1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_MMAN_H
3 #define _LINUX_MMAN_H
4
5 #include <linux/mm.h>
6 #include <linux/percpu_counter.h>
7
8 #include <linux/atomic.h>
9 #include <uapi/linux/mman.h>
10
11 /*
12 * Arrange for legacy / undefined architecture specific flags to be
13 * ignored by mmap handling code.
14 */
15 #ifndef MAP_32BIT
16 #define MAP_32BIT 0
17 #endif
18 #ifndef MAP_ABOVE4G
19 #define MAP_ABOVE4G 0
20 #endif
21 #ifndef MAP_HUGE_2MB
22 #define MAP_HUGE_2MB 0
23 #endif
24 #ifndef MAP_HUGE_1GB
25 #define MAP_HUGE_1GB 0
26 #endif
27 #ifndef MAP_UNINITIALIZED
28 #define MAP_UNINITIALIZED 0
29 #endif
30 #ifndef MAP_SYNC
31 #define MAP_SYNC 0
32 #endif
33
34 /*
35 * The historical set of flags that all mmap implementations implicitly
36 * support when a ->mmap_validate() op is not provided in file_operations.
37 *
38 * MAP_EXECUTABLE and MAP_DENYWRITE are completely ignored throughout the
39 * kernel.
40 */
41 #define LEGACY_MAP_MASK (MAP_SHARED \
42 | MAP_PRIVATE \
43 | MAP_FIXED \
44 | MAP_ANONYMOUS \
45 | MAP_DENYWRITE \
46 | MAP_EXECUTABLE \
47 | MAP_UNINITIALIZED \
48 | MAP_GROWSDOWN \
49 | MAP_LOCKED \
50 | MAP_NORESERVE \
51 | MAP_POPULATE \
52 | MAP_NONBLOCK \
53 | MAP_STACK \
54 | MAP_HUGETLB \
55 | MAP_32BIT \
56 | MAP_ABOVE4G \
57 | MAP_HUGE_2MB \
58 | MAP_HUGE_1GB)
59
60 extern int sysctl_overcommit_memory;
61 extern int sysctl_overcommit_ratio;
62 extern unsigned long sysctl_overcommit_kbytes;
63 extern struct percpu_counter vm_committed_as;
64
65 #ifdef CONFIG_SMP
66 extern s32 vm_committed_as_batch;
67 extern void mm_compute_batch(int overcommit_policy);
68 #else
69 #define vm_committed_as_batch 0
mm_compute_batch(int overcommit_policy)70 static inline void mm_compute_batch(int overcommit_policy)
71 {
72 }
73 #endif
74
75 unsigned long vm_memory_committed(void);
76
vm_acct_memory(long pages)77 static inline void vm_acct_memory(long pages)
78 {
79 percpu_counter_add_batch(&vm_committed_as, pages, vm_committed_as_batch);
80 }
81
vm_unacct_memory(long pages)82 static inline void vm_unacct_memory(long pages)
83 {
84 vm_acct_memory(-pages);
85 }
86
87 /*
88 * Allow architectures to handle additional protection and flag bits. The
89 * overriding macros must be defined in the arch-specific asm/mman.h file.
90 */
91
92 #ifndef arch_calc_vm_prot_bits
93 #define arch_calc_vm_prot_bits(prot, pkey) 0
94 #endif
95
96 #ifndef arch_calc_vm_flag_bits
97 #define arch_calc_vm_flag_bits(flags) 0
98 #endif
99
100 #ifndef arch_validate_prot
101 /*
102 * This is called from mprotect(). PROT_GROWSDOWN and PROT_GROWSUP have
103 * already been masked out.
104 *
105 * Returns true if the prot flags are valid
106 */
arch_validate_prot(unsigned long prot,unsigned long addr)107 static inline bool arch_validate_prot(unsigned long prot, unsigned long addr)
108 {
109 return (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM)) == 0;
110 }
111 #define arch_validate_prot arch_validate_prot
112 #endif
113
114 #ifndef arch_validate_flags
115 /*
116 * This is called from mmap() and mprotect() with the updated vma->vm_flags.
117 *
118 * Returns true if the VM_* flags are valid.
119 */
arch_validate_flags(unsigned long flags)120 static inline bool arch_validate_flags(unsigned long flags)
121 {
122 return true;
123 }
124 #define arch_validate_flags arch_validate_flags
125 #endif
126
127 /*
128 * Optimisation macro. It is equivalent to:
129 * (x & bit1) ? bit2 : 0
130 * but this version is faster.
131 * ("bit1" and "bit2" must be single bits)
132 */
133 #define _calc_vm_trans(x, bit1, bit2) \
134 ((!(bit1) || !(bit2)) ? 0 : \
135 ((bit1) <= (bit2) ? ((x) & (bit1)) * ((bit2) / (bit1)) \
136 : ((x) & (bit1)) / ((bit1) / (bit2))))
137
138 /*
139 * Combine the mmap "prot" argument into "vm_flags" used internally.
140 */
141 static inline unsigned long
calc_vm_prot_bits(unsigned long prot,unsigned long pkey)142 calc_vm_prot_bits(unsigned long prot, unsigned long pkey)
143 {
144 return _calc_vm_trans(prot, PROT_READ, VM_READ ) |
145 _calc_vm_trans(prot, PROT_WRITE, VM_WRITE) |
146 _calc_vm_trans(prot, PROT_EXEC, VM_EXEC) |
147 arch_calc_vm_prot_bits(prot, pkey);
148 }
149
150 /*
151 * Combine the mmap "flags" argument into "vm_flags" used internally.
152 */
153 static inline unsigned long
calc_vm_flag_bits(unsigned long flags)154 calc_vm_flag_bits(unsigned long flags)
155 {
156 return _calc_vm_trans(flags, MAP_GROWSDOWN, VM_GROWSDOWN ) |
157 _calc_vm_trans(flags, MAP_LOCKED, VM_LOCKED ) |
158 _calc_vm_trans(flags, MAP_SYNC, VM_SYNC ) |
159 arch_calc_vm_flag_bits(flags);
160 }
161
162 unsigned long vm_commit_limit(void);
163
164 #ifndef arch_memory_deny_write_exec_supported
arch_memory_deny_write_exec_supported(void)165 static inline bool arch_memory_deny_write_exec_supported(void)
166 {
167 return true;
168 }
169 #define arch_memory_deny_write_exec_supported arch_memory_deny_write_exec_supported
170 #endif
171
172 /*
173 * Denies creating a writable executable mapping or gaining executable permissions.
174 *
175 * This denies the following:
176 *
177 * a) mmap(PROT_WRITE | PROT_EXEC)
178 *
179 * b) mmap(PROT_WRITE)
180 * mprotect(PROT_EXEC)
181 *
182 * c) mmap(PROT_WRITE)
183 * mprotect(PROT_READ)
184 * mprotect(PROT_EXEC)
185 *
186 * But allows the following:
187 *
188 * d) mmap(PROT_READ | PROT_EXEC)
189 * mmap(PROT_READ | PROT_EXEC | PROT_BTI)
190 */
map_deny_write_exec(struct vm_area_struct * vma,unsigned long vm_flags)191 static inline bool map_deny_write_exec(struct vm_area_struct *vma, unsigned long vm_flags)
192 {
193 if (!test_bit(MMF_HAS_MDWE, ¤t->mm->flags))
194 return false;
195
196 if ((vm_flags & VM_EXEC) && (vm_flags & VM_WRITE))
197 return true;
198
199 if (!(vma->vm_flags & VM_EXEC) && (vm_flags & VM_EXEC))
200 return true;
201
202 return false;
203 }
204
205 #endif /* _LINUX_MMAN_H */
206