1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Helper functions used by the EFI stub on multiple 4 * architectures. This should be #included by the EFI stub 5 * implementation files. 6 * 7 * Copyright 2011 Intel Corporation; author Matt Fleming 8 */ 9 10 #include <linux/efi.h> 11 #include <asm/efi.h> 12 13 #include "efistub.h" 14 15 static bool __efistub_global efi_nochunk; 16 static bool __efistub_global efi_nokaslr; 17 static bool __efistub_global efi_quiet; 18 static bool __efistub_global efi_novamap; 19 static bool __efistub_global efi_nosoftreserve; 20 static bool __efistub_global efi_disable_pci_dma = 21 IS_ENABLED(CONFIG_EFI_DISABLE_PCI_DMA); 22 23 bool __pure nochunk(void) 24 { 25 return efi_nochunk; 26 } 27 bool __pure nokaslr(void) 28 { 29 return efi_nokaslr; 30 } 31 bool __pure is_quiet(void) 32 { 33 return efi_quiet; 34 } 35 bool __pure novamap(void) 36 { 37 return efi_novamap; 38 } 39 bool __pure __efi_soft_reserve_enabled(void) 40 { 41 return !efi_nosoftreserve; 42 } 43 44 void efi_printk(char *str) 45 { 46 char *s8; 47 48 for (s8 = str; *s8; s8++) { 49 efi_char16_t ch[2] = { 0 }; 50 51 ch[0] = *s8; 52 if (*s8 == '\n') { 53 efi_char16_t nl[2] = { '\r', 0 }; 54 efi_char16_printk(nl); 55 } 56 57 efi_char16_printk(ch); 58 } 59 } 60 61 /* 62 * Parse the ASCII string 'cmdline' for EFI options, denoted by the efi= 63 * option, e.g. efi=nochunk. 64 * 65 * It should be noted that efi= is parsed in two very different 66 * environments, first in the early boot environment of the EFI boot 67 * stub, and subsequently during the kernel boot. 68 */ 69 efi_status_t efi_parse_options(char const *cmdline) 70 { 71 size_t len = strlen(cmdline) + 1; 72 efi_status_t status; 73 char *str, *buf; 74 75 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, len, (void **)&buf); 76 if (status != EFI_SUCCESS) 77 return status; 78 79 str = skip_spaces(memcpy(buf, cmdline, len)); 80 81 while (*str) { 82 char *param, *val; 83 84 str = next_arg(str, ¶m, &val); 85 86 if (!strcmp(param, "nokaslr")) { 87 efi_nokaslr = true; 88 } else if (!strcmp(param, "quiet")) { 89 efi_quiet = true; 90 } else if (!strcmp(param, "efi") && val) { 91 efi_nochunk = parse_option_str(val, "nochunk"); 92 efi_novamap = parse_option_str(val, "novamap"); 93 94 efi_nosoftreserve = IS_ENABLED(CONFIG_EFI_SOFT_RESERVE) && 95 parse_option_str(val, "nosoftreserve"); 96 97 if (parse_option_str(val, "disable_early_pci_dma")) 98 efi_disable_pci_dma = true; 99 if (parse_option_str(val, "no_disable_early_pci_dma")) 100 efi_disable_pci_dma = false; 101 } 102 } 103 efi_bs_call(free_pool, buf); 104 return EFI_SUCCESS; 105 } 106 107 /* 108 * Get the number of UTF-8 bytes corresponding to an UTF-16 character. 109 * This overestimates for surrogates, but that is okay. 110 */ 111 static int efi_utf8_bytes(u16 c) 112 { 113 return 1 + (c >= 0x80) + (c >= 0x800); 114 } 115 116 /* 117 * Convert an UTF-16 string, not necessarily null terminated, to UTF-8. 118 */ 119 static u8 *efi_utf16_to_utf8(u8 *dst, const u16 *src, int n) 120 { 121 unsigned int c; 122 123 while (n--) { 124 c = *src++; 125 if (n && c >= 0xd800 && c <= 0xdbff && 126 *src >= 0xdc00 && *src <= 0xdfff) { 127 c = 0x10000 + ((c & 0x3ff) << 10) + (*src & 0x3ff); 128 src++; 129 n--; 130 } 131 if (c >= 0xd800 && c <= 0xdfff) 132 c = 0xfffd; /* Unmatched surrogate */ 133 if (c < 0x80) { 134 *dst++ = c; 135 continue; 136 } 137 if (c < 0x800) { 138 *dst++ = 0xc0 + (c >> 6); 139 goto t1; 140 } 141 if (c < 0x10000) { 142 *dst++ = 0xe0 + (c >> 12); 143 goto t2; 144 } 145 *dst++ = 0xf0 + (c >> 18); 146 *dst++ = 0x80 + ((c >> 12) & 0x3f); 147 t2: 148 *dst++ = 0x80 + ((c >> 6) & 0x3f); 149 t1: 150 *dst++ = 0x80 + (c & 0x3f); 151 } 152 153 return dst; 154 } 155 156 /* 157 * Convert the unicode UEFI command line to ASCII to pass to kernel. 158 * Size of memory allocated return in *cmd_line_len. 159 * Returns NULL on error. 160 */ 161 char *efi_convert_cmdline(efi_loaded_image_t *image, 162 int *cmd_line_len, unsigned long max_addr) 163 { 164 const u16 *s2; 165 u8 *s1 = NULL; 166 unsigned long cmdline_addr = 0; 167 int load_options_chars = image->load_options_size / 2; /* UTF-16 */ 168 const u16 *options = image->load_options; 169 int options_bytes = 0; /* UTF-8 bytes */ 170 int options_chars = 0; /* UTF-16 chars */ 171 efi_status_t status; 172 u16 zero = 0; 173 174 if (options) { 175 s2 = options; 176 while (*s2 && *s2 != '\n' 177 && options_chars < load_options_chars) { 178 options_bytes += efi_utf8_bytes(*s2++); 179 options_chars++; 180 } 181 } 182 183 if (!options_chars) { 184 /* No command line options, so return empty string*/ 185 options = &zero; 186 } 187 188 options_bytes++; /* NUL termination */ 189 190 status = efi_allocate_pages(options_bytes, &cmdline_addr, max_addr); 191 if (status != EFI_SUCCESS) 192 return NULL; 193 194 s1 = (u8 *)cmdline_addr; 195 s2 = (const u16 *)options; 196 197 s1 = efi_utf16_to_utf8(s1, s2, options_chars); 198 *s1 = '\0'; 199 200 *cmd_line_len = options_bytes; 201 return (char *)cmdline_addr; 202 } 203 204 /* 205 * Handle calling ExitBootServices according to the requirements set out by the 206 * spec. Obtains the current memory map, and returns that info after calling 207 * ExitBootServices. The client must specify a function to perform any 208 * processing of the memory map data prior to ExitBootServices. A client 209 * specific structure may be passed to the function via priv. The client 210 * function may be called multiple times. 211 */ 212 efi_status_t efi_exit_boot_services(void *handle, 213 struct efi_boot_memmap *map, 214 void *priv, 215 efi_exit_boot_map_processing priv_func) 216 { 217 efi_status_t status; 218 219 status = efi_get_memory_map(map); 220 221 if (status != EFI_SUCCESS) 222 goto fail; 223 224 status = priv_func(map, priv); 225 if (status != EFI_SUCCESS) 226 goto free_map; 227 228 if (efi_disable_pci_dma) 229 efi_pci_disable_bridge_busmaster(); 230 231 status = efi_bs_call(exit_boot_services, handle, *map->key_ptr); 232 233 if (status == EFI_INVALID_PARAMETER) { 234 /* 235 * The memory map changed between efi_get_memory_map() and 236 * exit_boot_services(). Per the UEFI Spec v2.6, Section 6.4: 237 * EFI_BOOT_SERVICES.ExitBootServices we need to get the 238 * updated map, and try again. The spec implies one retry 239 * should be sufficent, which is confirmed against the EDK2 240 * implementation. Per the spec, we can only invoke 241 * get_memory_map() and exit_boot_services() - we cannot alloc 242 * so efi_get_memory_map() cannot be used, and we must reuse 243 * the buffer. For all practical purposes, the headroom in the 244 * buffer should account for any changes in the map so the call 245 * to get_memory_map() is expected to succeed here. 246 */ 247 *map->map_size = *map->buff_size; 248 status = efi_bs_call(get_memory_map, 249 map->map_size, 250 *map->map, 251 map->key_ptr, 252 map->desc_size, 253 map->desc_ver); 254 255 /* exit_boot_services() was called, thus cannot free */ 256 if (status != EFI_SUCCESS) 257 goto fail; 258 259 status = priv_func(map, priv); 260 /* exit_boot_services() was called, thus cannot free */ 261 if (status != EFI_SUCCESS) 262 goto fail; 263 264 status = efi_bs_call(exit_boot_services, handle, *map->key_ptr); 265 } 266 267 /* exit_boot_services() was called, thus cannot free */ 268 if (status != EFI_SUCCESS) 269 goto fail; 270 271 return EFI_SUCCESS; 272 273 free_map: 274 efi_bs_call(free_pool, *map->map); 275 fail: 276 return status; 277 } 278 279 void *get_efi_config_table(efi_guid_t guid) 280 { 281 unsigned long tables = efi_table_attr(efi_system_table(), tables); 282 int nr_tables = efi_table_attr(efi_system_table(), nr_tables); 283 int i; 284 285 for (i = 0; i < nr_tables; i++) { 286 efi_config_table_t *t = (void *)tables; 287 288 if (efi_guidcmp(t->guid, guid) == 0) 289 return efi_table_attr(t, table); 290 291 tables += efi_is_native() ? sizeof(efi_config_table_t) 292 : sizeof(efi_config_table_32_t); 293 } 294 return NULL; 295 } 296 297 void efi_char16_printk(efi_char16_t *str) 298 { 299 efi_call_proto(efi_table_attr(efi_system_table(), con_out), 300 output_string, str); 301 } 302