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 /*
38 * You really shouldn't be using read() or write() on /dev/mem. This might go
39 * away in the future.
40 */
valid_phys_addr_range(phys_addr_t addr,size_t size)41 int valid_phys_addr_range(phys_addr_t addr, size_t size)
42 {
43 /*
44 * Check whether addr is covered by a memory region without the
45 * MEMBLOCK_NOMAP attribute, and whether that region covers the
46 * entire range. In theory, this could lead to false negatives
47 * if the range is covered by distinct but adjacent memory regions
48 * that only differ in other attributes. However, few of such
49 * attributes have been defined, and it is debatable whether it
50 * follows that /dev/mem read() calls should be able traverse
51 * such boundaries.
52 */
53 return memblock_is_region_memory(addr, size) &&
54 memblock_is_map_memory(addr);
55 }
56
57 /*
58 * Do not allow /dev/mem mappings beyond the supported physical range.
59 */
valid_mmap_phys_addr_range(unsigned long pfn,size_t size)60 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
61 {
62 return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK);
63 }
64
adjust_protection_map(void)65 static int __init adjust_protection_map(void)
66 {
67 /*
68 * With Enhanced PAN we can honour the execute-only permissions as
69 * there is no PAN override with such mappings.
70 */
71 if (cpus_have_const_cap(ARM64_HAS_EPAN)) {
72 protection_map[VM_EXEC] = PAGE_EXECONLY;
73 protection_map[VM_EXEC | VM_SHARED] = PAGE_EXECONLY;
74 }
75
76 return 0;
77 }
78 arch_initcall(adjust_protection_map);
79
vm_get_page_prot(unsigned long vm_flags)80 pgprot_t vm_get_page_prot(unsigned long vm_flags)
81 {
82 pteval_t prot = pgprot_val(protection_map[vm_flags &
83 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]);
84
85 if (vm_flags & VM_ARM64_BTI)
86 prot |= PTE_GP;
87
88 /*
89 * There are two conditions required for returning a Normal Tagged
90 * memory type: (1) the user requested it via PROT_MTE passed to
91 * mmap() or mprotect() and (2) the corresponding vma supports MTE. We
92 * register (1) as VM_MTE in the vma->vm_flags and (2) as
93 * VM_MTE_ALLOWED. Note that the latter can only be set during the
94 * mmap() call since mprotect() does not accept MAP_* flags.
95 * Checking for VM_MTE only is sufficient since arch_validate_flags()
96 * does not permit (VM_MTE & !VM_MTE_ALLOWED).
97 */
98 if (vm_flags & VM_MTE)
99 prot |= PTE_ATTRINDX(MT_NORMAL_TAGGED);
100
101 return __pgprot(prot);
102 }
103 EXPORT_SYMBOL(vm_get_page_prot);
104