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
60extern int sysctl_overcommit_memory;
61extern int sysctl_overcommit_ratio;
62extern unsigned long sysctl_overcommit_kbytes;
63extern struct percpu_counter vm_committed_as;
64
65#ifdef CONFIG_SMP
66extern s32 vm_committed_as_batch;
67extern void mm_compute_batch(int overcommit_policy);
68#else
69#define vm_committed_as_batch 0
70static inline void mm_compute_batch(int overcommit_policy)
71{
72}
73#endif
74
75unsigned long vm_memory_committed(void);
76
77static inline void vm_acct_memory(long pages)
78{
79 percpu_counter_add_batch(fbc: &vm_committed_as, amount: pages, batch: vm_committed_as_batch);
80}
81
82static inline void vm_unacct_memory(long pages)
83{
84 vm_acct_memory(pages: -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 */
107static 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 */
120static 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 */
141static inline unsigned long
142calc_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 */
153static inline unsigned long
154calc_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 _calc_vm_trans(flags, MAP_STACK, VM_NOHUGEPAGE) |
160 arch_calc_vm_flag_bits(flags);
161}
162
163unsigned long vm_commit_limit(void);
164
165#ifndef arch_memory_deny_write_exec_supported
166static inline bool arch_memory_deny_write_exec_supported(void)
167{
168 return true;
169}
170#define arch_memory_deny_write_exec_supported arch_memory_deny_write_exec_supported
171#endif
172
173/*
174 * Denies creating a writable executable mapping or gaining executable permissions.
175 *
176 * This denies the following:
177 *
178 * a) mmap(PROT_WRITE | PROT_EXEC)
179 *
180 * b) mmap(PROT_WRITE)
181 * mprotect(PROT_EXEC)
182 *
183 * c) mmap(PROT_WRITE)
184 * mprotect(PROT_READ)
185 * mprotect(PROT_EXEC)
186 *
187 * But allows the following:
188 *
189 * d) mmap(PROT_READ | PROT_EXEC)
190 * mmap(PROT_READ | PROT_EXEC | PROT_BTI)
191 */
192static inline bool map_deny_write_exec(struct vm_area_struct *vma, unsigned long vm_flags)
193{
194 if (!test_bit(MMF_HAS_MDWE, &current->mm->flags))
195 return false;
196
197 if ((vm_flags & VM_EXEC) && (vm_flags & VM_WRITE))
198 return true;
199
200 if (!(vma->vm_flags & VM_EXEC) && (vm_flags & VM_EXEC))
201 return true;
202
203 return false;
204}
205
206#endif /* _LINUX_MMAN_H */
207

source code of linux/include/linux/mman.h