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. 21 * 22 * For ARM/ARM64: 23 * This is in the low TTBR0 range so that we can use 24 * any allocation we choose, and eliminate the risk of a conflict after kexec. 25 * The value chosen is the largest non-zero power of 2 suitable for this purpose 26 * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can 27 * be mapped efficiently. 28 * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split, 29 * map everything below 1 GB. (512 MB is a reasonable upper bound for the 30 * entire footprint of the UEFI runtime services memory regions) 31 * 32 * For RISC-V: 33 * There is no specific reason for which, this address (512MB) can't be used 34 * EFI runtime virtual address for RISC-V. It also helps to use EFI runtime 35 * services on both RV32/RV64. Keep the same runtime virtual address for RISC-V 36 * as well to minimize the code churn. 37 */ 38 #define EFI_RT_VIRTUAL_BASE SZ_512M 39 #define EFI_RT_VIRTUAL_SIZE SZ_512M 40 41 #ifdef CONFIG_ARM64 42 # define EFI_RT_VIRTUAL_LIMIT DEFAULT_MAP_WINDOW_64 43 #elif defined(CONFIG_RISCV) || defined(CONFIG_LOONGARCH) 44 # define EFI_RT_VIRTUAL_LIMIT TASK_SIZE_MIN 45 #else /* Only if TASK_SIZE is a constant */ 46 # define EFI_RT_VIRTUAL_LIMIT TASK_SIZE 47 #endif 48 49 /* 50 * Some architectures map the EFI regions into the kernel's linear map using a 51 * fixed offset. 52 */ 53 #ifndef EFI_RT_VIRTUAL_OFFSET 54 #define EFI_RT_VIRTUAL_OFFSET 0 55 #endif 56 57 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE; 58 static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0); 59 60 const efi_system_table_t *efi_system_table; 61 62 static struct screen_info *setup_graphics(void) 63 { 64 efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID; 65 efi_status_t status; 66 unsigned long size; 67 void **gop_handle = NULL; 68 struct screen_info *si = NULL; 69 70 size = 0; 71 status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL, 72 &gop_proto, NULL, &size, gop_handle); 73 if (status == EFI_BUFFER_TOO_SMALL) { 74 si = alloc_screen_info(); 75 if (!si) 76 return NULL; 77 status = efi_setup_gop(si, &gop_proto, size); 78 if (status != EFI_SUCCESS) { 79 free_screen_info(si); 80 return NULL; 81 } 82 } 83 return si; 84 } 85 86 static void install_memreserve_table(void) 87 { 88 struct linux_efi_memreserve *rsv; 89 efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID; 90 efi_status_t status; 91 92 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv), 93 (void **)&rsv); 94 if (status != EFI_SUCCESS) { 95 efi_err("Failed to allocate memreserve entry!\n"); 96 return; 97 } 98 99 rsv->next = 0; 100 rsv->size = 0; 101 atomic_set(&rsv->count, 0); 102 103 status = efi_bs_call(install_configuration_table, 104 &memreserve_table_guid, rsv); 105 if (status != EFI_SUCCESS) 106 efi_err("Failed to install memreserve config table!\n"); 107 } 108 109 static u32 get_supported_rt_services(void) 110 { 111 const efi_rt_properties_table_t *rt_prop_table; 112 u32 supported = EFI_RT_SUPPORTED_ALL; 113 114 rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID); 115 if (rt_prop_table) 116 supported &= rt_prop_table->runtime_services_supported; 117 118 return supported; 119 } 120 121 /* 122 * EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint 123 * that is described in the PE/COFF header. Most of the code is the same 124 * for both archictectures, with the arch-specific code provided in the 125 * handle_kernel_image() function. 126 */ 127 efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, 128 efi_system_table_t *sys_table_arg) 129 { 130 efi_loaded_image_t *image; 131 efi_status_t status; 132 unsigned long image_addr; 133 unsigned long image_size = 0; 134 /* addr/point and size pairs for memory management*/ 135 unsigned long fdt_addr = 0; /* Original DTB */ 136 unsigned long fdt_size = 0; 137 char *cmdline_ptr = NULL; 138 int cmdline_size = 0; 139 efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID; 140 unsigned long reserve_addr = 0; 141 unsigned long reserve_size = 0; 142 enum efi_secureboot_mode secure_boot; 143 struct screen_info *si; 144 efi_properties_table_t *prop_tbl; 145 146 efi_system_table = sys_table_arg; 147 148 /* Check if we were booted by the EFI firmware */ 149 if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) { 150 status = EFI_INVALID_PARAMETER; 151 goto fail; 152 } 153 154 status = check_platform_features(); 155 if (status != EFI_SUCCESS) 156 goto fail; 157 158 /* 159 * Get a handle to the loaded image protocol. This is used to get 160 * information about the running image, such as size and the command 161 * line. 162 */ 163 status = efi_system_table->boottime->handle_protocol(handle, 164 &loaded_image_proto, (void *)&image); 165 if (status != EFI_SUCCESS) { 166 efi_err("Failed to get loaded image protocol\n"); 167 goto fail; 168 } 169 170 /* 171 * Get the command line from EFI, using the LOADED_IMAGE 172 * protocol. We are going to copy the command line into the 173 * device tree, so this can be allocated anywhere. 174 */ 175 cmdline_ptr = efi_convert_cmdline(image, &cmdline_size); 176 if (!cmdline_ptr) { 177 efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n"); 178 status = EFI_OUT_OF_RESOURCES; 179 goto fail; 180 } 181 182 if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || 183 IS_ENABLED(CONFIG_CMDLINE_FORCE) || 184 cmdline_size == 0) { 185 status = efi_parse_options(CONFIG_CMDLINE); 186 if (status != EFI_SUCCESS) { 187 efi_err("Failed to parse options\n"); 188 goto fail_free_cmdline; 189 } 190 } 191 192 if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) { 193 status = efi_parse_options(cmdline_ptr); 194 if (status != EFI_SUCCESS) { 195 efi_err("Failed to parse options\n"); 196 goto fail_free_cmdline; 197 } 198 } 199 200 efi_info("Booting Linux Kernel...\n"); 201 202 si = setup_graphics(); 203 204 status = handle_kernel_image(&image_addr, &image_size, 205 &reserve_addr, 206 &reserve_size, 207 image, handle); 208 if (status != EFI_SUCCESS) { 209 efi_err("Failed to relocate kernel\n"); 210 goto fail_free_screeninfo; 211 } 212 213 efi_retrieve_tpm2_eventlog(); 214 215 /* Ask the firmware to clear memory on unclean shutdown */ 216 efi_enable_reset_attack_mitigation(); 217 218 secure_boot = efi_get_secureboot(); 219 220 /* 221 * Unauthenticated device tree data is a security hazard, so ignore 222 * 'dtb=' unless UEFI Secure Boot is disabled. We assume that secure 223 * boot is enabled if we can't determine its state. 224 */ 225 if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) || 226 secure_boot != efi_secureboot_mode_disabled) { 227 if (strstr(cmdline_ptr, "dtb=")) 228 efi_err("Ignoring DTB from command line.\n"); 229 } else { 230 status = efi_load_dtb(image, &fdt_addr, &fdt_size); 231 232 if (status != EFI_SUCCESS && status != EFI_NOT_READY) { 233 efi_err("Failed to load device tree!\n"); 234 goto fail_free_image; 235 } 236 } 237 238 if (fdt_addr) { 239 efi_info("Using DTB from command line\n"); 240 } else { 241 /* Look for a device tree configuration table entry. */ 242 fdt_addr = (uintptr_t)get_fdt(&fdt_size); 243 if (fdt_addr) 244 efi_info("Using DTB from configuration table\n"); 245 } 246 247 if (!fdt_addr) 248 efi_info("Generating empty DTB\n"); 249 250 efi_load_initrd(image, ULONG_MAX, efi_get_max_initrd_addr(image_addr), 251 NULL); 252 253 efi_random_get_seed(); 254 255 /* 256 * If the NX PE data feature is enabled in the properties table, we 257 * should take care not to create a virtual mapping that changes the 258 * relative placement of runtime services code and data regions, as 259 * they may belong to the same PE/COFF executable image in memory. 260 * The easiest way to achieve that is to simply use a 1:1 mapping. 261 */ 262 prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID); 263 flat_va_mapping |= prop_tbl && 264 (prop_tbl->memory_protection_attribute & 265 EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA); 266 267 /* force efi_novamap if SetVirtualAddressMap() is unsupported */ 268 efi_novamap |= !(get_supported_rt_services() & 269 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP); 270 271 /* hibernation expects the runtime regions to stay in the same place */ 272 if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) { 273 /* 274 * Randomize the base of the UEFI runtime services region. 275 * Preserve the 2 MB alignment of the region by taking a 276 * shift of 21 bit positions into account when scaling 277 * the headroom value using a 32-bit random value. 278 */ 279 static const u64 headroom = EFI_RT_VIRTUAL_LIMIT - 280 EFI_RT_VIRTUAL_BASE - 281 EFI_RT_VIRTUAL_SIZE; 282 u32 rnd; 283 284 status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd); 285 if (status == EFI_SUCCESS) { 286 virtmap_base = EFI_RT_VIRTUAL_BASE + 287 (((headroom >> 21) * rnd) >> (32 - 21)); 288 } 289 } 290 291 install_memreserve_table(); 292 293 status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr, cmdline_ptr, 294 fdt_addr, fdt_size); 295 if (status != EFI_SUCCESS) 296 goto fail_free_fdt; 297 298 if (IS_ENABLED(CONFIG_ARM)) 299 efi_handle_post_ebs_state(); 300 301 efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr)); 302 /* not reached */ 303 304 fail_free_fdt: 305 efi_err("Failed to update FDT and exit boot services\n"); 306 307 efi_free(fdt_size, fdt_addr); 308 309 fail_free_image: 310 efi_free(image_size, image_addr); 311 efi_free(reserve_size, reserve_addr); 312 fail_free_screeninfo: 313 free_screen_info(si); 314 fail_free_cmdline: 315 efi_bs_call(free_pool, cmdline_ptr); 316 fail: 317 return status; 318 } 319 320 /* 321 * efi_allocate_virtmap() - create a pool allocation for the virtmap 322 * 323 * Create an allocation that is of sufficient size to hold all the memory 324 * descriptors that will be passed to SetVirtualAddressMap() to inform the 325 * firmware about the virtual mapping that will be used under the OS to call 326 * into the firmware. 327 */ 328 efi_status_t efi_alloc_virtmap(efi_memory_desc_t **virtmap, 329 unsigned long *desc_size, u32 *desc_ver) 330 { 331 unsigned long size, mmap_key; 332 efi_status_t status; 333 334 /* 335 * Use the size of the current memory map as an upper bound for the 336 * size of the buffer we need to pass to SetVirtualAddressMap() to 337 * cover all EFI_MEMORY_RUNTIME regions. 338 */ 339 size = 0; 340 status = efi_bs_call(get_memory_map, &size, NULL, &mmap_key, desc_size, 341 desc_ver); 342 if (status != EFI_BUFFER_TOO_SMALL) 343 return EFI_LOAD_ERROR; 344 345 return efi_bs_call(allocate_pool, EFI_LOADER_DATA, size, 346 (void **)virtmap); 347 } 348 349 /* 350 * efi_get_virtmap() - create a virtual mapping for the EFI memory map 351 * 352 * This function populates the virt_addr fields of all memory region descriptors 353 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors 354 * are also copied to @runtime_map, and their total count is returned in @count. 355 */ 356 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size, 357 unsigned long desc_size, efi_memory_desc_t *runtime_map, 358 int *count) 359 { 360 u64 efi_virt_base = virtmap_base; 361 efi_memory_desc_t *in, *out = runtime_map; 362 int l; 363 364 *count = 0; 365 366 for (l = 0; l < map_size; l += desc_size) { 367 u64 paddr, size; 368 369 in = (void *)memory_map + l; 370 if (!(in->attribute & EFI_MEMORY_RUNTIME)) 371 continue; 372 373 paddr = in->phys_addr; 374 size = in->num_pages * EFI_PAGE_SIZE; 375 376 in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET; 377 if (efi_novamap) { 378 continue; 379 } 380 381 /* 382 * Make the mapping compatible with 64k pages: this allows 383 * a 4k page size kernel to kexec a 64k page size kernel and 384 * vice versa. 385 */ 386 if (!flat_va_mapping) { 387 388 paddr = round_down(in->phys_addr, SZ_64K); 389 size += in->phys_addr - paddr; 390 391 /* 392 * Avoid wasting memory on PTEs by choosing a virtual 393 * base that is compatible with section mappings if this 394 * region has the appropriate size and physical 395 * alignment. (Sections are 2 MB on 4k granule kernels) 396 */ 397 if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M) 398 efi_virt_base = round_up(efi_virt_base, SZ_2M); 399 else 400 efi_virt_base = round_up(efi_virt_base, SZ_64K); 401 402 in->virt_addr += efi_virt_base - paddr; 403 efi_virt_base += size; 404 } 405 406 memcpy(out, in, desc_size); 407 out = (void *)out + desc_size; 408 ++*count; 409 } 410 } 411