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
39 static LinkerMemoryAllocator g_linker_allocator;
40 static 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.
__linker_enable_fallback_allocator()44 extern "C" bool __linker_enable_fallback_allocator() {
45 pid_t expected = 0;
46 return fallback_tid.compare_exchange_strong(expected, gettid());
47 }
48
__linker_disable_fallback_allocator()49 extern "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
get_fallback_allocator()59 static LinkerMemoryAllocator& get_fallback_allocator() {
60 static LinkerMemoryAllocator fallback_allocator;
61 return fallback_allocator;
62 }
63
get_allocator()64 static 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
malloc(size_t byte_count)71 void* malloc(size_t byte_count) {
72 return get_allocator().alloc(byte_count);
73 }
74
calloc(size_t item_count,size_t item_size)75 void* calloc(size_t item_count, size_t item_size) {
76 return get_allocator().alloc(item_count*item_size);
77 }
78
realloc(void * p,size_t byte_count)79 void* realloc(void* p, size_t byte_count) {
80 return get_allocator().realloc(p, byte_count);
81 }
82
free(void * ptr)83 void free(void* ptr) {
84 get_allocator().free(ptr);
85 }
86
87