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
12 extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
13 unsigned long init_val);
14
arch_pkeys_enabled(void)15 static inline bool arch_pkeys_enabled(void)
16 {
17 return cpu_feature_enabled(X86_FEATURE_OSPKE);
18 }
19
20 /*
21 * Try to dedicate one of the protection keys to be used as an
22 * execute-only protection key.
23 */
24 extern int __execute_only_pkey(struct mm_struct *mm);
execute_only_pkey(struct mm_struct * mm)25 static inline int execute_only_pkey(struct mm_struct *mm)
26 {
27 if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
28 return ARCH_DEFAULT_PKEY;
29
30 return __execute_only_pkey(mm);
31 }
32
33 extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
34 int prot, int pkey);
arch_override_mprotect_pkey(struct vm_area_struct * vma,int prot,int pkey)35 static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
36 int prot, int pkey)
37 {
38 if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
39 return 0;
40
41 return __arch_override_mprotect_pkey(vma, prot, pkey);
42 }
43
44 extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
45 unsigned long init_val);
46
47 #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | VM_PKEY_BIT3)
48
49 #define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map)
50 #define mm_set_pkey_allocated(mm, pkey) do { \
51 mm_pkey_allocation_map(mm) |= (1U << pkey); \
52 } while (0)
53 #define mm_set_pkey_free(mm, pkey) do { \
54 mm_pkey_allocation_map(mm) &= ~(1U << pkey); \
55 } while (0)
56
57 static inline
mm_pkey_is_allocated(struct mm_struct * mm,int pkey)58 bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
59 {
60 /*
61 * "Allocated" pkeys are those that have been returned
62 * from pkey_alloc() or pkey 0 which is allocated
63 * implicitly when the mm is created.
64 */
65 if (pkey < 0)
66 return false;
67 if (pkey >= arch_max_pkey())
68 return false;
69 /*
70 * The exec-only pkey is set in the allocation map, but
71 * is not available to any of the user interfaces like
72 * mprotect_pkey().
73 */
74 if (pkey == mm->context.execute_only_pkey)
75 return false;
76
77 return mm_pkey_allocation_map(mm) & (1U << pkey);
78 }
79
80 /*
81 * Returns a positive, 4-bit key on success, or -1 on failure.
82 */
83 static inline
mm_pkey_alloc(struct mm_struct * mm)84 int mm_pkey_alloc(struct mm_struct *mm)
85 {
86 /*
87 * Note: this is the one and only place we make sure
88 * that the pkey is valid as far as the hardware is
89 * concerned. The rest of the kernel trusts that
90 * only good, valid pkeys come out of here.
91 */
92 u16 all_pkeys_mask = ((1U << arch_max_pkey()) - 1);
93 int ret;
94
95 /*
96 * Are we out of pkeys? We must handle this specially
97 * because ffz() behavior is undefined if there are no
98 * zeros.
99 */
100 if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
101 return -1;
102
103 ret = ffz(mm_pkey_allocation_map(mm));
104
105 mm_set_pkey_allocated(mm, ret);
106
107 return ret;
108 }
109
110 static inline
mm_pkey_free(struct mm_struct * mm,int pkey)111 int mm_pkey_free(struct mm_struct *mm, int pkey)
112 {
113 if (!mm_pkey_is_allocated(mm, pkey))
114 return -EINVAL;
115
116 mm_set_pkey_free(mm, pkey);
117
118 return 0;
119 }
120
121 extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
122 unsigned long init_val);
123 extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
124 unsigned long init_val);
125
vma_pkey(struct vm_area_struct * vma)126 static inline int vma_pkey(struct vm_area_struct *vma)
127 {
128 unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 |
129 VM_PKEY_BIT2 | VM_PKEY_BIT3;
130
131 return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
132 }
133
134 #endif /*_ASM_X86_PKEYS_H */
135
