2 * Extensible Firmware Interface
4 * Based on Extensible Firmware Interface Specification version 2.4
6 * Copyright (C) 2013, 2014 Linaro Ltd.
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.
14 #include <linux/efi.h>
15 #include <linux/init.h>
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.
24 static __init pteval_t
create_mapping_protection(efi_memory_desc_t
*md
)
26 u64 attr
= md
->attribute
;
29 if (type
== EFI_MEMORY_MAPPED_IO
)
30 return PROT_DEVICE_nGnRE
;
32 if (WARN_ONCE(!PAGE_ALIGNED(md
->phys_addr
),
33 "UEFI Runtime regions are not aligned to 64 KB -- buggy firmware?"))
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.
39 return pgprot_val(PAGE_KERNEL_EXEC
);
42 if ((attr
& (EFI_MEMORY_XP
| EFI_MEMORY_RO
)) ==
43 (EFI_MEMORY_XP
| EFI_MEMORY_RO
))
44 return pgprot_val(PAGE_KERNEL_RO
);
47 if (attr
& EFI_MEMORY_RO
)
48 return pgprot_val(PAGE_KERNEL_ROX
);
51 if (((attr
& (EFI_MEMORY_RP
| EFI_MEMORY_WP
| EFI_MEMORY_XP
)) ==
53 type
!= EFI_RUNTIME_SERVICES_CODE
)
54 return pgprot_val(PAGE_KERNEL
);
57 return pgprot_val(PAGE_KERNEL_EXEC
);
60 /* we will fill this structure from the stub, so don't put it in .bss */
61 struct screen_info screen_info
__section(.data
);
63 int __init
efi_create_mapping(struct mm_struct
*mm
, efi_memory_desc_t
*md
)
65 pteval_t prot_val
= create_mapping_protection(md
);
66 bool page_mappings_only
= (md
->type
== EFI_RUNTIME_SERVICES_CODE
||
67 md
->type
== EFI_RUNTIME_SERVICES_DATA
);
69 if (!PAGE_ALIGNED(md
->phys_addr
) ||
70 !PAGE_ALIGNED(md
->num_pages
<< EFI_PAGE_SHIFT
)) {
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
80 page_mappings_only
= true;
83 create_pgd_mapping(mm
, md
->phys_addr
, md
->virt_addr
,
84 md
->num_pages
<< EFI_PAGE_SHIFT
,
85 __pgprot(prot_val
| PTE_NG
), page_mappings_only
);
89 static int __init
set_permissions(pte_t
*ptep
, pgtable_t token
,
90 unsigned long addr
, void *data
)
92 efi_memory_desc_t
*md
= data
;
93 pte_t pte
= READ_ONCE(*ptep
);
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
));
103 int __init
efi_set_mapping_permissions(struct mm_struct
*mm
,
104 efi_memory_desc_t
*md
)
106 BUG_ON(md
->type
!= EFI_RUNTIME_SERVICES_CODE
&&
107 md
->type
!= EFI_RUNTIME_SERVICES_DATA
);
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.
116 return apply_to_page_range(mm
, md
->virt_addr
,
117 md
->num_pages
<< EFI_PAGE_SHIFT
,
118 set_permissions
, md
);
122 * UpdateCapsule() depends on the system being shutdown via
125 bool efi_poweroff_required(void)
127 return efi_enabled(EFI_RUNTIME_SERVICES
);