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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2016 Linaro Ltd; <ard.biesheuvel@linaro.org>
4 */
5
6#include <linux/efi.h>
7#include <linux/log2.h>
8#include <asm/efi.h>
9
10#include "efistub.h"
11
12/*
13 * Return the number of slots covered by this entry, i.e., the number of
14 * addresses it covers that are suitably aligned and supply enough room
15 * for the allocation.
16 */
17static unsigned long get_entry_num_slots(efi_memory_desc_t *md,
18 unsigned long size,
19 unsigned long align_shift,
20 u64 alloc_min, u64 alloc_max)
21{
22 unsigned long align = 1UL << align_shift;
23 u64 first_slot, last_slot, region_end;
24
25 if (md->type != EFI_CONVENTIONAL_MEMORY)
26 return 0;
27
28 if (efi_soft_reserve_enabled() &&
29 (md->attribute & EFI_MEMORY_SP))
30 return 0;
31
32 region_end = min(md->phys_addr + md->num_pages * EFI_PAGE_SIZE - 1,
33 alloc_max);
34 if (region_end < size)
35 return 0;
36
37 first_slot = round_up(max(md->phys_addr, alloc_min), align);
38 last_slot = round_down(region_end - size + 1, align);
39
40 if (first_slot > last_slot)
41 return 0;
42
43 return ((unsigned long)(last_slot - first_slot) >> align_shift) + 1;
44}
45
46/*
47 * The UEFI memory descriptors have a virtual address field that is only used
48 * when installing the virtual mapping using SetVirtualAddressMap(). Since it
49 * is unused here, we can reuse it to keep track of each descriptor's slot
50 * count.
51 */
52#define MD_NUM_SLOTS(md) ((md)->virt_addr)
53
54efi_status_t efi_random_alloc(unsigned long size,
55 unsigned long align,
56 unsigned long *addr,
57 unsigned long random_seed,
58 int memory_type,
59 unsigned long alloc_min,
60 unsigned long alloc_max)
61{
62 unsigned long total_slots = 0, target_slot;
63 unsigned long total_mirrored_slots = 0;
64 struct efi_boot_memmap *map;
65 efi_status_t status;
66 int map_offset;
67
68 status = efi_get_memory_map(&map, false);
69 if (status != EFI_SUCCESS)
70 return status;
71
72 if (align < EFI_ALLOC_ALIGN)
73 align = EFI_ALLOC_ALIGN;
74
75 size = round_up(size, EFI_ALLOC_ALIGN);
76
77 /* count the suitable slots in each memory map entry */
78 for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) {
79 efi_memory_desc_t *md = (void *)map->map + map_offset;
80 unsigned long slots;
81
82 slots = get_entry_num_slots(md, size, ilog2(align), alloc_min,
83 alloc_max);
84 MD_NUM_SLOTS(md) = slots;
85 total_slots += slots;
86 if (md->attribute & EFI_MEMORY_MORE_RELIABLE)
87 total_mirrored_slots += slots;
88 }
89
90 /* consider only mirrored slots for randomization if any exist */
91 if (total_mirrored_slots > 0)
92 total_slots = total_mirrored_slots;
93
94 /* find a random number between 0 and total_slots */
95 target_slot = (total_slots * (u64)(random_seed & U32_MAX)) >> 32;
96
97 /*
98 * target_slot is now a value in the range [0, total_slots), and so
99 * it corresponds with exactly one of the suitable slots we recorded
100 * when iterating over the memory map the first time around.
101 *
102 * So iterate over the memory map again, subtracting the number of
103 * slots of each entry at each iteration, until we have found the entry
104 * that covers our chosen slot. Use the residual value of target_slot
105 * to calculate the randomly chosen address, and allocate it directly
106 * using EFI_ALLOCATE_ADDRESS.
107 */
108 status = EFI_OUT_OF_RESOURCES;
109 for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) {
110 efi_memory_desc_t *md = (void *)map->map + map_offset;
111 efi_physical_addr_t target;
112 unsigned long pages;
113
114 if (total_mirrored_slots > 0 &&
115 !(md->attribute & EFI_MEMORY_MORE_RELIABLE))
116 continue;
117
118 if (target_slot >= MD_NUM_SLOTS(md)) {
119 target_slot -= MD_NUM_SLOTS(md);
120 continue;
121 }
122
123 target = round_up(md->phys_addr, align) + target_slot * align;
124 pages = size / EFI_PAGE_SIZE;
125
126 status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
127 memory_type, pages, &target);
128 if (status == EFI_SUCCESS)
129 *addr = target;
130 break;
131 }
132
133 efi_bs_call(free_pool, map);
134
135 return status;
136}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2016 Linaro Ltd; <ard.biesheuvel@linaro.org>
4 */
5
6#include <linux/efi.h>
7#include <linux/log2.h>
8#include <asm/efi.h>
9
10#include "efistub.h"
11
12/*
13 * Return the number of slots covered by this entry, i.e., the number of
14 * addresses it covers that are suitably aligned and supply enough room
15 * for the allocation.
16 */
17static unsigned long get_entry_num_slots(efi_memory_desc_t *md,
18 unsigned long size,
19 unsigned long align_shift)
20{
21 unsigned long align = 1UL << align_shift;
22 u64 first_slot, last_slot, region_end;
23
24 if (md->type != EFI_CONVENTIONAL_MEMORY)
25 return 0;
26
27 if (efi_soft_reserve_enabled() &&
28 (md->attribute & EFI_MEMORY_SP))
29 return 0;
30
31 region_end = min(md->phys_addr + md->num_pages * EFI_PAGE_SIZE - 1,
32 (u64)EFI_ALLOC_LIMIT);
33 if (region_end < size)
34 return 0;
35
36 first_slot = round_up(md->phys_addr, align);
37 last_slot = round_down(region_end - size + 1, align);
38
39 if (first_slot > last_slot)
40 return 0;
41
42 return ((unsigned long)(last_slot - first_slot) >> align_shift) + 1;
43}
44
45/*
46 * The UEFI memory descriptors have a virtual address field that is only used
47 * when installing the virtual mapping using SetVirtualAddressMap(). Since it
48 * is unused here, we can reuse it to keep track of each descriptor's slot
49 * count.
50 */
51#define MD_NUM_SLOTS(md) ((md)->virt_addr)
52
53efi_status_t efi_random_alloc(unsigned long size,
54 unsigned long align,
55 unsigned long *addr,
56 unsigned long random_seed,
57 int memory_type)
58{
59 unsigned long total_slots = 0, target_slot;
60 unsigned long total_mirrored_slots = 0;
61 struct efi_boot_memmap *map;
62 efi_status_t status;
63 int map_offset;
64
65 status = efi_get_memory_map(&map, false);
66 if (status != EFI_SUCCESS)
67 return status;
68
69 if (align < EFI_ALLOC_ALIGN)
70 align = EFI_ALLOC_ALIGN;
71
72 size = round_up(size, EFI_ALLOC_ALIGN);
73
74 /* count the suitable slots in each memory map entry */
75 for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) {
76 efi_memory_desc_t *md = (void *)map->map + map_offset;
77 unsigned long slots;
78
79 slots = get_entry_num_slots(md, size, ilog2(align));
80 MD_NUM_SLOTS(md) = slots;
81 total_slots += slots;
82 if (md->attribute & EFI_MEMORY_MORE_RELIABLE)
83 total_mirrored_slots += slots;
84 }
85
86 /* consider only mirrored slots for randomization if any exist */
87 if (total_mirrored_slots > 0)
88 total_slots = total_mirrored_slots;
89
90 /* find a random number between 0 and total_slots */
91 target_slot = (total_slots * (u64)(random_seed & U32_MAX)) >> 32;
92
93 /*
94 * target_slot is now a value in the range [0, total_slots), and so
95 * it corresponds with exactly one of the suitable slots we recorded
96 * when iterating over the memory map the first time around.
97 *
98 * So iterate over the memory map again, subtracting the number of
99 * slots of each entry at each iteration, until we have found the entry
100 * that covers our chosen slot. Use the residual value of target_slot
101 * to calculate the randomly chosen address, and allocate it directly
102 * using EFI_ALLOCATE_ADDRESS.
103 */
104 for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) {
105 efi_memory_desc_t *md = (void *)map->map + map_offset;
106 efi_physical_addr_t target;
107 unsigned long pages;
108
109 if (total_mirrored_slots > 0 &&
110 !(md->attribute & EFI_MEMORY_MORE_RELIABLE))
111 continue;
112
113 if (target_slot >= MD_NUM_SLOTS(md)) {
114 target_slot -= MD_NUM_SLOTS(md);
115 continue;
116 }
117
118 target = round_up(md->phys_addr, align) + target_slot * align;
119 pages = size / EFI_PAGE_SIZE;
120
121 status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
122 memory_type, pages, &target);
123 if (status == EFI_SUCCESS)
124 *addr = target;
125 break;
126 }
127
128 efi_bs_call(free_pool, map);
129
130 return status;
131}