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