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