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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- */ | |
51 | if (attr & EFI_MEMORY_XP || type != EFI_RUNTIME_SERVICES_CODE) | |
52 | return pgprot_val(PAGE_KERNEL); | |
53 | ||
54 | /* RWX */ | |
55 | return pgprot_val(PAGE_KERNEL_EXEC); | |
56 | } | |
57 | ||
57fdb89a AB |
58 | /* we will fill this structure from the stub, so don't put it in .bss */ |
59 | struct screen_info screen_info __section(.data); | |
60 | ||
1fd55a9a AB |
61 | int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md) |
62 | { | |
63 | pteval_t prot_val = create_mapping_protection(md); | |
f14c66ce AB |
64 | bool page_mappings_only = (md->type == EFI_RUNTIME_SERVICES_CODE || |
65 | md->type == EFI_RUNTIME_SERVICES_DATA); | |
f7d92489 | 66 | |
74c102c9 AB |
67 | if (!PAGE_ALIGNED(md->phys_addr) || |
68 | !PAGE_ALIGNED(md->num_pages << EFI_PAGE_SHIFT)) { | |
69 | /* | |
70 | * If the end address of this region is not aligned to page | |
71 | * size, the mapping is rounded up, and may end up sharing a | |
72 | * page frame with the next UEFI memory region. If we create | |
73 | * a block entry now, we may need to split it again when mapping | |
74 | * the next region, and support for that is going to be removed | |
75 | * from the MMU routines. So avoid block mappings altogether in | |
76 | * that case. | |
77 | */ | |
f14c66ce | 78 | page_mappings_only = true; |
74c102c9 AB |
79 | } |
80 | ||
f7d92489 AB |
81 | create_pgd_mapping(mm, md->phys_addr, md->virt_addr, |
82 | md->num_pages << EFI_PAGE_SHIFT, | |
f14c66ce | 83 | __pgprot(prot_val | PTE_NG), page_mappings_only); |
f7d92489 AB |
84 | return 0; |
85 | } | |
86 | ||
bd264d04 AB |
87 | static int __init set_permissions(pte_t *ptep, pgtable_t token, |
88 | unsigned long addr, void *data) | |
89 | { | |
90 | efi_memory_desc_t *md = data; | |
91 | pte_t pte = *ptep; | |
92 | ||
93 | if (md->attribute & EFI_MEMORY_RO) | |
94 | pte = set_pte_bit(pte, __pgprot(PTE_RDONLY)); | |
95 | if (md->attribute & EFI_MEMORY_XP) | |
96 | pte = set_pte_bit(pte, __pgprot(PTE_PXN)); | |
97 | set_pte(ptep, pte); | |
98 | return 0; | |
99 | } | |
100 | ||
101 | int __init efi_set_mapping_permissions(struct mm_struct *mm, | |
102 | efi_memory_desc_t *md) | |
103 | { | |
104 | BUG_ON(md->type != EFI_RUNTIME_SERVICES_CODE && | |
105 | md->type != EFI_RUNTIME_SERVICES_DATA); | |
106 | ||
107 | /* | |
108 | * Calling apply_to_page_range() is only safe on regions that are | |
109 | * guaranteed to be mapped down to pages. Since we are only called | |
110 | * for regions that have been mapped using efi_create_mapping() above | |
111 | * (and this is checked by the generic Memory Attributes table parsing | |
112 | * routines), there is no need to check that again here. | |
113 | */ | |
114 | return apply_to_page_range(mm, md->virt_addr, | |
115 | md->num_pages << EFI_PAGE_SHIFT, | |
116 | set_permissions, md); | |
117 | } | |
118 | ||
60c0d45a AB |
119 | /* |
120 | * UpdateCapsule() depends on the system being shutdown via | |
121 | * ResetSystem(). | |
122 | */ | |
123 | bool efi_poweroff_required(void) | |
124 | { | |
125 | return efi_enabled(EFI_RUNTIME_SERVICES); | |
126 | } |