mem_map.cc revision fd7e7f1253927c8d7f17e7cbc259daaf51868bd3
1/* 2 * Copyright (C) 2008 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 "mem_map.h" 18 19#include <corkscrew/map_info.h> 20 21#include "base/stringprintf.h" 22#include "ScopedFd.h" 23#include "utils.h" 24 25#define USE_ASHMEM 1 26 27#ifdef USE_ASHMEM 28#include <cutils/ashmem.h> 29#endif 30 31namespace art { 32 33#if !defined(NDEBUG) 34 35static std::ostream& operator<<(std::ostream& os, map_info_t* rhs) { 36 for (map_info_t* m = rhs; m != NULL; m = m->next) { 37 os << StringPrintf("0x%08x-0x%08x %c%c %s\n", 38 static_cast<uint32_t>(m->start), 39 static_cast<uint32_t>(m->end), 40 m->is_readable ? 'r' : '-', m->is_executable ? 'x' : '-', m->name); 41 } 42 return os; 43} 44 45static void CheckMapRequest(byte* addr, size_t byte_count) { 46 if (addr == NULL) { 47 return; 48 } 49 50 uint32_t base = reinterpret_cast<size_t>(addr); 51 uint32_t limit = base + byte_count; 52 53 map_info_t* map_info_list = load_map_info_list(getpid()); 54 for (map_info_t* m = map_info_list; m != NULL; m = m->next) { 55 CHECK(!(base >= m->start && base < m->end) // start of new within old 56 && !(limit > m->start && limit < m->end) // end of new within old 57 && !(base <= m->start && limit > m->end)) // start/end of new includes all of old 58 << StringPrintf("Requested region 0x%08x-0x%08x overlaps with existing map 0x%08x-0x%08x (%s)\n", 59 base, limit, 60 static_cast<uint32_t>(m->start), static_cast<uint32_t>(m->end), m->name) 61 << map_info_list; 62 } 63 free_map_info_list(map_info_list); 64} 65 66#else 67static void CheckMapRequest(byte*, size_t) { } 68#endif 69 70MemMap* MemMap::MapAnonymous(const char* name, byte* addr, size_t byte_count, int prot, 71 std::string* error_msg) { 72 if (byte_count == 0) { 73 return new MemMap(name, NULL, 0, NULL, 0, prot); 74 } 75 size_t page_aligned_byte_count = RoundUp(byte_count, kPageSize); 76 CheckMapRequest(addr, page_aligned_byte_count); 77 78#ifdef USE_ASHMEM 79 // android_os_Debug.cpp read_mapinfo assumes all ashmem regions associated with the VM are 80 // prefixed "dalvik-". 81 std::string debug_friendly_name("dalvik-"); 82 debug_friendly_name += name; 83 ScopedFd fd(ashmem_create_region(debug_friendly_name.c_str(), page_aligned_byte_count)); 84 int flags = MAP_PRIVATE; 85 if (fd.get() == -1) { 86 *error_msg = StringPrintf("ashmem_create_region failed for '%s': %s", name, strerror(errno)); 87 return nullptr; 88 } 89#else 90 ScopedFd fd(-1); 91 int flags = MAP_PRIVATE | MAP_ANONYMOUS; 92#endif 93 94 byte* actual = reinterpret_cast<byte*>(mmap(addr, page_aligned_byte_count, prot, flags, fd.get(), 0)); 95 if (actual == MAP_FAILED) { 96 std::string maps; 97 ReadFileToString("/proc/self/maps", &maps); 98 *error_msg = StringPrintf("anonymous mmap(%p, %zd, %x, %x, %d, 0) failed\n%s", 99 addr, page_aligned_byte_count, prot, flags, fd.get(), 100 maps.c_str()); 101 return nullptr; 102 } 103 return new MemMap(name, actual, byte_count, actual, page_aligned_byte_count, prot); 104} 105 106MemMap* MemMap::MapFileAtAddress(byte* addr, size_t byte_count, int prot, int flags, int fd, 107 off_t start, bool reuse, const char* filename, 108 std::string* error_msg) { 109 CHECK_NE(0, prot); 110 CHECK_NE(0, flags & (MAP_SHARED | MAP_PRIVATE)); 111 if (byte_count == 0) { 112 return new MemMap("file", NULL, 0, NULL, 0, prot); 113 } 114 // Adjust 'offset' to be page-aligned as required by mmap. 115 int page_offset = start % kPageSize; 116 off_t page_aligned_offset = start - page_offset; 117 // Adjust 'byte_count' to be page-aligned as we will map this anyway. 118 size_t page_aligned_byte_count = RoundUp(byte_count + page_offset, kPageSize); 119 // The 'addr' is modified (if specified, ie non-null) to be page aligned to the file but not 120 // necessarily to virtual memory. mmap will page align 'addr' for us. 121 byte* page_aligned_addr = (addr == NULL) ? NULL : (addr - page_offset); 122 if (!reuse) { 123 // reuse means it is okay that it overlaps an existing page mapping. 124 // Only use this if you actually made the page reservation yourself. 125 CheckMapRequest(page_aligned_addr, page_aligned_byte_count); 126 } else { 127 CHECK(addr != NULL); 128 } 129 byte* actual = reinterpret_cast<byte*>(mmap(page_aligned_addr, 130 page_aligned_byte_count, 131 prot, 132 flags, 133 fd, 134 page_aligned_offset)); 135 if (actual == MAP_FAILED) { 136 std::string maps; 137 ReadFileToString("/proc/self/maps", &maps); 138 *error_msg = StringPrintf("mmap(%p, %zd, %x, %x, %d, %lld) of file '%s' failed\n%s", 139 page_aligned_addr, page_aligned_byte_count, prot, flags, fd, 140 static_cast<int64_t>(page_aligned_offset), 141 filename, maps.c_str()); 142 return NULL; 143 } 144 return new MemMap("file", actual + page_offset, byte_count, actual, page_aligned_byte_count, 145 prot); 146} 147 148MemMap::~MemMap() { 149 if (base_begin_ == NULL && base_size_ == 0) { 150 return; 151 } 152 int result = munmap(base_begin_, base_size_); 153 if (result == -1) { 154 PLOG(FATAL) << "munmap failed"; 155 } 156} 157 158MemMap::MemMap(const std::string& name, byte* begin, size_t size, void* base_begin, 159 size_t base_size, int prot) 160 : name_(name), begin_(begin), size_(size), base_begin_(base_begin), base_size_(base_size), 161 prot_(prot) { 162 if (size_ == 0) { 163 CHECK(begin_ == NULL); 164 CHECK(base_begin_ == NULL); 165 CHECK_EQ(base_size_, 0U); 166 } else { 167 CHECK(begin_ != NULL); 168 CHECK(base_begin_ != NULL); 169 CHECK_NE(base_size_, 0U); 170 } 171}; 172 173MemMap* MemMap::RemapAtEnd(byte* new_end, const char* tail_name, int tail_prot, 174 std::string* error_msg) { 175 DCHECK_GE(new_end, Begin()); 176 DCHECK_LE(new_end, End()); 177 DCHECK_LE(begin_ + size_, reinterpret_cast<byte*>(base_begin_) + base_size_); 178 DCHECK(IsAligned<kPageSize>(begin_)); 179 DCHECK(IsAligned<kPageSize>(base_begin_)); 180 DCHECK(IsAligned<kPageSize>(reinterpret_cast<byte*>(base_begin_) + base_size_)); 181 DCHECK(IsAligned<kPageSize>(new_end)); 182 byte* old_end = begin_ + size_; 183 byte* old_base_end = reinterpret_cast<byte*>(base_begin_) + base_size_; 184 byte* new_base_end = new_end; 185 DCHECK_LE(new_base_end, old_base_end); 186 if (new_base_end == old_base_end) { 187 return new MemMap(tail_name, NULL, 0, NULL, 0, tail_prot); 188 } 189 size_ = new_end - reinterpret_cast<byte*>(begin_); 190 base_size_ = new_base_end - reinterpret_cast<byte*>(base_begin_); 191 DCHECK_LE(begin_ + size_, reinterpret_cast<byte*>(base_begin_) + base_size_); 192 size_t tail_size = old_end - new_end; 193 byte* tail_base_begin = new_base_end; 194 size_t tail_base_size = old_base_end - new_base_end; 195 DCHECK_EQ(tail_base_begin + tail_base_size, old_base_end); 196 DCHECK(IsAligned<kPageSize>(tail_base_size)); 197 198#ifdef USE_ASHMEM 199 // android_os_Debug.cpp read_mapinfo assumes all ashmem regions associated with the VM are 200 // prefixed "dalvik-". 201 std::string debug_friendly_name("dalvik-"); 202 debug_friendly_name += tail_name; 203 ScopedFd fd(ashmem_create_region(debug_friendly_name.c_str(), tail_base_size)); 204 int flags = MAP_PRIVATE; 205 if (fd.get() == -1) { 206 *error_msg = StringPrintf("ashmem_create_region failed for '%s': %s", 207 tail_name, strerror(errno)); 208 return nullptr; 209 } 210#else 211 ScopedFd fd(-1); 212 int flags = MAP_PRIVATE | MAP_ANONYMOUS; 213#endif 214 215 // Unmap/map the tail region. 216 int result = munmap(tail_base_begin, tail_base_size); 217 if (result == -1) { 218 std::string maps; 219 ReadFileToString("/proc/self/maps", &maps); 220 *error_msg = StringPrintf("munmap(%p, %zd) failed for '%s'\n%s", 221 tail_base_begin, tail_base_size, name_.c_str(), 222 maps.c_str()); 223 return nullptr; 224 } 225 // Don't cause memory allocation between the munmap and the mmap 226 // calls. Otherwise, libc (or something else) might take this memory 227 // region. Note this isn't perfect as there's no way to prevent 228 // other threads to try to take this memory region here. 229 byte* actual = reinterpret_cast<byte*>(mmap(tail_base_begin, tail_base_size, tail_prot, 230 flags, fd.get(), 0)); 231 if (actual == MAP_FAILED) { 232 std::string maps; 233 ReadFileToString("/proc/self/maps", &maps); 234 *error_msg = StringPrintf("anonymous mmap(%p, %zd, %x, %x, %d, 0) failed\n%s", 235 tail_base_begin, tail_base_size, tail_prot, flags, fd.get(), 236 maps.c_str()); 237 return nullptr; 238 } 239 return new MemMap(tail_name, actual, tail_size, actual, tail_base_size, tail_prot); 240} 241 242bool MemMap::Protect(int prot) { 243 if (base_begin_ == NULL && base_size_ == 0) { 244 prot_ = prot; 245 return true; 246 } 247 248 if (mprotect(base_begin_, base_size_, prot) == 0) { 249 prot_ = prot; 250 return true; 251 } 252 253 PLOG(ERROR) << "mprotect(" << reinterpret_cast<void*>(base_begin_) << ", " << base_size_ << ", " 254 << prot << ") failed"; 255 return false; 256} 257 258} // namespace art 259