1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *  * Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *  * Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *    the documentation and/or other materials provided with the
13 *    distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include "linker_allocator.h"
30
31#include <stdlib.h>
32#include <sys/cdefs.h>
33#include <unistd.h>
34
35#include <atomic>
36
37#include <async_safe/log.h>
38
39static LinkerMemoryAllocator g_linker_allocator;
40static std::atomic<pid_t> fallback_tid(0);
41
42// Used by libdebuggerd_handler to switch allocators during a crash dump, in
43// case the linker heap is corrupted. Do not use this function.
44extern "C" bool __linker_enable_fallback_allocator() {
45  pid_t expected = 0;
46  return fallback_tid.compare_exchange_strong(expected, gettid());
47}
48
49extern "C" void __linker_disable_fallback_allocator() {
50  pid_t previous = fallback_tid.exchange(0);
51  if (previous == 0) {
52    async_safe_fatal("attempted to disable unused fallback allocator");
53  } else if (previous != gettid()) {
54    async_safe_fatal("attempted to disable fallback allocator in use by another thread (%d)",
55                     previous);
56  }
57}
58
59static LinkerMemoryAllocator& get_fallback_allocator() {
60  static LinkerMemoryAllocator fallback_allocator;
61  return fallback_allocator;
62}
63
64static LinkerMemoryAllocator& get_allocator() {
65  if (__predict_false(fallback_tid) && __predict_false(gettid() == fallback_tid)) {
66    return get_fallback_allocator();
67  }
68  return g_linker_allocator;
69}
70
71void* malloc(size_t byte_count) {
72  return get_allocator().alloc(byte_count);
73}
74
75void* calloc(size_t item_count, size_t item_size) {
76  return get_allocator().alloc(item_count*item_size);
77}
78
79void* realloc(void* p, size_t byte_count) {
80  return get_allocator().realloc(p, byte_count);
81}
82
83void free(void* ptr) {
84  get_allocator().free(ptr);
85}
86
87