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/screen_info.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 40 /* 41 * Some architectures map the EFI regions into the kernel's linear map using a 42 * fixed offset. 43 */ 44 #ifndef EFI_RT_VIRTUAL_OFFSET 45 #define EFI_RT_VIRTUAL_OFFSET 0 46 #endif 47 48 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE; 49 static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0); 50 51 void __weak free_screen_info(struct screen_info *si) 52 { 53 } 54 55 static struct screen_info *setup_graphics(void) 56 { 57 struct screen_info *si, tmp = {}; 58 59 if (efi_setup_gop(&tmp) != EFI_SUCCESS) 60 return NULL; 61 62 si = alloc_screen_info(); 63 if (!si) 64 return NULL; 65 66 *si = tmp; 67 return si; 68 } 69 70 static void install_memreserve_table(void) 71 { 72 struct linux_efi_memreserve *rsv; 73 efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID; 74 efi_status_t status; 75 76 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv), 77 (void **)&rsv); 78 if (status != EFI_SUCCESS) { 79 efi_err("Failed to allocate memreserve entry!\n"); 80 return; 81 } 82 83 rsv->next = 0; 84 rsv->size = 0; 85 atomic_set(&rsv->count, 0); 86 87 status = efi_bs_call(install_configuration_table, 88 &memreserve_table_guid, rsv); 89 if (status != EFI_SUCCESS) 90 efi_err("Failed to install memreserve config table!\n"); 91 } 92 93 static u32 get_supported_rt_services(void) 94 { 95 const efi_rt_properties_table_t *rt_prop_table; 96 u32 supported = EFI_RT_SUPPORTED_ALL; 97 98 rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID); 99 if (rt_prop_table) 100 supported &= rt_prop_table->runtime_services_supported; 101 102 return supported; 103 } 104 105 efi_status_t efi_handle_cmdline(efi_loaded_image_t *image, char **cmdline_ptr) 106 { 107 char *cmdline __free(efi_pool) = NULL; 108 efi_status_t status; 109 110 /* 111 * Get the command line from EFI, using the LOADED_IMAGE 112 * protocol. We are going to copy the command line into the 113 * device tree, so this can be allocated anywhere. 114 */ 115 cmdline = efi_convert_cmdline(image); 116 if (!cmdline) { 117 efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n"); 118 return EFI_OUT_OF_RESOURCES; 119 } 120 121 if (!IS_ENABLED(CONFIG_CMDLINE_FORCE)) { 122 status = efi_parse_options(cmdline); 123 if (status != EFI_SUCCESS) { 124 efi_err("Failed to parse EFI load options\n"); 125 return status; 126 } 127 } 128 129 if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || 130 IS_ENABLED(CONFIG_CMDLINE_FORCE) || 131 cmdline[0] == 0) { 132 status = efi_parse_options(CONFIG_CMDLINE); 133 if (status != EFI_SUCCESS) { 134 efi_err("Failed to parse built-in command line\n"); 135 return status; 136 } 137 } 138 139 *cmdline_ptr = no_free_ptr(cmdline); 140 return EFI_SUCCESS; 141 } 142 143 efi_status_t efi_stub_common(efi_handle_t handle, 144 efi_loaded_image_t *image, 145 unsigned long image_addr, 146 char *cmdline_ptr) 147 { 148 struct screen_info *si; 149 efi_status_t status; 150 151 status = check_platform_features(); 152 if (status != EFI_SUCCESS) 153 return status; 154 155 si = setup_graphics(); 156 157 efi_retrieve_eventlog(); 158 159 /* Ask the firmware to clear memory on unclean shutdown */ 160 efi_enable_reset_attack_mitigation(); 161 162 efi_load_initrd(image, ULONG_MAX, efi_get_max_initrd_addr(image_addr), 163 NULL); 164 165 efi_random_get_seed(); 166 167 /* force efi_novamap if SetVirtualAddressMap() is unsupported */ 168 efi_novamap |= !(get_supported_rt_services() & 169 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP); 170 171 install_memreserve_table(); 172 173 status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr); 174 175 free_screen_info(si); 176 return status; 177 } 178 179 /* 180 * efi_allocate_virtmap() - create a pool allocation for the virtmap 181 * 182 * Create an allocation that is of sufficient size to hold all the memory 183 * descriptors that will be passed to SetVirtualAddressMap() to inform the 184 * firmware about the virtual mapping that will be used under the OS to call 185 * into the firmware. 186 */ 187 efi_status_t efi_alloc_virtmap(efi_memory_desc_t **virtmap, 188 unsigned long *desc_size, u32 *desc_ver) 189 { 190 unsigned long size, mmap_key; 191 efi_status_t status; 192 193 /* 194 * Use the size of the current memory map as an upper bound for the 195 * size of the buffer we need to pass to SetVirtualAddressMap() to 196 * cover all EFI_MEMORY_RUNTIME regions. 197 */ 198 size = 0; 199 status = efi_bs_call(get_memory_map, &size, NULL, &mmap_key, desc_size, 200 desc_ver); 201 if (status != EFI_BUFFER_TOO_SMALL) 202 return EFI_LOAD_ERROR; 203 204 return efi_bs_call(allocate_pool, EFI_LOADER_DATA, size, 205 (void **)virtmap); 206 } 207 208 /* 209 * efi_get_virtmap() - create a virtual mapping for the EFI memory map 210 * 211 * This function populates the virt_addr fields of all memory region descriptors 212 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors 213 * are also copied to @runtime_map, and their total count is returned in @count. 214 */ 215 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size, 216 unsigned long desc_size, efi_memory_desc_t *runtime_map, 217 int *count) 218 { 219 u64 efi_virt_base = virtmap_base; 220 efi_memory_desc_t *in, *out = runtime_map; 221 int l; 222 223 *count = 0; 224 225 for (l = 0; l < map_size; l += desc_size) { 226 u64 paddr, size; 227 228 in = (void *)memory_map + l; 229 if (!(in->attribute & EFI_MEMORY_RUNTIME)) 230 continue; 231 232 paddr = in->phys_addr; 233 size = in->num_pages * EFI_PAGE_SIZE; 234 235 in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET; 236 if (efi_novamap) { 237 continue; 238 } 239 240 /* 241 * Make the mapping compatible with 64k pages: this allows 242 * a 4k page size kernel to kexec a 64k page size kernel and 243 * vice versa. 244 */ 245 if (!flat_va_mapping) { 246 247 paddr = round_down(in->phys_addr, SZ_64K); 248 size += in->phys_addr - paddr; 249 250 /* 251 * Avoid wasting memory on PTEs by choosing a virtual 252 * base that is compatible with section mappings if this 253 * region has the appropriate size and physical 254 * alignment. (Sections are 2 MB on 4k granule kernels) 255 */ 256 if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M) 257 efi_virt_base = round_up(efi_virt_base, SZ_2M); 258 else 259 efi_virt_base = round_up(efi_virt_base, SZ_64K); 260 261 in->virt_addr += efi_virt_base - paddr; 262 efi_virt_base += size; 263 } 264 265 memcpy(out, in, desc_size); 266 out = (void *)out + desc_size; 267 ++*count; 268 } 269 } 270