1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Copyright (C) 2023 Arm Ltd.
4 *
5 * Based on arch/x86/include/asm/pkeys.h
6 */
7
8 #ifndef _ASM_ARM64_PKEYS_H
9 #define _ASM_ARM64_PKEYS_H
10
11 #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2)
12
13 #define arch_max_pkey() 8
14
15 int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
16 unsigned long init_val);
17
18 static inline bool arch_pkeys_enabled(void)
19 {
20 return system_supports_poe();
21 }
22
23 static inline int vma_pkey(struct vm_area_struct *vma)
24 {
25 return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT;
26 }
27
28 static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
29 int prot, int pkey)
30 {
31 if (pkey != -1)
32 return pkey;
33
34 return vma_pkey(vma);
35 }
36
37 static inline int execute_only_pkey(struct mm_struct *mm)
38 {
39 // Execute-only mappings are handled by EPAN/FEAT_PAN3.
40 return -1;
41 }
42
43 #define mm_pkey_allocation_map(mm) (mm)->context.pkey_allocation_map
44 #define mm_set_pkey_allocated(mm, pkey) do { \
45 mm_pkey_allocation_map(mm) |= (1U << pkey); \
46 } while (0)
47 #define mm_set_pkey_free(mm, pkey) do { \
48 mm_pkey_allocation_map(mm) &= ~(1U << pkey); \
49 } while (0)
50
51 static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
52 {
53 /*
54 * "Allocated" pkeys are those that have been returned
55 * from pkey_alloc() or pkey 0 which is allocated
56 * implicitly when the mm is created.
57 */
58 if (pkey < 0 || pkey >= arch_max_pkey())
59 return false;
60
61 return mm_pkey_allocation_map(mm) & (1U << pkey);
62 }
63
64 /*
65 * Returns a positive, 3-bit key on success, or -1 on failure.
66 */
67 static inline int mm_pkey_alloc(struct mm_struct *mm)
68 {
69 /*
70 * Note: this is the one and only place we make sure
71 * that the pkey is valid as far as the hardware is
72 * concerned. The rest of the kernel trusts that
73 * only good, valid pkeys come out of here.
74 */
75 u8 all_pkeys_mask = GENMASK(arch_max_pkey() - 1, 0);
76 int ret;
77
78 if (!arch_pkeys_enabled())
79 return -1;
80
81 /*
82 * Are we out of pkeys? We must handle this specially
83 * because ffz() behavior is undefined if there are no
84 * zeros.
85 */
86 if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
87 return -1;
88
89 ret = ffz(mm_pkey_allocation_map(mm));
90
91 mm_set_pkey_allocated(mm, ret);
92
93 return ret;
94 }
95
96 static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
97 {
98 if (!mm_pkey_is_allocated(mm, pkey))
99 return -EINVAL;
100
101 mm_set_pkey_free(mm, pkey);
102
103 return 0;
104 }
105
106 #endif /* _ASM_ARM64_PKEYS_H */
107
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