1 #ifndef _LINUX_MMAP_LOCK_H
2 #define _LINUX_MMAP_LOCK_H
3 
4 #include <linux/lockdep.h>
5 #include <linux/mm_types.h>
6 #include <linux/mmdebug.h>
7 #include <linux/rwsem.h>
8 #include <linux/tracepoint-defs.h>
9 #include <linux/types.h>
10 
11 #define MMAP_LOCK_INITIALIZER(name) \
12 	.mmap_lock = __RWSEM_INITIALIZER((name).mmap_lock),
13 
14 DECLARE_TRACEPOINT(mmap_lock_start_locking);
15 DECLARE_TRACEPOINT(mmap_lock_acquire_returned);
16 DECLARE_TRACEPOINT(mmap_lock_released);
17 
18 #ifdef CONFIG_TRACING
19 
20 void __mmap_lock_do_trace_start_locking(struct mm_struct *mm, bool write);
21 void __mmap_lock_do_trace_acquire_returned(struct mm_struct *mm, bool write,
22 					   bool success);
23 void __mmap_lock_do_trace_released(struct mm_struct *mm, bool write);
24 
__mmap_lock_trace_start_locking(struct mm_struct * mm,bool write)25 static inline void __mmap_lock_trace_start_locking(struct mm_struct *mm,
26 						   bool write)
27 {
28 	if (tracepoint_enabled(mmap_lock_start_locking))
29 		__mmap_lock_do_trace_start_locking(mm, write);
30 }
31 
__mmap_lock_trace_acquire_returned(struct mm_struct * mm,bool write,bool success)32 static inline void __mmap_lock_trace_acquire_returned(struct mm_struct *mm,
33 						      bool write, bool success)
34 {
35 	if (tracepoint_enabled(mmap_lock_acquire_returned))
36 		__mmap_lock_do_trace_acquire_returned(mm, write, success);
37 }
38 
__mmap_lock_trace_released(struct mm_struct * mm,bool write)39 static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
40 {
41 	if (tracepoint_enabled(mmap_lock_released))
42 		__mmap_lock_do_trace_released(mm, write);
43 }
44 
45 #else /* !CONFIG_TRACING */
46 
__mmap_lock_trace_start_locking(struct mm_struct * mm,bool write)47 static inline void __mmap_lock_trace_start_locking(struct mm_struct *mm,
48 						   bool write)
49 {
50 }
51 
__mmap_lock_trace_acquire_returned(struct mm_struct * mm,bool write,bool success)52 static inline void __mmap_lock_trace_acquire_returned(struct mm_struct *mm,
53 						      bool write, bool success)
54 {
55 }
56 
__mmap_lock_trace_released(struct mm_struct * mm,bool write)57 static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
58 {
59 }
60 
61 #endif /* CONFIG_TRACING */
62 
mmap_assert_locked(const struct mm_struct * mm)63 static inline void mmap_assert_locked(const struct mm_struct *mm)
64 {
65 	rwsem_assert_held(&mm->mmap_lock);
66 }
67 
mmap_assert_write_locked(const struct mm_struct * mm)68 static inline void mmap_assert_write_locked(const struct mm_struct *mm)
69 {
70 	rwsem_assert_held_write(&mm->mmap_lock);
71 }
72 
73 #ifdef CONFIG_PER_VMA_LOCK
74 
mm_lock_seqcount_init(struct mm_struct * mm)75 static inline void mm_lock_seqcount_init(struct mm_struct *mm)
76 {
77 	seqcount_init(&mm->mm_lock_seq);
78 }
79 
mm_lock_seqcount_begin(struct mm_struct * mm)80 static inline void mm_lock_seqcount_begin(struct mm_struct *mm)
81 {
82 	do_raw_write_seqcount_begin(&mm->mm_lock_seq);
83 }
84 
mm_lock_seqcount_end(struct mm_struct * mm)85 static inline void mm_lock_seqcount_end(struct mm_struct *mm)
86 {
87 	ASSERT_EXCLUSIVE_WRITER(mm->mm_lock_seq);
88 	do_raw_write_seqcount_end(&mm->mm_lock_seq);
89 }
90 
mmap_lock_speculate_try_begin(struct mm_struct * mm,unsigned int * seq)91 static inline bool mmap_lock_speculate_try_begin(struct mm_struct *mm, unsigned int *seq)
92 {
93 	/*
94 	 * Since mmap_lock is a sleeping lock, and waiting for it to become
95 	 * unlocked is more or less equivalent with taking it ourselves, don't
96 	 * bother with the speculative path if mmap_lock is already write-locked
97 	 * and take the slow path, which takes the lock.
98 	 */
99 	return raw_seqcount_try_begin(&mm->mm_lock_seq, *seq);
100 }
101 
mmap_lock_speculate_retry(struct mm_struct * mm,unsigned int seq)102 static inline bool mmap_lock_speculate_retry(struct mm_struct *mm, unsigned int seq)
103 {
104 	return read_seqcount_retry(&mm->mm_lock_seq, seq);
105 }
106 
107 #else /* CONFIG_PER_VMA_LOCK */
108 
mm_lock_seqcount_init(struct mm_struct * mm)109 static inline void mm_lock_seqcount_init(struct mm_struct *mm) {}
mm_lock_seqcount_begin(struct mm_struct * mm)110 static inline void mm_lock_seqcount_begin(struct mm_struct *mm) {}
mm_lock_seqcount_end(struct mm_struct * mm)111 static inline void mm_lock_seqcount_end(struct mm_struct *mm) {}
112 
mmap_lock_speculate_try_begin(struct mm_struct * mm,unsigned int * seq)113 static inline bool mmap_lock_speculate_try_begin(struct mm_struct *mm, unsigned int *seq)
114 {
115 	return false;
116 }
117 
mmap_lock_speculate_retry(struct mm_struct * mm,unsigned int seq)118 static inline bool mmap_lock_speculate_retry(struct mm_struct *mm, unsigned int seq)
119 {
120 	return true;
121 }
122 
123 #endif /* CONFIG_PER_VMA_LOCK */
124 
mmap_init_lock(struct mm_struct * mm)125 static inline void mmap_init_lock(struct mm_struct *mm)
126 {
127 	init_rwsem(&mm->mmap_lock);
128 	mm_lock_seqcount_init(mm);
129 }
130 
mmap_write_lock(struct mm_struct * mm)131 static inline void mmap_write_lock(struct mm_struct *mm)
132 {
133 	__mmap_lock_trace_start_locking(mm, true);
134 	down_write(&mm->mmap_lock);
135 	mm_lock_seqcount_begin(mm);
136 	__mmap_lock_trace_acquire_returned(mm, true, true);
137 }
138 
mmap_write_lock_nested(struct mm_struct * mm,int subclass)139 static inline void mmap_write_lock_nested(struct mm_struct *mm, int subclass)
140 {
141 	__mmap_lock_trace_start_locking(mm, true);
142 	down_write_nested(&mm->mmap_lock, subclass);
143 	mm_lock_seqcount_begin(mm);
144 	__mmap_lock_trace_acquire_returned(mm, true, true);
145 }
146 
mmap_write_lock_killable(struct mm_struct * mm)147 static inline int mmap_write_lock_killable(struct mm_struct *mm)
148 {
149 	int ret;
150 
151 	__mmap_lock_trace_start_locking(mm, true);
152 	ret = down_write_killable(&mm->mmap_lock);
153 	if (!ret)
154 		mm_lock_seqcount_begin(mm);
155 	__mmap_lock_trace_acquire_returned(mm, true, ret == 0);
156 	return ret;
157 }
158 
159 /*
160  * Drop all currently-held per-VMA locks.
161  * This is called from the mmap_lock implementation directly before releasing
162  * a write-locked mmap_lock (or downgrading it to read-locked).
163  * This should normally NOT be called manually from other places.
164  * If you want to call this manually anyway, keep in mind that this will release
165  * *all* VMA write locks, including ones from further up the stack.
166  */
vma_end_write_all(struct mm_struct * mm)167 static inline void vma_end_write_all(struct mm_struct *mm)
168 {
169 	mmap_assert_write_locked(mm);
170 	mm_lock_seqcount_end(mm);
171 }
172 
mmap_write_unlock(struct mm_struct * mm)173 static inline void mmap_write_unlock(struct mm_struct *mm)
174 {
175 	__mmap_lock_trace_released(mm, true);
176 	vma_end_write_all(mm);
177 	up_write(&mm->mmap_lock);
178 }
179 
mmap_write_downgrade(struct mm_struct * mm)180 static inline void mmap_write_downgrade(struct mm_struct *mm)
181 {
182 	__mmap_lock_trace_acquire_returned(mm, false, true);
183 	vma_end_write_all(mm);
184 	downgrade_write(&mm->mmap_lock);
185 }
186 
mmap_read_lock(struct mm_struct * mm)187 static inline void mmap_read_lock(struct mm_struct *mm)
188 {
189 	__mmap_lock_trace_start_locking(mm, false);
190 	down_read(&mm->mmap_lock);
191 	__mmap_lock_trace_acquire_returned(mm, false, true);
192 }
193 
mmap_read_lock_killable(struct mm_struct * mm)194 static inline int mmap_read_lock_killable(struct mm_struct *mm)
195 {
196 	int ret;
197 
198 	__mmap_lock_trace_start_locking(mm, false);
199 	ret = down_read_killable(&mm->mmap_lock);
200 	__mmap_lock_trace_acquire_returned(mm, false, ret == 0);
201 	return ret;
202 }
203 
mmap_read_trylock(struct mm_struct * mm)204 static inline bool mmap_read_trylock(struct mm_struct *mm)
205 {
206 	bool ret;
207 
208 	__mmap_lock_trace_start_locking(mm, false);
209 	ret = down_read_trylock(&mm->mmap_lock) != 0;
210 	__mmap_lock_trace_acquire_returned(mm, false, ret);
211 	return ret;
212 }
213 
mmap_read_unlock(struct mm_struct * mm)214 static inline void mmap_read_unlock(struct mm_struct *mm)
215 {
216 	__mmap_lock_trace_released(mm, false);
217 	up_read(&mm->mmap_lock);
218 }
219 
mmap_read_unlock_non_owner(struct mm_struct * mm)220 static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
221 {
222 	__mmap_lock_trace_released(mm, false);
223 	up_read_non_owner(&mm->mmap_lock);
224 }
225 
mmap_lock_is_contended(struct mm_struct * mm)226 static inline int mmap_lock_is_contended(struct mm_struct *mm)
227 {
228 	return rwsem_is_contended(&mm->mmap_lock);
229 }
230 
231 #endif /* _LINUX_MMAP_LOCK_H */
232