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