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Linux kernel mirror (for testing)
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linux
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * fake_mem.c
4 *
5 * Copyright (C) 2015 FUJITSU LIMITED
6 * Author: Taku Izumi <izumi.taku@jp.fujitsu.com>
7 *
8 * This code introduces new boot option named "efi_fake_mem"
9 * By specifying this parameter, you can add arbitrary attribute to
10 * specific memory range by updating original (firmware provided) EFI
11 * memmap.
12 */
13
14#include <linux/kernel.h>
15#include <linux/efi.h>
16#include <linux/init.h>
17#include <linux/memblock.h>
18#include <linux/types.h>
19#include <linux/sort.h>
20#include "fake_mem.h"
21
22struct efi_mem_range efi_fake_mems[EFI_MAX_FAKEMEM];
23int nr_fake_mem;
24
25static int __init cmp_fake_mem(const void *x1, const void *x2)
26{
27 const struct efi_mem_range *m1 = x1;
28 const struct efi_mem_range *m2 = x2;
29
30 if (m1->range.start < m2->range.start)
31 return -1;
32 if (m1->range.start > m2->range.start)
33 return 1;
34 return 0;
35}
36
37void __init efi_fake_memmap(void)
38{
39 int new_nr_map = efi.memmap.nr_map;
40 efi_memory_desc_t *md;
41 phys_addr_t new_memmap_phy;
42 void *new_memmap;
43 int i;
44
45 if (!efi_enabled(EFI_MEMMAP) || !nr_fake_mem)
46 return;
47
48 /* count up the number of EFI memory descriptor */
49 for (i = 0; i < nr_fake_mem; i++) {
50 for_each_efi_memory_desc(md) {
51 struct range *r = &efi_fake_mems[i].range;
52
53 new_nr_map += efi_memmap_split_count(md, r);
54 }
55 }
56
57 /* allocate memory for new EFI memmap */
58 new_memmap_phy = efi_memmap_alloc(new_nr_map);
59 if (!new_memmap_phy)
60 return;
61
62 /* create new EFI memmap */
63 new_memmap = early_memremap(new_memmap_phy,
64 efi.memmap.desc_size * new_nr_map);
65 if (!new_memmap) {
66 memblock_free(new_memmap_phy, efi.memmap.desc_size * new_nr_map);
67 return;
68 }
69
70 for (i = 0; i < nr_fake_mem; i++)
71 efi_memmap_insert(&efi.memmap, new_memmap, &efi_fake_mems[i]);
72
73 /* swap into new EFI memmap */
74 early_memunmap(new_memmap, efi.memmap.desc_size * new_nr_map);
75
76 efi_memmap_install(new_memmap_phy, new_nr_map);
77
78 /* print new EFI memmap */
79 efi_print_memmap();
80}
81
82static int __init setup_fake_mem(char *p)
83{
84 u64 start = 0, mem_size = 0, attribute = 0;
85 int i;
86
87 if (!p)
88 return -EINVAL;
89
90 while (*p != '\0') {
91 mem_size = memparse(p, &p);
92 if (*p == '@')
93 start = memparse(p+1, &p);
94 else
95 break;
96
97 if (*p == ':')
98 attribute = simple_strtoull(p+1, &p, 0);
99 else
100 break;
101
102 if (nr_fake_mem >= EFI_MAX_FAKEMEM)
103 break;
104
105 efi_fake_mems[nr_fake_mem].range.start = start;
106 efi_fake_mems[nr_fake_mem].range.end = start + mem_size - 1;
107 efi_fake_mems[nr_fake_mem].attribute = attribute;
108 nr_fake_mem++;
109
110 if (*p == ',')
111 p++;
112 }
113
114 sort(efi_fake_mems, nr_fake_mem, sizeof(struct efi_mem_range),
115 cmp_fake_mem, NULL);
116
117 for (i = 0; i < nr_fake_mem; i++)
118 pr_info("efi_fake_mem: add attr=0x%016llx to [mem 0x%016llx-0x%016llx]",
119 efi_fake_mems[i].attribute, efi_fake_mems[i].range.start,
120 efi_fake_mems[i].range.end);
121
122 return *p == '\0' ? 0 : -EINVAL;
123}
124
125early_param("efi_fake_mem", setup_fake_mem);