mem_map.cc revision 3ae250c16bae3462e040b844dbc2e2fc732d67ba
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 <backtrace/BacktraceMap.h> 20#include <inttypes.h> 21 22#include <memory> 23#include <sstream> 24 25// See CreateStartPos below. 26#ifdef __BIONIC__ 27#include <sys/auxv.h> 28#endif 29 30#include "base/stringprintf.h" 31 32#pragma GCC diagnostic push 33#pragma GCC diagnostic ignored "-Wshadow" 34#include "ScopedFd.h" 35#pragma GCC diagnostic pop 36 37#include "thread-inl.h" 38#include "utils.h" 39 40#define USE_ASHMEM 1 41 42#ifdef USE_ASHMEM 43#include <cutils/ashmem.h> 44#ifndef ANDROID_OS 45#include <sys/resource.h> 46#endif 47#endif 48 49#ifndef MAP_ANONYMOUS 50#define MAP_ANONYMOUS MAP_ANON 51#endif 52 53namespace art { 54 55static std::ostream& operator<<( 56 std::ostream& os, 57 std::pair<BacktraceMap::const_iterator, BacktraceMap::const_iterator> iters) { 58 for (BacktraceMap::const_iterator it = iters.first; it != iters.second; ++it) { 59 os << StringPrintf("0x%08x-0x%08x %c%c%c %s\n", 60 static_cast<uint32_t>(it->start), 61 static_cast<uint32_t>(it->end), 62 (it->flags & PROT_READ) ? 'r' : '-', 63 (it->flags & PROT_WRITE) ? 'w' : '-', 64 (it->flags & PROT_EXEC) ? 'x' : '-', it->name.c_str()); 65 } 66 return os; 67} 68 69std::ostream& operator<<(std::ostream& os, const MemMap::Maps& mem_maps) { 70 os << "MemMap:" << std::endl; 71 for (auto it = mem_maps.begin(); it != mem_maps.end(); ++it) { 72 void* base = it->first; 73 MemMap* map = it->second; 74 CHECK_EQ(base, map->BaseBegin()); 75 os << *map << std::endl; 76 } 77 return os; 78} 79 80MemMap::Maps* MemMap::maps_ = nullptr; 81 82#if USE_ART_LOW_4G_ALLOCATOR 83// Handling mem_map in 32b address range for 64b architectures that do not support MAP_32BIT. 84 85// The regular start of memory allocations. The first 64KB is protected by SELinux. 86static constexpr uintptr_t LOW_MEM_START = 64 * KB; 87 88// Generate random starting position. 89// To not interfere with image position, take the image's address and only place it below. Current 90// formula (sketch): 91// 92// ART_BASE_ADDR = 0001XXXXXXXXXXXXXXX 93// ---------------------------------------- 94// = 0000111111111111111 95// & ~(kPageSize - 1) =~0000000000000001111 96// ---------------------------------------- 97// mask = 0000111111111110000 98// & random data = YYYYYYYYYYYYYYYYYYY 99// ----------------------------------- 100// tmp = 0000YYYYYYYYYYY0000 101// + LOW_MEM_START = 0000000000001000000 102// -------------------------------------- 103// start 104// 105// getauxval as an entropy source is exposed in Bionic, but not in glibc before 2.16. When we 106// do not have Bionic, simply start with LOW_MEM_START. 107 108// Function is standalone so it can be tested somewhat in mem_map_test.cc. 109#ifdef __BIONIC__ 110uintptr_t CreateStartPos(uint64_t input) { 111 CHECK_NE(0, ART_BASE_ADDRESS); 112 113 // Start with all bits below highest bit in ART_BASE_ADDRESS. 114 constexpr size_t leading_zeros = CLZ(static_cast<uint32_t>(ART_BASE_ADDRESS)); 115 constexpr uintptr_t mask_ones = (1 << (31 - leading_zeros)) - 1; 116 117 // Lowest (usually 12) bits are not used, as aligned by page size. 118 constexpr uintptr_t mask = mask_ones & ~(kPageSize - 1); 119 120 // Mask input data. 121 return (input & mask) + LOW_MEM_START; 122} 123#endif 124 125static uintptr_t GenerateNextMemPos() { 126#ifdef __BIONIC__ 127 uint8_t* random_data = reinterpret_cast<uint8_t*>(getauxval(AT_RANDOM)); 128 // The lower 8B are taken for the stack guard. Use the upper 8B (with mask). 129 return CreateStartPos(*reinterpret_cast<uintptr_t*>(random_data + 8)); 130#else 131 // No auxv on host, see above. 132 return LOW_MEM_START; 133#endif 134} 135 136// Initialize linear scan to random position. 137uintptr_t MemMap::next_mem_pos_ = GenerateNextMemPos(); 138#endif 139 140// Return true if the address range is contained in a single /proc/self/map entry. 141static bool ContainedWithinExistingMap(uint8_t* ptr, size_t size, 142 std::string* error_msg) { 143 uintptr_t begin = reinterpret_cast<uintptr_t>(ptr); 144 uintptr_t end = begin + size; 145 std::unique_ptr<BacktraceMap> map(BacktraceMap::Create(getpid(), true)); 146 if (map.get() == nullptr) { 147 *error_msg = StringPrintf("Failed to build process map"); 148 return false; 149 } 150 for (BacktraceMap::const_iterator it = map->begin(); it != map->end(); ++it) { 151 if ((begin >= it->start && begin < it->end) // start of new within old 152 && (end > it->start && end <= it->end)) { // end of new within old 153 return true; 154 } 155 } 156 PrintFileToLog("/proc/self/maps", LogSeverity::ERROR); 157 *error_msg = StringPrintf("Requested region 0x%08" PRIxPTR "-0x%08" PRIxPTR " does not overlap " 158 "any existing map. See process maps in the log.", begin, end); 159 return false; 160} 161 162// Return true if the address range does not conflict with any /proc/self/maps entry. 163static bool CheckNonOverlapping(uintptr_t begin, 164 uintptr_t end, 165 std::string* error_msg) { 166 std::unique_ptr<BacktraceMap> map(BacktraceMap::Create(getpid(), true)); 167 if (map.get() == nullptr) { 168 *error_msg = StringPrintf("Failed to build process map"); 169 return false; 170 } 171 for (BacktraceMap::const_iterator it = map->begin(); it != map->end(); ++it) { 172 if ((begin >= it->start && begin < it->end) // start of new within old 173 || (end > it->start && end < it->end) // end of new within old 174 || (begin <= it->start && end > it->end)) { // start/end of new includes all of old 175 std::ostringstream map_info; 176 map_info << std::make_pair(it, map->end()); 177 *error_msg = StringPrintf("Requested region 0x%08" PRIxPTR "-0x%08" PRIxPTR " overlaps with " 178 "existing map 0x%08" PRIxPTR "-0x%08" PRIxPTR " (%s)\n%s", 179 begin, end, 180 static_cast<uintptr_t>(it->start), static_cast<uintptr_t>(it->end), 181 it->name.c_str(), 182 map_info.str().c_str()); 183 return false; 184 } 185 } 186 return true; 187} 188 189// CheckMapRequest to validate a non-MAP_FAILED mmap result based on 190// the expected value, calling munmap if validation fails, giving the 191// reason in error_msg. 192// 193// If the expected_ptr is null, nothing is checked beyond the fact 194// that the actual_ptr is not MAP_FAILED. However, if expected_ptr is 195// non-null, we check that pointer is the actual_ptr == expected_ptr, 196// and if not, report in error_msg what the conflict mapping was if 197// found, or a generic error in other cases. 198static bool CheckMapRequest(uint8_t* expected_ptr, void* actual_ptr, size_t byte_count, 199 std::string* error_msg) { 200 // Handled first by caller for more specific error messages. 201 CHECK(actual_ptr != MAP_FAILED); 202 203 if (expected_ptr == nullptr) { 204 return true; 205 } 206 207 uintptr_t actual = reinterpret_cast<uintptr_t>(actual_ptr); 208 uintptr_t expected = reinterpret_cast<uintptr_t>(expected_ptr); 209 uintptr_t limit = expected + byte_count; 210 211 if (expected_ptr == actual_ptr) { 212 return true; 213 } 214 215 // We asked for an address but didn't get what we wanted, all paths below here should fail. 216 int result = munmap(actual_ptr, byte_count); 217 if (result == -1) { 218 PLOG(WARNING) << StringPrintf("munmap(%p, %zd) failed", actual_ptr, byte_count); 219 } 220 221 // We call this here so that we can try and generate a full error 222 // message with the overlapping mapping. There's no guarantee that 223 // that there will be an overlap though, since 224 // - The kernel is not *required* to honour expected_ptr unless MAP_FIXED is 225 // true, even if there is no overlap 226 // - There might have been an overlap at the point of mmap, but the 227 // overlapping region has since been unmapped. 228 std::string error_detail; 229 CheckNonOverlapping(expected, limit, &error_detail); 230 231 std::ostringstream os; 232 os << StringPrintf("Failed to mmap at expected address, mapped at " 233 "0x%08" PRIxPTR " instead of 0x%08" PRIxPTR, 234 actual, expected); 235 if (!error_detail.empty()) { 236 os << " : " << error_detail; 237 } 238 239 *error_msg = os.str(); 240 return false; 241} 242 243#if USE_ART_LOW_4G_ALLOCATOR 244static inline void* TryMemMapLow4GB(void* ptr, size_t page_aligned_byte_count, int prot, int flags, 245 int fd) { 246 void* actual = mmap(ptr, page_aligned_byte_count, prot, flags, fd, 0); 247 if (actual != MAP_FAILED) { 248 // Since we didn't use MAP_FIXED the kernel may have mapped it somewhere not in the low 249 // 4GB. If this is the case, unmap and retry. 250 if (reinterpret_cast<uintptr_t>(actual) + page_aligned_byte_count >= 4 * GB) { 251 munmap(actual, page_aligned_byte_count); 252 actual = MAP_FAILED; 253 } 254 } 255 return actual; 256} 257#endif 258 259MemMap* MemMap::MapAnonymous(const char* name, uint8_t* expected_ptr, size_t byte_count, int prot, 260 bool low_4gb, bool reuse, std::string* error_msg) { 261#ifndef __LP64__ 262 UNUSED(low_4gb); 263#endif 264 if (byte_count == 0) { 265 return new MemMap(name, nullptr, 0, nullptr, 0, prot, false); 266 } 267 size_t page_aligned_byte_count = RoundUp(byte_count, kPageSize); 268 269 int flags = MAP_PRIVATE | MAP_ANONYMOUS; 270 if (reuse) { 271 // reuse means it is okay that it overlaps an existing page mapping. 272 // Only use this if you actually made the page reservation yourself. 273 CHECK(expected_ptr != nullptr); 274 275 DCHECK(ContainedWithinExistingMap(expected_ptr, byte_count, error_msg)) << *error_msg; 276 flags |= MAP_FIXED; 277 } 278 279 ScopedFd fd(-1); 280 281#ifdef USE_ASHMEM 282#ifdef HAVE_ANDROID_OS 283 const bool use_ashmem = true; 284#else 285 // When not on Android ashmem is faked using files in /tmp. Ensure that such files won't 286 // fail due to ulimit restrictions. If they will then use a regular mmap. 287 struct rlimit rlimit_fsize; 288 CHECK_EQ(getrlimit(RLIMIT_FSIZE, &rlimit_fsize), 0); 289 const bool use_ashmem = (rlimit_fsize.rlim_cur == RLIM_INFINITY) || 290 (page_aligned_byte_count < rlimit_fsize.rlim_cur); 291#endif 292 if (use_ashmem) { 293 // android_os_Debug.cpp read_mapinfo assumes all ashmem regions associated with the VM are 294 // prefixed "dalvik-". 295 std::string debug_friendly_name("dalvik-"); 296 debug_friendly_name += name; 297 fd.reset(ashmem_create_region(debug_friendly_name.c_str(), page_aligned_byte_count)); 298 if (fd.get() == -1) { 299 *error_msg = StringPrintf("ashmem_create_region failed for '%s': %s", name, strerror(errno)); 300 return nullptr; 301 } 302 flags &= ~MAP_ANONYMOUS; 303 } 304#endif 305 306 // We need to store and potentially set an error number for pretty printing of errors 307 int saved_errno = 0; 308 309#ifdef __LP64__ 310 // When requesting low_4g memory and having an expectation, the requested range should fit into 311 // 4GB. 312 if (low_4gb && ( 313 // Start out of bounds. 314 (reinterpret_cast<uintptr_t>(expected_ptr) >> 32) != 0 || 315 // End out of bounds. For simplicity, this will fail for the last page of memory. 316 (reinterpret_cast<uintptr_t>(expected_ptr + page_aligned_byte_count) >> 32) != 0)) { 317 *error_msg = StringPrintf("The requested address space (%p, %p) cannot fit in low_4gb", 318 expected_ptr, expected_ptr + page_aligned_byte_count); 319 return nullptr; 320 } 321#endif 322 323 // TODO: 324 // A page allocator would be a useful abstraction here, as 325 // 1) It is doubtful that MAP_32BIT on x86_64 is doing the right job for us 326 // 2) The linear scheme, even with simple saving of the last known position, is very crude 327#if USE_ART_LOW_4G_ALLOCATOR 328 // MAP_32BIT only available on x86_64. 329 void* actual = MAP_FAILED; 330 if (low_4gb && expected_ptr == nullptr) { 331 bool first_run = true; 332 333 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 334 for (uintptr_t ptr = next_mem_pos_; ptr < 4 * GB; ptr += kPageSize) { 335 // Use maps_ as an optimization to skip over large maps. 336 // Find the first map which is address > ptr. 337 auto it = maps_->upper_bound(reinterpret_cast<void*>(ptr)); 338 if (it != maps_->begin()) { 339 auto before_it = it; 340 --before_it; 341 // Start at the end of the map before the upper bound. 342 ptr = std::max(ptr, reinterpret_cast<uintptr_t>(before_it->second->BaseEnd())); 343 CHECK_ALIGNED(ptr, kPageSize); 344 } 345 while (it != maps_->end()) { 346 // How much space do we have until the next map? 347 size_t delta = reinterpret_cast<uintptr_t>(it->first) - ptr; 348 // If the space may be sufficient, break out of the loop. 349 if (delta >= page_aligned_byte_count) { 350 break; 351 } 352 // Otherwise, skip to the end of the map. 353 ptr = reinterpret_cast<uintptr_t>(it->second->BaseEnd()); 354 CHECK_ALIGNED(ptr, kPageSize); 355 ++it; 356 } 357 358 // Try to see if we get lucky with this address since none of the ART maps overlap. 359 actual = TryMemMapLow4GB(reinterpret_cast<void*>(ptr), page_aligned_byte_count, prot, flags, 360 fd.get()); 361 if (actual != MAP_FAILED) { 362 next_mem_pos_ = reinterpret_cast<uintptr_t>(actual) + page_aligned_byte_count; 363 break; 364 } 365 366 if (4U * GB - ptr < page_aligned_byte_count) { 367 // Not enough memory until 4GB. 368 if (first_run) { 369 // Try another time from the bottom; 370 ptr = LOW_MEM_START - kPageSize; 371 first_run = false; 372 continue; 373 } else { 374 // Second try failed. 375 break; 376 } 377 } 378 379 uintptr_t tail_ptr; 380 381 // Check pages are free. 382 bool safe = true; 383 for (tail_ptr = ptr; tail_ptr < ptr + page_aligned_byte_count; tail_ptr += kPageSize) { 384 if (msync(reinterpret_cast<void*>(tail_ptr), kPageSize, 0) == 0) { 385 safe = false; 386 break; 387 } else { 388 DCHECK_EQ(errno, ENOMEM); 389 } 390 } 391 392 next_mem_pos_ = tail_ptr; // update early, as we break out when we found and mapped a region 393 394 if (safe == true) { 395 actual = TryMemMapLow4GB(reinterpret_cast<void*>(ptr), page_aligned_byte_count, prot, flags, 396 fd.get()); 397 if (actual != MAP_FAILED) { 398 break; 399 } 400 } else { 401 // Skip over last page. 402 ptr = tail_ptr; 403 } 404 } 405 406 if (actual == MAP_FAILED) { 407 LOG(ERROR) << "Could not find contiguous low-memory space."; 408 saved_errno = ENOMEM; 409 } 410 } else { 411 actual = mmap(expected_ptr, page_aligned_byte_count, prot, flags, fd.get(), 0); 412 saved_errno = errno; 413 } 414 415#else 416#if defined(__LP64__) 417 if (low_4gb && expected_ptr == nullptr) { 418 flags |= MAP_32BIT; 419 } 420#endif 421 422 void* actual = mmap(expected_ptr, page_aligned_byte_count, prot, flags, fd.get(), 0); 423 saved_errno = errno; 424#endif 425 426 if (actual == MAP_FAILED) { 427 PrintFileToLog("/proc/self/maps", LogSeverity::WARNING); 428 429 *error_msg = StringPrintf("Failed anonymous mmap(%p, %zd, 0x%x, 0x%x, %d, 0): %s. See process " 430 "maps in the log.", expected_ptr, page_aligned_byte_count, prot, 431 flags, fd.get(), strerror(saved_errno)); 432 return nullptr; 433 } 434 std::ostringstream check_map_request_error_msg; 435 if (!CheckMapRequest(expected_ptr, actual, page_aligned_byte_count, error_msg)) { 436 return nullptr; 437 } 438 return new MemMap(name, reinterpret_cast<uint8_t*>(actual), byte_count, actual, 439 page_aligned_byte_count, prot, false); 440} 441 442MemMap* MemMap::MapFileAtAddress(uint8_t* expected_ptr, size_t byte_count, int prot, int flags, 443 int fd, off_t start, bool reuse, const char* filename, 444 std::string* error_msg) { 445 CHECK_NE(0, prot); 446 CHECK_NE(0, flags & (MAP_SHARED | MAP_PRIVATE)); 447 448 // Note that we do not allow MAP_FIXED unless reuse == true, i.e we 449 // expect his mapping to be contained within an existing map. 450 if (reuse) { 451 // reuse means it is okay that it overlaps an existing page mapping. 452 // Only use this if you actually made the page reservation yourself. 453 CHECK(expected_ptr != nullptr); 454 455 DCHECK(ContainedWithinExistingMap(expected_ptr, byte_count, error_msg)) << *error_msg; 456 flags |= MAP_FIXED; 457 } else { 458 CHECK_EQ(0, flags & MAP_FIXED); 459 // Don't bother checking for an overlapping region here. We'll 460 // check this if required after the fact inside CheckMapRequest. 461 } 462 463 if (byte_count == 0) { 464 return new MemMap(filename, nullptr, 0, nullptr, 0, prot, false); 465 } 466 // Adjust 'offset' to be page-aligned as required by mmap. 467 int page_offset = start % kPageSize; 468 off_t page_aligned_offset = start - page_offset; 469 // Adjust 'byte_count' to be page-aligned as we will map this anyway. 470 size_t page_aligned_byte_count = RoundUp(byte_count + page_offset, kPageSize); 471 // The 'expected_ptr' is modified (if specified, ie non-null) to be page aligned to the file but 472 // not necessarily to virtual memory. mmap will page align 'expected' for us. 473 uint8_t* page_aligned_expected = 474 (expected_ptr == nullptr) ? nullptr : (expected_ptr - page_offset); 475 476 uint8_t* actual = reinterpret_cast<uint8_t*>(mmap(page_aligned_expected, 477 page_aligned_byte_count, 478 prot, 479 flags, 480 fd, 481 page_aligned_offset)); 482 if (actual == MAP_FAILED) { 483 auto saved_errno = errno; 484 485 PrintFileToLog("/proc/self/maps", LogSeverity::WARNING); 486 487 *error_msg = StringPrintf("mmap(%p, %zd, 0x%x, 0x%x, %d, %" PRId64 488 ") of file '%s' failed: %s. See process maps in the log.", 489 page_aligned_expected, page_aligned_byte_count, prot, flags, fd, 490 static_cast<int64_t>(page_aligned_offset), filename, 491 strerror(saved_errno)); 492 return nullptr; 493 } 494 std::ostringstream check_map_request_error_msg; 495 if (!CheckMapRequest(expected_ptr, actual, page_aligned_byte_count, error_msg)) { 496 return nullptr; 497 } 498 return new MemMap(filename, actual + page_offset, byte_count, actual, page_aligned_byte_count, 499 prot, reuse); 500} 501 502MemMap::~MemMap() { 503 if (base_begin_ == nullptr && base_size_ == 0) { 504 return; 505 } 506 if (!reuse_) { 507 int result = munmap(base_begin_, base_size_); 508 if (result == -1) { 509 PLOG(FATAL) << "munmap failed"; 510 } 511 } 512 513 // Remove it from maps_. 514 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 515 bool found = false; 516 DCHECK(maps_ != nullptr); 517 for (auto it = maps_->lower_bound(base_begin_), end = maps_->end(); 518 it != end && it->first == base_begin_; ++it) { 519 if (it->second == this) { 520 found = true; 521 maps_->erase(it); 522 break; 523 } 524 } 525 CHECK(found) << "MemMap not found"; 526} 527 528MemMap::MemMap(const std::string& name, uint8_t* begin, size_t size, void* base_begin, 529 size_t base_size, int prot, bool reuse) 530 : name_(name), begin_(begin), size_(size), base_begin_(base_begin), base_size_(base_size), 531 prot_(prot), reuse_(reuse) { 532 if (size_ == 0) { 533 CHECK(begin_ == nullptr); 534 CHECK(base_begin_ == nullptr); 535 CHECK_EQ(base_size_, 0U); 536 } else { 537 CHECK(begin_ != nullptr); 538 CHECK(base_begin_ != nullptr); 539 CHECK_NE(base_size_, 0U); 540 541 // Add it to maps_. 542 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 543 DCHECK(maps_ != nullptr); 544 maps_->insert(std::make_pair(base_begin_, this)); 545 } 546} 547 548MemMap* MemMap::RemapAtEnd(uint8_t* new_end, const char* tail_name, int tail_prot, 549 std::string* error_msg) { 550 DCHECK_GE(new_end, Begin()); 551 DCHECK_LE(new_end, End()); 552 DCHECK_LE(begin_ + size_, reinterpret_cast<uint8_t*>(base_begin_) + base_size_); 553 DCHECK(IsAligned<kPageSize>(begin_)); 554 DCHECK(IsAligned<kPageSize>(base_begin_)); 555 DCHECK(IsAligned<kPageSize>(reinterpret_cast<uint8_t*>(base_begin_) + base_size_)); 556 DCHECK(IsAligned<kPageSize>(new_end)); 557 uint8_t* old_end = begin_ + size_; 558 uint8_t* old_base_end = reinterpret_cast<uint8_t*>(base_begin_) + base_size_; 559 uint8_t* new_base_end = new_end; 560 DCHECK_LE(new_base_end, old_base_end); 561 if (new_base_end == old_base_end) { 562 return new MemMap(tail_name, nullptr, 0, nullptr, 0, tail_prot, false); 563 } 564 size_ = new_end - reinterpret_cast<uint8_t*>(begin_); 565 base_size_ = new_base_end - reinterpret_cast<uint8_t*>(base_begin_); 566 DCHECK_LE(begin_ + size_, reinterpret_cast<uint8_t*>(base_begin_) + base_size_); 567 size_t tail_size = old_end - new_end; 568 uint8_t* tail_base_begin = new_base_end; 569 size_t tail_base_size = old_base_end - new_base_end; 570 DCHECK_EQ(tail_base_begin + tail_base_size, old_base_end); 571 DCHECK(IsAligned<kPageSize>(tail_base_size)); 572 573#ifdef USE_ASHMEM 574 // android_os_Debug.cpp read_mapinfo assumes all ashmem regions associated with the VM are 575 // prefixed "dalvik-". 576 std::string debug_friendly_name("dalvik-"); 577 debug_friendly_name += tail_name; 578 ScopedFd fd(ashmem_create_region(debug_friendly_name.c_str(), tail_base_size)); 579 int flags = MAP_PRIVATE | MAP_FIXED; 580 if (fd.get() == -1) { 581 *error_msg = StringPrintf("ashmem_create_region failed for '%s': %s", 582 tail_name, strerror(errno)); 583 return nullptr; 584 } 585#else 586 ScopedFd fd(-1); 587 int flags = MAP_PRIVATE | MAP_ANONYMOUS; 588#endif 589 590 // Unmap/map the tail region. 591 int result = munmap(tail_base_begin, tail_base_size); 592 if (result == -1) { 593 PrintFileToLog("/proc/self/maps", LogSeverity::WARNING); 594 *error_msg = StringPrintf("munmap(%p, %zd) failed for '%s'. See process maps in the log.", 595 tail_base_begin, tail_base_size, name_.c_str()); 596 return nullptr; 597 } 598 // Don't cause memory allocation between the munmap and the mmap 599 // calls. Otherwise, libc (or something else) might take this memory 600 // region. Note this isn't perfect as there's no way to prevent 601 // other threads to try to take this memory region here. 602 uint8_t* actual = reinterpret_cast<uint8_t*>(mmap(tail_base_begin, tail_base_size, tail_prot, 603 flags, fd.get(), 0)); 604 if (actual == MAP_FAILED) { 605 PrintFileToLog("/proc/self/maps", LogSeverity::WARNING); 606 *error_msg = StringPrintf("anonymous mmap(%p, %zd, 0x%x, 0x%x, %d, 0) failed. See process " 607 "maps in the log.", tail_base_begin, tail_base_size, tail_prot, flags, 608 fd.get()); 609 return nullptr; 610 } 611 return new MemMap(tail_name, actual, tail_size, actual, tail_base_size, tail_prot, false); 612} 613 614void MemMap::MadviseDontNeedAndZero() { 615 if (base_begin_ != nullptr || base_size_ != 0) { 616 if (!kMadviseZeroes) { 617 memset(base_begin_, 0, base_size_); 618 } 619 int result = madvise(base_begin_, base_size_, MADV_DONTNEED); 620 if (result == -1) { 621 PLOG(WARNING) << "madvise failed"; 622 } 623 } 624} 625 626bool MemMap::Protect(int prot) { 627 if (base_begin_ == nullptr && base_size_ == 0) { 628 prot_ = prot; 629 return true; 630 } 631 632 if (mprotect(base_begin_, base_size_, prot) == 0) { 633 prot_ = prot; 634 return true; 635 } 636 637 PLOG(ERROR) << "mprotect(" << reinterpret_cast<void*>(base_begin_) << ", " << base_size_ << ", " 638 << prot << ") failed"; 639 return false; 640} 641 642bool MemMap::CheckNoGaps(MemMap* begin_map, MemMap* end_map) { 643 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 644 CHECK(begin_map != nullptr); 645 CHECK(end_map != nullptr); 646 CHECK(HasMemMap(begin_map)); 647 CHECK(HasMemMap(end_map)); 648 CHECK_LE(begin_map->BaseBegin(), end_map->BaseBegin()); 649 MemMap* map = begin_map; 650 while (map->BaseBegin() != end_map->BaseBegin()) { 651 MemMap* next_map = GetLargestMemMapAt(map->BaseEnd()); 652 if (next_map == nullptr) { 653 // Found a gap. 654 return false; 655 } 656 map = next_map; 657 } 658 return true; 659} 660 661void MemMap::DumpMaps(std::ostream& os, bool terse) { 662 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 663 DumpMapsLocked(os, terse); 664} 665 666void MemMap::DumpMapsLocked(std::ostream& os, bool terse) { 667 const auto& mem_maps = *maps_; 668 if (!terse) { 669 os << mem_maps; 670 return; 671 } 672 673 // Terse output example: 674 // [MemMap: 0x409be000+0x20P~0x11dP+0x20P~0x61cP+0x20P prot=0x3 LinearAlloc] 675 // [MemMap: 0x451d6000+0x6bP(3) prot=0x3 large object space allocation] 676 // The details: 677 // "+0x20P" means 0x20 pages taken by a single mapping, 678 // "~0x11dP" means a gap of 0x11d pages, 679 // "+0x6bP(3)" means 3 mappings one after another, together taking 0x6b pages. 680 os << "MemMap:" << std::endl; 681 for (auto it = mem_maps.begin(), maps_end = mem_maps.end(); it != maps_end;) { 682 MemMap* map = it->second; 683 void* base = it->first; 684 CHECK_EQ(base, map->BaseBegin()); 685 os << "[MemMap: " << base; 686 ++it; 687 // Merge consecutive maps with the same protect flags and name. 688 constexpr size_t kMaxGaps = 9; 689 size_t num_gaps = 0; 690 size_t num = 1u; 691 size_t size = map->BaseSize(); 692 CHECK(IsAligned<kPageSize>(size)); 693 void* end = map->BaseEnd(); 694 while (it != maps_end && 695 it->second->GetProtect() == map->GetProtect() && 696 it->second->GetName() == map->GetName() && 697 (it->second->BaseBegin() == end || num_gaps < kMaxGaps)) { 698 if (it->second->BaseBegin() != end) { 699 ++num_gaps; 700 os << "+0x" << std::hex << (size / kPageSize) << "P"; 701 if (num != 1u) { 702 os << "(" << std::dec << num << ")"; 703 } 704 size_t gap = 705 reinterpret_cast<uintptr_t>(it->second->BaseBegin()) - reinterpret_cast<uintptr_t>(end); 706 CHECK(IsAligned<kPageSize>(gap)); 707 os << "~0x" << std::hex << (gap / kPageSize) << "P"; 708 num = 0u; 709 size = 0u; 710 } 711 CHECK(IsAligned<kPageSize>(it->second->BaseSize())); 712 ++num; 713 size += it->second->BaseSize(); 714 end = it->second->BaseEnd(); 715 ++it; 716 } 717 os << "+0x" << std::hex << (size / kPageSize) << "P"; 718 if (num != 1u) { 719 os << "(" << std::dec << num << ")"; 720 } 721 os << " prot=0x" << std::hex << map->GetProtect() << " " << map->GetName() << "]" << std::endl; 722 } 723} 724 725bool MemMap::HasMemMap(MemMap* map) { 726 void* base_begin = map->BaseBegin(); 727 for (auto it = maps_->lower_bound(base_begin), end = maps_->end(); 728 it != end && it->first == base_begin; ++it) { 729 if (it->second == map) { 730 return true; 731 } 732 } 733 return false; 734} 735 736MemMap* MemMap::GetLargestMemMapAt(void* address) { 737 size_t largest_size = 0; 738 MemMap* largest_map = nullptr; 739 DCHECK(maps_ != nullptr); 740 for (auto it = maps_->lower_bound(address), end = maps_->end(); 741 it != end && it->first == address; ++it) { 742 MemMap* map = it->second; 743 CHECK(map != nullptr); 744 if (largest_size < map->BaseSize()) { 745 largest_size = map->BaseSize(); 746 largest_map = map; 747 } 748 } 749 return largest_map; 750} 751 752void MemMap::Init() { 753 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 754 if (maps_ == nullptr) { 755 // dex2oat calls MemMap::Init twice since its needed before the runtime is created. 756 maps_ = new Maps; 757 } 758} 759 760void MemMap::Shutdown() { 761 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 762 delete maps_; 763 maps_ = nullptr; 764} 765 766void MemMap::SetSize(size_t new_size) { 767 if (new_size == base_size_) { 768 return; 769 } 770 CHECK_ALIGNED(new_size, kPageSize); 771 CHECK_EQ(base_size_, size_) << "Unsupported"; 772 CHECK_LE(new_size, base_size_); 773 CHECK_EQ(munmap(reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(BaseBegin()) + new_size), 774 base_size_ - new_size), 0) << new_size << " " << base_size_; 775 base_size_ = new_size; 776 size_ = new_size; 777} 778 779std::ostream& operator<<(std::ostream& os, const MemMap& mem_map) { 780 os << StringPrintf("[MemMap: %p-%p prot=0x%x %s]", 781 mem_map.BaseBegin(), mem_map.BaseEnd(), mem_map.GetProtect(), 782 mem_map.GetName().c_str()); 783 return os; 784} 785 786} // namespace art 787