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) 44 # define EFI_RT_VIRTUAL_LIMIT TASK_SIZE_MIN 45 #else 46 # define EFI_RT_VIRTUAL_LIMIT TASK_SIZE 47 #endif 48 49 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE; 50 static bool flat_va_mapping; 51 52 const efi_system_table_t *efi_system_table; 53 54 static struct screen_info *setup_graphics(void) 55 { 56 efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID; 57 efi_status_t status; 58 unsigned long size; 59 void **gop_handle = NULL; 60 struct screen_info *si = NULL; 61 62 size = 0; 63 status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL, 64 &gop_proto, NULL, &size, gop_handle); 65 if (status == EFI_BUFFER_TOO_SMALL) { 66 si = alloc_screen_info(); 67 if (!si) 68 return NULL; 69 status = efi_setup_gop(si, &gop_proto, size); 70 if (status != EFI_SUCCESS) { 71 free_screen_info(si); 72 return NULL; 73 } 74 } 75 return si; 76 } 77 78 static void install_memreserve_table(void) 79 { 80 struct linux_efi_memreserve *rsv; 81 efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID; 82 efi_status_t status; 83 84 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv), 85 (void **)&rsv); 86 if (status != EFI_SUCCESS) { 87 efi_err("Failed to allocate memreserve entry!\n"); 88 return; 89 } 90 91 rsv->next = 0; 92 rsv->size = 0; 93 atomic_set(&rsv->count, 0); 94 95 status = efi_bs_call(install_configuration_table, 96 &memreserve_table_guid, rsv); 97 if (status != EFI_SUCCESS) 98 efi_err("Failed to install memreserve config table!\n"); 99 } 100 101 static u32 get_supported_rt_services(void) 102 { 103 const efi_rt_properties_table_t *rt_prop_table; 104 u32 supported = EFI_RT_SUPPORTED_ALL; 105 106 rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID); 107 if (rt_prop_table) 108 supported &= rt_prop_table->runtime_services_supported; 109 110 return supported; 111 } 112 113 /* 114 * EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint 115 * that is described in the PE/COFF header. Most of the code is the same 116 * for both archictectures, with the arch-specific code provided in the 117 * handle_kernel_image() function. 118 */ 119 efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, 120 efi_system_table_t *sys_table_arg) 121 { 122 efi_loaded_image_t *image; 123 efi_status_t status; 124 unsigned long image_addr; 125 unsigned long image_size = 0; 126 /* addr/point and size pairs for memory management*/ 127 unsigned long initrd_addr = 0; 128 unsigned long initrd_size = 0; 129 unsigned long fdt_addr = 0; /* Original DTB */ 130 unsigned long fdt_size = 0; 131 char *cmdline_ptr = NULL; 132 int cmdline_size = 0; 133 efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID; 134 unsigned long reserve_addr = 0; 135 unsigned long reserve_size = 0; 136 enum efi_secureboot_mode secure_boot; 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_system_table->boottime->handle_protocol(handle, 158 &loaded_image_proto, (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 secure_boot = efi_get_secureboot(); 213 214 /* 215 * Unauthenticated device tree data is a security hazard, so ignore 216 * 'dtb=' unless UEFI Secure Boot is disabled. We assume that secure 217 * boot is enabled if we can't determine its state. 218 */ 219 if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) || 220 secure_boot != efi_secureboot_mode_disabled) { 221 if (strstr(cmdline_ptr, "dtb=")) 222 efi_err("Ignoring DTB from command line.\n"); 223 } else { 224 status = efi_load_dtb(image, &fdt_addr, &fdt_size); 225 226 if (status != EFI_SUCCESS) { 227 efi_err("Failed to load device tree!\n"); 228 goto fail_free_image; 229 } 230 } 231 232 if (fdt_addr) { 233 efi_info("Using DTB from command line\n"); 234 } else { 235 /* Look for a device tree configuration table entry. */ 236 fdt_addr = (uintptr_t)get_fdt(&fdt_size); 237 if (fdt_addr) 238 efi_info("Using DTB from configuration table\n"); 239 } 240 241 if (!fdt_addr) 242 efi_info("Generating empty DTB\n"); 243 244 efi_load_initrd(image, &initrd_addr, &initrd_size, ULONG_MAX, 245 efi_get_max_initrd_addr(image_addr)); 246 247 efi_random_get_seed(); 248 249 /* 250 * If the NX PE data feature is enabled in the properties table, we 251 * should take care not to create a virtual mapping that changes the 252 * relative placement of runtime services code and data regions, as 253 * they may belong to the same PE/COFF executable image in memory. 254 * The easiest way to achieve that is to simply use a 1:1 mapping. 255 */ 256 prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID); 257 flat_va_mapping = prop_tbl && 258 (prop_tbl->memory_protection_attribute & 259 EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA); 260 261 /* force efi_novamap if SetVirtualAddressMap() is unsupported */ 262 efi_novamap |= !(get_supported_rt_services() & 263 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP); 264 265 /* hibernation expects the runtime regions to stay in the same place */ 266 if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) { 267 /* 268 * Randomize the base of the UEFI runtime services region. 269 * Preserve the 2 MB alignment of the region by taking a 270 * shift of 21 bit positions into account when scaling 271 * the headroom value using a 32-bit random value. 272 */ 273 static const u64 headroom = EFI_RT_VIRTUAL_LIMIT - 274 EFI_RT_VIRTUAL_BASE - 275 EFI_RT_VIRTUAL_SIZE; 276 u32 rnd; 277 278 status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd); 279 if (status == EFI_SUCCESS) { 280 virtmap_base = EFI_RT_VIRTUAL_BASE + 281 (((headroom >> 21) * rnd) >> (32 - 21)); 282 } 283 } 284 285 install_memreserve_table(); 286 287 status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr, 288 initrd_addr, initrd_size, 289 cmdline_ptr, fdt_addr, fdt_size); 290 if (status != EFI_SUCCESS) 291 goto fail_free_initrd; 292 293 if (IS_ENABLED(CONFIG_ARM)) 294 efi_handle_post_ebs_state(); 295 296 efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr)); 297 /* not reached */ 298 299 fail_free_initrd: 300 efi_err("Failed to update FDT and exit boot services\n"); 301 302 efi_free(initrd_size, initrd_addr); 303 efi_free(fdt_size, fdt_addr); 304 305 fail_free_image: 306 efi_free(image_size, image_addr); 307 efi_free(reserve_size, reserve_addr); 308 fail_free_screeninfo: 309 free_screen_info(si); 310 fail_free_cmdline: 311 efi_bs_call(free_pool, cmdline_ptr); 312 fail: 313 return status; 314 } 315 316 /* 317 * efi_get_virtmap() - create a virtual mapping for the EFI memory map 318 * 319 * This function populates the virt_addr fields of all memory region descriptors 320 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors 321 * are also copied to @runtime_map, and their total count is returned in @count. 322 */ 323 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size, 324 unsigned long desc_size, efi_memory_desc_t *runtime_map, 325 int *count) 326 { 327 u64 efi_virt_base = virtmap_base; 328 efi_memory_desc_t *in, *out = runtime_map; 329 int l; 330 331 for (l = 0; l < map_size; l += desc_size) { 332 u64 paddr, size; 333 334 in = (void *)memory_map + l; 335 if (!(in->attribute & EFI_MEMORY_RUNTIME)) 336 continue; 337 338 paddr = in->phys_addr; 339 size = in->num_pages * EFI_PAGE_SIZE; 340 341 in->virt_addr = in->phys_addr; 342 if (efi_novamap) { 343 continue; 344 } 345 346 /* 347 * Make the mapping compatible with 64k pages: this allows 348 * a 4k page size kernel to kexec a 64k page size kernel and 349 * vice versa. 350 */ 351 if (!flat_va_mapping) { 352 353 paddr = round_down(in->phys_addr, SZ_64K); 354 size += in->phys_addr - paddr; 355 356 /* 357 * Avoid wasting memory on PTEs by choosing a virtual 358 * base that is compatible with section mappings if this 359 * region has the appropriate size and physical 360 * alignment. (Sections are 2 MB on 4k granule kernels) 361 */ 362 if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M) 363 efi_virt_base = round_up(efi_virt_base, SZ_2M); 364 else 365 efi_virt_base = round_up(efi_virt_base, SZ_64K); 366 367 in->virt_addr += efi_virt_base - paddr; 368 efi_virt_base += size; 369 } 370 371 memcpy(out, in, desc_size); 372 out = (void *)out + desc_size; 373 ++*count; 374 } 375 } 376