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lib/efi/efi_stub.c
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/* * Copyright (c) 2015 Google, Inc * * SPDX-License-Identifier: GPL-2.0+ * * EFI information obtained here: * http://wiki.phoenix.com/wiki/index.php/EFI_BOOT_SERVICES * * Loads a payload (U-Boot) within the EFI environment. This is built as an * EFI application. It can be built either in 32-bit or 64-bit mode. */ #include <common.h> #include <debug_uart.h> #include <efi.h> #include <efi_api.h> #include <errno.h> #include <ns16550.h> #include <asm/cpu.h> #include <asm/io.h> #include <linux/err.h> #include <linux/types.h> DECLARE_GLOBAL_DATA_PTR; #ifndef CONFIG_X86 /* * Problem areas: * - putc() uses the ns16550 address directly and assumed I/O access. Many * platforms will use memory access * get_codeseg32() is only meaningful on x86 */ #error "This file needs to be ported for use on architectures" #endif static struct efi_priv *global_priv; static bool use_uart; struct __packed desctab_info { uint16_t limit; uint64_t addr; uint16_t pad; }; /* * EFI uses Unicode and we don't. The easiest way to get a sensible output * function is to use the U-Boot debug UART. We use EFI's console output * function where available, and assume the built-in UART after that. We rely * on EFI to set up the UART for us and just bring in the functions here. * This last bit is a bit icky, but it's only for debugging anyway. We could * build in ns16550.c with some effort, but this is a payload loader after * all. * * Note: We avoid using printf() so we don't need to bring in lib/vsprintf.c. * That would require some refactoring since we already build this for U-Boot. * Building an EFI shared library version would have to be a separate stem. * That might push us to using the SPL framework to build this stub. However * that would involve a round of EFI-specific changes in SPL. Worth * considering if we start needing more U-Boot functionality. Note that we * could then move get_codeseg32() to arch/x86/cpu/cpu.c. */ void _debug_uart_init(void) { } void putc(const char ch) { if (ch == ' ') putc('\r'); if (use_uart) { NS16550_t com_port = (NS16550_t)0x3f8; while ((inb((ulong)&com_port->lsr) & UART_LSR_THRE) == 0) ; outb(ch, (ulong)&com_port->thr); } else { efi_putc(global_priv, ch); } } void puts(const char *str) { while (*str) putc(*str++); } static void _debug_uart_putc(int ch) { putc(ch); } DEBUG_UART_FUNCS void *memcpy(void *dest, const void *src, size_t size) { unsigned char *dptr = dest; const unsigned char *ptr = src; const unsigned char *end = src + size; while (ptr < end) *dptr++ = *ptr++; return dest; } void *memset(void *inptr, int ch, size_t size) { char *ptr = inptr; char *end = ptr + size; while (ptr < end) *ptr++ = ch; return ptr; } static void jump_to_uboot(ulong cs32, ulong addr, ulong info) { #ifdef CONFIG_EFI_STUB_32BIT /* * U-Boot requires these parameters in registers, not on the stack. * See _x86boot_start() for this code. */ typedef void (*func_t)(int bist, int unused, ulong info) __attribute__((regparm(3))); ((func_t)addr)(0, 0, info); #else cpu_call32(cs32, CONFIG_SYS_TEXT_BASE, info); #endif } #ifdef CONFIG_EFI_STUB_64BIT static void get_gdt(struct desctab_info *info) { asm volatile ("sgdt %0" : : "m"(*info) : "memory"); } #endif static inline unsigned long read_cr3(void) { unsigned long val; asm volatile("mov %%cr3,%0" : "=r" (val) : : "memory"); return val; } /** * get_codeseg32() - Find the code segment to use for 32-bit code * * U-Boot only works in 32-bit mode at present, so when booting from 64-bit * EFI we must first change to 32-bit mode. To do this we need to find the * correct code segment to use (an entry in the Global Descriptor Table). * * @return code segment GDT offset, or 0 for 32-bit EFI, -ENOENT if not found */ static int get_codeseg32(void) { int cs32 = 0; #ifdef CONFIG_EFI_STUB_64BIT struct desctab_info gdt; uint64_t *ptr; int i; get_gdt(&gdt); for (ptr = (uint64_t *)(unsigned long)gdt.addr, i = 0; i < gdt.limit; i += 8, ptr++) { uint64_t desc = *ptr; uint64_t base, limit; /* * Check that the target U-Boot jump address is within the * selector and that the selector is of the right type. */ base = ((desc >> GDT_BASE_LOW_SHIFT) & GDT_BASE_LOW_MASK) | ((desc >> GDT_BASE_HIGH_SHIFT) & GDT_BASE_HIGH_MASK) << 16; limit = ((desc >> GDT_LIMIT_LOW_SHIFT) & GDT_LIMIT_LOW_MASK) | ((desc >> GDT_LIMIT_HIGH_SHIFT) & GDT_LIMIT_HIGH_MASK) << 16; base <<= 12; /* 4KB granularity */ limit <<= 12; if ((desc & GDT_PRESENT) && (desc && GDT_NOTSYS) && !(desc & GDT_LONG) && (desc & GDT_4KB) && (desc & GDT_32BIT) && (desc & GDT_CODE) && CONFIG_SYS_TEXT_BASE > base && CONFIG_SYS_TEXT_BASE + CONFIG_SYS_MONITOR_LEN < limit ) { cs32 = i; break; } } #ifdef DEBUG puts(" gdt: "); printhex8(gdt.limit); puts(", addr: "); printhex8(gdt.addr >> 32); printhex8(gdt.addr); for (i = 0; i < gdt.limit; i += 8) { uint32_t *ptr = (uint32_t *)((unsigned long)gdt.addr + i); puts(" "); printhex2(i); puts(": "); printhex8(ptr[1]); puts(" "); printhex8(ptr[0]); } puts(" "); puts("32-bit code segment: "); printhex2(cs32); puts(" "); puts("page_table: "); printhex8(read_cr3()); puts(" "); #endif if (!cs32) { puts("Can't find 32-bit code segment "); return -ENOENT; } #endif return cs32; } static int setup_info_table(struct efi_priv *priv, int size) { struct efi_info_hdr *info; efi_status_t ret; /* Get some memory for our info table */ priv->info_size = size; info = efi_malloc(priv, priv->info_size, &ret); if (ret) { printhex2(ret); puts(" No memory for info table: "); return ret; } memset(info, '\0', sizeof(*info)); info->version = EFI_TABLE_VERSION; info->hdr_size = sizeof(*info); priv->info = info; priv->next_hdr = (char *)info + info->hdr_size; return 0; } static void add_entry_addr(struct efi_priv *priv, enum efi_entry_t type, void *ptr1, int size1, void *ptr2, int size2) { struct efi_entry_hdr *hdr = priv->next_hdr; hdr->type = type; hdr->size = size1 + size2; hdr->addr = 0; hdr->link = ALIGN(sizeof(*hdr) + hdr->size, 16); priv->next_hdr += hdr->link; memcpy(hdr + 1, ptr1, size1); memcpy((void *)(hdr + 1) + size1, ptr2, size2); priv->info->total_size = (ulong)priv->next_hdr - (ulong)priv->info; } /** * efi_main() - Start an EFI image * * This function is called by our EFI start-up code. It handles running * U-Boot. If it returns, EFI will continue. */ efi_status_t efi_main(efi_handle_t image, struct efi_system_table *sys_table) { struct efi_priv local_priv, *priv = &local_priv; struct efi_boot_services *boot = sys_table->boottime; struct efi_mem_desc *desc; struct efi_entry_memmap map; efi_uintn_t key, desc_size, size; efi_status_t ret; u32 version; int cs32; ret = efi_init(priv, "Payload", image, sys_table); if (ret) { printhex2(ret); puts(" efi_init() failed "); return ret; } global_priv = priv; cs32 = get_codeseg32(); if (cs32 < 0) return EFI_UNSUPPORTED; /* Get the memory map so we can switch off EFI */ size = 0; ret = boot->get_memory_map(&size, NULL, &key, &desc_size, &version); if (ret != EFI_BUFFER_TOO_SMALL) { printhex2(BITS_PER_LONG); printhex2(ret); puts(" No memory map "); return ret; } size += 1024; /* Since doing a malloc() may change the memory map! */ desc = efi_malloc(priv, size, &ret); if (!desc) { printhex2(ret); puts(" No memory for memory descriptor: "); return ret; } ret = setup_info_table(priv, size + 128); if (ret) return ret; ret = boot->get_memory_map(&size, desc, &key, &desc_size, &version); if (ret) { printhex2(ret); puts(" Can't get memory map "); return ret; } ret = boot->exit_boot_services(image, key); if (ret) { /* * Unfortunately it happens that we cannot exit boot services * the first time. But the second time it work. I don't know * why but this seems to be a repeatable problem. To get * around it, just try again. */ printhex2(ret); puts(" Can't exit boot services "); size = sizeof(desc); ret = boot->get_memory_map(&size, desc, &key, &desc_size, &version); if (ret) { printhex2(ret); puts(" Can't get memory map "); return ret; } ret = boot->exit_boot_services(image, key); if (ret) { printhex2(ret); puts(" Can't exit boot services 2 "); return ret; } } map.version = version; map.desc_size = desc_size; add_entry_addr(priv, EFIET_MEMORY_MAP, &map, sizeof(map), desc, size); add_entry_addr(priv, EFIET_END, NULL, 0, 0, 0); /* The EFI UART won't work now, switch to a debug one */ use_uart = true; memcpy((void *)CONFIG_SYS_TEXT_BASE, _binary_u_boot_bin_start, (ulong)_binary_u_boot_bin_end - (ulong)_binary_u_boot_bin_start); #ifdef DEBUG puts("EFI table at "); printhex8((ulong)priv->info); puts(" size "); printhex8(priv->info->total_size); #endif putc(' '); jump_to_uboot(cs32, CONFIG_SYS_TEXT_BASE, (ulong)priv->info); return EFI_LOAD_ERROR; } |