mem_map.cc revision ebe2dfcb1346d2010787ebbb15ae2965fcd2b223
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 "base/memory_tool.h" 20#include <backtrace/BacktraceMap.h> 21#include <inttypes.h> 22#include <stdlib.h> 23 24#include <memory> 25#include <sstream> 26 27#include "base/stringprintf.h" 28 29#pragma GCC diagnostic push 30#pragma GCC diagnostic ignored "-Wshadow" 31#include "ScopedFd.h" 32#pragma GCC diagnostic pop 33 34#include "thread-inl.h" 35#include "utils.h" 36 37#define USE_ASHMEM 1 38 39#ifdef USE_ASHMEM 40#include <cutils/ashmem.h> 41#ifndef ANDROID_OS 42#include <sys/resource.h> 43#endif 44#endif 45 46#ifndef MAP_ANONYMOUS 47#define MAP_ANONYMOUS MAP_ANON 48#endif 49 50namespace art { 51 52static std::ostream& operator<<( 53 std::ostream& os, 54 std::pair<BacktraceMap::const_iterator, BacktraceMap::const_iterator> iters) { 55 for (BacktraceMap::const_iterator it = iters.first; it != iters.second; ++it) { 56 os << StringPrintf("0x%08x-0x%08x %c%c%c %s\n", 57 static_cast<uint32_t>(it->start), 58 static_cast<uint32_t>(it->end), 59 (it->flags & PROT_READ) ? 'r' : '-', 60 (it->flags & PROT_WRITE) ? 'w' : '-', 61 (it->flags & PROT_EXEC) ? 'x' : '-', it->name.c_str()); 62 } 63 return os; 64} 65 66std::ostream& operator<<(std::ostream& os, const MemMap::Maps& mem_maps) { 67 os << "MemMap:" << std::endl; 68 for (auto it = mem_maps.begin(); it != mem_maps.end(); ++it) { 69 void* base = it->first; 70 MemMap* map = it->second; 71 CHECK_EQ(base, map->BaseBegin()); 72 os << *map << std::endl; 73 } 74 return os; 75} 76 77MemMap::Maps* MemMap::maps_ = nullptr; 78 79#if USE_ART_LOW_4G_ALLOCATOR 80// Handling mem_map in 32b address range for 64b architectures that do not support MAP_32BIT. 81 82// The regular start of memory allocations. The first 64KB is protected by SELinux. 83static constexpr uintptr_t LOW_MEM_START = 64 * KB; 84 85// Generate random starting position. 86// To not interfere with image position, take the image's address and only place it below. Current 87// formula (sketch): 88// 89// ART_BASE_ADDR = 0001XXXXXXXXXXXXXXX 90// ---------------------------------------- 91// = 0000111111111111111 92// & ~(kPageSize - 1) =~0000000000000001111 93// ---------------------------------------- 94// mask = 0000111111111110000 95// & random data = YYYYYYYYYYYYYYYYYYY 96// ----------------------------------- 97// tmp = 0000YYYYYYYYYYY0000 98// + LOW_MEM_START = 0000000000001000000 99// -------------------------------------- 100// start 101// 102// arc4random as an entropy source is exposed in Bionic, but not in glibc. When we 103// do not have Bionic, simply start with LOW_MEM_START. 104 105// Function is standalone so it can be tested somewhat in mem_map_test.cc. 106#ifdef __BIONIC__ 107uintptr_t CreateStartPos(uint64_t input) { 108 CHECK_NE(0, ART_BASE_ADDRESS); 109 110 // Start with all bits below highest bit in ART_BASE_ADDRESS. 111 constexpr size_t leading_zeros = CLZ(static_cast<uint32_t>(ART_BASE_ADDRESS)); 112 constexpr uintptr_t mask_ones = (1 << (31 - leading_zeros)) - 1; 113 114 // Lowest (usually 12) bits are not used, as aligned by page size. 115 constexpr uintptr_t mask = mask_ones & ~(kPageSize - 1); 116 117 // Mask input data. 118 return (input & mask) + LOW_MEM_START; 119} 120#endif 121 122static uintptr_t GenerateNextMemPos() { 123#ifdef __BIONIC__ 124 uint64_t random_data; 125 arc4random_buf(&random_data, sizeof(random_data)); 126 return CreateStartPos(random_data); 127#else 128 // No arc4random on host, see above. 129 return LOW_MEM_START; 130#endif 131} 132 133// Initialize linear scan to random position. 134uintptr_t MemMap::next_mem_pos_ = GenerateNextMemPos(); 135#endif 136 137// Return true if the address range is contained in a single memory map by either reading 138// the maps_ variable or the /proc/self/map entry. 139bool MemMap::ContainedWithinExistingMap(uint8_t* ptr, size_t size, std::string* error_msg) { 140 uintptr_t begin = reinterpret_cast<uintptr_t>(ptr); 141 uintptr_t end = begin + size; 142 143 // There is a suspicion that BacktraceMap::Create is occasionally missing maps. TODO: Investigate 144 // further. 145 { 146 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 147 for (auto& pair : *maps_) { 148 MemMap* const map = pair.second; 149 if (begin >= reinterpret_cast<uintptr_t>(map->Begin()) && 150 end <= reinterpret_cast<uintptr_t>(map->End())) { 151 return true; 152 } 153 } 154 } 155 156 std::unique_ptr<BacktraceMap> map(BacktraceMap::Create(getpid(), true)); 157 if (map == nullptr) { 158 if (error_msg != nullptr) { 159 *error_msg = StringPrintf("Failed to build process map"); 160 } 161 return false; 162 } 163 for (BacktraceMap::const_iterator it = map->begin(); it != map->end(); ++it) { 164 if ((begin >= it->start && begin < it->end) // start of new within old 165 && (end > it->start && end <= it->end)) { // end of new within old 166 return true; 167 } 168 } 169 if (error_msg != nullptr) { 170 PrintFileToLog("/proc/self/maps", LogSeverity::ERROR); 171 *error_msg = StringPrintf("Requested region 0x%08" PRIxPTR "-0x%08" PRIxPTR " does not overlap " 172 "any existing map. See process maps in the log.", begin, end); 173 } 174 return false; 175} 176 177// Return true if the address range does not conflict with any /proc/self/maps entry. 178static bool CheckNonOverlapping(uintptr_t begin, 179 uintptr_t end, 180 std::string* error_msg) { 181 std::unique_ptr<BacktraceMap> map(BacktraceMap::Create(getpid(), true)); 182 if (map.get() == nullptr) { 183 *error_msg = StringPrintf("Failed to build process map"); 184 return false; 185 } 186 for (BacktraceMap::const_iterator it = map->begin(); it != map->end(); ++it) { 187 if ((begin >= it->start && begin < it->end) // start of new within old 188 || (end > it->start && end < it->end) // end of new within old 189 || (begin <= it->start && end > it->end)) { // start/end of new includes all of old 190 std::ostringstream map_info; 191 map_info << std::make_pair(it, map->end()); 192 *error_msg = StringPrintf("Requested region 0x%08" PRIxPTR "-0x%08" PRIxPTR " overlaps with " 193 "existing map 0x%08" PRIxPTR "-0x%08" PRIxPTR " (%s)\n%s", 194 begin, end, 195 static_cast<uintptr_t>(it->start), static_cast<uintptr_t>(it->end), 196 it->name.c_str(), 197 map_info.str().c_str()); 198 return false; 199 } 200 } 201 return true; 202} 203 204// CheckMapRequest to validate a non-MAP_FAILED mmap result based on 205// the expected value, calling munmap if validation fails, giving the 206// reason in error_msg. 207// 208// If the expected_ptr is null, nothing is checked beyond the fact 209// that the actual_ptr is not MAP_FAILED. However, if expected_ptr is 210// non-null, we check that pointer is the actual_ptr == expected_ptr, 211// and if not, report in error_msg what the conflict mapping was if 212// found, or a generic error in other cases. 213static bool CheckMapRequest(uint8_t* expected_ptr, void* actual_ptr, size_t byte_count, 214 std::string* error_msg) { 215 // Handled first by caller for more specific error messages. 216 CHECK(actual_ptr != MAP_FAILED); 217 218 if (expected_ptr == nullptr) { 219 return true; 220 } 221 222 uintptr_t actual = reinterpret_cast<uintptr_t>(actual_ptr); 223 uintptr_t expected = reinterpret_cast<uintptr_t>(expected_ptr); 224 uintptr_t limit = expected + byte_count; 225 226 if (expected_ptr == actual_ptr) { 227 return true; 228 } 229 230 // We asked for an address but didn't get what we wanted, all paths below here should fail. 231 int result = munmap(actual_ptr, byte_count); 232 if (result == -1) { 233 PLOG(WARNING) << StringPrintf("munmap(%p, %zd) failed", actual_ptr, byte_count); 234 } 235 236 // We call this here so that we can try and generate a full error 237 // message with the overlapping mapping. There's no guarantee that 238 // that there will be an overlap though, since 239 // - The kernel is not *required* to honor expected_ptr unless MAP_FIXED is 240 // true, even if there is no overlap 241 // - There might have been an overlap at the point of mmap, but the 242 // overlapping region has since been unmapped. 243 std::string error_detail; 244 CheckNonOverlapping(expected, limit, &error_detail); 245 246 if (error_msg != nullptr) { 247 std::ostringstream os; 248 os << StringPrintf("Failed to mmap at expected address, mapped at " 249 "0x%08" PRIxPTR " instead of 0x%08" PRIxPTR, 250 actual, expected); 251 if (!error_detail.empty()) { 252 os << " : " << error_detail; 253 } 254 *error_msg = os.str(); 255 } 256 return false; 257} 258 259#if USE_ART_LOW_4G_ALLOCATOR 260static inline void* TryMemMapLow4GB(void* ptr, 261 size_t page_aligned_byte_count, 262 int prot, 263 int flags, 264 int fd, 265 off_t offset) { 266 void* actual = mmap(ptr, page_aligned_byte_count, prot, flags, fd, offset); 267 if (actual != MAP_FAILED) { 268 // Since we didn't use MAP_FIXED the kernel may have mapped it somewhere not in the low 269 // 4GB. If this is the case, unmap and retry. 270 if (reinterpret_cast<uintptr_t>(actual) + page_aligned_byte_count >= 4 * GB) { 271 munmap(actual, page_aligned_byte_count); 272 actual = MAP_FAILED; 273 } 274 } 275 return actual; 276} 277#endif 278 279MemMap* MemMap::MapAnonymous(const char* name, 280 uint8_t* expected_ptr, 281 size_t byte_count, 282 int prot, 283 bool low_4gb, 284 bool reuse, 285 std::string* error_msg) { 286#ifndef __LP64__ 287 UNUSED(low_4gb); 288#endif 289 if (byte_count == 0) { 290 return new MemMap(name, nullptr, 0, nullptr, 0, prot, false); 291 } 292 size_t page_aligned_byte_count = RoundUp(byte_count, kPageSize); 293 294 int flags = MAP_PRIVATE | MAP_ANONYMOUS; 295 if (reuse) { 296 // reuse means it is okay that it overlaps an existing page mapping. 297 // Only use this if you actually made the page reservation yourself. 298 CHECK(expected_ptr != nullptr); 299 300 DCHECK(ContainedWithinExistingMap(expected_ptr, byte_count, error_msg)) << *error_msg; 301 flags |= MAP_FIXED; 302 } 303 304 ScopedFd fd(-1); 305 306#ifdef USE_ASHMEM 307#ifdef __ANDROID__ 308 const bool use_ashmem = true; 309#else 310 // When not on Android ashmem is faked using files in /tmp. Ensure that such files won't 311 // fail due to ulimit restrictions. If they will then use a regular mmap. 312 struct rlimit rlimit_fsize; 313 CHECK_EQ(getrlimit(RLIMIT_FSIZE, &rlimit_fsize), 0); 314 const bool use_ashmem = (rlimit_fsize.rlim_cur == RLIM_INFINITY) || 315 (page_aligned_byte_count < rlimit_fsize.rlim_cur); 316#endif 317 if (use_ashmem) { 318 // android_os_Debug.cpp read_mapinfo assumes all ashmem regions associated with the VM are 319 // prefixed "dalvik-". 320 std::string debug_friendly_name("dalvik-"); 321 debug_friendly_name += name; 322 fd.reset(ashmem_create_region(debug_friendly_name.c_str(), page_aligned_byte_count)); 323 if (fd.get() == -1) { 324 *error_msg = StringPrintf("ashmem_create_region failed for '%s': %s", name, strerror(errno)); 325 return nullptr; 326 } 327 flags &= ~MAP_ANONYMOUS; 328 } 329#endif 330 331 // We need to store and potentially set an error number for pretty printing of errors 332 int saved_errno = 0; 333 334 void* actual = MapInternal(expected_ptr, 335 page_aligned_byte_count, 336 prot, 337 flags, 338 fd.get(), 339 0, 340 low_4gb); 341 saved_errno = errno; 342 343 if (actual == MAP_FAILED) { 344 PrintFileToLog("/proc/self/maps", LogSeverity::WARNING); 345 346 *error_msg = StringPrintf("Failed anonymous mmap(%p, %zd, 0x%x, 0x%x, %d, 0): %s. See process " 347 "maps in the log.", expected_ptr, page_aligned_byte_count, prot, 348 flags, fd.get(), strerror(saved_errno)); 349 return nullptr; 350 } 351 std::ostringstream check_map_request_error_msg; 352 if (!CheckMapRequest(expected_ptr, actual, page_aligned_byte_count, error_msg)) { 353 return nullptr; 354 } 355 return new MemMap(name, reinterpret_cast<uint8_t*>(actual), byte_count, actual, 356 page_aligned_byte_count, prot, reuse); 357} 358 359MemMap* MemMap::MapDummy(const char* name, uint8_t* addr, size_t byte_count) { 360 if (byte_count == 0) { 361 return new MemMap(name, nullptr, 0, nullptr, 0, 0, false); 362 } 363 const size_t page_aligned_byte_count = RoundUp(byte_count, kPageSize); 364 return new MemMap(name, addr, byte_count, addr, page_aligned_byte_count, 0, true /* reuse */); 365} 366 367MemMap* MemMap::MapFileAtAddress(uint8_t* expected_ptr, 368 size_t byte_count, 369 int prot, 370 int flags, 371 int fd, 372 off_t start, 373 bool low_4gb, 374 bool reuse, 375 const char* filename, 376 std::string* error_msg) { 377 CHECK_NE(0, prot); 378 CHECK_NE(0, flags & (MAP_SHARED | MAP_PRIVATE)); 379 380 // Note that we do not allow MAP_FIXED unless reuse == true, i.e we 381 // expect his mapping to be contained within an existing map. 382 if (reuse) { 383 // reuse means it is okay that it overlaps an existing page mapping. 384 // Only use this if you actually made the page reservation yourself. 385 CHECK(expected_ptr != nullptr); 386 387 DCHECK(ContainedWithinExistingMap(expected_ptr, byte_count, error_msg)) 388 << ((error_msg != nullptr) ? *error_msg : std::string()); 389 flags |= MAP_FIXED; 390 } else { 391 CHECK_EQ(0, flags & MAP_FIXED); 392 // Don't bother checking for an overlapping region here. We'll 393 // check this if required after the fact inside CheckMapRequest. 394 } 395 396 if (byte_count == 0) { 397 return new MemMap(filename, nullptr, 0, nullptr, 0, prot, false); 398 } 399 // Adjust 'offset' to be page-aligned as required by mmap. 400 int page_offset = start % kPageSize; 401 off_t page_aligned_offset = start - page_offset; 402 // Adjust 'byte_count' to be page-aligned as we will map this anyway. 403 size_t page_aligned_byte_count = RoundUp(byte_count + page_offset, kPageSize); 404 // The 'expected_ptr' is modified (if specified, ie non-null) to be page aligned to the file but 405 // not necessarily to virtual memory. mmap will page align 'expected' for us. 406 uint8_t* page_aligned_expected = 407 (expected_ptr == nullptr) ? nullptr : (expected_ptr - page_offset); 408 409 size_t redzone_size = 0; 410 if (RUNNING_ON_MEMORY_TOOL && kMemoryToolAddsRedzones && expected_ptr == nullptr) { 411 redzone_size = kPageSize; 412 page_aligned_byte_count += redzone_size; 413 } 414 415 uint8_t* actual = reinterpret_cast<uint8_t*>(MapInternal(page_aligned_expected, 416 page_aligned_byte_count, 417 prot, 418 flags, 419 fd, 420 page_aligned_offset, 421 low_4gb)); 422 if (actual == MAP_FAILED) { 423 if (error_msg != nullptr) { 424 auto saved_errno = errno; 425 426 PrintFileToLog("/proc/self/maps", LogSeverity::WARNING); 427 428 *error_msg = StringPrintf("mmap(%p, %zd, 0x%x, 0x%x, %d, %" PRId64 429 ") of file '%s' failed: %s. See process maps in the log.", 430 page_aligned_expected, page_aligned_byte_count, prot, flags, fd, 431 static_cast<int64_t>(page_aligned_offset), filename, 432 strerror(saved_errno)); 433 } 434 return nullptr; 435 } 436 std::ostringstream check_map_request_error_msg; 437 if (!CheckMapRequest(expected_ptr, actual, page_aligned_byte_count, error_msg)) { 438 return nullptr; 439 } 440 if (redzone_size != 0) { 441 const uint8_t *real_start = actual + page_offset; 442 const uint8_t *real_end = actual + page_offset + byte_count; 443 const uint8_t *mapping_end = actual + page_aligned_byte_count; 444 445 MEMORY_TOOL_MAKE_NOACCESS(actual, real_start - actual); 446 MEMORY_TOOL_MAKE_NOACCESS(real_end, mapping_end - real_end); 447 page_aligned_byte_count -= redzone_size; 448 } 449 450 return new MemMap(filename, actual + page_offset, byte_count, actual, page_aligned_byte_count, 451 prot, reuse, redzone_size); 452} 453 454MemMap::~MemMap() { 455 if (base_begin_ == nullptr && base_size_ == 0) { 456 return; 457 } 458 459 // Unlike Valgrind, AddressSanitizer requires that all manually poisoned memory is unpoisoned 460 // before it is returned to the system. 461 if (redzone_size_ != 0) { 462 MEMORY_TOOL_MAKE_UNDEFINED( 463 reinterpret_cast<char*>(base_begin_) + base_size_ - redzone_size_, 464 redzone_size_); 465 } 466 467 if (!reuse_) { 468 MEMORY_TOOL_MAKE_UNDEFINED(base_begin_, base_size_); 469 int result = munmap(base_begin_, base_size_); 470 if (result == -1) { 471 PLOG(FATAL) << "munmap failed"; 472 } 473 } 474 475 // Remove it from maps_. 476 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 477 bool found = false; 478 DCHECK(maps_ != nullptr); 479 for (auto it = maps_->lower_bound(base_begin_), end = maps_->end(); 480 it != end && it->first == base_begin_; ++it) { 481 if (it->second == this) { 482 found = true; 483 maps_->erase(it); 484 break; 485 } 486 } 487 CHECK(found) << "MemMap not found"; 488} 489 490MemMap::MemMap(const std::string& name, uint8_t* begin, size_t size, void* base_begin, 491 size_t base_size, int prot, bool reuse, size_t redzone_size) 492 : name_(name), begin_(begin), size_(size), base_begin_(base_begin), base_size_(base_size), 493 prot_(prot), reuse_(reuse), redzone_size_(redzone_size) { 494 if (size_ == 0) { 495 CHECK(begin_ == nullptr); 496 CHECK(base_begin_ == nullptr); 497 CHECK_EQ(base_size_, 0U); 498 } else { 499 CHECK(begin_ != nullptr); 500 CHECK(base_begin_ != nullptr); 501 CHECK_NE(base_size_, 0U); 502 503 // Add it to maps_. 504 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 505 DCHECK(maps_ != nullptr); 506 maps_->insert(std::make_pair(base_begin_, this)); 507 } 508} 509 510MemMap* MemMap::RemapAtEnd(uint8_t* new_end, const char* tail_name, int tail_prot, 511 std::string* error_msg) { 512 DCHECK_GE(new_end, Begin()); 513 DCHECK_LE(new_end, End()); 514 DCHECK_LE(begin_ + size_, reinterpret_cast<uint8_t*>(base_begin_) + base_size_); 515 DCHECK_ALIGNED(begin_, kPageSize); 516 DCHECK_ALIGNED(base_begin_, kPageSize); 517 DCHECK_ALIGNED(reinterpret_cast<uint8_t*>(base_begin_) + base_size_, kPageSize); 518 DCHECK_ALIGNED(new_end, kPageSize); 519 uint8_t* old_end = begin_ + size_; 520 uint8_t* old_base_end = reinterpret_cast<uint8_t*>(base_begin_) + base_size_; 521 uint8_t* new_base_end = new_end; 522 DCHECK_LE(new_base_end, old_base_end); 523 if (new_base_end == old_base_end) { 524 return new MemMap(tail_name, nullptr, 0, nullptr, 0, tail_prot, false); 525 } 526 size_ = new_end - reinterpret_cast<uint8_t*>(begin_); 527 base_size_ = new_base_end - reinterpret_cast<uint8_t*>(base_begin_); 528 DCHECK_LE(begin_ + size_, reinterpret_cast<uint8_t*>(base_begin_) + base_size_); 529 size_t tail_size = old_end - new_end; 530 uint8_t* tail_base_begin = new_base_end; 531 size_t tail_base_size = old_base_end - new_base_end; 532 DCHECK_EQ(tail_base_begin + tail_base_size, old_base_end); 533 DCHECK_ALIGNED(tail_base_size, kPageSize); 534 535#ifdef USE_ASHMEM 536 // android_os_Debug.cpp read_mapinfo assumes all ashmem regions associated with the VM are 537 // prefixed "dalvik-". 538 std::string debug_friendly_name("dalvik-"); 539 debug_friendly_name += tail_name; 540 ScopedFd fd(ashmem_create_region(debug_friendly_name.c_str(), tail_base_size)); 541 int flags = MAP_PRIVATE | MAP_FIXED; 542 if (fd.get() == -1) { 543 *error_msg = StringPrintf("ashmem_create_region failed for '%s': %s", 544 tail_name, strerror(errno)); 545 return nullptr; 546 } 547#else 548 ScopedFd fd(-1); 549 int flags = MAP_PRIVATE | MAP_ANONYMOUS; 550#endif 551 552 553 MEMORY_TOOL_MAKE_UNDEFINED(tail_base_begin, tail_base_size); 554 // Unmap/map the tail region. 555 int result = munmap(tail_base_begin, tail_base_size); 556 if (result == -1) { 557 PrintFileToLog("/proc/self/maps", LogSeverity::WARNING); 558 *error_msg = StringPrintf("munmap(%p, %zd) failed for '%s'. See process maps in the log.", 559 tail_base_begin, tail_base_size, name_.c_str()); 560 return nullptr; 561 } 562 // Don't cause memory allocation between the munmap and the mmap 563 // calls. Otherwise, libc (or something else) might take this memory 564 // region. Note this isn't perfect as there's no way to prevent 565 // other threads to try to take this memory region here. 566 uint8_t* actual = reinterpret_cast<uint8_t*>(mmap(tail_base_begin, tail_base_size, tail_prot, 567 flags, fd.get(), 0)); 568 if (actual == MAP_FAILED) { 569 PrintFileToLog("/proc/self/maps", LogSeverity::WARNING); 570 *error_msg = StringPrintf("anonymous mmap(%p, %zd, 0x%x, 0x%x, %d, 0) failed. See process " 571 "maps in the log.", tail_base_begin, tail_base_size, tail_prot, flags, 572 fd.get()); 573 return nullptr; 574 } 575 return new MemMap(tail_name, actual, tail_size, actual, tail_base_size, tail_prot, false); 576} 577 578void MemMap::MadviseDontNeedAndZero() { 579 if (base_begin_ != nullptr || base_size_ != 0) { 580 if (!kMadviseZeroes) { 581 memset(base_begin_, 0, base_size_); 582 } 583 int result = madvise(base_begin_, base_size_, MADV_DONTNEED); 584 if (result == -1) { 585 PLOG(WARNING) << "madvise failed"; 586 } 587 } 588} 589 590bool MemMap::Protect(int prot) { 591 if (base_begin_ == nullptr && base_size_ == 0) { 592 prot_ = prot; 593 return true; 594 } 595 596 if (mprotect(base_begin_, base_size_, prot) == 0) { 597 prot_ = prot; 598 return true; 599 } 600 601 PLOG(ERROR) << "mprotect(" << reinterpret_cast<void*>(base_begin_) << ", " << base_size_ << ", " 602 << prot << ") failed"; 603 return false; 604} 605 606bool MemMap::CheckNoGaps(MemMap* begin_map, MemMap* end_map) { 607 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 608 CHECK(begin_map != nullptr); 609 CHECK(end_map != nullptr); 610 CHECK(HasMemMap(begin_map)); 611 CHECK(HasMemMap(end_map)); 612 CHECK_LE(begin_map->BaseBegin(), end_map->BaseBegin()); 613 MemMap* map = begin_map; 614 while (map->BaseBegin() != end_map->BaseBegin()) { 615 MemMap* next_map = GetLargestMemMapAt(map->BaseEnd()); 616 if (next_map == nullptr) { 617 // Found a gap. 618 return false; 619 } 620 map = next_map; 621 } 622 return true; 623} 624 625void MemMap::DumpMaps(std::ostream& os, bool terse) { 626 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 627 DumpMapsLocked(os, terse); 628} 629 630void MemMap::DumpMapsLocked(std::ostream& os, bool terse) { 631 const auto& mem_maps = *maps_; 632 if (!terse) { 633 os << mem_maps; 634 return; 635 } 636 637 // Terse output example: 638 // [MemMap: 0x409be000+0x20P~0x11dP+0x20P~0x61cP+0x20P prot=0x3 LinearAlloc] 639 // [MemMap: 0x451d6000+0x6bP(3) prot=0x3 large object space allocation] 640 // The details: 641 // "+0x20P" means 0x20 pages taken by a single mapping, 642 // "~0x11dP" means a gap of 0x11d pages, 643 // "+0x6bP(3)" means 3 mappings one after another, together taking 0x6b pages. 644 os << "MemMap:" << std::endl; 645 for (auto it = mem_maps.begin(), maps_end = mem_maps.end(); it != maps_end;) { 646 MemMap* map = it->second; 647 void* base = it->first; 648 CHECK_EQ(base, map->BaseBegin()); 649 os << "[MemMap: " << base; 650 ++it; 651 // Merge consecutive maps with the same protect flags and name. 652 constexpr size_t kMaxGaps = 9; 653 size_t num_gaps = 0; 654 size_t num = 1u; 655 size_t size = map->BaseSize(); 656 CHECK_ALIGNED(size, kPageSize); 657 void* end = map->BaseEnd(); 658 while (it != maps_end && 659 it->second->GetProtect() == map->GetProtect() && 660 it->second->GetName() == map->GetName() && 661 (it->second->BaseBegin() == end || num_gaps < kMaxGaps)) { 662 if (it->second->BaseBegin() != end) { 663 ++num_gaps; 664 os << "+0x" << std::hex << (size / kPageSize) << "P"; 665 if (num != 1u) { 666 os << "(" << std::dec << num << ")"; 667 } 668 size_t gap = 669 reinterpret_cast<uintptr_t>(it->second->BaseBegin()) - reinterpret_cast<uintptr_t>(end); 670 CHECK_ALIGNED(gap, kPageSize); 671 os << "~0x" << std::hex << (gap / kPageSize) << "P"; 672 num = 0u; 673 size = 0u; 674 } 675 CHECK_ALIGNED(it->second->BaseSize(), kPageSize); 676 ++num; 677 size += it->second->BaseSize(); 678 end = it->second->BaseEnd(); 679 ++it; 680 } 681 os << "+0x" << std::hex << (size / kPageSize) << "P"; 682 if (num != 1u) { 683 os << "(" << std::dec << num << ")"; 684 } 685 os << " prot=0x" << std::hex << map->GetProtect() << " " << map->GetName() << "]" << std::endl; 686 } 687} 688 689bool MemMap::HasMemMap(MemMap* map) { 690 void* base_begin = map->BaseBegin(); 691 for (auto it = maps_->lower_bound(base_begin), end = maps_->end(); 692 it != end && it->first == base_begin; ++it) { 693 if (it->second == map) { 694 return true; 695 } 696 } 697 return false; 698} 699 700MemMap* MemMap::GetLargestMemMapAt(void* address) { 701 size_t largest_size = 0; 702 MemMap* largest_map = nullptr; 703 DCHECK(maps_ != nullptr); 704 for (auto it = maps_->lower_bound(address), end = maps_->end(); 705 it != end && it->first == address; ++it) { 706 MemMap* map = it->second; 707 CHECK(map != nullptr); 708 if (largest_size < map->BaseSize()) { 709 largest_size = map->BaseSize(); 710 largest_map = map; 711 } 712 } 713 return largest_map; 714} 715 716void MemMap::Init() { 717 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 718 if (maps_ == nullptr) { 719 // dex2oat calls MemMap::Init twice since its needed before the runtime is created. 720 maps_ = new Maps; 721 } 722} 723 724void MemMap::Shutdown() { 725 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 726 delete maps_; 727 maps_ = nullptr; 728} 729 730void MemMap::SetSize(size_t new_size) { 731 if (new_size == base_size_) { 732 return; 733 } 734 CHECK_ALIGNED(new_size, kPageSize); 735 CHECK_EQ(base_size_, size_) << "Unsupported"; 736 CHECK_LE(new_size, base_size_); 737 MEMORY_TOOL_MAKE_UNDEFINED( 738 reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(BaseBegin()) + 739 new_size), 740 base_size_ - new_size); 741 CHECK_EQ(munmap(reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(BaseBegin()) + new_size), 742 base_size_ - new_size), 0) << new_size << " " << base_size_; 743 base_size_ = new_size; 744 size_ = new_size; 745} 746 747void* MemMap::MapInternal(void* addr, 748 size_t length, 749 int prot, 750 int flags, 751 int fd, 752 off_t offset, 753 bool low_4gb) { 754#ifdef __LP64__ 755 // When requesting low_4g memory and having an expectation, the requested range should fit into 756 // 4GB. 757 if (low_4gb && ( 758 // Start out of bounds. 759 (reinterpret_cast<uintptr_t>(addr) >> 32) != 0 || 760 // End out of bounds. For simplicity, this will fail for the last page of memory. 761 ((reinterpret_cast<uintptr_t>(addr) + length) >> 32) != 0)) { 762 LOG(ERROR) << "The requested address space (" << addr << ", " 763 << reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(addr) + length) 764 << ") cannot fit in low_4gb"; 765 return MAP_FAILED; 766 } 767#else 768 UNUSED(low_4gb); 769#endif 770 DCHECK_ALIGNED(length, kPageSize); 771 if (low_4gb) { 772 DCHECK_EQ(flags & MAP_FIXED, 0); 773 } 774 // TODO: 775 // A page allocator would be a useful abstraction here, as 776 // 1) It is doubtful that MAP_32BIT on x86_64 is doing the right job for us 777 void* actual = MAP_FAILED; 778#if USE_ART_LOW_4G_ALLOCATOR 779 // MAP_32BIT only available on x86_64. 780 if (low_4gb && addr == nullptr) { 781 bool first_run = true; 782 783 MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); 784 for (uintptr_t ptr = next_mem_pos_; ptr < 4 * GB; ptr += kPageSize) { 785 // Use maps_ as an optimization to skip over large maps. 786 // Find the first map which is address > ptr. 787 auto it = maps_->upper_bound(reinterpret_cast<void*>(ptr)); 788 if (it != maps_->begin()) { 789 auto before_it = it; 790 --before_it; 791 // Start at the end of the map before the upper bound. 792 ptr = std::max(ptr, reinterpret_cast<uintptr_t>(before_it->second->BaseEnd())); 793 CHECK_ALIGNED(ptr, kPageSize); 794 } 795 while (it != maps_->end()) { 796 // How much space do we have until the next map? 797 size_t delta = reinterpret_cast<uintptr_t>(it->first) - ptr; 798 // If the space may be sufficient, break out of the loop. 799 if (delta >= length) { 800 break; 801 } 802 // Otherwise, skip to the end of the map. 803 ptr = reinterpret_cast<uintptr_t>(it->second->BaseEnd()); 804 CHECK_ALIGNED(ptr, kPageSize); 805 ++it; 806 } 807 808 // Try to see if we get lucky with this address since none of the ART maps overlap. 809 actual = TryMemMapLow4GB(reinterpret_cast<void*>(ptr), length, prot, flags, fd, offset); 810 if (actual != MAP_FAILED) { 811 next_mem_pos_ = reinterpret_cast<uintptr_t>(actual) + length; 812 return actual; 813 } 814 815 if (4U * GB - ptr < length) { 816 // Not enough memory until 4GB. 817 if (first_run) { 818 // Try another time from the bottom; 819 ptr = LOW_MEM_START - kPageSize; 820 first_run = false; 821 continue; 822 } else { 823 // Second try failed. 824 break; 825 } 826 } 827 828 uintptr_t tail_ptr; 829 830 // Check pages are free. 831 bool safe = true; 832 for (tail_ptr = ptr; tail_ptr < ptr + length; tail_ptr += kPageSize) { 833 if (msync(reinterpret_cast<void*>(tail_ptr), kPageSize, 0) == 0) { 834 safe = false; 835 break; 836 } else { 837 DCHECK_EQ(errno, ENOMEM); 838 } 839 } 840 841 next_mem_pos_ = tail_ptr; // update early, as we break out when we found and mapped a region 842 843 if (safe == true) { 844 actual = TryMemMapLow4GB(reinterpret_cast<void*>(ptr), length, prot, flags, fd, offset); 845 if (actual != MAP_FAILED) { 846 return actual; 847 } 848 } else { 849 // Skip over last page. 850 ptr = tail_ptr; 851 } 852 } 853 854 if (actual == MAP_FAILED) { 855 LOG(ERROR) << "Could not find contiguous low-memory space."; 856 errno = ENOMEM; 857 } 858 } else { 859 actual = mmap(addr, length, prot, flags, fd, offset); 860 } 861 862#else 863#if defined(__LP64__) 864 if (low_4gb && addr == nullptr) { 865 flags |= MAP_32BIT; 866 } 867#endif 868 actual = mmap(addr, length, prot, flags, fd, offset); 869#endif 870 return actual; 871} 872 873std::ostream& operator<<(std::ostream& os, const MemMap& mem_map) { 874 os << StringPrintf("[MemMap: %p-%p prot=0x%x %s]", 875 mem_map.BaseBegin(), mem_map.BaseEnd(), mem_map.GetProtect(), 876 mem_map.GetName().c_str()); 877 return os; 878} 879 880} // namespace art 881