1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Based on arch/arm/mm/mmap.c
4 *
5 * Copyright (C) 2012 ARM Ltd.
6 */
7
8 #include <linux/io.h>
9 #include <linux/memblock.h>
10 #include <linux/mm.h>
11 #include <linux/types.h>
12
13 #include <asm/cpufeature.h>
14 #include <asm/page.h>
15
16 static pgprot_t protection_map[16] __ro_after_init = {
17 [VM_NONE] = PAGE_NONE,
18 [VM_READ] = PAGE_READONLY,
19 [VM_WRITE] = PAGE_READONLY,
20 [VM_WRITE | VM_READ] = PAGE_READONLY,
21 /* PAGE_EXECONLY if Enhanced PAN */
22 [VM_EXEC] = PAGE_READONLY_EXEC,
23 [VM_EXEC | VM_READ] = PAGE_READONLY_EXEC,
24 [VM_EXEC | VM_WRITE] = PAGE_READONLY_EXEC,
25 [VM_EXEC | VM_WRITE | VM_READ] = PAGE_READONLY_EXEC,
26 [VM_SHARED] = PAGE_NONE,
27 [VM_SHARED | VM_READ] = PAGE_READONLY,
28 [VM_SHARED | VM_WRITE] = PAGE_SHARED,
29 [VM_SHARED | VM_WRITE | VM_READ] = PAGE_SHARED,
30 /* PAGE_EXECONLY if Enhanced PAN */
31 [VM_SHARED | VM_EXEC] = PAGE_READONLY_EXEC,
32 [VM_SHARED | VM_EXEC | VM_READ] = PAGE_READONLY_EXEC,
33 [VM_SHARED | VM_EXEC | VM_WRITE] = PAGE_SHARED_EXEC,
34 [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = PAGE_SHARED_EXEC
35 };
36
37 static ptdesc_t gcs_page_prot __ro_after_init = _PAGE_GCS_RO;
38
39 /*
40 * You really shouldn't be using read() or write() on /dev/mem. This might go
41 * away in the future.
42 */
valid_phys_addr_range(phys_addr_t addr,size_t size)43 int valid_phys_addr_range(phys_addr_t addr, size_t size)
44 {
45 /*
46 * Check whether addr is covered by a memory region without the
47 * MEMBLOCK_NOMAP attribute, and whether that region covers the
48 * entire range. In theory, this could lead to false negatives
49 * if the range is covered by distinct but adjacent memory regions
50 * that only differ in other attributes. However, few of such
51 * attributes have been defined, and it is debatable whether it
52 * follows that /dev/mem read() calls should be able traverse
53 * such boundaries.
54 */
55 return memblock_is_region_memory(addr, size) &&
56 memblock_is_map_memory(addr);
57 }
58
59 /*
60 * Do not allow /dev/mem mappings beyond the supported physical range.
61 */
valid_mmap_phys_addr_range(unsigned long pfn,size_t size)62 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
63 {
64 return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK);
65 }
66
adjust_protection_map(void)67 static int __init adjust_protection_map(void)
68 {
69 /*
70 * With Enhanced PAN we can honour the execute-only permissions as
71 * there is no PAN override with such mappings.
72 */
73 if (cpus_have_cap(ARM64_HAS_EPAN)) {
74 protection_map[VM_EXEC] = PAGE_EXECONLY;
75 protection_map[VM_EXEC | VM_SHARED] = PAGE_EXECONLY;
76 }
77
78 if (lpa2_is_enabled()) {
79 for (int i = 0; i < ARRAY_SIZE(protection_map); i++)
80 pgprot_val(protection_map[i]) &= ~PTE_SHARED;
81 gcs_page_prot &= ~PTE_SHARED;
82 }
83
84 return 0;
85 }
86 arch_initcall(adjust_protection_map);
87
vm_get_page_prot(vm_flags_t vm_flags)88 pgprot_t vm_get_page_prot(vm_flags_t vm_flags)
89 {
90 ptdesc_t prot;
91
92 /* Short circuit GCS to avoid bloating the table. */
93 if (system_supports_gcs() && (vm_flags & VM_SHADOW_STACK)) {
94 /* Honour mprotect(PROT_NONE) on shadow stack mappings */
95 if (vm_flags & VM_ACCESS_FLAGS)
96 prot = gcs_page_prot;
97 else
98 prot = pgprot_val(protection_map[VM_NONE]);
99 } else {
100 prot = pgprot_val(protection_map[vm_flags &
101 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]);
102 }
103
104 if (vm_flags & VM_ARM64_BTI)
105 prot |= PTE_GP;
106
107 /*
108 * There are two conditions required for returning a Normal Tagged
109 * memory type: (1) the user requested it via PROT_MTE passed to
110 * mmap() or mprotect() and (2) the corresponding vma supports MTE. We
111 * register (1) as VM_MTE in the vma->vm_flags and (2) as
112 * VM_MTE_ALLOWED. Note that the latter can only be set during the
113 * mmap() call since mprotect() does not accept MAP_* flags.
114 * Checking for VM_MTE only is sufficient since arch_validate_flags()
115 * does not permit (VM_MTE & !VM_MTE_ALLOWED).
116 */
117 if (vm_flags & VM_MTE)
118 prot |= PTE_ATTRINDX(MT_NORMAL_TAGGED);
119
120 #ifdef CONFIG_ARCH_HAS_PKEYS
121 if (system_supports_poe()) {
122 if (vm_flags & VM_PKEY_BIT0)
123 prot |= PTE_PO_IDX_0;
124 if (vm_flags & VM_PKEY_BIT1)
125 prot |= PTE_PO_IDX_1;
126 if (vm_flags & VM_PKEY_BIT2)
127 prot |= PTE_PO_IDX_2;
128 }
129 #endif
130
131 return __pgprot(prot);
132 }
133 EXPORT_SYMBOL(vm_get_page_prot);
134