1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/efi.h>
4#include <asm/efi.h>
5
6#include "efistub.h"
7
8/**
9 * efi_low_alloc_above() - allocate pages at or above given address
10 * @size: size of the memory area to allocate
11 * @align: minimum alignment of the allocated memory area. It should
12 * a power of two.
13 * @addr: on exit the address of the allocated memory
14 * @min: minimum address to used for the memory allocation
15 *
16 * Allocate at the lowest possible address that is not below @min as
17 * EFI_LOADER_DATA. The allocated pages are aligned according to @align but at
18 * least EFI_ALLOC_ALIGN. The first allocated page will not below the address
19 * given by @min.
20 *
21 * Return: status code
22 */
23efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,
24 unsigned long *addr, unsigned long min)
25{
26 struct efi_boot_memmap *map __free(efi_pool) = NULL;
27 efi_status_t status;
28 unsigned long nr_pages;
29 int i;
30
31 status = efi_get_memory_map(map: &map, install_cfg_tbl: false);
32 if (status != EFI_SUCCESS)
33 return status;
34
35 /*
36 * Enforce minimum alignment that EFI or Linux requires when
37 * requesting a specific address. We are doing page-based (or
38 * larger) allocations, and both the address and size must meet
39 * alignment constraints.
40 */
41 if (align < EFI_ALLOC_ALIGN)
42 align = EFI_ALLOC_ALIGN;
43
44 size = round_up(size, EFI_ALLOC_ALIGN);
45 nr_pages = size / EFI_PAGE_SIZE;
46 for (i = 0; i < map->map_size / map->desc_size; i++) {
47 efi_memory_desc_t *desc;
48 unsigned long m = (unsigned long)map->map;
49 u64 start, end;
50
51 desc = efi_memdesc_ptr(m, map->desc_size, i);
52
53 if (desc->type != EFI_CONVENTIONAL_MEMORY)
54 continue;
55
56 if (desc->attribute & EFI_MEMORY_HOT_PLUGGABLE)
57 continue;
58
59 if (efi_soft_reserve_enabled() &&
60 (desc->attribute & EFI_MEMORY_SP))
61 continue;
62
63 if (desc->num_pages < nr_pages)
64 continue;
65
66 start = desc->phys_addr;
67 end = start + desc->num_pages * EFI_PAGE_SIZE;
68
69 if (start < min)
70 start = min;
71
72 start = round_up(start, align);
73 if ((start + size) > end)
74 continue;
75
76 status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
77 EFI_LOADER_DATA, nr_pages, &start);
78 if (status == EFI_SUCCESS) {
79 *addr = start;
80 break;
81 }
82 }
83
84 if (i == map->map_size / map->desc_size)
85 return EFI_NOT_FOUND;
86
87 return EFI_SUCCESS;
88}
89
90/**
91 * efi_relocate_kernel() - copy memory area
92 * @image_addr: pointer to address of memory area to copy
93 * @image_size: size of memory area to copy
94 * @alloc_size: minimum size of memory to allocate, must be greater or
95 * equal to image_size
96 * @preferred_addr: preferred target address
97 * @alignment: minimum alignment of the allocated memory area. It
98 * should be a power of two.
99 * @min_addr: minimum target address
100 *
101 * Copy a memory area to a newly allocated memory area aligned according
102 * to @alignment but at least EFI_ALLOC_ALIGN. If the preferred address
103 * is not available, the allocated address will not be below @min_addr.
104 * On exit, @image_addr is updated to the target copy address that was used.
105 *
106 * This function is used to copy the Linux kernel verbatim. It does not apply
107 * any relocation changes.
108 *
109 * Return: status code
110 */
111efi_status_t efi_relocate_kernel(unsigned long *image_addr,
112 unsigned long image_size,
113 unsigned long alloc_size,
114 unsigned long preferred_addr,
115 unsigned long alignment,
116 unsigned long min_addr)
117{
118 unsigned long cur_image_addr;
119 unsigned long new_addr = 0;
120 efi_status_t status;
121 unsigned long nr_pages;
122 efi_physical_addr_t efi_addr = preferred_addr;
123
124 if (!image_addr || !image_size || !alloc_size)
125 return EFI_INVALID_PARAMETER;
126 if (alloc_size < image_size)
127 return EFI_INVALID_PARAMETER;
128
129 cur_image_addr = *image_addr;
130
131 /*
132 * The EFI firmware loader could have placed the kernel image
133 * anywhere in memory, but the kernel has restrictions on the
134 * max physical address it can run at. Some architectures
135 * also have a preferred address, so first try to relocate
136 * to the preferred address. If that fails, allocate as low
137 * as possible while respecting the required alignment.
138 */
139 nr_pages = round_up(alloc_size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
140 status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
141 EFI_LOADER_DATA, nr_pages, &efi_addr);
142 new_addr = efi_addr;
143 /*
144 * If preferred address allocation failed allocate as low as
145 * possible.
146 */
147 if (status != EFI_SUCCESS) {
148 status = efi_low_alloc_above(size: alloc_size, align: alignment, addr: &new_addr,
149 min: min_addr);
150 }
151 if (status != EFI_SUCCESS) {
152 efi_err("Failed to allocate usable memory for kernel.\n");
153 return status;
154 }
155
156 /*
157 * We know source/dest won't overlap since both memory ranges
158 * have been allocated by UEFI, so we can safely use memcpy.
159 */
160 memcpy(to: (void *)new_addr, from: (void *)cur_image_addr, len: image_size);
161
162 /* Return the new address of the relocated image. */
163 *image_addr = new_addr;
164
165 return status;
166}
167

source code of linux/drivers/firmware/efi/libstub/relocate.c