_efi_err("Failed to load initrd!\n");
 289         }
 290
 291         efi_random_get_seed();
 292
 293         /*
 294          * If the NX PE data feature is enabled in the properties table, we
 295          * should take care not to create a virtual mapping that changes the
 296          * relative placement of runtime services code and data regions, as
 297          * they may belong to the same PE/COFF executable image in memory.
 298          * The easiest way to achieve that is to simply use a 1:1 mapping.
 299          */
 300         prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID);
 301         flat_va_mapping = prop_tbl &&
 302                           (prop_tbl->memory_protection_attribute &
 303                            EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);
 304
 305         /* hibernation expects the runtime regions to stay in the same place */
 306         if (!IS_ENABLED(CONFIG_HIBERNATION) && !nokaslr() && !flat_va_mapping) {
 307                 /*
 308                  * Randomize the base of the UEFI runtime services region.
 309                  * Preserve the 2 MB alignment of the region by taking a
 310                  * shift of 21 bit positions into account when scaling
 311                  * the headroom value using a 32-bit random value.
 312                  */
 313                 static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
 314                                             EFI_RT_VIRTUAL_BASE -
 315                                             EFI_RT_VIRTUAL_SIZE;
 316                 u32 rnd;
 317
 318                 status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd);
 319                 if (status == EFI_SUCCESS) {
 320                         virtmap_base = EFI_RT_VIRTUAL_BASE +
 321                                        (((headroom >> 21) * rnd) >> (32 - 21));
 322                 }
 323         }
 324
 325         install_memreserve_table();
 326
 327         status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr,
 328                                                 efi_get_max_fdt_addr(dram_base),
 329                                                 initrd_addr, initrd_size,
 330                                                 cmdline_ptr, fdt_addr, fdt_size);
 331         if (status != EFI_SUCCESS)
 332                 goto fail_free_initrd;
 333
 334         efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));
 335         /* not reached */
 336
 337 fail_free_initrd:
 338         pr_efi_err("Failed to update FDT and exit boot services\n");
 339
 340         efi_free(initrd_size, initrd_addr);
 341         efi_free(fdt_size, fdt_addr);
 342
 343 fail_free_image:
 344         efi_free(image_size, image_addr);
 345         efi_free(reserve_size, reserve_addr);
 346 fail_free_cmdline:
 347         free_screen_info(si);
 348         efi_free(cmdline_size, (unsigned long)cmdline_ptr);
 349 fail:
 350         return status;
 351 }
 352
 353 /*
 354  * efi_get_virtmap() - create a virtual mapping for the EFI memory map
 355  *
 356  * This function populates the virt_addr fields of all memory region descriptors
 357  * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
 358  * are also copied to @runtime_map, and their total count is returned in @count.
 359  */
 360 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
 361                      unsigned long desc_size, efi_memory_desc_t *runtime_map,
 362                      int *count)
 363 {
 364         u64 efi_virt_base = virtmap_base;
 365         efi_memory_desc_t *in, *out = runtime_map;
 366         int l;
 367
 368         for (l = 0; l < map_size; l += desc_size) {
 369                 u64 paddr, size;
 370
 371                 in = (void *)memory_map + l;
 372                 if (!(in->attribute & EFI_MEMORY_RUNTIME))
 373                         continue;
 374
 375                 paddr = in->phys_addr;
 376                 size = in->num_pages * EFI_PAGE_SIZE;
 377
 378                 in->virt_addr = in->phys_addr;
 379                 if (novamap()) {
 380                         continue;
 381                 }
 382
 383                 /*
 384                  * Make the mapping compatible with 64k pages: this allows
 385                  * a 4k page size kernel to kexec a 64k page size kernel and
 386                  * vice versa.
 387                  */
 388                 if (!flat_va_mapping) {
 389
 390                         paddr = round_down(in->phys_addr, SZ_64K);
 391                         size += in->phys_addr - paddr;
 392
 393                         /*
 394                          * Avoid wasting memory on PTEs by choosing a virtual
 395                          * base that is compatible with section mappings if this
 396                          * region has the appropriate size and physical
 397                          * alignment. (Sections are 2 MB on 4k granule kernels)
 398                          */
 399                         if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
 400                                 efi_virt_base = round_up(efi_virt_base, SZ_2M);
 401                         else
 402                                 efi_virt_base = round_up(efi_virt_base, SZ_64K);
 403
 404                         in->virt_addr += efi_virt_base - paddr;
 405                         efi_virt_base += size;
 406                 }
 407
 408                 memcpy(out, in, desc_size);
 409                 out = (void *)out + desc_size;
 410                 ++*count;
 411         }
 412 }