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);
130 asmlinkage efi_status_t efi_handle_corrupted_x18(efi_status_t s, const char *f)
132 pr_err_ratelimited(FW_BUG "register x18 corrupted by EFI %s\n", f);