1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Copyright (c) 2015 Google, Inc 4 * 5 * EFI information obtained here: 6 * http://wiki.phoenix.com/wiki/index.php/EFI_BOOT_SERVICES 7 * 8 * Loads a payload (U-Boot) within the EFI environment. This is built as an 9 * EFI application. It can be built either in 32-bit or 64-bit mode. 10 */ 11 12 #include <common.h> 13 #include <debug_uart.h> 14 #include <efi.h> 15 #include <efi_api.h> 16 #include <errno.h> 17 #include <ns16550.h> 18 #include <asm/cpu.h> 19 #include <asm/io.h> 20 #include <linux/err.h> 21 #include <linux/types.h> 22 23 #ifndef CONFIG_X86 24 /* 25 * Problem areas: 26 * - putc() uses the ns16550 address directly and assumed I/O access. Many 27 * platforms will use memory access 28 * get_codeseg32() is only meaningful on x86 29 */ 30 #error "This file needs to be ported for use on architectures" 31 #endif 32 33 static struct efi_priv *global_priv; 34 static bool use_uart; 35 36 struct __packed desctab_info { 37 uint16_t limit; 38 uint64_t addr; 39 uint16_t pad; 40 }; 41 42 /* 43 * EFI uses Unicode and we don't. The easiest way to get a sensible output 44 * function is to use the U-Boot debug UART. We use EFI's console output 45 * function where available, and assume the built-in UART after that. We rely 46 * on EFI to set up the UART for us and just bring in the functions here. 47 * This last bit is a bit icky, but it's only for debugging anyway. We could 48 * build in ns16550.c with some effort, but this is a payload loader after 49 * all. 50 * 51 * Note: We avoid using printf() so we don't need to bring in lib/vsprintf.c. 52 * That would require some refactoring since we already build this for U-Boot. 53 * Building an EFI shared library version would have to be a separate stem. 54 * That might push us to using the SPL framework to build this stub. However 55 * that would involve a round of EFI-specific changes in SPL. Worth 56 * considering if we start needing more U-Boot functionality. Note that we 57 * could then move get_codeseg32() to arch/x86/cpu/cpu.c. 58 */ 59 void _debug_uart_init(void) 60 { 61 } 62 63 void putc(const char ch) 64 { 65 if (ch == '\n') 66 putc('\r'); 67 68 if (use_uart) { 69 NS16550_t com_port = (NS16550_t)0x3f8; 70 71 while ((inb((ulong)&com_port->lsr) & UART_LSR_THRE) == 0) 72 ; 73 outb(ch, (ulong)&com_port->thr); 74 } else { 75 efi_putc(global_priv, ch); 76 } 77 } 78 79 void puts(const char *str) 80 { 81 while (*str) 82 putc(*str++); 83 } 84 85 static void _debug_uart_putc(int ch) 86 { 87 putc(ch); 88 } 89 90 DEBUG_UART_FUNCS 91 92 void *memcpy(void *dest, const void *src, size_t size) 93 { 94 unsigned char *dptr = dest; 95 const unsigned char *ptr = src; 96 const unsigned char *end = src + size; 97 98 while (ptr < end) 99 *dptr++ = *ptr++; 100 101 return dest; 102 } 103 104 void *memset(void *inptr, int ch, size_t size) 105 { 106 char *ptr = inptr; 107 char *end = ptr + size; 108 109 while (ptr < end) 110 *ptr++ = ch; 111 112 return ptr; 113 } 114 115 static void jump_to_uboot(ulong cs32, ulong addr, ulong info) 116 { 117 #ifdef CONFIG_EFI_STUB_32BIT 118 /* 119 * U-Boot requires these parameters in registers, not on the stack. 120 * See _x86boot_start() for this code. 121 */ 122 typedef void (*func_t)(int bist, int unused, ulong info) 123 __attribute__((regparm(3))); 124 125 ((func_t)addr)(0, 0, info); 126 #else 127 cpu_call32(cs32, CONFIG_SYS_TEXT_BASE, info); 128 #endif 129 } 130 131 #ifdef CONFIG_EFI_STUB_64BIT 132 static void get_gdt(struct desctab_info *info) 133 { 134 asm volatile ("sgdt %0" : : "m"(*info) : "memory"); 135 } 136 #endif 137 138 static inline unsigned long read_cr3(void) 139 { 140 unsigned long val; 141 142 asm volatile("mov %%cr3,%0" : "=r" (val) : : "memory"); 143 return val; 144 } 145 146 /** 147 * get_codeseg32() - Find the code segment to use for 32-bit code 148 * 149 * U-Boot only works in 32-bit mode at present, so when booting from 64-bit 150 * EFI we must first change to 32-bit mode. To do this we need to find the 151 * correct code segment to use (an entry in the Global Descriptor Table). 152 * 153 * @return code segment GDT offset, or 0 for 32-bit EFI, -ENOENT if not found 154 */ 155 static int get_codeseg32(void) 156 { 157 int cs32 = 0; 158 159 #ifdef CONFIG_EFI_STUB_64BIT 160 struct desctab_info gdt; 161 uint64_t *ptr; 162 int i; 163 164 get_gdt(&gdt); 165 for (ptr = (uint64_t *)(unsigned long)gdt.addr, i = 0; i < gdt.limit; 166 i += 8, ptr++) { 167 uint64_t desc = *ptr; 168 uint64_t base, limit; 169 170 /* 171 * Check that the target U-Boot jump address is within the 172 * selector and that the selector is of the right type. 173 */ 174 base = ((desc >> GDT_BASE_LOW_SHIFT) & GDT_BASE_LOW_MASK) | 175 ((desc >> GDT_BASE_HIGH_SHIFT) & GDT_BASE_HIGH_MASK) 176 << 16; 177 limit = ((desc >> GDT_LIMIT_LOW_SHIFT) & GDT_LIMIT_LOW_MASK) | 178 ((desc >> GDT_LIMIT_HIGH_SHIFT) & GDT_LIMIT_HIGH_MASK) 179 << 16; 180 base <<= 12; /* 4KB granularity */ 181 limit <<= 12; 182 if ((desc & GDT_PRESENT) && (desc & GDT_NOTSYS) && 183 !(desc & GDT_LONG) && (desc & GDT_4KB) && 184 (desc & GDT_32BIT) && (desc & GDT_CODE) && 185 CONFIG_SYS_TEXT_BASE > base && 186 CONFIG_SYS_TEXT_BASE + CONFIG_SYS_MONITOR_LEN < limit 187 ) { 188 cs32 = i; 189 break; 190 } 191 } 192 193 #ifdef DEBUG 194 puts("\ngdt: "); 195 printhex8(gdt.limit); 196 puts(", addr: "); 197 printhex8(gdt.addr >> 32); 198 printhex8(gdt.addr); 199 for (i = 0; i < gdt.limit; i += 8) { 200 uint32_t *ptr = (uint32_t *)((unsigned long)gdt.addr + i); 201 202 puts("\n"); 203 printhex2(i); 204 puts(": "); 205 printhex8(ptr[1]); 206 puts(" "); 207 printhex8(ptr[0]); 208 } 209 puts("\n "); 210 puts("32-bit code segment: "); 211 printhex2(cs32); 212 puts("\n "); 213 214 puts("page_table: "); 215 printhex8(read_cr3()); 216 puts("\n "); 217 #endif 218 if (!cs32) { 219 puts("Can't find 32-bit code segment\n"); 220 return -ENOENT; 221 } 222 #endif 223 224 return cs32; 225 } 226 227 static int setup_info_table(struct efi_priv *priv, int size) 228 { 229 struct efi_info_hdr *info; 230 efi_status_t ret; 231 232 /* Get some memory for our info table */ 233 priv->info_size = size; 234 info = efi_malloc(priv, priv->info_size, &ret); 235 if (ret) { 236 printhex2(ret); 237 puts(" No memory for info table: "); 238 return ret; 239 } 240 241 memset(info, '\0', sizeof(*info)); 242 info->version = EFI_TABLE_VERSION; 243 info->hdr_size = sizeof(*info); 244 priv->info = info; 245 priv->next_hdr = (char *)info + info->hdr_size; 246 247 return 0; 248 } 249 250 static void add_entry_addr(struct efi_priv *priv, enum efi_entry_t type, 251 void *ptr1, int size1, void *ptr2, int size2) 252 { 253 struct efi_entry_hdr *hdr = priv->next_hdr; 254 255 hdr->type = type; 256 hdr->size = size1 + size2; 257 hdr->addr = 0; 258 hdr->link = ALIGN(sizeof(*hdr) + hdr->size, 16); 259 priv->next_hdr += hdr->link; 260 memcpy(hdr + 1, ptr1, size1); 261 memcpy((void *)(hdr + 1) + size1, ptr2, size2); 262 priv->info->total_size = (ulong)priv->next_hdr - (ulong)priv->info; 263 } 264 265 /** 266 * efi_main() - Start an EFI image 267 * 268 * This function is called by our EFI start-up code. It handles running 269 * U-Boot. If it returns, EFI will continue. 270 */ 271 efi_status_t EFIAPI efi_main(efi_handle_t image, 272 struct efi_system_table *sys_table) 273 { 274 struct efi_priv local_priv, *priv = &local_priv; 275 struct efi_boot_services *boot = sys_table->boottime; 276 struct efi_mem_desc *desc; 277 struct efi_entry_memmap map; 278 struct efi_gop *gop; 279 struct efi_entry_gopmode mode; 280 struct efi_entry_systable table; 281 efi_guid_t efi_gop_guid = EFI_GOP_GUID; 282 efi_uintn_t key, desc_size, size; 283 efi_status_t ret; 284 u32 version; 285 int cs32; 286 287 ret = efi_init(priv, "Payload", image, sys_table); 288 if (ret) { 289 printhex2(ret); 290 puts(" efi_init() failed\n"); 291 return ret; 292 } 293 global_priv = priv; 294 295 cs32 = get_codeseg32(); 296 if (cs32 < 0) 297 return EFI_UNSUPPORTED; 298 299 /* Get the memory map so we can switch off EFI */ 300 size = 0; 301 ret = boot->get_memory_map(&size, NULL, &key, &desc_size, &version); 302 if (ret != EFI_BUFFER_TOO_SMALL) { 303 printhex2(EFI_BITS_PER_LONG); 304 putc(' '); 305 printhex2(ret); 306 puts(" No memory map\n"); 307 return ret; 308 } 309 size += 1024; /* Since doing a malloc() may change the memory map! */ 310 desc = efi_malloc(priv, size, &ret); 311 if (!desc) { 312 printhex2(ret); 313 puts(" No memory for memory descriptor\n"); 314 return ret; 315 } 316 ret = setup_info_table(priv, size + 128); 317 if (ret) 318 return ret; 319 320 ret = boot->locate_protocol(&efi_gop_guid, NULL, (void **)&gop); 321 if (ret) { 322 puts(" GOP unavailable\n"); 323 } else { 324 mode.fb_base = gop->mode->fb_base; 325 mode.fb_size = gop->mode->fb_size; 326 mode.info_size = gop->mode->info_size; 327 add_entry_addr(priv, EFIET_GOP_MODE, &mode, sizeof(mode), 328 gop->mode->info, 329 sizeof(struct efi_gop_mode_info)); 330 } 331 332 ret = boot->get_memory_map(&size, desc, &key, &desc_size, &version); 333 if (ret) { 334 printhex2(ret); 335 puts(" Can't get memory map\n"); 336 return ret; 337 } 338 339 table.sys_table = (ulong)sys_table; 340 add_entry_addr(priv, EFIET_SYS_TABLE, &table, sizeof(table), NULL, 0); 341 342 ret = boot->exit_boot_services(image, key); 343 if (ret) { 344 /* 345 * Unfortunately it happens that we cannot exit boot services 346 * the first time. But the second time it work. I don't know 347 * why but this seems to be a repeatable problem. To get 348 * around it, just try again. 349 */ 350 printhex2(ret); 351 puts(" Can't exit boot services\n"); 352 size = sizeof(desc); 353 ret = boot->get_memory_map(&size, desc, &key, &desc_size, 354 &version); 355 if (ret) { 356 printhex2(ret); 357 puts(" Can't get memory map\n"); 358 return ret; 359 } 360 ret = boot->exit_boot_services(image, key); 361 if (ret) { 362 printhex2(ret); 363 puts(" Can't exit boot services 2\n"); 364 return ret; 365 } 366 } 367 368 /* The EFI UART won't work now, switch to a debug one */ 369 use_uart = true; 370 371 map.version = version; 372 map.desc_size = desc_size; 373 add_entry_addr(priv, EFIET_MEMORY_MAP, &map, sizeof(map), desc, size); 374 add_entry_addr(priv, EFIET_END, NULL, 0, 0, 0); 375 376 memcpy((void *)CONFIG_SYS_TEXT_BASE, _binary_u_boot_bin_start, 377 (ulong)_binary_u_boot_bin_end - 378 (ulong)_binary_u_boot_bin_start); 379 380 #ifdef DEBUG 381 puts("EFI table at "); 382 printhex8((ulong)priv->info); 383 puts(" size "); 384 printhex8(priv->info->total_size); 385 #endif 386 putc('\n'); 387 jump_to_uboot(cs32, CONFIG_SYS_TEXT_BASE, (ulong)priv->info); 388 389 return EFI_LOAD_ERROR; 390 } 391