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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_X86_PKEYS_H
3#define _ASM_X86_PKEYS_H
4
5/*
6 * If more than 16 keys are ever supported, a thorough audit
7 * will be necessary to ensure that the types that store key
8 * numbers and masks have sufficient capacity.
9 */
10#define arch_max_pkey() (cpu_feature_enabled(X86_FEATURE_OSPKE) ? 16 : 1)
11
12extern int arch_set_user_pkey_access(int pkey, unsigned long init_val);
13
14static inline bool arch_pkeys_enabled(void)
15{
16 return cpu_feature_enabled(X86_FEATURE_OSPKE);
17}
18
19/*
20 * Try to dedicate one of the protection keys to be used as an
21 * execute-only protection key.
22 */
23extern int __execute_only_pkey(struct mm_struct *mm);
24static inline int execute_only_pkey(struct mm_struct *mm)
25{
26 if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
27 return ARCH_DEFAULT_PKEY;
28
29 return __execute_only_pkey(mm);
30}
31
32extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
33 int prot, int pkey);
34static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
35 int prot, int pkey)
36{
37 if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
38 return 0;
39
40 return __arch_override_mprotect_pkey(vma, prot, pkey);
41}
42
43#define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | VM_PKEY_BIT3)
44
45#define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map)
46#define mm_set_pkey_allocated(mm, pkey) do { \
47 mm_pkey_allocation_map(mm) |= (1U << pkey); \
48} while (0)
49#define mm_set_pkey_free(mm, pkey) do { \
50 mm_pkey_allocation_map(mm) &= ~(1U << pkey); \
51} while (0)
52
53static inline
54bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
55{
56 /*
57 * "Allocated" pkeys are those that have been returned
58 * from pkey_alloc() or pkey 0 which is allocated
59 * implicitly when the mm is created.
60 */
61 if (pkey < 0)
62 return false;
63 if (pkey >= arch_max_pkey())
64 return false;
65 /*
66 * The exec-only pkey is set in the allocation map, but
67 * is not available to any of the user interfaces like
68 * mprotect_pkey().
69 */
70 if (pkey == mm->context.execute_only_pkey)
71 return false;
72
73 return mm_pkey_allocation_map(mm) & (1U << pkey);
74}
75
76/*
77 * Returns a positive, 4-bit key on success, or -1 on failure.
78 */
79static inline
80int mm_pkey_alloc(struct mm_struct *mm)
81{
82 /*
83 * Note: this is the one and only place we make sure
84 * that the pkey is valid as far as the hardware is
85 * concerned. The rest of the kernel trusts that
86 * only good, valid pkeys come out of here.
87 */
88 u16 all_pkeys_mask = ((1U << arch_max_pkey()) - 1);
89 int ret;
90
91 /*
92 * Are we out of pkeys? We must handle this specially
93 * because ffz() behavior is undefined if there are no
94 * zeros.
95 */
96 if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
97 return -1;
98
99 ret = ffz(mm_pkey_allocation_map(mm));
100
101 mm_set_pkey_allocated(mm, ret);
102
103 return ret;
104}
105
106static inline
107int mm_pkey_free(struct mm_struct *mm, int pkey)
108{
109 if (!mm_pkey_is_allocated(mm, pkey))
110 return -EINVAL;
111
112 mm_set_pkey_free(mm, pkey);
113
114 return 0;
115}
116
117static inline int vma_pkey(struct vm_area_struct *vma)
118{
119 unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 |
120 VM_PKEY_BIT2 | VM_PKEY_BIT3;
121
122 return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
123}
124
125#endif /*_ASM_X86_PKEYS_H */