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 * EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint 126 * that is described in the PE/COFF header. Most of the code is the same 127 * for both archictectures, with the arch-specific code provided in the 128 * handle_kernel_image() function. 129 */ 130 efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, 131 efi_system_table_t *sys_table_arg) 132 { 133 efi_loaded_image_t *image; 134 efi_status_t status; 135 unsigned long image_addr; 136 unsigned long image_size = 0; 137 unsigned long dram_base; 138 /* addr/point and size pairs for memory management*/ 139 unsigned long initrd_addr = 0; 140 unsigned long initrd_size = 0; 141 unsigned long fdt_addr = 0; /* Original DTB */ 142 unsigned long fdt_size = 0; 143 char *cmdline_ptr = NULL; 144 int cmdline_size = 0; 145 efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID; 146 unsigned long reserve_addr = 0; 147 unsigned long reserve_size = 0; 148 enum efi_secureboot_mode secure_boot; 149 struct screen_info *si; 150 efi_properties_table_t *prop_tbl; 151 unsigned long max_addr; 152 153 efi_system_table = sys_table_arg; 154 155 /* Check if we were booted by the EFI firmware */ 156 if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) { 157 status = EFI_INVALID_PARAMETER; 158 goto fail; 159 } 160 161 status = check_platform_features(); 162 if (status != EFI_SUCCESS) 163 goto fail; 164 165 /* 166 * Get a handle to the loaded image protocol. This is used to get 167 * information about the running image, such as size and the command 168 * line. 169 */ 170 status = efi_system_table->boottime->handle_protocol(handle, 171 &loaded_image_proto, (void *)&image); 172 if (status != EFI_SUCCESS) { 173 efi_err("Failed to get loaded image protocol\n"); 174 goto fail; 175 } 176 177 dram_base = get_dram_base(); 178 if (dram_base == EFI_ERROR) { 179 efi_err("Failed to find DRAM base\n"); 180 status = EFI_LOAD_ERROR; 181 goto fail; 182 } 183 184 /* 185 * Get the command line from EFI, using the LOADED_IMAGE 186 * protocol. We are going to copy the command line into the 187 * device tree, so this can be allocated anywhere. 188 */ 189 cmdline_ptr = efi_convert_cmdline(image, &cmdline_size); 190 if (!cmdline_ptr) { 191 efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n"); 192 status = EFI_OUT_OF_RESOURCES; 193 goto fail; 194 } 195 196 if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || 197 IS_ENABLED(CONFIG_CMDLINE_FORCE) || 198 cmdline_size == 0) { 199 status = efi_parse_options(CONFIG_CMDLINE); 200 if (status != EFI_SUCCESS) { 201 efi_err("Failed to parse options\n"); 202 goto fail_free_cmdline; 203 } 204 } 205 206 if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) { 207 status = efi_parse_options(cmdline_ptr); 208 if (status != EFI_SUCCESS) { 209 efi_err("Failed to parse options\n"); 210 goto fail_free_cmdline; 211 } 212 } 213 214 efi_info("Booting Linux Kernel...\n"); 215 216 si = setup_graphics(); 217 218 status = handle_kernel_image(&image_addr, &image_size, 219 &reserve_addr, 220 &reserve_size, 221 dram_base, image); 222 if (status != EFI_SUCCESS) { 223 efi_err("Failed to relocate kernel\n"); 224 goto fail_free_screeninfo; 225 } 226 227 efi_retrieve_tpm2_eventlog(); 228 229 /* Ask the firmware to clear memory on unclean shutdown */ 230 efi_enable_reset_attack_mitigation(); 231 232 secure_boot = efi_get_secureboot(); 233 234 /* 235 * Unauthenticated device tree data is a security hazard, so ignore 236 * 'dtb=' unless UEFI Secure Boot is disabled. We assume that secure 237 * boot is enabled if we can't determine its state. 238 */ 239 if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) || 240 secure_boot != efi_secureboot_mode_disabled) { 241 if (strstr(cmdline_ptr, "dtb=")) 242 efi_err("Ignoring DTB from command line.\n"); 243 } else { 244 status = efi_load_dtb(image, &fdt_addr, &fdt_size); 245 246 if (status != EFI_SUCCESS) { 247 efi_err("Failed to load device tree!\n"); 248 goto fail_free_image; 249 } 250 } 251 252 if (fdt_addr) { 253 efi_info("Using DTB from command line\n"); 254 } else { 255 /* Look for a device tree configuration table entry. */ 256 fdt_addr = (uintptr_t)get_fdt(&fdt_size); 257 if (fdt_addr) 258 efi_info("Using DTB from configuration table\n"); 259 } 260 261 if (!fdt_addr) 262 efi_info("Generating empty DTB\n"); 263 264 if (!efi_noinitrd) { 265 max_addr = efi_get_max_initrd_addr(image_addr); 266 status = efi_load_initrd(image, &initrd_addr, &initrd_size, 267 ULONG_MAX, max_addr); 268 if (status != EFI_SUCCESS) 269 efi_err("Failed to load initrd!\n"); 270 } 271 272 efi_random_get_seed(); 273 274 /* 275 * If the NX PE data feature is enabled in the properties table, we 276 * should take care not to create a virtual mapping that changes the 277 * relative placement of runtime services code and data regions, as 278 * they may belong to the same PE/COFF executable image in memory. 279 * The easiest way to achieve that is to simply use a 1:1 mapping. 280 */ 281 prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID); 282 flat_va_mapping = prop_tbl && 283 (prop_tbl->memory_protection_attribute & 284 EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA); 285 286 /* hibernation expects the runtime regions to stay in the same place */ 287 if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) { 288 /* 289 * Randomize the base of the UEFI runtime services region. 290 * Preserve the 2 MB alignment of the region by taking a 291 * shift of 21 bit positions into account when scaling 292 * the headroom value using a 32-bit random value. 293 */ 294 static const u64 headroom = EFI_RT_VIRTUAL_LIMIT - 295 EFI_RT_VIRTUAL_BASE - 296 EFI_RT_VIRTUAL_SIZE; 297 u32 rnd; 298 299 status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd); 300 if (status == EFI_SUCCESS) { 301 virtmap_base = EFI_RT_VIRTUAL_BASE + 302 (((headroom >> 21) * rnd) >> (32 - 21)); 303 } 304 } 305 306 install_memreserve_table(); 307 308 status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr, 309 efi_get_max_fdt_addr(image_addr), 310 initrd_addr, initrd_size, 311 cmdline_ptr, fdt_addr, fdt_size); 312 if (status != EFI_SUCCESS) 313 goto fail_free_initrd; 314 315 if (IS_ENABLED(CONFIG_ARM)) 316 efi_handle_post_ebs_state(); 317 318 efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr)); 319 /* not reached */ 320 321 fail_free_initrd: 322 efi_err("Failed to update FDT and exit boot services\n"); 323 324 efi_free(initrd_size, initrd_addr); 325 efi_free(fdt_size, fdt_addr); 326 327 fail_free_image: 328 efi_free(image_size, image_addr); 329 efi_free(reserve_size, reserve_addr); 330 fail_free_screeninfo: 331 free_screen_info(si); 332 fail_free_cmdline: 333 efi_bs_call(free_pool, cmdline_ptr); 334 fail: 335 return status; 336 } 337 338 /* 339 * efi_get_virtmap() - create a virtual mapping for the EFI memory map 340 * 341 * This function populates the virt_addr fields of all memory region descriptors 342 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors 343 * are also copied to @runtime_map, and their total count is returned in @count. 344 */ 345 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size, 346 unsigned long desc_size, efi_memory_desc_t *runtime_map, 347 int *count) 348 { 349 u64 efi_virt_base = virtmap_base; 350 efi_memory_desc_t *in, *out = runtime_map; 351 int l; 352 353 for (l = 0; l < map_size; l += desc_size) { 354 u64 paddr, size; 355 356 in = (void *)memory_map + l; 357 if (!(in->attribute & EFI_MEMORY_RUNTIME)) 358 continue; 359 360 paddr = in->phys_addr; 361 size = in->num_pages * EFI_PAGE_SIZE; 362 363 in->virt_addr = in->phys_addr; 364 if (efi_novamap) { 365 continue; 366 } 367 368 /* 369 * Make the mapping compatible with 64k pages: this allows 370 * a 4k page size kernel to kexec a 64k page size kernel and 371 * vice versa. 372 */ 373 if (!flat_va_mapping) { 374 375 paddr = round_down(in->phys_addr, SZ_64K); 376 size += in->phys_addr - paddr; 377 378 /* 379 * Avoid wasting memory on PTEs by choosing a virtual 380 * base that is compatible with section mappings if this 381 * region has the appropriate size and physical 382 * alignment. (Sections are 2 MB on 4k granule kernels) 383 */ 384 if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M) 385 efi_virt_base = round_up(efi_virt_base, SZ_2M); 386 else 387 efi_virt_base = round_up(efi_virt_base, SZ_64K); 388 389 in->virt_addr += efi_virt_base - paddr; 390 efi_virt_base += size; 391 } 392 393 memcpy(out, in, desc_size); 394 out = (void *)out + desc_size; 395 ++*count; 396 } 397 } 398