uboot/lib/efi/efi_stub.c
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   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
  24DECLARE_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
  36static struct efi_priv *global_priv;
  37static bool use_uart;
  38
  39struct __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 */
  62void _debug_uart_init(void)
  63{
  64}
  65
  66void 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
  82void puts(const char *str)
  83{
  84        while (*str)
  85                putc(*str++);
  86}
  87
  88static void _debug_uart_putc(int ch)
  89{
  90        putc(ch);
  91}
  92
  93DEBUG_UART_FUNCS
  94
  95void *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
 107void *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
 118static 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
 135static void get_gdt(struct desctab_info *info)
 136{
 137        asm volatile ("sgdt %0" : : "m"(*info) : "memory");
 138}
 139#endif
 140
 141static 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 */
 158static 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
 230static 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
 253static 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 */
 274efi_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}
 372