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 <asm/efi.h> 14 15 #include "efistub.h" 16 17 /* 18 * This is the base address at which to start allocating virtual memory ranges 19 * for UEFI Runtime Services. 20 * 21 * For ARM/ARM64: 22 * This is in the low TTBR0 range so that we can use 23 * any allocation we choose, and eliminate the risk of a conflict after kexec. 24 * The value chosen is the largest non-zero power of 2 suitable for this purpose 25 * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can 26 * be mapped efficiently. 27 * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split, 28 * map everything below 1 GB. (512 MB is a reasonable upper bound for the 29 * entire footprint of the UEFI runtime services memory regions) 30 * 31 * For RISC-V: 32 * There is no specific reason for which, this address (512MB) can't be used 33 * EFI runtime virtual address for RISC-V. It also helps to use EFI runtime 34 * services on both RV32/RV64. Keep the same runtime virtual address for RISC-V 35 * as well to minimize the code churn. 36 */ 37 #define EFI_RT_VIRTUAL_BASE SZ_512M 38 #define EFI_RT_VIRTUAL_SIZE SZ_512M 39 40 #ifdef CONFIG_ARM64 41 # define EFI_RT_VIRTUAL_LIMIT DEFAULT_MAP_WINDOW_64 42 #elif defined(CONFIG_RISCV) || defined(CONFIG_LOONGARCH) 43 # define EFI_RT_VIRTUAL_LIMIT TASK_SIZE_MIN 44 #else /* Only if TASK_SIZE is a constant */ 45 # define EFI_RT_VIRTUAL_LIMIT TASK_SIZE 46 #endif 47 48 /* 49 * Some architectures map the EFI regions into the kernel's linear map using a 50 * fixed offset. 51 */ 52 #ifndef EFI_RT_VIRTUAL_OFFSET 53 #define EFI_RT_VIRTUAL_OFFSET 0 54 #endif 55 56 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE; 57 static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0); 58 59 static struct screen_info *setup_graphics(void) 60 { 61 efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID; 62 efi_status_t status; 63 unsigned long size; 64 void **gop_handle = NULL; 65 struct screen_info *si = NULL; 66 67 size = 0; 68 status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL, 69 &gop_proto, NULL, &size, gop_handle); 70 if (status == EFI_BUFFER_TOO_SMALL) { 71 si = alloc_screen_info(); 72 if (!si) 73 return NULL; 74 status = efi_setup_gop(si, &gop_proto, size); 75 if (status != EFI_SUCCESS) { 76 free_screen_info(si); 77 return NULL; 78 } 79 } 80 return si; 81 } 82 83 static void install_memreserve_table(void) 84 { 85 struct linux_efi_memreserve *rsv; 86 efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID; 87 efi_status_t status; 88 89 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv), 90 (void **)&rsv); 91 if (status != EFI_SUCCESS) { 92 efi_err("Failed to allocate memreserve entry!\n"); 93 return; 94 } 95 96 rsv->next = 0; 97 rsv->size = 0; 98 atomic_set(&rsv->count, 0); 99 100 status = efi_bs_call(install_configuration_table, 101 &memreserve_table_guid, rsv); 102 if (status != EFI_SUCCESS) 103 efi_err("Failed to install memreserve config table!\n"); 104 } 105 106 static u32 get_supported_rt_services(void) 107 { 108 const efi_rt_properties_table_t *rt_prop_table; 109 u32 supported = EFI_RT_SUPPORTED_ALL; 110 111 rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID); 112 if (rt_prop_table) 113 supported &= rt_prop_table->runtime_services_supported; 114 115 return supported; 116 } 117 118 /* 119 * EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint 120 * that is described in the PE/COFF header. Most of the code is the same 121 * for both archictectures, with the arch-specific code provided in the 122 * handle_kernel_image() function. 123 */ 124 efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, 125 efi_system_table_t *sys_table_arg) 126 { 127 efi_loaded_image_t *image; 128 efi_status_t status; 129 unsigned long image_addr; 130 unsigned long image_size = 0; 131 /* addr/point and size pairs for memory management*/ 132 char *cmdline_ptr = NULL; 133 int cmdline_size = 0; 134 efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID; 135 unsigned long reserve_addr = 0; 136 unsigned long reserve_size = 0; 137 struct screen_info *si; 138 efi_properties_table_t *prop_tbl; 139 140 efi_system_table = sys_table_arg; 141 142 /* Check if we were booted by the EFI firmware */ 143 if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) { 144 status = EFI_INVALID_PARAMETER; 145 goto fail; 146 } 147 148 status = check_platform_features(); 149 if (status != EFI_SUCCESS) 150 goto fail; 151 152 /* 153 * Get a handle to the loaded image protocol. This is used to get 154 * information about the running image, such as size and the command 155 * line. 156 */ 157 status = efi_bs_call(handle_protocol, handle, &loaded_image_proto, 158 (void *)&image); 159 if (status != EFI_SUCCESS) { 160 efi_err("Failed to get loaded image protocol\n"); 161 goto fail; 162 } 163 164 /* 165 * Get the command line from EFI, using the LOADED_IMAGE 166 * protocol. We are going to copy the command line into the 167 * device tree, so this can be allocated anywhere. 168 */ 169 cmdline_ptr = efi_convert_cmdline(image, &cmdline_size); 170 if (!cmdline_ptr) { 171 efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n"); 172 status = EFI_OUT_OF_RESOURCES; 173 goto fail; 174 } 175 176 if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || 177 IS_ENABLED(CONFIG_CMDLINE_FORCE) || 178 cmdline_size == 0) { 179 status = efi_parse_options(CONFIG_CMDLINE); 180 if (status != EFI_SUCCESS) { 181 efi_err("Failed to parse options\n"); 182 goto fail_free_cmdline; 183 } 184 } 185 186 if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) { 187 status = efi_parse_options(cmdline_ptr); 188 if (status != EFI_SUCCESS) { 189 efi_err("Failed to parse options\n"); 190 goto fail_free_cmdline; 191 } 192 } 193 194 efi_info("Booting Linux Kernel...\n"); 195 196 si = setup_graphics(); 197 198 status = handle_kernel_image(&image_addr, &image_size, 199 &reserve_addr, 200 &reserve_size, 201 image, handle); 202 if (status != EFI_SUCCESS) { 203 efi_err("Failed to relocate kernel\n"); 204 goto fail_free_screeninfo; 205 } 206 207 efi_retrieve_tpm2_eventlog(); 208 209 /* Ask the firmware to clear memory on unclean shutdown */ 210 efi_enable_reset_attack_mitigation(); 211 212 efi_load_initrd(image, ULONG_MAX, efi_get_max_initrd_addr(image_addr), 213 NULL); 214 215 efi_random_get_seed(); 216 217 /* 218 * If the NX PE data feature is enabled in the properties table, we 219 * should take care not to create a virtual mapping that changes the 220 * relative placement of runtime services code and data regions, as 221 * they may belong to the same PE/COFF executable image in memory. 222 * The easiest way to achieve that is to simply use a 1:1 mapping. 223 */ 224 prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID); 225 flat_va_mapping |= prop_tbl && 226 (prop_tbl->memory_protection_attribute & 227 EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA); 228 229 /* force efi_novamap if SetVirtualAddressMap() is unsupported */ 230 efi_novamap |= !(get_supported_rt_services() & 231 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP); 232 233 /* hibernation expects the runtime regions to stay in the same place */ 234 if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) { 235 /* 236 * Randomize the base of the UEFI runtime services region. 237 * Preserve the 2 MB alignment of the region by taking a 238 * shift of 21 bit positions into account when scaling 239 * the headroom value using a 32-bit random value. 240 */ 241 static const u64 headroom = EFI_RT_VIRTUAL_LIMIT - 242 EFI_RT_VIRTUAL_BASE - 243 EFI_RT_VIRTUAL_SIZE; 244 u32 rnd; 245 246 status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd); 247 if (status == EFI_SUCCESS) { 248 virtmap_base = EFI_RT_VIRTUAL_BASE + 249 (((headroom >> 21) * rnd) >> (32 - 21)); 250 } 251 } 252 253 install_memreserve_table(); 254 255 status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr); 256 257 efi_free(image_size, image_addr); 258 efi_free(reserve_size, reserve_addr); 259 fail_free_screeninfo: 260 free_screen_info(si); 261 fail_free_cmdline: 262 efi_bs_call(free_pool, cmdline_ptr); 263 fail: 264 return status; 265 } 266 267 /* 268 * efi_allocate_virtmap() - create a pool allocation for the virtmap 269 * 270 * Create an allocation that is of sufficient size to hold all the memory 271 * descriptors that will be passed to SetVirtualAddressMap() to inform the 272 * firmware about the virtual mapping that will be used under the OS to call 273 * into the firmware. 274 */ 275 efi_status_t efi_alloc_virtmap(efi_memory_desc_t **virtmap, 276 unsigned long *desc_size, u32 *desc_ver) 277 { 278 unsigned long size, mmap_key; 279 efi_status_t status; 280 281 /* 282 * Use the size of the current memory map as an upper bound for the 283 * size of the buffer we need to pass to SetVirtualAddressMap() to 284 * cover all EFI_MEMORY_RUNTIME regions. 285 */ 286 size = 0; 287 status = efi_bs_call(get_memory_map, &size, NULL, &mmap_key, desc_size, 288 desc_ver); 289 if (status != EFI_BUFFER_TOO_SMALL) 290 return EFI_LOAD_ERROR; 291 292 return efi_bs_call(allocate_pool, EFI_LOADER_DATA, size, 293 (void **)virtmap); 294 } 295 296 /* 297 * efi_get_virtmap() - create a virtual mapping for the EFI memory map 298 * 299 * This function populates the virt_addr fields of all memory region descriptors 300 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors 301 * are also copied to @runtime_map, and their total count is returned in @count. 302 */ 303 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size, 304 unsigned long desc_size, efi_memory_desc_t *runtime_map, 305 int *count) 306 { 307 u64 efi_virt_base = virtmap_base; 308 efi_memory_desc_t *in, *out = runtime_map; 309 int l; 310 311 *count = 0; 312 313 for (l = 0; l < map_size; l += desc_size) { 314 u64 paddr, size; 315 316 in = (void *)memory_map + l; 317 if (!(in->attribute & EFI_MEMORY_RUNTIME)) 318 continue; 319 320 paddr = in->phys_addr; 321 size = in->num_pages * EFI_PAGE_SIZE; 322 323 in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET; 324 if (efi_novamap) { 325 continue; 326 } 327 328 /* 329 * Make the mapping compatible with 64k pages: this allows 330 * a 4k page size kernel to kexec a 64k page size kernel and 331 * vice versa. 332 */ 333 if (!flat_va_mapping) { 334 335 paddr = round_down(in->phys_addr, SZ_64K); 336 size += in->phys_addr - paddr; 337 338 /* 339 * Avoid wasting memory on PTEs by choosing a virtual 340 * base that is compatible with section mappings if this 341 * region has the appropriate size and physical 342 * alignment. (Sections are 2 MB on 4k granule kernels) 343 */ 344 if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M) 345 efi_virt_base = round_up(efi_virt_base, SZ_2M); 346 else 347 efi_virt_base = round_up(efi_virt_base, SZ_64K); 348 349 in->virt_addr += efi_virt_base - paddr; 350 efi_virt_base += size; 351 } 352 353 memcpy(out, in, desc_size); 354 out = (void *)out + desc_size; 355 ++*count; 356 } 357 } 358