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 if (IS_ENABLED(CONFIG_ARM)) 333 efi_handle_post_ebs_state(); 334 335 efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr)); 336 /* not reached */ 337 338 fail_free_initrd: 339 efi_err("Failed to update FDT and exit boot services\n"); 340 341 efi_free(initrd_size, initrd_addr); 342 efi_free(fdt_size, fdt_addr); 343 344 fail_free_image: 345 efi_free(image_size, image_addr); 346 efi_free(reserve_size, reserve_addr); 347 fail_free_screeninfo: 348 free_screen_info(si); 349 fail_free_cmdline: 350 efi_bs_call(free_pool, cmdline_ptr); 351 fail: 352 return status; 353 } 354 355 /* 356 * efi_get_virtmap() - create a virtual mapping for the EFI memory map 357 * 358 * This function populates the virt_addr fields of all memory region descriptors 359 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors 360 * are also copied to @runtime_map, and their total count is returned in @count. 361 */ 362 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size, 363 unsigned long desc_size, efi_memory_desc_t *runtime_map, 364 int *count) 365 { 366 u64 efi_virt_base = virtmap_base; 367 efi_memory_desc_t *in, *out = runtime_map; 368 int l; 369 370 for (l = 0; l < map_size; l += desc_size) { 371 u64 paddr, size; 372 373 in = (void *)memory_map + l; 374 if (!(in->attribute & EFI_MEMORY_RUNTIME)) 375 continue; 376 377 paddr = in->phys_addr; 378 size = in->num_pages * EFI_PAGE_SIZE; 379 380 in->virt_addr = in->phys_addr; 381 if (efi_novamap) { 382 continue; 383 } 384 385 /* 386 * Make the mapping compatible with 64k pages: this allows 387 * a 4k page size kernel to kexec a 64k page size kernel and 388 * vice versa. 389 */ 390 if (!flat_va_mapping) { 391 392 paddr = round_down(in->phys_addr, SZ_64K); 393 size += in->phys_addr - paddr; 394 395 /* 396 * Avoid wasting memory on PTEs by choosing a virtual 397 * base that is compatible with section mappings if this 398 * region has the appropriate size and physical 399 * alignment. (Sections are 2 MB on 4k granule kernels) 400 */ 401 if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M) 402 efi_virt_base = round_up(efi_virt_base, SZ_2M); 403 else 404 efi_virt_base = round_up(efi_virt_base, SZ_64K); 405 406 in->virt_addr += efi_virt_base - paddr; 407 efi_virt_base += size; 408 } 409 410 memcpy(out, in, desc_size); 411 out = (void *)out + desc_size; 412 ++*count; 413 } 414 } 415