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 */ 26 #define ENFORCE_READ_ONLY false 27 28 /* 29 * Linear allocation state. We could tuck this into the start of the 30 * allocated region, but that would prevent us from sharing the rest of 31 * that first page. 32 */ 33 typedef struct LinearAllocHdr { 34 int curOffset; /* offset where next data goes */ 35 pthread_mutex_t lock; /* controls updates to this struct */ 36 37 char* mapAddr; /* start of mmap()ed region */ 38 int mapLength; /* length of region */ 39 int firstOffset; /* for chasing through */ 40 41 short* writeRefCount; /* for ENFORCE_READ_ONLY */ 42 } LinearAllocHdr; 43 44 45 /* 46 * Create a new alloc region. 47 */ 48 LinearAllocHdr* dvmLinearAllocCreate(Object* classLoader); 49 50 /* 51 * Destroy a region. 52 */ 53 void dvmLinearAllocDestroy(Object* classLoader); 54 55 /* 56 * Allocate a chunk of memory. The memory will be zeroed out. 57 * 58 * For ENFORCE_READ_ONLY, call dvmLinearReadOnly on the result. 59 */ 60 void* dvmLinearAlloc(Object* classLoader, size_t size); 61 62 /* 63 * Reallocate a chunk. The original storage is not released, but may be 64 * erased to aid debugging. 65 * 66 * For ENFORCE_READ_ONLY, call dvmLinearReadOnly on the result. Also, the 67 * caller should probably mark the "mem" argument read-only before calling. 68 */ 69 void* dvmLinearRealloc(Object* classLoader, void* mem, size_t newSize); 70 71 /* don't call these directly */ 72 void dvmLinearSetReadOnly(Object* classLoader, void* mem); 73 void dvmLinearSetReadWrite(Object* classLoader, void* mem); 74 75 /* 76 * Mark a chunk of memory from Alloc or Realloc as read-only. This must 77 * be done after all changes to the block of memory have been made. This 78 * actually operates on a page granularity. 79 */ 80 INLINE void dvmLinearReadOnly(Object* classLoader, void* mem) 81 { 82 if (ENFORCE_READ_ONLY && mem != NULL) 83 dvmLinearSetReadOnly(classLoader, mem); 84 } 85 86 /* 87 * Make a chunk of memory writable again. 88 */ 89 INLINE void dvmLinearReadWrite(Object* classLoader, void* mem) 90 { 91 if (ENFORCE_READ_ONLY && mem != NULL) 92 dvmLinearSetReadWrite(classLoader, mem); 93 } 94 95 /* 96 * Free a chunk. Does not increase available storage, but the freed area 97 * may be erased to aid debugging. 98 */ 99 void dvmLinearFree(Object* classLoader, void* mem); 100 101 /* 102 * Helper function; allocates new storage and copies "str" into it. 103 * 104 * For ENFORCE_READ_ONLY, do *not* call dvmLinearReadOnly on the result. 105 * This is done automatically. 106 */ 107 char* dvmLinearStrdup(Object* classLoader, const char* str); 108 109 /* 110 * Dump the contents of a linear alloc area. 111 */ 112 void dvmLinearAllocDump(Object* classLoader); 113 114 /* 115 * Determine if [start, start+length) is contained in the in-use area of 116 * a single LinearAlloc. The full set of linear allocators is scanned. 117 */ 118 bool dvmLinearAllocContains(const void* start, size_t length); 119 120 #endif /*_DALVIK_LINEARALLOC*/ 121
