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