lib/efi/efi_stub.c

   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 (ch == '\n')
  69                 putc('\r');
  70
  71         if (use_uart) {
  72                 NS16550_t com_port = (NS16550_t)0x3f8;
  73
  74                 while ((inb((ulong)&com_port->lsr) & UART_LSR_THRE) == 0)
  75                         ;
  76                 outb(ch, (ulong)&com_port->thr);
  77         } else {
  78                 efi_putc(global_priv, ch);
  79         }
  80 }
  81
  82 void puts(const char *str)
  83 {
  84         while (*str)
  85                 putc(*str++);
  86 }
  87
  88 static void _debug_uart_putc(int ch)
  89 {
  90         putc(ch);
  91 }
  92
  93 DEBUG_UART_FUNCS
  94
  95 void *memcpy(void *dest, const void *src, size_t size)
  96 {
  97         unsigned char *dptr = dest;
  98         const unsigned char *ptr = src;
  99         const unsigned char *end = src + size;
 100
 101         while (ptr < end)
 102                 *dptr++ = *ptr++;
 103
 104         return dest;
 105 }
 106
 107 void *memset(void *inptr, int ch, size_t size)
 108 {
 109         char *ptr = inptr;
 110         char *end = ptr + size;
 111
 112         while (ptr < end)
 113                 *ptr++ = ch;
 114
 115         return ptr;
 116 }
 117
 118 static void jump_to_uboot(ulong cs32, ulong addr, ulong info)
 119 {
 120 #ifdef CONFIG_EFI_STUB_32BIT
 121         /*
 122          * U-Boot requires these parameters in registers, not on the stack.
 123          * See _x86boot_start() for this code.
 124          */
 125         typedef void (*func_t)(int bist, int unused, ulong info)
 126                 __attribute__((regparm(3)));
 127
 128         ((func_t)addr)(0, 0, info);
 129 #else
 130         cpu_call32(cs32, CONFIG_SYS_TEXT_BASE, info);
 131 #endif
 132 }
 133
 134 #ifdef CONFIG_EFI_STUB_64BIT
 135 static void get_gdt(struct desctab_info *info)
 136 {
 137         asm volatile ("sgdt %0" : : "m"(*info) : "memory");
 138 }
 139 #endif
 140
 141 static inline unsigned long read_cr3(void)
 142 {
 143         unsigned long val;
 144
 145         asm volatile("mov %%cr3,%0" : "=r" (val) : : "memory");
 146         return val;
 147 }
 148
 149 /**
 150  * get_codeseg32() - Find the code segment to use for 32-bit code
 151  *
 152  * U-Boot only works in 32-bit mode at present, so when booting from 64-bit
 153  * EFI we must first change to 32-bit mode. To do this we need to find the
 154  * correct code segment to use (an entry in the Global Descriptor Table).
 155  *
 156  * @return code segment GDT offset, or 0 for 32-bit EFI, -ENOENT if not found
 157  */
 158 static int get_codeseg32(void)
 159 {
 160         int cs32 = 0;
 161
 162 #ifdef CONFIG_EFI_STUB_64BIT
 163         struct desctab_info gdt;
 164         uint64_t *ptr;
 165         int i;
 166
 167         get_gdt(&gdt);
 168         for (ptr = (uint64_t *)(unsigned long)gdt.addr, i = 0; i < gdt.limit;
 169              i += 8, ptr++) {
 170                 uint64_t desc = *ptr;
 171                 uint64_t base, limit;
 172
 173                 /*
 174                  * Check that the target U-Boot jump address is within the
 175                  * selector and that the selector is of the right type.
 176                  */
 177                 base = ((desc >> GDT_BASE_LOW_SHIFT) & GDT_BASE_LOW_MASK) |
 178                         ((desc >> GDT_BASE_HIGH_SHIFT) & GDT_BASE_HIGH_MASK)
 179                                 << 16;
 180                 limit = ((desc >> GDT_LIMIT_LOW_SHIFT) & GDT_LIMIT_LOW_MASK) |
 181                         ((desc >> GDT_LIMIT_HIGH_SHIFT) & GDT_LIMIT_HIGH_MASK)
 182                                 << 16;
 183                 base <<= 12;    /* 4KB granularity */
 184                 limit <<= 12;
 185                 if ((desc & GDT_PRESENT) && (desc && GDT_NOTSYS) &&
 186                     !(desc & GDT_LONG) && (desc & GDT_4KB) &&
 187                     (desc & GDT_32BIT) && (desc & GDT_CODE) &&
 188                     CONFIG_SYS_TEXT_BASE > base &&
 189                     CONFIG_SYS_TEXT_BASE + CONFIG_SYS_MONITOR_LEN < limit
 190                 ) {
 191                         cs32 = i;
 192                         break;
 193                 }
 194         }
 195
 196 #ifdef DEBUG
 197         puts("\ngdt: ");
 198         printhex8(gdt.limit);
 199         puts(", addr: ");
 200         printhex8(gdt.addr >> 32);
 201         printhex8(gdt.addr);
 202         for (i = 0; i < gdt.limit; i += 8) {
 203                 uint32_t *ptr = (uint32_t *)((unsigned long)gdt.addr + i);
 204
 205                 puts("\n");
 206                 printhex2(i);
 207                 puts(": ");
 208                 printhex8(ptr[1]);
 209                 puts("  ");
 210                 printhex8(ptr[0]);
 211         }
 212         puts("\n ");
 213         puts("32-bit code segment: ");
 214         printhex2(cs32);
 215         puts("\n ");
 216
 217         puts("page_table: ");
 218         printhex8(read_cr3());
 219         puts("\n ");
 220 #endif
 221         if (!cs32) {
 222                 puts("Can't find 32-bit code segment\n");
 223                 return -ENOENT;
 224         }
 225 #endif
 226
 227         return cs32;
 228 }
 229
 230 static int setup_info_table(struct efi_priv *priv, int size)
 231 {
 232         struct efi_info_hdr *info;
 233         efi_status_t ret;
 234
 235         /* Get some memory for our info table */
 236         priv->info_size = size;
 237         info = efi_malloc(priv, priv->info_size, &ret);
 238         if (ret) {
 239                 printhex2(ret);
 240                 puts(" No memory for info table: ");
 241                 return ret;
 242         }
 243
 244         memset(info, '\0', sizeof(*info));
 245         info->version = EFI_TABLE_VERSION;
 246         info->hdr_size = sizeof(*info);
 247         priv->info = info;
 248         priv->next_hdr = (char *)info + info->hdr_size;
 249
 250         return 0;
 251 }
 252
 253 static void add_entry_addr(struct efi_priv *priv, enum efi_entry_t type,
 254                            void *ptr1, int size1, void *ptr2, int size2)
 255 {
 256         struct efi_entry_hdr *hdr = priv->next_hdr;
 257
 258         hdr->type = type;
 259         hdr->size = size1 + size2;
 260         hdr->addr = 0;
 261         hdr->link = ALIGN(sizeof(*hdr) + hdr->size, 16);
 262         priv->next_hdr += hdr->link;
 263         memcpy(hdr + 1, ptr1, size1);
 264         memcpy((void *)(hdr + 1) + size1, ptr2, size2);
 265         priv->info->total_size = (ulong)priv->next_hdr - (ulong)priv->info;
 266 }
 267
 268 /**
 269  * efi_main() - Start an EFI image
 270  *
 271  * This function is called by our EFI start-up code. It handles running
 272  * U-Boot. If it returns, EFI will continue.
 273  */
 274 efi_status_t efi_main(efi_handle_t image, struct efi_system_table *sys_table)
 275 {
 276         struct efi_priv local_priv, *priv = &local_priv;
 277         struct efi_boot_services *boot = sys_table->boottime;
 278         struct efi_mem_desc *desc;
 279         struct efi_entry_memmap map;
 280         efi_uintn_t key, desc_size, size;
 281         efi_status_t ret;
 282         u32 version;
 283         int cs32;
 284
 285         ret = efi_init(priv, "Payload", image, sys_table);
 286         if (ret) {
 287                 printhex2(ret); puts(" efi_init() failed\n");
 288                 return ret;
 289         }
 290         global_priv = priv;
 291
 292         cs32 = get_codeseg32();
 293         if (cs32 < 0)
 294                 return EFI_UNSUPPORTED;
 295
 296         /* Get the memory map so we can switch off EFI */
 297         size = 0;
 298         ret = boot->get_memory_map(&size, NULL, &key, &desc_size, &version);
 299         if (ret != EFI_BUFFER_TOO_SMALL) {
 300                 printhex2(BITS_PER_LONG);
 301                 printhex2(ret);
 302                 puts(" No memory map\n");
 303                 return ret;
 304         }
 305         size += 1024;   /* Since doing a malloc() may change the memory map! */
 306         desc = efi_malloc(priv, size, &ret);
 307         if (!desc) {
 308                 printhex2(ret);
 309                 puts(" No memory for memory descriptor: ");
 310                 return ret;
 311         }
 312         ret = setup_info_table(priv, size + 128);
 313         if (ret)
 314                 return ret;
 315
 316         ret = boot->get_memory_map(&size, desc, &key, &desc_size, &version);
 317         if (ret) {
 318                 printhex2(ret);
 319                 puts(" Can't get memory map\n");
 320                 return ret;
 321         }
 322
 323         ret = boot->exit_boot_services(image, key);
 324         if (ret) {
 325                 /*
 326                  * Unfortunately it happens that we cannot exit boot services
 327                  * the first time. But the second time it work. I don't know
 328                  * why but this seems to be a repeatable problem. To get
 329                  * around it, just try again.
 330                  */
 331                 printhex2(ret);
 332                 puts(" Can't exit boot services\n");
 333                 size = sizeof(desc);
 334                 ret = boot->get_memory_map(&size, desc, &key, &desc_size,
 335                                            &version);
 336                 if (ret) {
 337                         printhex2(ret);
 338                         puts(" Can't get memory map\n");
 339                         return ret;
 340                 }
 341                 ret = boot->exit_boot_services(image, key);
 342                 if (ret) {
 343                         printhex2(ret);
 344                         puts(" Can't exit boot services 2\n");
 345                         return ret;
 346                 }
 347         }
 348
 349         map.version = version;
 350         map.desc_size = desc_size;
 351         add_entry_addr(priv, EFIET_MEMORY_MAP, &map, sizeof(map), desc, size);
 352         add_entry_addr(priv, EFIET_END, NULL, 0, 0, 0);
 353
 354         /* The EFI UART won't work now, switch to a debug one */
 355         use_uart = true;
 356
 357         memcpy((void *)CONFIG_SYS_TEXT_BASE, _binary_u_boot_bin_start,
 358                (ulong)_binary_u_boot_bin_end -
 359                (ulong)_binary_u_boot_bin_start);
 360
 361 #ifdef DEBUG
 362         puts("EFI table at ");
 363         printhex8((ulong)priv->info);
 364         puts(" size ");
 365         printhex8(priv->info->total_size);
 366 #endif
 367         putc('\n');
 368         jump_to_uboot(cs32, CONFIG_SYS_TEXT_BASE, (ulong)priv->info);
 369
 370         return EFI_LOAD_ERROR;
 371 }