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