lib/efi_loader/efi_memory.c - filogic/uboot - Gitiles

 /*
  *  EFI application memory management
  *
  *  Copyright (c) 2016 Alexander Graf
  *
  *  SPDX-License-Identifier:     GPL-2.0+
  */

 #include <common.h>
 #include <efi_loader.h>
 #include <malloc.h>
 #include <asm/global_data.h>
 #include <libfdt_env.h>
 #include <linux/list_sort.h>
 #include <inttypes.h>
 #include <watchdog.h>

 DECLARE_GLOBAL_DATA_PTR;

 struct efi_mem_list {
 	struct list_head link;
 	struct efi_mem_desc desc;
 };

 #define EFI_CARVE_NO_OVERLAP		-1
 #define EFI_CARVE_LOOP_AGAIN		-2
 #define EFI_CARVE_OVERLAPS_NONRAM	-3

 /* This list contains all memory map items */
 LIST_HEAD(efi_mem);

 #ifdef CONFIG_EFI_LOADER_BOUNCE_BUFFER
 void *efi_bounce_buffer;
 #endif

 /*
  * U-Boot services each EFI AllocatePool request as a separate
  * (multiple) page allocation.  We have to track the number of pages
  * to be able to free the correct amount later.
  * EFI requires 8 byte alignment for pool allocations, so we can
  * prepend each allocation with an 64 bit header tracking the
  * allocation size, and hand out the remainder to the caller.
  */
 struct efi_pool_allocation {
 	u64 num_pages;
 	char data[] __aligned(ARCH_DMA_MINALIGN);
 };

 /*
  * Sorts the memory list from highest address to lowest address
  *
  * When allocating memory we should always start from the highest
  * address chunk, so sort the memory list such that the first list
  * iterator gets the highest address and goes lower from there.
  */
 static int efi_mem_cmp(void *priv, struct list_head *a, struct list_head *b)
 {
 	struct efi_mem_list *mema = list_entry(a, struct efi_mem_list, link);
 	struct efi_mem_list *memb = list_entry(b, struct efi_mem_list, link);

 	if (mema->desc.physical_start == memb->desc.physical_start)
 		return 0;
 	else if (mema->desc.physical_start < memb->desc.physical_start)
 		return 1;
 	else
 		return -1;
 }

 static void efi_mem_sort(void)
 {
 	list_sort(NULL, &efi_mem, efi_mem_cmp);
 }

 /*
  * Unmaps all memory occupied by the carve_desc region from the
  * list entry pointed to by map.
  *
  * Returns EFI_CARVE_NO_OVERLAP if the regions don't overlap.
  * Returns EFI_CARVE_OVERLAPS_NONRAM if the carve and map overlap,
  *    and the map contains anything but free ram.
  *    (only when overlap_only_ram is true)
  * Returns EFI_CARVE_LOOP_AGAIN if the mapping list should be traversed
  *    again, as it has been altered
  * Returns the number of overlapping pages. The pages are removed from
  *     the mapping list.
  *
  * In case of EFI_CARVE_OVERLAPS_NONRAM it is the callers responsibility
  * to readd the already carved out pages to the mapping.
  */
 static int efi_mem_carve_out(struct efi_mem_list *map,
 			     struct efi_mem_desc *carve_desc,
 			     bool overlap_only_ram)
 {
 	struct efi_mem_list *newmap;
 	struct efi_mem_desc *map_desc = &map->desc;
 	uint64_t map_start = map_desc->physical_start;
 	uint64_t map_end = map_start + (map_desc->num_pages << EFI_PAGE_SHIFT);
 	uint64_t carve_start = carve_desc->physical_start;
 	uint64_t carve_end = carve_start +
 			     (carve_desc->num_pages << EFI_PAGE_SHIFT);

 	/* check whether we're overlapping */
 	if ((carve_end <= map_start) || (carve_start >= map_end))
 		return EFI_CARVE_NO_OVERLAP;

 	/* We're overlapping with non-RAM, warn the caller if desired */
 	if (overlap_only_ram && (map_desc->type != EFI_CONVENTIONAL_MEMORY))
 		return EFI_CARVE_OVERLAPS_NONRAM;

 	/* Sanitize carve_start and carve_end to lie within our bounds */
 	carve_start = max(carve_start, map_start);
 	carve_end = min(carve_end, map_end);

 	/* Carving at the beginning of our map? Just move it! */
 	if (carve_start == map_start) {
 		if (map_end == carve_end) {
 			/* Full overlap, just remove map */
 			list_del(&map->link);
 			free(map);
 		} else {
 			map->desc.physical_start = carve_end;
 			map->desc.num_pages = (map_end - carve_end)
 					      >> EFI_PAGE_SHIFT;
 		}

 		return (carve_end - carve_start) >> EFI_PAGE_SHIFT;
 	}

 	/*
 	 * Overlapping maps, just split the list map at carve_start,
 	 * it will get moved or removed in the next iteration.
 	 *
 	 * [ map_desc |__carve_start__| newmap ]
 	 */

 	/* Create a new map from [ carve_start ... map_end ] */
 	newmap = calloc(1, sizeof(*newmap));
 	newmap->desc = map->desc;
 	newmap->desc.physical_start = carve_start;
 	newmap->desc.num_pages = (map_end - carve_start) >> EFI_PAGE_SHIFT;
 	/* Insert before current entry (descending address order) */
 	list_add_tail(&newmap->link, &map->link);

 	/* Shrink the map to [ map_start ... carve_start ] */
 	map_desc->num_pages = (carve_start - map_start) >> EFI_PAGE_SHIFT;

 	return EFI_CARVE_LOOP_AGAIN;
 }

 uint64_t efi_add_memory_map(uint64_t start, uint64_t pages, int memory_type,
 			    bool overlap_only_ram)
 {
 	struct list_head *lhandle;
 	struct efi_mem_list *newlist;
 	bool carve_again;
 	uint64_t carved_pages = 0;

 	debug("%s: 0x%" PRIx64 " 0x%" PRIx64 " %d %s\n", __func__,
 	      start, pages, memory_type, overlap_only_ram ? "yes" : "no");

 	if (!pages)
 		return start;

 	newlist = calloc(1, sizeof(*newlist));
 	newlist->desc.type = memory_type;
 	newlist->desc.physical_start = start;
 	newlist->desc.virtual_start = start;
 	newlist->desc.num_pages = pages;

 	switch (memory_type) {
 	case EFI_RUNTIME_SERVICES_CODE:
 	case EFI_RUNTIME_SERVICES_DATA:
 		newlist->desc.attribute = (1 << EFI_MEMORY_WB_SHIFT) |
 					  (1ULL << EFI_MEMORY_RUNTIME_SHIFT);
 		break;
 	case EFI_MMAP_IO:
 		newlist->desc.attribute = 1ULL << EFI_MEMORY_RUNTIME_SHIFT;
 		break;
 	default:
 		newlist->desc.attribute = 1 << EFI_MEMORY_WB_SHIFT;
 		break;
 	}

 	/* Add our new map */
 	do {
 		carve_again = false;
 		list_for_each(lhandle, &efi_mem) {
 			struct efi_mem_list *lmem;
 			int r;

 			lmem = list_entry(lhandle, struct efi_mem_list, link);
 			r = efi_mem_carve_out(lmem, &newlist->desc,
 					      overlap_only_ram);
 			switch (r) {
 			case EFI_CARVE_OVERLAPS_NONRAM:
 				/*
 				 * The user requested to only have RAM overlaps,
 				 * but we hit a non-RAM region. Error out.
 				 */
 				return 0;
 			case EFI_CARVE_NO_OVERLAP:
 				/* Just ignore this list entry */
 				break;
 			case EFI_CARVE_LOOP_AGAIN:
 				/*
 				 * We split an entry, but need to loop through
 				 * the list again to actually carve it.
 				 */
 				carve_again = true;
 				break;
 			default:
 				/* We carved a number of pages */
 				carved_pages += r;
 				carve_again = true;
 				break;
 			}

 			if (carve_again) {
 				/* The list changed, we need to start over */
 				break;
 			}
 		}
 	} while (carve_again);

 	if (overlap_only_ram && (carved_pages != pages)) {
 		/*
 		 * The payload wanted to have RAM overlaps, but we overlapped
 		 * with an unallocated region. Error out.
 		 */
 		return 0;
 	}

 	/* Add our new map */
         list_add_tail(&newlist->link, &efi_mem);

 	/* And make sure memory is listed in descending order */
 	efi_mem_sort();

 	return start;
 }

 static uint64_t efi_find_free_memory(uint64_t len, uint64_t max_addr)
 {
 	struct list_head *lhandle;

 	list_for_each(lhandle, &efi_mem) {
 		struct efi_mem_list *lmem = list_entry(lhandle,
 			struct efi_mem_list, link);
 		struct efi_mem_desc *desc = &lmem->desc;
 		uint64_t desc_len = desc->num_pages << EFI_PAGE_SHIFT;
 		uint64_t desc_end = desc->physical_start + desc_len;
 		uint64_t curmax = min(max_addr, desc_end);
 		uint64_t ret = curmax - len;

 		/* We only take memory from free RAM */
 		if (desc->type != EFI_CONVENTIONAL_MEMORY)
 			continue;

 		/* Out of bounds for max_addr */
 		if ((ret + len) > max_addr)
 			continue;

 		/* Out of bounds for upper map limit */
 		if ((ret + len) > desc_end)
 			continue;

 		/* Out of bounds for lower map limit */
 		if (ret < desc->physical_start)
 			continue;

 		/* Return the highest address in this map within bounds */
 		return ret;
 	}

 	return 0;
 }

 efi_status_t efi_allocate_pages(int type, int memory_type,
 				unsigned long pages, uint64_t *memory)
 {
 	u64 len = pages << EFI_PAGE_SHIFT;
 	efi_status_t r = EFI_SUCCESS;
 	uint64_t addr;

 	switch (type) {
 	case 0:
 		/* Any page */
 		addr = efi_find_free_memory(len, gd->start_addr_sp);
 		if (!addr) {
 			r = EFI_NOT_FOUND;
 			break;
 		}
 		break;
 	case 1:
 		/* Max address */
 		addr = efi_find_free_memory(len, *memory);
 		if (!addr) {
 			r = EFI_NOT_FOUND;
 			break;
 		}
 		break;
 	case 2:
 		/* Exact address, reserve it. The addr is already in *memory. */
 		addr = *memory;
 		break;
 	default:
 		/* UEFI doesn't specify other allocation types */
 		r = EFI_INVALID_PARAMETER;
 		break;
 	}

 	if (r == EFI_SUCCESS) {
 		uint64_t ret;

 		/* Reserve that map in our memory maps */
 		ret = efi_add_memory_map(addr, pages, memory_type, true);
 		if (ret == addr) {
 			*memory = addr;
 		} else {
 			/* Map would overlap, bail out */
 			r = EFI_OUT_OF_RESOURCES;
 		}
 	}

 	return r;
 }

 void *efi_alloc(uint64_t len, int memory_type)
 {
 	uint64_t ret = 0;
 	uint64_t pages = (len + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT;
 	efi_status_t r;

 	r = efi_allocate_pages(0, memory_type, pages, &ret);
 	if (r == EFI_SUCCESS)
 		return (void*)(uintptr_t)ret;

 	return NULL;
 }

 efi_status_t efi_free_pages(uint64_t memory, unsigned long pages)
 {
 	uint64_t r = 0;

 	r = efi_add_memory_map(memory, pages, EFI_CONVENTIONAL_MEMORY, false);
 	/* Merging of adjacent free regions is missing */

 	if (r == memory)
 		return EFI_SUCCESS;

 	return EFI_NOT_FOUND;
 }

 efi_status_t efi_allocate_pool(int pool_type, unsigned long size,
 			       void **buffer)
 {
 	efi_status_t r;
 	efi_physical_addr_t t;
 	u64 num_pages = (size + sizeof(struct efi_pool_allocation) +
 			 EFI_PAGE_MASK) >> EFI_PAGE_SHIFT;

 	if (size == 0) {
 		*buffer = NULL;
 		return EFI_SUCCESS;
 	}

 	r = efi_allocate_pages(0, pool_type, num_pages, &t);

 	if (r == EFI_SUCCESS) {
 		struct efi_pool_allocation *alloc = (void *)(uintptr_t)t;
 		alloc->num_pages = num_pages;
 		*buffer = alloc->data;
 	}

 	return r;
 }

 efi_status_t efi_free_pool(void *buffer)
 {
 	efi_status_t r;
 	struct efi_pool_allocation *alloc;

 	if (buffer == NULL)
 		return EFI_INVALID_PARAMETER;

 	alloc = container_of(buffer, struct efi_pool_allocation, data);
 	/* Sanity check, was the supplied address returned by allocate_pool */
 	assert(((uintptr_t)alloc & EFI_PAGE_MASK) == 0);

 	r = efi_free_pages((uintptr_t)alloc, alloc->num_pages);

 	return r;
 }

 efi_status_t efi_get_memory_map(unsigned long *memory_map_size,
 			       struct efi_mem_desc *memory_map,
 			       unsigned long *map_key,
 			       unsigned long *descriptor_size,
 			       uint32_t *descriptor_version)
 {
 	ulong map_size = 0;
 	int map_entries = 0;
 	struct list_head *lhandle;
 	unsigned long provided_map_size = *memory_map_size;

 	list_for_each(lhandle, &efi_mem)
 		map_entries++;

 	map_size = map_entries * sizeof(struct efi_mem_desc);

 	*memory_map_size = map_size;

 	if (provided_map_size < map_size)
 		return EFI_BUFFER_TOO_SMALL;

 	if (descriptor_size)
 		*descriptor_size = sizeof(struct efi_mem_desc);

 	if (descriptor_version)
 		*descriptor_version = EFI_MEMORY_DESCRIPTOR_VERSION;

 	/* Copy list into array */
 	if (memory_map) {
 		/* Return the list in ascending order */
 		memory_map = &memory_map[map_entries - 1];
 		list_for_each(lhandle, &efi_mem) {
 			struct efi_mem_list *lmem;

 			lmem = list_entry(lhandle, struct efi_mem_list, link);
 			*memory_map = lmem->desc;
 			memory_map--;
 		}
 	}

 	*map_key = 0;

 	return EFI_SUCCESS;
 }

 __weak void efi_add_known_memory(void)
 {
 	int i;

 	/* Add RAM */
 	for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
 		u64 ram_start = gd->bd->bi_dram[i].start;
 		u64 ram_size = gd->bd->bi_dram[i].size;
 		u64 start = (ram_start + EFI_PAGE_MASK) & ~EFI_PAGE_MASK;
 		u64 pages = (ram_size + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT;

 		efi_add_memory_map(start, pages, EFI_CONVENTIONAL_MEMORY,
 				   false);
 	}
 }

 int efi_memory_init(void)
 {
 	unsigned long runtime_start, runtime_end, runtime_pages;
 	unsigned long uboot_start, uboot_pages;
 	unsigned long uboot_stack_size = 16 * 1024 * 1024;

 	efi_add_known_memory();

 	/* Add U-Boot */
 	uboot_start = (gd->start_addr_sp - uboot_stack_size) & ~EFI_PAGE_MASK;
 	uboot_pages = (gd->ram_top - uboot_start) >> EFI_PAGE_SHIFT;
 	efi_add_memory_map(uboot_start, uboot_pages, EFI_LOADER_DATA, false);

 	/* Add Runtime Services */
 	runtime_start = (ulong)&__efi_runtime_start & ~EFI_PAGE_MASK;
 	runtime_end = (ulong)&__efi_runtime_stop;
 	runtime_end = (runtime_end + EFI_PAGE_MASK) & ~EFI_PAGE_MASK;
 	runtime_pages = (runtime_end - runtime_start) >> EFI_PAGE_SHIFT;
 	efi_add_memory_map(runtime_start, runtime_pages,
 			   EFI_RUNTIME_SERVICES_CODE, false);

 #ifdef CONFIG_EFI_LOADER_BOUNCE_BUFFER
 	/* Request a 32bit 64MB bounce buffer region */
 	uint64_t efi_bounce_buffer_addr = 0xffffffff;

 	if (efi_allocate_pages(1, EFI_LOADER_DATA,
 			       (64 * 1024 * 1024) >> EFI_PAGE_SHIFT,
 			       &efi_bounce_buffer_addr) != EFI_SUCCESS)
 		return -1;

 	efi_bounce_buffer = (void*)(uintptr_t)efi_bounce_buffer_addr;
 #endif

 	return 0;
 }
	/*
	* EFI application memory management
	*
	* Copyright (c) 2016 Alexander Graf
	*
	* SPDX-License-Identifier: GPL-2.0+
	*/

	#include <common.h>
	#include <efi_loader.h>
	#include <malloc.h>
	#include <asm/global_data.h>
	#include <libfdt_env.h>
	#include <linux/list_sort.h>
	#include <inttypes.h>
	#include <watchdog.h>

	DECLARE_GLOBAL_DATA_PTR;

	struct efi_mem_list {
	struct list_head link;
	struct efi_mem_desc desc;
	};

	#define EFI_CARVE_NO_OVERLAP -1
	#define EFI_CARVE_LOOP_AGAIN -2
	#define EFI_CARVE_OVERLAPS_NONRAM -3

	/* This list contains all memory map items */
	LIST_HEAD(efi_mem);

	#ifdef CONFIG_EFI_LOADER_BOUNCE_BUFFER
	void *efi_bounce_buffer;
	#endif

	/*
	* U-Boot services each EFI AllocatePool request as a separate
	* (multiple) page allocation. We have to track the number of pages
	* to be able to free the correct amount later.
	* EFI requires 8 byte alignment for pool allocations, so we can
	* prepend each allocation with an 64 bit header tracking the
	* allocation size, and hand out the remainder to the caller.
	*/
	struct efi_pool_allocation {
	u64 num_pages;
	char data[] __aligned(ARCH_DMA_MINALIGN);
	};

	/*
	* Sorts the memory list from highest address to lowest address
	*
	* When allocating memory we should always start from the highest
	* address chunk, so sort the memory list such that the first list
	* iterator gets the highest address and goes lower from there.
	*/
	static int efi_mem_cmp(void priv, struct list_head a, struct list_head *b)
	{
	struct efi_mem_list *mema = list_entry(a, struct efi_mem_list, link);
	struct efi_mem_list *memb = list_entry(b, struct efi_mem_list, link);

	if (mema->desc.physical_start == memb->desc.physical_start)
	return 0;
	else if (mema->desc.physical_start < memb->desc.physical_start)
	return 1;
	else
	return -1;
	}

	static void efi_mem_sort(void)
	{
	list_sort(NULL, &efi_mem, efi_mem_cmp);
	}

	/*
	* Unmaps all memory occupied by the carve_desc region from the
	* list entry pointed to by map.
	*
	* Returns EFI_CARVE_NO_OVERLAP if the regions don't overlap.
	* Returns EFI_CARVE_OVERLAPS_NONRAM if the carve and map overlap,
	* and the map contains anything but free ram.
	* (only when overlap_only_ram is true)
	* Returns EFI_CARVE_LOOP_AGAIN if the mapping list should be traversed
	* again, as it has been altered
	* Returns the number of overlapping pages. The pages are removed from
	* the mapping list.
	*
	* In case of EFI_CARVE_OVERLAPS_NONRAM it is the callers responsibility
	* to readd the already carved out pages to the mapping.
	*/
	static int efi_mem_carve_out(struct efi_mem_list *map,
	struct efi_mem_desc *carve_desc,
	bool overlap_only_ram)
	{
	struct efi_mem_list *newmap;
	struct efi_mem_desc *map_desc = &map->desc;
	uint64_t map_start = map_desc->physical_start;
	uint64_t map_end = map_start + (map_desc->num_pages << EFI_PAGE_SHIFT);
	uint64_t carve_start = carve_desc->physical_start;
	uint64_t carve_end = carve_start +
	(carve_desc->num_pages << EFI_PAGE_SHIFT);

	/* check whether we're overlapping */
	if ((carve_end <= map_start) \|\| (carve_start >= map_end))
	return EFI_CARVE_NO_OVERLAP;

	/* We're overlapping with non-RAM, warn the caller if desired */
	if (overlap_only_ram && (map_desc->type != EFI_CONVENTIONAL_MEMORY))
	return EFI_CARVE_OVERLAPS_NONRAM;

	/* Sanitize carve_start and carve_end to lie within our bounds */
	carve_start = max(carve_start, map_start);
	carve_end = min(carve_end, map_end);

	/* Carving at the beginning of our map? Just move it! */
	if (carve_start == map_start) {
	if (map_end == carve_end) {
	/* Full overlap, just remove map */
	list_del(&map->link);
	free(map);
	} else {
	map->desc.physical_start = carve_end;
	map->desc.num_pages = (map_end - carve_end)
	>> EFI_PAGE_SHIFT;
	}

	return (carve_end - carve_start) >> EFI_PAGE_SHIFT;
	}

	/*
	* Overlapping maps, just split the list map at carve_start,
	* it will get moved or removed in the next iteration.
	*
	* [ map_desc \|__carve_start__\| newmap ]
	*/

	/* Create a new map from [ carve_start ... map_end ] */
	newmap = calloc(1, sizeof(*newmap));
	newmap->desc = map->desc;
	newmap->desc.physical_start = carve_start;
	newmap->desc.num_pages = (map_end - carve_start) >> EFI_PAGE_SHIFT;
	/* Insert before current entry (descending address order) */
	list_add_tail(&newmap->link, &map->link);

	/* Shrink the map to [ map_start ... carve_start ] */
	map_desc->num_pages = (carve_start - map_start) >> EFI_PAGE_SHIFT;

	return EFI_CARVE_LOOP_AGAIN;
	}

	uint64_t efi_add_memory_map(uint64_t start, uint64_t pages, int memory_type,
	bool overlap_only_ram)
	{
	struct list_head *lhandle;
	struct efi_mem_list *newlist;
	bool carve_again;
	uint64_t carved_pages = 0;

	debug("%s: 0x%" PRIx64 " 0x%" PRIx64 " %d %s\n", __func__,
	start, pages, memory_type, overlap_only_ram ? "yes" : "no");

	if (!pages)
	return start;

	newlist = calloc(1, sizeof(*newlist));
	newlist->desc.type = memory_type;
	newlist->desc.physical_start = start;
	newlist->desc.virtual_start = start;
	newlist->desc.num_pages = pages;

	switch (memory_type) {
	case EFI_RUNTIME_SERVICES_CODE:
	case EFI_RUNTIME_SERVICES_DATA:
	newlist->desc.attribute = (1 << EFI_MEMORY_WB_SHIFT) \|
	(1ULL << EFI_MEMORY_RUNTIME_SHIFT);
	break;
	case EFI_MMAP_IO:
	newlist->desc.attribute = 1ULL << EFI_MEMORY_RUNTIME_SHIFT;
	break;
	default:
	newlist->desc.attribute = 1 << EFI_MEMORY_WB_SHIFT;
	break;
	}

	/* Add our new map */
	do {
	carve_again = false;
	list_for_each(lhandle, &efi_mem) {
	struct efi_mem_list *lmem;
	int r;

	lmem = list_entry(lhandle, struct efi_mem_list, link);
	r = efi_mem_carve_out(lmem, &newlist->desc,
	overlap_only_ram);
	switch (r) {
	case EFI_CARVE_OVERLAPS_NONRAM:
	/*
	* The user requested to only have RAM overlaps,
	* but we hit a non-RAM region. Error out.
	*/
	return 0;
	case EFI_CARVE_NO_OVERLAP:
	/* Just ignore this list entry */
	break;
	case EFI_CARVE_LOOP_AGAIN:
	/*
	* We split an entry, but need to loop through
	* the list again to actually carve it.
	*/
	carve_again = true;
	break;
	default:
	/* We carved a number of pages */
	carved_pages += r;
	carve_again = true;
	break;
	}

	if (carve_again) {
	/* The list changed, we need to start over */
	break;
	}
	}
	} while (carve_again);

	if (overlap_only_ram && (carved_pages != pages)) {
	/*
	* The payload wanted to have RAM overlaps, but we overlapped
	* with an unallocated region. Error out.
	*/
	return 0;
	}

	/* Add our new map */
	list_add_tail(&newlist->link, &efi_mem);

	/* And make sure memory is listed in descending order */
	efi_mem_sort();

	return start;
	}

	static uint64_t efi_find_free_memory(uint64_t len, uint64_t max_addr)
	{
	struct list_head *lhandle;

	list_for_each(lhandle, &efi_mem) {
	struct efi_mem_list *lmem = list_entry(lhandle,
	struct efi_mem_list, link);
	struct efi_mem_desc *desc = &lmem->desc;
	uint64_t desc_len = desc->num_pages << EFI_PAGE_SHIFT;
	uint64_t desc_end = desc->physical_start + desc_len;
	uint64_t curmax = min(max_addr, desc_end);
	uint64_t ret = curmax - len;

	/* We only take memory from free RAM */
	if (desc->type != EFI_CONVENTIONAL_MEMORY)
	continue;

	/* Out of bounds for max_addr */
	if ((ret + len) > max_addr)
	continue;

	/* Out of bounds for upper map limit */
	if ((ret + len) > desc_end)
	continue;

	/* Out of bounds for lower map limit */
	if (ret < desc->physical_start)
	continue;

	/* Return the highest address in this map within bounds */
	return ret;
	}

	return 0;
	}

	efi_status_t efi_allocate_pages(int type, int memory_type,
	unsigned long pages, uint64_t *memory)
	{
	u64 len = pages << EFI_PAGE_SHIFT;
	efi_status_t r = EFI_SUCCESS;
	uint64_t addr;

	switch (type) {
	case 0:
	/* Any page */
	addr = efi_find_free_memory(len, gd->start_addr_sp);
	if (!addr) {
	r = EFI_NOT_FOUND;
	break;
	}
	break;
	case 1:
	/* Max address */
	addr = efi_find_free_memory(len, *memory);
	if (!addr) {
	r = EFI_NOT_FOUND;
	break;
	}
	break;
	case 2:
	/* Exact address, reserve it. The addr is already in memory. /
	addr = *memory;
	break;
	default:
	/* UEFI doesn't specify other allocation types */
	r = EFI_INVALID_PARAMETER;
	break;
	}

	if (r == EFI_SUCCESS) {
	uint64_t ret;

	/* Reserve that map in our memory maps */
	ret = efi_add_memory_map(addr, pages, memory_type, true);
	if (ret == addr) {
	*memory = addr;
	} else {
	/* Map would overlap, bail out */
	r = EFI_OUT_OF_RESOURCES;
	}
	}

	return r;
	}

	void *efi_alloc(uint64_t len, int memory_type)
	{
	uint64_t ret = 0;
	uint64_t pages = (len + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT;
	efi_status_t r;

	r = efi_allocate_pages(0, memory_type, pages, &ret);
	if (r == EFI_SUCCESS)
	return (void*)(uintptr_t)ret;

	return NULL;
	}

	efi_status_t efi_free_pages(uint64_t memory, unsigned long pages)
	{
	uint64_t r = 0;

	r = efi_add_memory_map(memory, pages, EFI_CONVENTIONAL_MEMORY, false);
	/* Merging of adjacent free regions is missing */

	if (r == memory)
	return EFI_SUCCESS;

	return EFI_NOT_FOUND;
	}

	efi_status_t efi_allocate_pool(int pool_type, unsigned long size,
	void **buffer)
	{
	efi_status_t r;
	efi_physical_addr_t t;
	u64 num_pages = (size + sizeof(struct efi_pool_allocation) +
	EFI_PAGE_MASK) >> EFI_PAGE_SHIFT;

	if (size == 0) {
	*buffer = NULL;
	return EFI_SUCCESS;
	}

	r = efi_allocate_pages(0, pool_type, num_pages, &t);

	if (r == EFI_SUCCESS) {
	struct efi_pool_allocation alloc = (void )(uintptr_t)t;
	alloc->num_pages = num_pages;
	*buffer = alloc->data;
	}

	return r;
	}

	efi_status_t efi_free_pool(void *buffer)
	{
	efi_status_t r;
	struct efi_pool_allocation *alloc;

	if (buffer == NULL)
	return EFI_INVALID_PARAMETER;

	alloc = container_of(buffer, struct efi_pool_allocation, data);
	/* Sanity check, was the supplied address returned by allocate_pool */
	assert(((uintptr_t)alloc & EFI_PAGE_MASK) == 0);

	r = efi_free_pages((uintptr_t)alloc, alloc->num_pages);

	return r;
	}

	efi_status_t efi_get_memory_map(unsigned long *memory_map_size,
	struct efi_mem_desc *memory_map,
	unsigned long *map_key,
	unsigned long *descriptor_size,
	uint32_t *descriptor_version)
	{
	ulong map_size = 0;
	int map_entries = 0;
	struct list_head *lhandle;
	unsigned long provided_map_size = *memory_map_size;

	list_for_each(lhandle, &efi_mem)
	map_entries++;

	map_size = map_entries * sizeof(struct efi_mem_desc);

	*memory_map_size = map_size;

	if (provided_map_size < map_size)
	return EFI_BUFFER_TOO_SMALL;

	if (descriptor_size)
	*descriptor_size = sizeof(struct efi_mem_desc);

	if (descriptor_version)
	*descriptor_version = EFI_MEMORY_DESCRIPTOR_VERSION;

	/* Copy list into array */
	if (memory_map) {
	/* Return the list in ascending order */
	memory_map = &memory_map[map_entries - 1];
	list_for_each(lhandle, &efi_mem) {
	struct efi_mem_list *lmem;

	lmem = list_entry(lhandle, struct efi_mem_list, link);
	*memory_map = lmem->desc;
	memory_map--;
	}
	}

	*map_key = 0;

	return EFI_SUCCESS;
	}

	__weak void efi_add_known_memory(void)
	{
	int i;

	/* Add RAM */
	for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
	u64 ram_start = gd->bd->bi_dram[i].start;
	u64 ram_size = gd->bd->bi_dram[i].size;
	u64 start = (ram_start + EFI_PAGE_MASK) & ~EFI_PAGE_MASK;
	u64 pages = (ram_size + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT;

	efi_add_memory_map(start, pages, EFI_CONVENTIONAL_MEMORY,
	false);
	}
	}

	int efi_memory_init(void)
	{
	unsigned long runtime_start, runtime_end, runtime_pages;
	unsigned long uboot_start, uboot_pages;
	unsigned long uboot_stack_size = 16 * 1024 * 1024;

	efi_add_known_memory();

	/* Add U-Boot */
	uboot_start = (gd->start_addr_sp - uboot_stack_size) & ~EFI_PAGE_MASK;
	uboot_pages = (gd->ram_top - uboot_start) >> EFI_PAGE_SHIFT;
	efi_add_memory_map(uboot_start, uboot_pages, EFI_LOADER_DATA, false);

	/* Add Runtime Services */
	runtime_start = (ulong)&__efi_runtime_start & ~EFI_PAGE_MASK;
	runtime_end = (ulong)&__efi_runtime_stop;
	runtime_end = (runtime_end + EFI_PAGE_MASK) & ~EFI_PAGE_MASK;
	runtime_pages = (runtime_end - runtime_start) >> EFI_PAGE_SHIFT;
	efi_add_memory_map(runtime_start, runtime_pages,
	EFI_RUNTIME_SERVICES_CODE, false);

	#ifdef CONFIG_EFI_LOADER_BOUNCE_BUFFER
	/* Request a 32bit 64MB bounce buffer region */
	uint64_t efi_bounce_buffer_addr = 0xffffffff;

	if (efi_allocate_pages(1, EFI_LOADER_DATA,
	(64 * 1024 * 1024) >> EFI_PAGE_SHIFT,
	&efi_bounce_buffer_addr) != EFI_SUCCESS)
	return -1;

	efi_bounce_buffer = (void*)(uintptr_t)efi_bounce_buffer_addr;
	#endif

	return 0;
	}