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 struct efi_mem_range efi_fake_mems[EFI_MAX_FAKEMEM];
25 static int __init cmp_fake_mem(const void *x1, const void *x2)
27 const struct efi_mem_range *m1 = x1;
28 const struct efi_mem_range *m2 = x2;
30 if (m1->range.start < m2->range.start)
32 if (m1->range.start > m2->range.start)
37 void __init efi_fake_memmap(void)
39 int new_nr_map = efi.memmap.nr_map;
40 efi_memory_desc_t *md;
41 phys_addr_t new_memmap_phy;
45 if (!efi_enabled(EFI_MEMMAP) || !nr_fake_mem)
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;
53 new_nr_map += efi_memmap_split_count(md, r);
57 /* allocate memory for new EFI memmap */
58 new_memmap_phy = efi_memmap_alloc(new_nr_map);
62 /* create new EFI memmap */
63 new_memmap = early_memremap(new_memmap_phy,
64 efi.memmap.desc_size * new_nr_map);
66 memblock_free(new_memmap_phy, efi.memmap.desc_size * new_nr_map);
70 for (i = 0; i < nr_fake_mem; i++)
71 efi_memmap_insert(&efi.memmap, new_memmap, &efi_fake_mems[i]);
73 /* swap into new EFI memmap */
74 early_memunmap(new_memmap, efi.memmap.desc_size * new_nr_map);
76 efi_memmap_install(new_memmap_phy, new_nr_map);
78 /* print new EFI memmap */
82 static int __init setup_fake_mem(char *p)
84 u64 start = 0, mem_size = 0, attribute = 0;
91 mem_size = memparse(p, &p);
93 start = memparse(p+1, &p);
98 attribute = simple_strtoull(p+1, &p, 0);
102 if (nr_fake_mem >= EFI_MAX_FAKEMEM)
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;
114 sort(efi_fake_mems, nr_fake_mem, sizeof(struct efi_mem_range),
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);
122 return *p == '\0' ? 0 : -EINVAL;
125 early_param("efi_fake_mem", setup_fake_mem);