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
14 extern int num_pkey;
15 extern 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
33 static inline u64 pkey_to_vmflag_bits(u16 pkey)
34 {
35 return (((u64)pkey << VM_PKEY_SHIFT) & ARCH_VM_PKEY_FLAGS);
36 }
37
38 static 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
45 static 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
68 static 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 */
85 static 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
110 static 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 */
127 extern int execute_only_pkey(struct mm_struct *mm);
128 extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
129 int prot, int pkey);
130 static 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
146 extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
147 unsigned long init_val);
148 static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
149 unsigned long init_val)
150 {
151 if (!mmu_has_feature(MMU_FTR_PKEY))
152 return -EINVAL;
153
154 /*
155 * userspace should not change pkey-0 permissions.
156 * pkey-0 is associated with every page in the kernel.
157 * If userspace denies any permission on pkey-0, the
158 * kernel cannot operate.
159 */
160 if (pkey == 0)
161 return init_val ? -EINVAL : 0;
162
163 return __arch_set_user_pkey_access(tsk, pkey, init_val);
164 }
165
166 static inline bool arch_pkeys_enabled(void)
167 {
168 return mmu_has_feature(MMU_FTR_PKEY);
169 }
170
171 extern void pkey_mm_init(struct mm_struct *mm);
172 #endif /*_ASM_POWERPC_KEYS_H */
173
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