1 /*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 /*
17 * Simple linear memory allocator.
18 */
19 #ifndef _DALVIK_LINEARALLOC
20 #define _DALVIK_LINEARALLOC
21
22 /*
23 * If this is set, we create additional data structures and make many
24 * additional mprotect() calls.
25 * (this breaks the debugger because the debugBreakpointCount cannot be updated)
26 */
27 #define ENFORCE_READ_ONLY false
28
29 /*
30 * Linear allocation state. We could tuck this into the start of the
31 * allocated region, but that would prevent us from sharing the rest of
32 * that first page.
33 */
34 typedef struct LinearAllocHdr {
35 int curOffset; /* offset where next data goes */
36 pthread_mutex_t lock; /* controls updates to this struct */
37
38 char* mapAddr; /* start of mmap()ed region */
39 int mapLength; /* length of region */
40 int firstOffset; /* for chasing through */
41
42 short* writeRefCount; /* for ENFORCE_READ_ONLY */
43 } LinearAllocHdr;
44
45
46 /*
47 * Create a new alloc region.
48 */
49 LinearAllocHdr* dvmLinearAllocCreate(Object* classLoader);
50
51 /*
52 * Destroy a region.
53 */
54 void dvmLinearAllocDestroy(Object* classLoader);
55
56 /*
57 * Allocate a chunk of memory. The memory will be zeroed out.
58 *
59 * For ENFORCE_READ_ONLY, call dvmLinearReadOnly on the result.
60 */
61 void* dvmLinearAlloc(Object* classLoader, size_t size);
62
63 /*
64 * Reallocate a chunk. The original storage is not released, but may be
65 * erased to aid debugging.
66 *
67 * For ENFORCE_READ_ONLY, call dvmLinearReadOnly on the result. Also, the
68 * caller should probably mark the "mem" argument read-only before calling.
69 */
70 void* dvmLinearRealloc(Object* classLoader, void* mem, size_t newSize);
71
72 /* don't call these directly */
73 void dvmLinearSetReadOnly(Object* classLoader, void* mem);
74 void dvmLinearSetReadWrite(Object* classLoader, void* mem);
75
76 /*
77 * Mark a chunk of memory from Alloc or Realloc as read-only. This must
78 * be done after all changes to the block of memory have been made. This
79 * actually operates on a page granularity.
80 */
dvmLinearReadOnly(Object * classLoader,void * mem)81 INLINE void dvmLinearReadOnly(Object* classLoader, void* mem)
82 {
83 if (ENFORCE_READ_ONLY && mem != NULL)
84 dvmLinearSetReadOnly(classLoader, mem);
85 }
86
87 /*
88 * Make a chunk of memory writable again.
89 */
dvmLinearReadWrite(Object * classLoader,void * mem)90 INLINE void dvmLinearReadWrite(Object* classLoader, void* mem)
91 {
92 if (ENFORCE_READ_ONLY && mem != NULL)
93 dvmLinearSetReadWrite(classLoader, mem);
94 }
95
96 /*
97 * Free a chunk. Does not increase available storage, but the freed area
98 * may be erased to aid debugging.
99 */
100 void dvmLinearFree(Object* classLoader, void* mem);
101
102 /*
103 * Helper function; allocates new storage and copies "str" into it.
104 *
105 * For ENFORCE_READ_ONLY, do *not* call dvmLinearReadOnly on the result.
106 * This is done automatically.
107 */
108 char* dvmLinearStrdup(Object* classLoader, const char* str);
109
110 /*
111 * Dump the contents of a linear alloc area.
112 */
113 void dvmLinearAllocDump(Object* classLoader);
114
115 #endif /*_DALVIK_LINEARALLOC*/
116