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 (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 }