1 // SPDX-License-Identifier: GPL-2.0
5 * Copyright (C) 2015 FUJITSU LIMITED
6 * Author: Taku Izumi <izumi.taku@jp.fujitsu.com>
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
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>
22 #define EFI_MAX_FAKEMEM CONFIG_EFI_MAX_FAKE_MEM
24 static struct efi_mem_range fake_mems[EFI_MAX_FAKEMEM];
25 static int nr_fake_mem;
27 static int __init cmp_fake_mem(const void *x1, const void *x2)
29 const struct efi_mem_range *m1 = x1;
30 const struct efi_mem_range *m2 = x2;
32 if (m1->range.start < m2->range.start)
34 if (m1->range.start > m2->range.start)
39 void __init efi_fake_memmap(void)
41 int new_nr_map = efi.memmap.nr_map;
42 efi_memory_desc_t *md;
43 phys_addr_t new_memmap_phy;
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;
55 new_nr_map += efi_memmap_split_count(md, r);
59 /* allocate memory for new EFI memmap */
60 new_memmap_phy = efi_memmap_alloc(new_nr_map);
64 /* create new EFI memmap */
65 new_memmap = early_memremap(new_memmap_phy,
66 efi.memmap.desc_size * new_nr_map);
68 memblock_free(new_memmap_phy, efi.memmap.desc_size * new_nr_map);
72 for (i = 0; i < nr_fake_mem; i++)
73 efi_memmap_insert(&efi.memmap, new_memmap, &fake_mems[i]);
75 /* swap into new EFI memmap */
76 early_memunmap(new_memmap, efi.memmap.desc_size * new_nr_map);
78 efi_memmap_install(new_memmap_phy, new_nr_map);
80 /* print new EFI memmap */
84 static int __init setup_fake_mem(char *p)
86 u64 start = 0, mem_size = 0, attribute = 0;
93 mem_size = memparse(p, &p);
95 start = memparse(p+1, &p);
100 attribute = simple_strtoull(p+1, &p, 0);
104 if (nr_fake_mem >= EFI_MAX_FAKEMEM)
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;
116 sort(fake_mems, nr_fake_mem, sizeof(struct efi_mem_range),
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);
124 return *p == '\0' ? 0 : -EINVAL;
127 early_param("efi_fake_mem", setup_fake_mem);