1 /* 2 * Copyright (C) 2012 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 <ctype.h> 30 #include <elf.h> 31 #include <inttypes.h> 32 #include <link.h> 33 #include <stdio.h> 34 #include <string.h> 35 #include <stdlib.h> 36 37 #include <vector> 38 39 #include "MapData.h" 40 41 // Format of /proc/<PID>/maps: 42 // 6f000000-6f01e000 rwxp 00000000 00:0c 16389419 /system/lib/libcomposer.so 43 static MapEntry* parse_line(char* line) { 44 uintptr_t start; 45 uintptr_t end; 46 uintptr_t offset; 47 char permissions[5]; 48 int name_pos; 49 if (sscanf(line, "%" PRIxPTR "-%" PRIxPTR " %4s %" PRIxPTR " %*x:%*x %*d %n", &start, 50 &end, permissions, &offset, &name_pos) < 2) { 51 return nullptr; 52 } 53 54 const char* name = line + name_pos; 55 size_t name_len = strlen(name); 56 if (name_len && name[name_len - 1] == '\n') { 57 name_len -= 1; 58 } 59 60 MapEntry* entry = new MapEntry(start, end, offset, name, name_len); 61 if (permissions[0] != 'r') { 62 // Any unreadable map will just get a zero load base. 63 entry->load_base = 0; 64 entry->load_base_read = true; 65 } 66 return entry; 67 } 68 69 template<typename T> 70 static inline bool get_val(MapEntry* entry, uintptr_t addr, T* store) { 71 if (addr < entry->start || addr + sizeof(T) > entry->end) { 72 return false; 73 } 74 // Make sure the address is aligned properly. 75 if (addr & (sizeof(T)-1)) { 76 return false; 77 } 78 *store = *reinterpret_cast<T*>(addr); 79 return true; 80 } 81 82 static void read_loadbase(MapEntry* entry) { 83 entry->load_base = 0; 84 entry->load_base_read = true; 85 uintptr_t addr = entry->start; 86 ElfW(Ehdr) ehdr; 87 if (!get_val<ElfW(Half)>(entry, addr + offsetof(ElfW(Ehdr), e_phnum), &ehdr.e_phnum)) { 88 return; 89 } 90 if (!get_val<ElfW(Off)>(entry, addr + offsetof(ElfW(Ehdr), e_phoff), &ehdr.e_phoff)) { 91 return; 92 } 93 addr += ehdr.e_phoff; 94 for (size_t i = 0; i < ehdr.e_phnum; i++) { 95 ElfW(Phdr) phdr; 96 if (!get_val<ElfW(Word)>(entry, addr + offsetof(ElfW(Phdr), p_type), &phdr.p_type)) { 97 return; 98 } 99 if (!get_val<ElfW(Off)>(entry, addr + offsetof(ElfW(Phdr), p_offset), &phdr.p_offset)) { 100 return; 101 } 102 if (phdr.p_type == PT_LOAD && phdr.p_offset == entry->offset) { 103 if (!get_val<ElfW(Addr)>(entry, addr + offsetof(ElfW(Phdr), p_vaddr), &phdr.p_vaddr)) { 104 return; 105 } 106 entry->load_base = phdr.p_vaddr; 107 return; 108 } 109 addr += sizeof(phdr); 110 } 111 } 112 113 bool MapData::ReadMaps() { 114 FILE* fp = fopen("/proc/self/maps", "re"); 115 if (fp == nullptr) { 116 return false; 117 } 118 119 std::vector<char> buffer(1024); 120 while (fgets(buffer.data(), buffer.size(), fp) != nullptr) { 121 MapEntry* entry = parse_line(buffer.data()); 122 if (entry == nullptr) { 123 fclose(fp); 124 return false; 125 } 126 127 auto it = entries_.find(entry); 128 if (it == entries_.end()) { 129 entries_.insert(entry); 130 } else { 131 delete entry; 132 } 133 } 134 fclose(fp); 135 return true; 136 } 137 138 MapData::~MapData() { 139 for (auto* entry : entries_) { 140 delete entry; 141 } 142 entries_.clear(); 143 } 144 145 // Find the containing map info for the PC. 146 const MapEntry* MapData::find(uintptr_t pc, uintptr_t* rel_pc) { 147 MapEntry pc_entry(pc); 148 149 std::lock_guard<std::mutex> lock(m_); 150 151 auto it = entries_.find(&pc_entry); 152 if (it == entries_.end()) { 153 ReadMaps(); 154 } 155 it = entries_.find(&pc_entry); 156 if (it == entries_.end()) { 157 return nullptr; 158 } 159 160 MapEntry *entry = *it; 161 if (!entry->load_base_read) { 162 read_loadbase(entry); 163 } 164 if (rel_pc) { 165 *rel_pc = pc - entry->start + entry->load_base; 166 } 167 return entry; 168 } 169
