Commit | Line | Data |
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f84d0275 MS |
1 | /* |
2 | * Extensible Firmware Interface | |
3 | * | |
4 | * Based on Extensible Firmware Interface Specification version 2.4 | |
5 | * | |
6 | * Copyright (C) 2013, 2014 Linaro Ltd. | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License version 2 as | |
10 | * published by the Free Software Foundation. | |
11 | * | |
12 | */ | |
13 | ||
14 | #include <linux/efi.h> | |
e5bc22a4 | 15 | #include <linux/init.h> |
f84d0275 | 16 | |
f84d0275 | 17 | #include <asm/efi.h> |
d1ae8c00 | 18 | |
1fd55a9a AB |
19 | /* |
20 | * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be | |
21 | * executable, everything else can be mapped with the XN bits | |
22 | * set. Also take the new (optional) RO/XP bits into account. | |
23 | */ | |
24 | static __init pteval_t create_mapping_protection(efi_memory_desc_t *md) | |
f7d92489 | 25 | { |
1fd55a9a AB |
26 | u64 attr = md->attribute; |
27 | u32 type = md->type; | |
f7d92489 | 28 | |
1fd55a9a AB |
29 | if (type == EFI_MEMORY_MAPPED_IO) |
30 | return PROT_DEVICE_nGnRE; | |
31 | ||
32 | if (WARN_ONCE(!PAGE_ALIGNED(md->phys_addr), | |
33 | "UEFI Runtime regions are not aligned to 64 KB -- buggy firmware?")) | |
34 | /* | |
35 | * If the region is not aligned to the page size of the OS, we | |
36 | * can not use strict permissions, since that would also affect | |
37 | * the mapping attributes of the adjacent regions. | |
38 | */ | |
39 | return pgprot_val(PAGE_KERNEL_EXEC); | |
40 | ||
41 | /* R-- */ | |
42 | if ((attr & (EFI_MEMORY_XP | EFI_MEMORY_RO)) == | |
43 | (EFI_MEMORY_XP | EFI_MEMORY_RO)) | |
44 | return pgprot_val(PAGE_KERNEL_RO); | |
45 | ||
46 | /* R-X */ | |
47 | if (attr & EFI_MEMORY_RO) | |
48 | return pgprot_val(PAGE_KERNEL_ROX); | |
49 | ||
50 | /* RW- */ | |
1e9de1d2 AB |
51 | if (((attr & (EFI_MEMORY_RP | EFI_MEMORY_WP | EFI_MEMORY_XP)) == |
52 | EFI_MEMORY_XP) || | |
53 | type != EFI_RUNTIME_SERVICES_CODE) | |
1fd55a9a AB |
54 | return pgprot_val(PAGE_KERNEL); |
55 | ||
56 | /* RWX */ | |
57 | return pgprot_val(PAGE_KERNEL_EXEC); | |
58 | } | |
59 | ||
57fdb89a AB |
60 | /* we will fill this structure from the stub, so don't put it in .bss */ |
61 | struct screen_info screen_info __section(.data); | |
62 | ||
1fd55a9a AB |
63 | int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md) |
64 | { | |
65 | pteval_t prot_val = create_mapping_protection(md); | |
f14c66ce AB |
66 | bool page_mappings_only = (md->type == EFI_RUNTIME_SERVICES_CODE || |
67 | md->type == EFI_RUNTIME_SERVICES_DATA); | |
f7d92489 | 68 | |
74c102c9 AB |
69 | if (!PAGE_ALIGNED(md->phys_addr) || |
70 | !PAGE_ALIGNED(md->num_pages << EFI_PAGE_SHIFT)) { | |
71 | /* | |
72 | * If the end address of this region is not aligned to page | |
73 | * size, the mapping is rounded up, and may end up sharing a | |
74 | * page frame with the next UEFI memory region. If we create | |
75 | * a block entry now, we may need to split it again when mapping | |
76 | * the next region, and support for that is going to be removed | |
77 | * from the MMU routines. So avoid block mappings altogether in | |
78 | * that case. | |
79 | */ | |
f14c66ce | 80 | page_mappings_only = true; |
74c102c9 AB |
81 | } |
82 | ||
f7d92489 AB |
83 | create_pgd_mapping(mm, md->phys_addr, md->virt_addr, |
84 | md->num_pages << EFI_PAGE_SHIFT, | |
f14c66ce | 85 | __pgprot(prot_val | PTE_NG), page_mappings_only); |
f7d92489 AB |
86 | return 0; |
87 | } | |
88 | ||
bd264d04 AB |
89 | static int __init set_permissions(pte_t *ptep, pgtable_t token, |
90 | unsigned long addr, void *data) | |
91 | { | |
92 | efi_memory_desc_t *md = data; | |
20a004e7 | 93 | pte_t pte = READ_ONCE(*ptep); |
bd264d04 AB |
94 | |
95 | if (md->attribute & EFI_MEMORY_RO) | |
96 | pte = set_pte_bit(pte, __pgprot(PTE_RDONLY)); | |
97 | if (md->attribute & EFI_MEMORY_XP) | |
98 | pte = set_pte_bit(pte, __pgprot(PTE_PXN)); | |
99 | set_pte(ptep, pte); | |
100 | return 0; | |
101 | } | |
102 | ||
103 | int __init efi_set_mapping_permissions(struct mm_struct *mm, | |
104 | efi_memory_desc_t *md) | |
105 | { | |
106 | BUG_ON(md->type != EFI_RUNTIME_SERVICES_CODE && | |
107 | md->type != EFI_RUNTIME_SERVICES_DATA); | |
108 | ||
109 | /* | |
110 | * Calling apply_to_page_range() is only safe on regions that are | |
111 | * guaranteed to be mapped down to pages. Since we are only called | |
112 | * for regions that have been mapped using efi_create_mapping() above | |
113 | * (and this is checked by the generic Memory Attributes table parsing | |
114 | * routines), there is no need to check that again here. | |
115 | */ | |
116 | return apply_to_page_range(mm, md->virt_addr, | |
117 | md->num_pages << EFI_PAGE_SHIFT, | |
118 | set_permissions, md); | |
119 | } | |
120 | ||
60c0d45a AB |
121 | /* |
122 | * UpdateCapsule() depends on the system being shutdown via | |
123 | * ResetSystem(). | |
124 | */ | |
125 | bool efi_poweroff_required(void) | |
126 | { | |
127 | return efi_enabled(EFI_RUNTIME_SERVICES); | |
128 | } |