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