1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2015 Linaro Ltd <ard.biesheuvel@linaro.org>
4 */
5
6 #include <linux/efi.h>
7 #include <asm/efi.h>
8 #include <asm/mach/map.h>
9 #include <asm/mmu_context.h>
10
11 static int __init set_permissions(pte_t *ptep, unsigned long addr, void *data)
12 {
13 efi_memory_desc_t *md = data;
14 pte_t pte = *ptep;
15
16 if (md->attribute & EFI_MEMORY_RO)
17 pte = set_pte_bit(pte, __pgprot(L_PTE_RDONLY));
18 if (md->attribute & EFI_MEMORY_XP)
19 pte = set_pte_bit(pte, __pgprot(L_PTE_XN));
20 set_pte_ext(ptep, pte, PTE_EXT_NG);
21 return 0;
22 }
23
24 int __init efi_set_mapping_permissions(struct mm_struct *mm,
25 efi_memory_desc_t *md)
26 {
27 unsigned long base, size;
28
29 base = md->virt_addr;
30 size = md->num_pages << EFI_PAGE_SHIFT;
31
32 /*
33 * We can only use apply_to_page_range() if we can guarantee that the
34 * entire region was mapped using pages. This should be the case if the
35 * region does not cover any naturally aligned SECTION_SIZE sized
36 * blocks.
37 */
38 if (round_down(base + size, SECTION_SIZE) <
39 round_up(base, SECTION_SIZE) + SECTION_SIZE)
40 return apply_to_page_range(mm, base, size, set_permissions, md);
41
42 return 0;
43 }
44
45 int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
46 {
47 struct map_desc desc = {
48 .virtual = md->virt_addr,
49 .pfn = __phys_to_pfn(md->phys_addr),
50 .length = md->num_pages * EFI_PAGE_SIZE,
51 };
52
53 /*
54 * Order is important here: memory regions may have all of the
55 * bits below set (and usually do), so we check them in order of
56 * preference.
57 */
58 if (md->attribute & EFI_MEMORY_WB)
59 desc.type = MT_MEMORY_RWX;
60 else if (md->attribute & EFI_MEMORY_WT)
61 desc.type = MT_MEMORY_RWX_NONCACHED;
62 else if (md->attribute & EFI_MEMORY_WC)
63 desc.type = MT_DEVICE_WC;
64 else
65 desc.type = MT_DEVICE;
66
67 create_mapping_late(mm, &desc, true);
68
69 /*
70 * If stricter permissions were specified, apply them now.
71 */
72 if (md->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))
73 return efi_set_mapping_permissions(mm, md);
74 return 0;
75 }
76
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