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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(max_t(u64, md->phys_addr, alloc_min), 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 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 (md->attribute & EFI_MEMORY_HOT_PLUGGABLE)
29 return 0;
30
31 if (efi_soft_reserve_enabled() &&
32 (md->attribute & EFI_MEMORY_SP))
33 return 0;
34
35 region_end = min(md->phys_addr + md->num_pages * EFI_PAGE_SIZE - 1,
36 alloc_max);
37 if (region_end < size)
38 return 0;
39
40 first_slot = round_up(max(md->phys_addr, alloc_min), align);
41 last_slot = round_down(region_end - size + 1, align);
42
43 if (first_slot > last_slot)
44 return 0;
45
46 return ((unsigned long)(last_slot - first_slot) >> align_shift) + 1;
47}
48
49/*
50 * The UEFI memory descriptors have a virtual address field that is only used
51 * when installing the virtual mapping using SetVirtualAddressMap(). Since it
52 * is unused here, we can reuse it to keep track of each descriptor's slot
53 * count.
54 */
55#define MD_NUM_SLOTS(md) ((md)->virt_addr)
56
57efi_status_t efi_random_alloc(unsigned long size,
58 unsigned long align,
59 unsigned long *addr,
60 unsigned long random_seed,
61 int memory_type,
62 unsigned long alloc_min,
63 unsigned long alloc_max)
64{
65 unsigned long total_slots = 0, target_slot;
66 unsigned long total_mirrored_slots = 0;
67 struct efi_boot_memmap *map;
68 efi_status_t status;
69 int map_offset;
70
71 status = efi_get_memory_map(&map, false);
72 if (status != EFI_SUCCESS)
73 return status;
74
75 if (align < EFI_ALLOC_ALIGN)
76 align = EFI_ALLOC_ALIGN;
77
78 size = round_up(size, EFI_ALLOC_ALIGN);
79
80 /* count the suitable slots in each memory map entry */
81 for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) {
82 efi_memory_desc_t *md = (void *)map->map + map_offset;
83 unsigned long slots;
84
85 slots = get_entry_num_slots(md, size, ilog2(align), alloc_min,
86 alloc_max);
87 MD_NUM_SLOTS(md) = slots;
88 total_slots += slots;
89 if (md->attribute & EFI_MEMORY_MORE_RELIABLE)
90 total_mirrored_slots += slots;
91 }
92
93 /* consider only mirrored slots for randomization if any exist */
94 if (total_mirrored_slots > 0)
95 total_slots = total_mirrored_slots;
96
97 /* find a random number between 0 and total_slots */
98 target_slot = (total_slots * (u64)(random_seed & U32_MAX)) >> 32;
99
100 /*
101 * target_slot is now a value in the range [0, total_slots), and so
102 * it corresponds with exactly one of the suitable slots we recorded
103 * when iterating over the memory map the first time around.
104 *
105 * So iterate over the memory map again, subtracting the number of
106 * slots of each entry at each iteration, until we have found the entry
107 * that covers our chosen slot. Use the residual value of target_slot
108 * to calculate the randomly chosen address, and allocate it directly
109 * using EFI_ALLOCATE_ADDRESS.
110 */
111 status = EFI_OUT_OF_RESOURCES;
112 for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) {
113 efi_memory_desc_t *md = (void *)map->map + map_offset;
114 efi_physical_addr_t target;
115 unsigned long pages;
116
117 if (total_mirrored_slots > 0 &&
118 !(md->attribute & EFI_MEMORY_MORE_RELIABLE))
119 continue;
120
121 if (target_slot >= MD_NUM_SLOTS(md)) {
122 target_slot -= MD_NUM_SLOTS(md);
123 continue;
124 }
125
126 target = round_up(max_t(u64, md->phys_addr, alloc_min), align) + target_slot * align;
127 pages = size / EFI_PAGE_SIZE;
128
129 status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
130 memory_type, pages, &target);
131 if (status == EFI_SUCCESS)
132 *addr = target;
133 break;
134 }
135
136 efi_bs_call(free_pool, map);
137
138 return status;
139}