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