1 /* 2 * Copyright (C) 2016 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_gdb_support.h" 30 31 #include <pthread.h> 32 33 #include "private/ScopedPthreadMutexLocker.h" 34 35 // This function is an empty stub where GDB locates a breakpoint to get notified 36 // about linker activity. 37 extern "C" 38 void __attribute__((noinline)) __attribute__((visibility("default"))) rtld_db_dlactivity(); 39 40 r_debug _r_debug = 41 {1, nullptr, reinterpret_cast<uintptr_t>(&rtld_db_dlactivity), r_debug::RT_CONSISTENT, 0}; 42 43 static pthread_mutex_t g__r_debug_mutex = PTHREAD_MUTEX_INITIALIZER; 44 static link_map* r_debug_tail = nullptr; 45 46 void insert_link_map_into_debug_map(link_map* map) { 47 // Stick the new library at the end of the list. 48 // gdb tends to care more about libc than it does 49 // about leaf libraries, and ordering it this way 50 // reduces the back-and-forth over the wire. 51 if (r_debug_tail != nullptr) { 52 r_debug_tail->l_next = map; 53 map->l_prev = r_debug_tail; 54 map->l_next = nullptr; 55 } else { 56 _r_debug.r_map = map; 57 map->l_prev = nullptr; 58 map->l_next = nullptr; 59 } 60 r_debug_tail = map; 61 } 62 63 void remove_link_map_from_debug_map(link_map* map) { 64 if (r_debug_tail == map) { 65 r_debug_tail = map->l_prev; 66 } 67 68 if (map->l_prev) { 69 map->l_prev->l_next = map->l_next; 70 } 71 if (map->l_next) { 72 map->l_next->l_prev = map->l_prev; 73 } 74 } 75 76 void notify_gdb_of_load(link_map* map) { 77 ScopedPthreadMutexLocker locker(&g__r_debug_mutex); 78 79 _r_debug.r_state = r_debug::RT_ADD; 80 rtld_db_dlactivity(); 81 82 insert_link_map_into_debug_map(map); 83 84 _r_debug.r_state = r_debug::RT_CONSISTENT; 85 rtld_db_dlactivity(); 86 } 87 88 void notify_gdb_of_unload(link_map* map) { 89 ScopedPthreadMutexLocker locker(&g__r_debug_mutex); 90 91 _r_debug.r_state = r_debug::RT_DELETE; 92 rtld_db_dlactivity(); 93 94 remove_link_map_from_debug_map(map); 95 96 _r_debug.r_state = r_debug::RT_CONSISTENT; 97 rtld_db_dlactivity(); 98 } 99 100 void notify_gdb_of_libraries() { 101 _r_debug.r_state = r_debug::RT_ADD; 102 rtld_db_dlactivity(); 103 _r_debug.r_state = r_debug::RT_CONSISTENT; 104 rtld_db_dlactivity(); 105 } 106 107