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_HUGE_2MB 19 #define MAP_HUGE_2MB 0 20 #endif 21 #ifndef MAP_HUGE_1GB 22 #define MAP_HUGE_1GB 0 23 #endif 24 #ifndef MAP_UNINITIALIZED 25 #define MAP_UNINITIALIZED 0 26 #endif 27 #ifndef MAP_SYNC 28 #define MAP_SYNC 0 29 #endif 30 31 /* 32 * The historical set of flags that all mmap implementations implicitly 33 * support when a ->mmap_validate() op is not provided in file_operations. 34 * 35 * MAP_EXECUTABLE and MAP_DENYWRITE are completely ignored throughout the 36 * kernel. 37 */ 38 #define LEGACY_MAP_MASK (MAP_SHARED \ 39 | MAP_PRIVATE \ 40 | MAP_FIXED \ 41 | MAP_ANONYMOUS \ 42 | MAP_DENYWRITE \ 43 | MAP_EXECUTABLE \ 44 | MAP_UNINITIALIZED \ 45 | MAP_GROWSDOWN \ 46 | MAP_LOCKED \ 47 | MAP_NORESERVE \ 48 | MAP_POPULATE \ 49 | MAP_NONBLOCK \ 50 | MAP_STACK \ 51 | MAP_HUGETLB \ 52 | MAP_32BIT \ 53 | MAP_HUGE_2MB \ 54 | MAP_HUGE_1GB) 55 56 extern int sysctl_overcommit_memory; 57 extern int sysctl_overcommit_ratio; 58 extern unsigned long sysctl_overcommit_kbytes; 59 extern struct percpu_counter vm_committed_as; 60 61 #ifdef CONFIG_SMP 62 extern s32 vm_committed_as_batch; 63 extern void mm_compute_batch(int overcommit_policy); 64 #else 65 #define vm_committed_as_batch 0 66 static inline void mm_compute_batch(int overcommit_policy) 67 { 68 } 69 #endif 70 71 unsigned long vm_memory_committed(void); 72 73 static inline void vm_acct_memory(long pages) 74 { 75 percpu_counter_add_batch(&vm_committed_as, pages, vm_committed_as_batch); 76 } 77 78 static inline void vm_unacct_memory(long pages) 79 { 80 vm_acct_memory(-pages); 81 } 82 83 /* 84 * Allow architectures to handle additional protection and flag bits. The 85 * overriding macros must be defined in the arch-specific asm/mman.h file. 86 */ 87 88 #ifndef arch_calc_vm_prot_bits 89 #define arch_calc_vm_prot_bits(prot, pkey) 0 90 #endif 91 92 #ifndef arch_calc_vm_flag_bits 93 #define arch_calc_vm_flag_bits(flags) 0 94 #endif 95 96 #ifndef arch_validate_prot 97 /* 98 * This is called from mprotect(). PROT_GROWSDOWN and PROT_GROWSUP have 99 * already been masked out. 100 * 101 * Returns true if the prot flags are valid 102 */ 103 static inline bool arch_validate_prot(unsigned long prot, unsigned long addr) 104 { 105 return (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM)) == 0; 106 } 107 #define arch_validate_prot arch_validate_prot 108 #endif 109 110 #ifndef arch_validate_flags 111 /* 112 * This is called from mmap() and mprotect() with the updated vma->vm_flags. 113 * 114 * Returns true if the VM_* flags are valid. 115 */ 116 static inline bool arch_validate_flags(unsigned long flags) 117 { 118 return true; 119 } 120 #define arch_validate_flags arch_validate_flags 121 #endif 122 123 /* 124 * Optimisation macro. It is equivalent to: 125 * (x & bit1) ? bit2 : 0 126 * but this version is faster. 127 * ("bit1" and "bit2" must be single bits) 128 */ 129 #define _calc_vm_trans(x, bit1, bit2) \ 130 ((!(bit1) || !(bit2)) ? 0 : \ 131 ((bit1) <= (bit2) ? ((x) & (bit1)) * ((bit2) / (bit1)) \ 132 : ((x) & (bit1)) / ((bit1) / (bit2)))) 133 134 /* 135 * Combine the mmap "prot" argument into "vm_flags" used internally. 136 */ 137 static inline unsigned long 138 calc_vm_prot_bits(unsigned long prot, unsigned long pkey) 139 { 140 return _calc_vm_trans(prot, PROT_READ, VM_READ ) | 141 _calc_vm_trans(prot, PROT_WRITE, VM_WRITE) | 142 _calc_vm_trans(prot, PROT_EXEC, VM_EXEC) | 143 arch_calc_vm_prot_bits(prot, pkey); 144 } 145 146 /* 147 * Combine the mmap "flags" argument into "vm_flags" used internally. 148 */ 149 static inline unsigned long 150 calc_vm_flag_bits(unsigned long flags) 151 { 152 return _calc_vm_trans(flags, MAP_GROWSDOWN, VM_GROWSDOWN ) | 153 _calc_vm_trans(flags, MAP_LOCKED, VM_LOCKED ) | 154 _calc_vm_trans(flags, MAP_SYNC, VM_SYNC ) | 155 arch_calc_vm_flag_bits(flags); 156 } 157 158 unsigned long vm_commit_limit(void); 159 160 /* 161 * Denies creating a writable executable mapping or gaining executable permissions. 162 * 163 * This denies the following: 164 * 165 * a) mmap(PROT_WRITE | PROT_EXEC) 166 * 167 * b) mmap(PROT_WRITE) 168 * mprotect(PROT_EXEC) 169 * 170 * c) mmap(PROT_WRITE) 171 * mprotect(PROT_READ) 172 * mprotect(PROT_EXEC) 173 * 174 * But allows the following: 175 * 176 * d) mmap(PROT_READ | PROT_EXEC) 177 * mmap(PROT_READ | PROT_EXEC | PROT_BTI) 178 */ 179 static inline bool map_deny_write_exec(struct vm_area_struct *vma, unsigned long vm_flags) 180 { 181 if (!test_bit(MMF_HAS_MDWE, ¤t->mm->flags)) 182 return false; 183 184 if ((vm_flags & VM_EXEC) && (vm_flags & VM_WRITE)) 185 return true; 186 187 if (!(vma->vm_flags & VM_EXEC) && (vm_flags & VM_EXEC)) 188 return true; 189 190 return false; 191 } 192 193 #endif /* _LINUX_MMAN_H */ 194