1 /* 2 * Copyright (C) 2016 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 #include "linker_gdb_support.h" 18 19 #include <pthread.h> 20 21 #include "private/ScopedPthreadMutexLocker.h" 22 23 // This function is an empty stub where GDB locates a breakpoint to get notified 24 // about linker activity. 25 extern "C" 26 void __attribute__((noinline)) __attribute__((visibility("default"))) rtld_db_dlactivity(); 27 28 r_debug _r_debug = 29 {1, nullptr, reinterpret_cast<uintptr_t>(&rtld_db_dlactivity), r_debug::RT_CONSISTENT, 0}; 30 31 static pthread_mutex_t g__r_debug_mutex = PTHREAD_MUTEX_INITIALIZER; 32 static link_map* r_debug_tail = nullptr; 33 34 void insert_link_map_into_debug_map(link_map* map) { 35 // Stick the new library at the end of the list. 36 // gdb tends to care more about libc than it does 37 // about leaf libraries, and ordering it this way 38 // reduces the back-and-forth over the wire. 39 if (r_debug_tail != nullptr) { 40 r_debug_tail->l_next = map; 41 map->l_prev = r_debug_tail; 42 map->l_next = nullptr; 43 } else { 44 _r_debug.r_map = map; 45 map->l_prev = nullptr; 46 map->l_next = nullptr; 47 } 48 r_debug_tail = map; 49 } 50 51 void remove_link_map_from_debug_map(link_map* map) { 52 if (r_debug_tail == map) { 53 r_debug_tail = map->l_prev; 54 } 55 56 if (map->l_prev) { 57 map->l_prev->l_next = map->l_next; 58 } 59 if (map->l_next) { 60 map->l_next->l_prev = map->l_prev; 61 } 62 } 63 64 void notify_gdb_of_load(link_map* map) { 65 ScopedPthreadMutexLocker locker(&g__r_debug_mutex); 66 67 _r_debug.r_state = r_debug::RT_ADD; 68 rtld_db_dlactivity(); 69 70 insert_link_map_into_debug_map(map); 71 72 _r_debug.r_state = r_debug::RT_CONSISTENT; 73 rtld_db_dlactivity(); 74 } 75 76 void notify_gdb_of_unload(link_map* map) { 77 ScopedPthreadMutexLocker locker(&g__r_debug_mutex); 78 79 _r_debug.r_state = r_debug::RT_DELETE; 80 rtld_db_dlactivity(); 81 82 remove_link_map_from_debug_map(map); 83 84 _r_debug.r_state = r_debug::RT_CONSISTENT; 85 rtld_db_dlactivity(); 86 } 87 88 void notify_gdb_of_libraries() { 89 _r_debug.r_state = r_debug::RT_ADD; 90 rtld_db_dlactivity(); 91 _r_debug.r_state = r_debug::RT_CONSISTENT; 92 rtld_db_dlactivity(); 93 } 94 95
