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1/* SPDX-License-Identifier: GPL-2.0+ */
2/*
3 * PowerPC Memory Protection Keys management
4 *
5 * Copyright 2017, Ram Pai, IBM Corporation.
6 */
7
8#ifndef _ASM_POWERPC_KEYS_H
9#define _ASM_POWERPC_KEYS_H
10
11#include <linux/jump_label.h>
12#include <asm/firmware.h>
13
14extern int num_pkey;
15extern u32 reserved_allocation_mask; /* bits set for reserved keys */
16
17#define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \
18 VM_PKEY_BIT3 | VM_PKEY_BIT4)
19
20/* Override any generic PKEY permission defines */
21#define PKEY_DISABLE_EXECUTE 0x4
22#define PKEY_ACCESS_MASK (PKEY_DISABLE_ACCESS | \
23 PKEY_DISABLE_WRITE | \
24 PKEY_DISABLE_EXECUTE)
25
26#ifdef CONFIG_PPC_BOOK3S_64
27#include <asm/book3s/64/pkeys.h>
28#else
29#error "Not supported"
30#endif
31
32
33static inline vm_flags_t pkey_to_vmflag_bits(u16 pkey)
34{
35 return (((vm_flags_t)pkey << VM_PKEY_SHIFT) & ARCH_VM_PKEY_FLAGS);
36}
37
38static inline int vma_pkey(struct vm_area_struct *vma)
39{
40 if (!mmu_has_feature(MMU_FTR_PKEY))
41 return 0;
42 return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT;
43}
44
45static inline int arch_max_pkey(void)
46{
47 return num_pkey;
48}
49
50#define pkey_alloc_mask(pkey) (0x1 << pkey)
51
52#define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map)
53
54#define __mm_pkey_allocated(mm, pkey) { \
55 mm_pkey_allocation_map(mm) |= pkey_alloc_mask(pkey); \
56}
57
58#define __mm_pkey_free(mm, pkey) { \
59 mm_pkey_allocation_map(mm) &= ~pkey_alloc_mask(pkey); \
60}
61
62#define __mm_pkey_is_allocated(mm, pkey) \
63 (mm_pkey_allocation_map(mm) & pkey_alloc_mask(pkey))
64
65#define __mm_pkey_is_reserved(pkey) (reserved_allocation_mask & \
66 pkey_alloc_mask(pkey))
67
68static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
69{
70 if (pkey < 0 || pkey >= arch_max_pkey())
71 return false;
72
73 /* Reserved keys are never allocated. */
74 if (__mm_pkey_is_reserved(pkey))
75 return false;
76
77 return __mm_pkey_is_allocated(mm, pkey);
78}
79
80/*
81 * Returns a positive, 5-bit key on success, or -1 on failure.
82 * Relies on the mmap_lock to protect against concurrency in mm_pkey_alloc() and
83 * mm_pkey_free().
84 */
85static inline int mm_pkey_alloc(struct mm_struct *mm)
86{
87 /*
88 * Note: this is the one and only place we make sure that the pkey is
89 * valid as far as the hardware is concerned. The rest of the kernel
90 * trusts that only good, valid pkeys come out of here.
91 */
92 u32 all_pkeys_mask = (u32)(~(0x0));
93 int ret;
94
95 if (!mmu_has_feature(MMU_FTR_PKEY))
96 return -1;
97 /*
98 * Are we out of pkeys? We must handle this specially because ffz()
99 * behavior is undefined if there are no zeros.
100 */
101 if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
102 return -1;
103
104 ret = ffz((u32)mm_pkey_allocation_map(mm));
105 __mm_pkey_allocated(mm, ret);
106
107 return ret;
108}
109
110static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
111{
112 if (!mmu_has_feature(MMU_FTR_PKEY))
113 return -1;
114
115 if (!mm_pkey_is_allocated(mm, pkey))
116 return -EINVAL;
117
118 __mm_pkey_free(mm, pkey);
119
120 return 0;
121}
122
123/*
124 * Try to dedicate one of the protection keys to be used as an
125 * execute-only protection key.
126 */
127extern int execute_only_pkey(struct mm_struct *mm);
128extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
129 int prot, int pkey);
130static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
131 int prot, int pkey)
132{
133 if (!mmu_has_feature(MMU_FTR_PKEY))
134 return 0;
135
136 /*
137 * Is this an mprotect_pkey() call? If so, never override the value that
138 * came from the user.
139 */
140 if (pkey != -1)
141 return pkey;
142
143 return __arch_override_mprotect_pkey(vma, prot, pkey);
144}
145
146extern int __arch_set_user_pkey_access(int pkey, unsigned long init_val);
147static inline int arch_set_user_pkey_access(int pkey, unsigned long init_val)
148{
149 if (!mmu_has_feature(MMU_FTR_PKEY))
150 return -EINVAL;
151
152 /*
153 * userspace should not change pkey-0 permissions.
154 * pkey-0 is associated with every page in the kernel.
155 * If userspace denies any permission on pkey-0, the
156 * kernel cannot operate.
157 */
158 if (pkey == 0)
159 return init_val ? -EINVAL : 0;
160
161 return __arch_set_user_pkey_access(pkey, init_val);
162}
163
164static inline bool arch_pkeys_enabled(void)
165{
166 return mmu_has_feature(MMU_FTR_PKEY);
167}
168
169extern void pkey_mm_init(struct mm_struct *mm);
170#endif /*_ASM_POWERPC_KEYS_H */