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 struct efi_memory_map_data data = { 0 };
40 int new_nr_map = efi.memmap.nr_map;
41 efi_memory_desc_t *md;
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 if (efi_memmap_alloc(new_nr_map, &data) != 0)
61 /* create new EFI memmap */
62 new_memmap = early_memremap(data.phys_map, data.size);
64 memblock_free(data.phys_map, data.size);
68 for (i = 0; i < nr_fake_mem; i++)
69 efi_memmap_insert(&efi.memmap, new_memmap, &efi_fake_mems[i]);
71 /* swap into new EFI memmap */
72 early_memunmap(new_memmap, data.size);
74 efi_memmap_install(&data);
76 /* print new EFI memmap */
80 static int __init setup_fake_mem(char *p)
82 u64 start = 0, mem_size = 0, attribute = 0;
89 mem_size = memparse(p, &p);
91 start = memparse(p+1, &p);
96 attribute = simple_strtoull(p+1, &p, 0);
100 if (nr_fake_mem >= EFI_MAX_FAKEMEM)
103 efi_fake_mems[nr_fake_mem].range.start = start;
104 efi_fake_mems[nr_fake_mem].range.end = start + mem_size - 1;
105 efi_fake_mems[nr_fake_mem].attribute = attribute;
112 sort(efi_fake_mems, nr_fake_mem, sizeof(struct efi_mem_range),
115 for (i = 0; i < nr_fake_mem; i++)
116 pr_info("efi_fake_mem: add attr=0x%016llx to [mem 0x%016llx-0x%016llx]",
117 efi_fake_mems[i].attribute, efi_fake_mems[i].range.start,
118 efi_fake_mems[i].range.end);
120 return *p == '\0' ? 0 : -EINVAL;
123 early_param("efi_fake_mem", setup_fake_mem);