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