1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_PKEYS_H
3 #define _ASM_X86_PKEYS_H
4
5 #define ARCH_DEFAULT_PKEY 0
6
7 /*
8 * If more than 16 keys are ever supported, a thorough audit
9 * will be necessary to ensure that the types that store key
10 * numbers and masks have sufficient capacity.
11 */
12 #define arch_max_pkey() (boot_cpu_has(X86_FEATURE_OSPKE) ? 16 : 1)
13
14 extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
15 unsigned long init_val);
16
arch_pkeys_enabled(void)17 static inline bool arch_pkeys_enabled(void)
18 {
19 return boot_cpu_has(X86_FEATURE_OSPKE);
20 }
21
22 /*
23 * Try to dedicate one of the protection keys to be used as an
24 * execute-only protection key.
25 */
26 extern int __execute_only_pkey(struct mm_struct *mm);
execute_only_pkey(struct mm_struct * mm)27 static inline int execute_only_pkey(struct mm_struct *mm)
28 {
29 if (!boot_cpu_has(X86_FEATURE_OSPKE))
30 return ARCH_DEFAULT_PKEY;
31
32 return __execute_only_pkey(mm);
33 }
34
35 extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
36 int prot, int pkey);
arch_override_mprotect_pkey(struct vm_area_struct * vma,int prot,int pkey)37 static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
38 int prot, int pkey)
39 {
40 if (!boot_cpu_has(X86_FEATURE_OSPKE))
41 return 0;
42
43 return __arch_override_mprotect_pkey(vma, prot, pkey);
44 }
45
46 extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
47 unsigned long init_val);
48
49 #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | VM_PKEY_BIT3)
50
51 #define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map)
52 #define mm_set_pkey_allocated(mm, pkey) do { \
53 mm_pkey_allocation_map(mm) |= (1U << pkey); \
54 } while (0)
55 #define mm_set_pkey_free(mm, pkey) do { \
56 mm_pkey_allocation_map(mm) &= ~(1U << pkey); \
57 } while (0)
58
59 static inline
mm_pkey_is_allocated(struct mm_struct * mm,int pkey)60 bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
61 {
62 /*
63 * "Allocated" pkeys are those that have been returned
64 * from pkey_alloc() or pkey 0 which is allocated
65 * implicitly when the mm is created.
66 */
67 if (pkey < 0)
68 return false;
69 if (pkey >= arch_max_pkey())
70 return false;
71 /*
72 * The exec-only pkey is set in the allocation map, but
73 * is not available to any of the user interfaces like
74 * mprotect_pkey().
75 */
76 if (pkey == mm->context.execute_only_pkey)
77 return false;
78
79 return mm_pkey_allocation_map(mm) & (1U << pkey);
80 }
81
82 /*
83 * Returns a positive, 4-bit key on success, or -1 on failure.
84 */
85 static inline
mm_pkey_alloc(struct mm_struct * mm)86 int mm_pkey_alloc(struct mm_struct *mm)
87 {
88 /*
89 * Note: this is the one and only place we make sure
90 * that the pkey is valid as far as the hardware is
91 * concerned. The rest of the kernel trusts that
92 * only good, valid pkeys come out of here.
93 */
94 u16 all_pkeys_mask = ((1U << arch_max_pkey()) - 1);
95 int ret;
96
97 /*
98 * Are we out of pkeys? We must handle this specially
99 * because ffz() behavior is undefined if there are no
100 * zeros.
101 */
102 if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
103 return -1;
104
105 ret = ffz(mm_pkey_allocation_map(mm));
106
107 mm_set_pkey_allocated(mm, ret);
108
109 return ret;
110 }
111
112 static inline
mm_pkey_free(struct mm_struct * mm,int pkey)113 int mm_pkey_free(struct mm_struct *mm, int pkey)
114 {
115 if (!mm_pkey_is_allocated(mm, pkey))
116 return -EINVAL;
117
118 mm_set_pkey_free(mm, pkey);
119
120 return 0;
121 }
122
123 extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
124 unsigned long init_val);
125 extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
126 unsigned long init_val);
127 extern void copy_init_pkru_to_fpregs(void);
128
vma_pkey(struct vm_area_struct * vma)129 static inline int vma_pkey(struct vm_area_struct *vma)
130 {
131 unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 |
132 VM_PKEY_BIT2 | VM_PKEY_BIT3;
133
134 return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
135 }
136
137 #endif /*_ASM_X86_PKEYS_H */
138