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 <asm/efi.h>
21
22 #define EFI_MAX_FAKEMEM CONFIG_EFI_MAX_FAKE_MEM
23
24 static struct efi_mem_range fake_mems[EFI_MAX_FAKEMEM];
25 static int nr_fake_mem;
26
cmp_fake_mem(const void * x1,const void * x2)27 static int __init cmp_fake_mem(const void *x1, const void *x2)
28 {
29 const struct efi_mem_range *m1 = x1;
30 const struct efi_mem_range *m2 = x2;
31
32 if (m1->range.start < m2->range.start)
33 return -1;
34 if (m1->range.start > m2->range.start)
35 return 1;
36 return 0;
37 }
38
efi_fake_memmap(void)39 void __init efi_fake_memmap(void)
40 {
41 int new_nr_map = efi.memmap.nr_map;
42 efi_memory_desc_t *md;
43 phys_addr_t new_memmap_phy;
44 void *new_memmap;
45 int i;
46
47 if (!nr_fake_mem)
48 return;
49
50 /* count up the number of EFI memory descriptor */
51 for (i = 0; i < nr_fake_mem; i++) {
52 for_each_efi_memory_desc(md) {
53 struct range *r = &fake_mems[i].range;
54
55 new_nr_map += efi_memmap_split_count(md, r);
56 }
57 }
58
59 /* allocate memory for new EFI memmap */
60 new_memmap_phy = efi_memmap_alloc(new_nr_map);
61 if (!new_memmap_phy)
62 return;
63
64 /* create new EFI memmap */
65 new_memmap = early_memremap(new_memmap_phy,
66 efi.memmap.desc_size * new_nr_map);
67 if (!new_memmap) {
68 memblock_free(new_memmap_phy, efi.memmap.desc_size * new_nr_map);
69 return;
70 }
71
72 for (i = 0; i < nr_fake_mem; i++)
73 efi_memmap_insert(&efi.memmap, new_memmap, &fake_mems[i]);
74
75 /* swap into new EFI memmap */
76 early_memunmap(new_memmap, efi.memmap.desc_size * new_nr_map);
77
78 efi_memmap_install(new_memmap_phy, new_nr_map);
79
80 /* print new EFI memmap */
81 efi_print_memmap();
82 }
83
setup_fake_mem(char * p)84 static int __init setup_fake_mem(char *p)
85 {
86 u64 start = 0, mem_size = 0, attribute = 0;
87 int i;
88
89 if (!p)
90 return -EINVAL;
91
92 while (*p != '\0') {
93 mem_size = memparse(p, &p);
94 if (*p == '@')
95 start = memparse(p+1, &p);
96 else
97 break;
98
99 if (*p == ':')
100 attribute = simple_strtoull(p+1, &p, 0);
101 else
102 break;
103
104 if (nr_fake_mem >= EFI_MAX_FAKEMEM)
105 break;
106
107 fake_mems[nr_fake_mem].range.start = start;
108 fake_mems[nr_fake_mem].range.end = start + mem_size - 1;
109 fake_mems[nr_fake_mem].attribute = attribute;
110 nr_fake_mem++;
111
112 if (*p == ',')
113 p++;
114 }
115
116 sort(fake_mems, nr_fake_mem, sizeof(struct efi_mem_range),
117 cmp_fake_mem, NULL);
118
119 for (i = 0; i < nr_fake_mem; i++)
120 pr_info("efi_fake_mem: add attr=0x%016llx to [mem 0x%016llx-0x%016llx]",
121 fake_mems[i].attribute, fake_mems[i].range.start,
122 fake_mems[i].range.end);
123
124 return *p == '\0' ? 0 : -EINVAL;
125 }
126
127 early_param("efi_fake_mem", setup_fake_mem);
128
