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