lib/efi/efi_stub.c - u-boot - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright (c) 2015 Google, Inc
  *
  * 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>

 #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 == '\n')
 		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("\ngdt: ");
 	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("\n");
 		printhex2(i);
 		puts(": ");
 		printhex8(ptr[1]);
 		puts("  ");
 		printhex8(ptr[0]);
 	}
 	puts("\n ");
 	puts("32-bit code segment: ");
 	printhex2(cs32);
 	puts("\n ");

 	puts("page_table: ");
 	printhex8(read_cr3());
 	puts("\n ");
 #endif
 	if (!cs32) {
 		puts("Can't find 32-bit code segment\n");
 		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\n");
 		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\n");
 		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\n");
 		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\n");
 		size = sizeof(desc);
 		ret = boot->get_memory_map(&size, desc, &key, &desc_size,
 					   &version);
 		if (ret) {
 			printhex2(ret);
 			puts(" Can't get memory map\n");
 			return ret;
 		}
 		ret = boot->exit_boot_services(image, key);
 		if (ret) {
 			printhex2(ret);
 			puts(" Can't exit boot services 2\n");
 			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('\n');
 	jump_to_uboot(cs32, CONFIG_SYS_TEXT_BASE, (ulong)priv->info);

 	return EFI_LOAD_ERROR;
 }
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Copyright (c) 2015 Google, Inc
	*
	* 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>

	#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 == '\n')
	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("\ngdt: ");
	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("\n");
	printhex2(i);
	puts(": ");
	printhex8(ptr[1]);
	puts(" ");
	printhex8(ptr[0]);
	}
	puts("\n ");
	puts("32-bit code segment: ");
	printhex2(cs32);
	puts("\n ");

	puts("page_table: ");
	printhex8(read_cr3());
	puts("\n ");
	#endif
	if (!cs32) {
	puts("Can't find 32-bit code segment\n");
	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\n");
	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\n");
	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\n");
	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\n");
	size = sizeof(desc);
	ret = boot->get_memory_map(&size, desc, &key, &desc_size,
	&version);
	if (ret) {
	printhex2(ret);
	puts(" Can't get memory map\n");
	return ret;
	}
	ret = boot->exit_boot_services(image, key);
	if (ret) {
	printhex2(ret);
	puts(" Can't exit boot services 2\n");
	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('\n');
	jump_to_uboot(cs32, CONFIG_SYS_TEXT_BASE, (ulong)priv->info);

	return EFI_LOAD_ERROR;
	}