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  */
23 static efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,
24 					unsigned long *addr, unsigned long min)
25 {
26 	unsigned long map_size, desc_size, buff_size;
27 	efi_memory_desc_t *map;
28 	efi_status_t status;
29 	unsigned long nr_pages;
30 	int i;
31 	struct efi_boot_memmap boot_map;
32 
33 	boot_map.map		= &map;
34 	boot_map.map_size	= &map_size;
35 	boot_map.desc_size	= &desc_size;
36 	boot_map.desc_ver	= NULL;
37 	boot_map.key_ptr	= NULL;
38 	boot_map.buff_size	= &buff_size;
39 
40 	status = efi_get_memory_map(&boot_map);
41 	if (status != EFI_SUCCESS)
42 		goto fail;
43 
44 	/*
45 	 * Enforce minimum alignment that EFI or Linux requires when
46 	 * requesting a specific address.  We are doing page-based (or
47 	 * larger) allocations, and both the address and size must meet
48 	 * alignment constraints.
49 	 */
50 	if (align < EFI_ALLOC_ALIGN)
51 		align = EFI_ALLOC_ALIGN;
52 
53 	size = round_up(size, EFI_ALLOC_ALIGN);
54 	nr_pages = size / EFI_PAGE_SIZE;
55 	for (i = 0; i < map_size / desc_size; i++) {
56 		efi_memory_desc_t *desc;
57 		unsigned long m = (unsigned long)map;
58 		u64 start, end;
59 
60 		desc = efi_early_memdesc_ptr(m, desc_size, i);
61 
62 		if (desc->type != EFI_CONVENTIONAL_MEMORY)
63 			continue;
64 
65 		if (efi_soft_reserve_enabled() &&
66 		    (desc->attribute & EFI_MEMORY_SP))
67 			continue;
68 
69 		if (desc->num_pages < nr_pages)
70 			continue;
71 
72 		start = desc->phys_addr;
73 		end = start + desc->num_pages * EFI_PAGE_SIZE;
74 
75 		if (start < min)
76 			start = min;
77 
78 		start = round_up(start, align);
79 		if ((start + size) > end)
80 			continue;
81 
82 		status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
83 				     EFI_LOADER_DATA, nr_pages, &start);
84 		if (status == EFI_SUCCESS) {
85 			*addr = start;
86 			break;
87 		}
88 	}
89 
90 	if (i == map_size / desc_size)
91 		status = EFI_NOT_FOUND;
92 
93 	efi_bs_call(free_pool, map);
94 fail:
95 	return status;
96 }
97 
98 /**
99  * efi_relocate_kernel() - copy memory area
100  * @image_addr:		pointer to address of memory area to copy
101  * @image_size:		size of memory area to copy
102  * @alloc_size:		minimum size of memory to allocate, must be greater or
103  *			equal to image_size
104  * @preferred_addr:	preferred target address
105  * @alignment:		minimum alignment of the allocated memory area. It
106  *			should be a power of two.
107  * @min_addr:		minimum target address
108  *
109  * Copy a memory area to a newly allocated memory area aligned according
110  * to @alignment but at least EFI_ALLOC_ALIGN. If the preferred address
111  * is not available, the allocated address will not be below @min_addr.
112  * On exit, @image_addr is updated to the target copy address that was used.
113  *
114  * This function is used to copy the Linux kernel verbatim. It does not apply
115  * any relocation changes.
116  *
117  * Return:		status code
118  */
119 efi_status_t efi_relocate_kernel(unsigned long *image_addr,
120 				 unsigned long image_size,
121 				 unsigned long alloc_size,
122 				 unsigned long preferred_addr,
123 				 unsigned long alignment,
124 				 unsigned long min_addr)
125 {
126 	unsigned long cur_image_addr;
127 	unsigned long new_addr = 0;
128 	efi_status_t status;
129 	unsigned long nr_pages;
130 	efi_physical_addr_t efi_addr = preferred_addr;
131 
132 	if (!image_addr || !image_size || !alloc_size)
133 		return EFI_INVALID_PARAMETER;
134 	if (alloc_size < image_size)
135 		return EFI_INVALID_PARAMETER;
136 
137 	cur_image_addr = *image_addr;
138 
139 	/*
140 	 * The EFI firmware loader could have placed the kernel image
141 	 * anywhere in memory, but the kernel has restrictions on the
142 	 * max physical address it can run at.  Some architectures
143 	 * also have a preferred address, so first try to relocate
144 	 * to the preferred address.  If that fails, allocate as low
145 	 * as possible while respecting the required alignment.
146 	 */
147 	nr_pages = round_up(alloc_size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
148 	status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
149 			     EFI_LOADER_DATA, nr_pages, &efi_addr);
150 	new_addr = efi_addr;
151 	/*
152 	 * If preferred address allocation failed allocate as low as
153 	 * possible.
154 	 */
155 	if (status != EFI_SUCCESS) {
156 		status = efi_low_alloc_above(alloc_size, alignment, &new_addr,
157 					     min_addr);
158 	}
159 	if (status != EFI_SUCCESS) {
160 		efi_err("Failed to allocate usable memory for kernel.\n");
161 		return status;
162 	}
163 
164 	/*
165 	 * We know source/dest won't overlap since both memory ranges
166 	 * have been allocated by UEFI, so we can safely use memcpy.
167 	 */
168 	memcpy((void *)new_addr, (void *)cur_image_addr, image_size);
169 
170 	/* Return the new address of the relocated image. */
171 	*image_addr = new_addr;
172 
173 	return status;
174 }
175