1// SPDX-License-Identifier: GPL-2.0
  2
  3#include <linux/efi.h>
  4#include <asm/efi.h>
  5
  6#include "efistub.h"
  7
  8static inline bool mmap_has_headroom(unsigned long buff_size,
  9				     unsigned long map_size,
 10				     unsigned long desc_size)
 11{
 12	unsigned long slack = buff_size - map_size;
 13
 14	return slack / desc_size >= EFI_MMAP_NR_SLACK_SLOTS;
 15}
 16
 17/**
 18 * efi_get_memory_map() - get memory map
 19 * @map:	on return pointer to memory map
 20 *
 21 * Retrieve the UEFI memory map. The allocated memory leaves room for
 22 * up to EFI_MMAP_NR_SLACK_SLOTS additional memory map entries.
 23 *
 24 * Return:	status code
 25 */
 26efi_status_t efi_get_memory_map(struct efi_boot_memmap *map)
 27{
 28	efi_memory_desc_t *m = NULL;
 29	efi_status_t status;
 30	unsigned long key;
 31	u32 desc_version;
 32
 33	*map->desc_size =	sizeof(*m);
 34	*map->map_size =	*map->desc_size * 32;
 35	*map->buff_size =	*map->map_size;
 36again:
 37	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA,
 38			     *map->map_size, (void **)&m);
 39	if (status != EFI_SUCCESS)
 40		goto fail;
 41
 42	*map->desc_size = 0;
 43	key = 0;
 44	status = efi_bs_call(get_memory_map, map->map_size, m,
 45			     &key, map->desc_size, &desc_version);
 46	if (status == EFI_BUFFER_TOO_SMALL ||
 47	    !mmap_has_headroom(*map->buff_size, *map->map_size,
 48			       *map->desc_size)) {
 49		efi_bs_call(free_pool, m);
 50		/*
 51		 * Make sure there is some entries of headroom so that the
 52		 * buffer can be reused for a new map after allocations are
 53		 * no longer permitted.  Its unlikely that the map will grow to
 54		 * exceed this headroom once we are ready to trigger
 55		 * ExitBootServices()
 56		 */
 57		*map->map_size += *map->desc_size * EFI_MMAP_NR_SLACK_SLOTS;
 58		*map->buff_size = *map->map_size;
 59		goto again;
 60	}
 61
 62	if (status == EFI_SUCCESS) {
 63		if (map->key_ptr)
 64			*map->key_ptr = key;
 65		if (map->desc_ver)
 66			*map->desc_ver = desc_version;
 67	} else {
 68		efi_bs_call(free_pool, m);
 69	}
 70
 71fail:
 72	*map->map = m;
 73	return status;
 74}
 75
 76/**
 77 * efi_allocate_pages() - Allocate memory pages
 78 * @size:	minimum number of bytes to allocate
 79 * @addr:	On return the address of the first allocated page. The first
 80 *		allocated page has alignment EFI_ALLOC_ALIGN which is an
 81 *		architecture dependent multiple of the page size.
 82 * @max:	the address that the last allocated memory page shall not
 83 *		exceed
 84 *
 85 * Allocate pages as EFI_LOADER_DATA. The allocated pages are aligned according
 86 * to EFI_ALLOC_ALIGN. The last allocated page will not exceed the address
 87 * given by @max.
 88 *
 89 * Return:	status code
 90 */
 91efi_status_t efi_allocate_pages(unsigned long size, unsigned long *addr,
 92				unsigned long max)
 93{
 94	efi_physical_addr_t alloc_addr;
 95	efi_status_t status;
 96
 97	if (EFI_ALLOC_ALIGN > EFI_PAGE_SIZE)
 98		return efi_allocate_pages_aligned(size, addr, max,
 99						  EFI_ALLOC_ALIGN);
100
101	alloc_addr = ALIGN_DOWN(max + 1, EFI_ALLOC_ALIGN) - 1;
102	status = efi_bs_call(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,
103			     EFI_LOADER_DATA, DIV_ROUND_UP(size, EFI_PAGE_SIZE),
104			     &alloc_addr);
105	if (status != EFI_SUCCESS)
106		return status;
107
108	*addr = alloc_addr;
109	return EFI_SUCCESS;
110}
111
112/**
113 * efi_free() - free memory pages
114 * @size:	size of the memory area to free in bytes
115 * @addr:	start of the memory area to free (must be EFI_PAGE_SIZE
116 *		aligned)
117 *
118 * @size is rounded up to a multiple of EFI_ALLOC_ALIGN which is an
119 * architecture specific multiple of EFI_PAGE_SIZE. So this function should
120 * only be used to return pages allocated with efi_allocate_pages() or
121 * efi_low_alloc_above().
122 */
123void efi_free(unsigned long size, unsigned long addr)
124{
125	unsigned long nr_pages;
126
127	if (!size)
128		return;
129
130	nr_pages = round_up(size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
131	efi_bs_call(free_pages, addr, nr_pages);
132}