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
14extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
15		unsigned long init_val);
16
17static 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 */
26extern int __execute_only_pkey(struct mm_struct *mm);
27static 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
35extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
36		int prot, int pkey);
37static 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
46extern 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
59static inline
60bool 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 */
85static inline
86int 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
112static inline
113int 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
123extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
124		unsigned long init_val);
125extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
126		unsigned long init_val);
127extern void copy_init_pkru_to_fpregs(void);
128
129static 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