path: root/drivers/firmware/efi/libstub/efi-stub-helper.c

/*
 * Helper functions used by the EFI stub on multiple
 * architectures. This should be #included by the EFI stub
 * implementation files.
 *
 * Copyright 2011 Intel Corporation; author Matt Fleming
 *
 * This file is part of the Linux kernel, and is made available
 * under the terms of the GNU General Public License version 2.
 *
 */

#include <linux/efi.h>
#include <asm/efi.h>

#include "efistub.h"

/*
 * Some firmware implementations have problems reading files in one go.
 * A read chunk size of 1MB seems to work for most platforms.
 *
 * Unfortunately, reading files in chunks triggers *other* bugs on some
 * platforms, so we provide a way to disable this workaround, which can
 * be done by passing "efi=nochunk" on the EFI boot stub command line.
 *
 * If you experience issues with initrd images being corrupt it's worth
 * trying efi=nochunk, but chunking is enabled by default because there
 * are far more machines that require the workaround than those that
 * break with it enabled.
 */
#define EFI_READ_CHUNK_SIZE	(1024 * 1024)

static unsigned long __chunk_size = EFI_READ_CHUNK_SIZE;

/*
 * Allow the platform to override the allocation granularity: this allows
 * systems that have the capability to run with a larger page size to deal
 * with the allocations for initrd and fdt more efficiently.
 */
#ifndef EFI_ALLOC_ALIGN
#define EFI_ALLOC_ALIGN		EFI_PAGE_SIZE
#endif

#define EFI_MMAP_NR_SLACK_SLOTS	8

struct file_info {
	efi_file_handle_t *handle;
	u64 size;
};

void efi_printk(efi_system_table_t *sys_table_arg, char *str)
{
	char *s8;

	for (s8 = str; *s8; s8++) {
		efi_char16_t ch[2] = { 0 };

		ch[0] = *s8;
		if (*s8 == '\n') {
			efi_char16_t nl[2] = { '\r', 0 };
			efi_char16_printk(sys_table_arg, nl);
		}

		efi_char16_printk(sys_table_arg, ch);
	}
}

static inline bool mmap_has_headroom(unsigned long buff_size,
				     unsigned long map_size,
				     unsigned long desc_size)
{
	unsigned long slack = buff_size - map_size;

	return slack / desc_size >= EFI_MMAP_NR_SLACK_SLOTS;
}

efi_status_t efi_get_memory_map(efi_system_table_t *sys_table_arg,
				struct efi_boot_memmap *map)
{
	efi_memory_desc_t *m = NULL;
	efi_status_t status;
	unsigned long key;
	u32 desc_version;

	*map->desc_size =	sizeof(*m);
	*map->map_size =	*map->desc_size * 32;
	*map->buff_size =	*map->map_size;
again:
	status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
				*map->map_size, (void **)&m);
	if (status != EFI_SUCCESS)
		goto fail;

	*map->desc_size = 0;
	key = 0;
	status = efi_call_early(get_memory_map, map->map_size, m,
				&key, map->desc_size, &desc_version);
	if (status == EFI_BUFFER_TOO_SMALL ||
	    !mmap_has_headroom(*map->buff_size, *map->map_size,
			       *map->desc_size)) {
		efi_call_early(free_pool, m);
		/*
		 * Make sure there is some entries of headroom so that the
		 * buffer can be reused for a new map after allocations are
		 * no longer permitted.  Its unlikely that the map will grow to
		 * exceed this headroom once we are ready to trigger
		 * ExitBootServices()
		 */
		*map->map_size += *map->desc_size * EFI_MMAP_NR_SLACK_SLOTS;
		*map->buff_size = *map->map_size;
		goto again;
	}

	if (status != EFI_SUCCESS)
		efi_call_early(free_pool, m);

	if (map->key_ptr && status == EFI_SUCCESS)
		*map->key_ptr = key;
	if (map->desc_ver && status == EFI_SUCCESS)
		*map->desc_ver = desc_version;

fail:
	*map->map = m;
	return status;
}


unsigned long get_dram_base(efi_system_table_t *sys_table_arg)
{
	efi_status_t status;
	unsigned long map_size, buff_size;
	unsigned long membase  = EFI_ERROR;
	struct efi_memory_map map;
	efi_memory_desc_t *md;
	struct efi_boot_memmap boot_map;

	boot_map.map =		(efi_memory_desc_t **)&map.map;
	boot_map.map_size =	&map_size;
	boot_map.desc_size =	&map.desc_size;
	boot_map.desc_ver =	NULL;
	boot_map.key_ptr =	NULL;
	boot_map.buff_size =	&buff_size;

	status = efi_get_memory_map(sys_table_arg, &boot_map);
	if (status != EFI_SUCCESS)
		return membase;

	map.map_end = map.map + map_size;

	for_each_efi_memory_desc_in_map(&map, md) {
		if (md->attribute & EFI_MEMORY_WB) {
			if (membase > md->phys_addr)
				membase = md->phys_addr;
		}
	}

	efi_call_early(free_pool, map.map);

	return membase;
}

/*
 * Allocate at the highest possible address that is not above 'max'.
 */
efi_status_t efi_high_alloc(efi_system_table_t *sys_table_arg,
			    unsigned long size, unsigned long align,
			    unsigned long *addr, unsigned long max)
{
	unsigned long map_size, desc_size, buff_size;
	efi_memory_desc_t *map;
	efi_status_t status;
	unsigned long nr_pages;
	u64 max_addr = 0;
	int i;
	struct efi_boot_memmap boot_map;

	boot_map.map =		&map;
	boot_map.map_size =	&map_size;
	boot_map.desc_size =	&desc_size;
	boot_map.desc_ver =	NULL;
	boot_map.key_ptr =	NULL;
	boot_map.buff_size =	&buff_size;

	status = efi_get_memory_map(sys_table_arg, &boot_map);
	if (status != EFI_SUCCESS)
		goto fail;

	/*
	 * Enforce minimum alignment that EFI requires when requesting
	 * a specific address.  We are doing page-based allocations,