| /* |
| * Copyright (C) 2008 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "mem_map.h" |
| #include "thread-inl.h" |
| |
| #include <inttypes.h> |
| #include <backtrace/BacktraceMap.h> |
| #include <memory> |
| |
| // See CreateStartPos below. |
| #ifdef __BIONIC__ |
| #include <sys/auxv.h> |
| #endif |
| |
| #include "base/stringprintf.h" |
| #include "ScopedFd.h" |
| #include "utils.h" |
| |
| #define USE_ASHMEM 1 |
| |
| #ifdef USE_ASHMEM |
| #include <cutils/ashmem.h> |
| #endif |
| |
| namespace art { |
| |
| static std::ostream& operator<<( |
| std::ostream& os, |
| std::pair<BacktraceMap::const_iterator, BacktraceMap::const_iterator> iters) { |
| for (BacktraceMap::const_iterator it = iters.first; it != iters.second; ++it) { |
| os << StringPrintf("0x%08x-0x%08x %c%c%c %s\n", |
| static_cast<uint32_t>(it->start), |
| static_cast<uint32_t>(it->end), |
| (it->flags & PROT_READ) ? 'r' : '-', |
| (it->flags & PROT_WRITE) ? 'w' : '-', |
| (it->flags & PROT_EXEC) ? 'x' : '-', it->name.c_str()); |
| } |
| return os; |
| } |
| |
| std::ostream& operator<<(std::ostream& os, const std::multimap<void*, MemMap*>& mem_maps) { |
| os << "MemMap:" << std::endl; |
| for (auto it = mem_maps.begin(); it != mem_maps.end(); ++it) { |
| void* base = it->first; |
| MemMap* map = it->second; |
| CHECK_EQ(base, map->BaseBegin()); |
| os << *map << std::endl; |
| } |
| return os; |
| } |
| |
| std::multimap<void*, MemMap*> MemMap::maps_; |
| |
| #if defined(__LP64__) && !defined(__x86_64__) |
| // Handling mem_map in 32b address range for 64b architectures that do not support MAP_32BIT. |
| |
| // The regular start of memory allocations. The first 64KB is protected by SELinux. |
| static constexpr uintptr_t LOW_MEM_START = 64 * KB; |
| |
| // Generate random starting position. |
| // To not interfere with image position, take the image's address and only place it below. Current |
| // formula (sketch): |
| // |
| // ART_BASE_ADDR = 0001XXXXXXXXXXXXXXX |
| // ---------------------------------------- |
| // = 0000111111111111111 |
| // & ~(kPageSize - 1) =~0000000000000001111 |
| // ---------------------------------------- |
| // mask = 0000111111111110000 |
| // & random data = YYYYYYYYYYYYYYYYYYY |
| // ----------------------------------- |
| // tmp = 0000YYYYYYYYYYY0000 |
| // + LOW_MEM_START = 0000000000001000000 |
| // -------------------------------------- |
| // start |
| // |
| // getauxval as an entropy source is exposed in Bionic, but not in glibc before 2.16. When we |
| // do not have Bionic, simply start with LOW_MEM_START. |
| |
| // Function is standalone so it can be tested somewhat in mem_map_test.cc. |
| #ifdef __BIONIC__ |
| uintptr_t CreateStartPos(uint64_t input) { |
| CHECK_NE(0, ART_BASE_ADDRESS); |
| |
| // Start with all bits below highest bit in ART_BASE_ADDRESS. |
| constexpr size_t leading_zeros = CLZ(static_cast<uint32_t>(ART_BASE_ADDRESS)); |
| constexpr uintptr_t mask_ones = (1 << (31 - leading_zeros)) - 1; |
| |
| // Lowest (usually 12) bits are not used, as aligned by page size. |
| constexpr uintptr_t mask = mask_ones & ~(kPageSize - 1); |
| |
| // Mask input data. |
| return (input & mask) + LOW_MEM_START; |
| } |
| #endif |
| |
| static uintptr_t GenerateNextMemPos() { |
| #ifdef __BIONIC__ |
| uint8_t* random_data = reinterpret_cast<uint8_t*>(getauxval(AT_RANDOM)); |
| // The lower 8B are taken for the stack guard. Use the upper 8B (with mask). |
| return CreateStartPos(*reinterpret_cast<uintptr_t*>(random_data + 8)); |
| #else |
| // No auxv on host, see above. |
| return LOW_MEM_START; |
| #endif |
| } |
| |
| // Initialize linear scan to random position. |
| uintptr_t MemMap::next_mem_pos_ = GenerateNextMemPos(); |
| #endif |
| |
| static bool CheckMapRequest(byte* expected_ptr, void* actual_ptr, size_t byte_count, |
| std::ostringstream* error_msg) { |
| // Handled first by caller for more specific error messages. |
| CHECK(actual_ptr != MAP_FAILED); |
| |
| if (expected_ptr == nullptr) { |
| return true; |
| } |
| |
| if (expected_ptr == actual_ptr) { |
| return true; |
| } |
| |
| // We asked for an address but didn't get what we wanted, all paths below here should fail. |
| int result = munmap(actual_ptr, byte_count); |
| if (result == -1) { |
| PLOG(WARNING) << StringPrintf("munmap(%p, %zd) failed", actual_ptr, byte_count); |
| } |
| |
| uintptr_t actual = reinterpret_cast<uintptr_t>(actual_ptr); |
| uintptr_t expected = reinterpret_cast<uintptr_t>(expected_ptr); |
| uintptr_t limit = expected + byte_count; |
| |
| std::unique_ptr<BacktraceMap> map(BacktraceMap::Create(getpid())); |
| if (!map->Build()) { |
| *error_msg << StringPrintf("Failed to build process map to determine why mmap returned " |
| "0x%08" PRIxPTR " instead of 0x%08" PRIxPTR, actual, expected); |
| |
| return false; |
| } |
| for (BacktraceMap::const_iterator it = map->begin(); it != map->end(); ++it) { |
| if ((expected >= it->start && expected < it->end) // start of new within old |
| || (limit > it->start && limit < it->end) // end of new within old |
| || (expected <= it->start && limit > it->end)) { // start/end of new includes all of old |
| *error_msg |
| << StringPrintf("Requested region 0x%08" PRIxPTR "-0x%08" PRIxPTR " overlaps with " |
| "existing map 0x%08" PRIxPTR "-0x%08" PRIxPTR " (%s)\n", |
| expected, limit, |
| static_cast<uintptr_t>(it->start), static_cast<uintptr_t>(it->end), |
| it->name.c_str()) |
| << std::make_pair(it, map->end()); |
| return false; |
| } |
| } |
| *error_msg << StringPrintf("Failed to mmap at expected address, mapped at " |
| "0x%08" PRIxPTR " instead of 0x%08" PRIxPTR, actual, expected); |
| return false; |
| } |
| |
| MemMap* MemMap::MapAnonymous(const char* name, byte* expected, size_t byte_count, int prot, |
| bool low_4gb, std::string* error_msg) { |
| if (byte_count == 0) { |
| return new MemMap(name, nullptr, 0, nullptr, 0, prot); |
| } |
| size_t page_aligned_byte_count = RoundUp(byte_count, kPageSize); |
| |
| #ifdef USE_ASHMEM |
| // android_os_Debug.cpp read_mapinfo assumes all ashmem regions associated with the VM are |
| // prefixed "dalvik-". |
| std::string debug_friendly_name("dalvik-"); |
| debug_friendly_name += name; |
| ScopedFd fd(ashmem_create_region(debug_friendly_name.c_str(), page_aligned_byte_count)); |
| if (fd.get() == -1) { |
| *error_msg = StringPrintf("ashmem_create_region failed for '%s': %s", name, strerror(errno)); |
| return nullptr; |
| } |
| int flags = MAP_PRIVATE; |
| #else |
| ScopedFd fd(-1); |
| int flags = MAP_PRIVATE | MAP_ANONYMOUS; |
| #endif |
| |
| // We need to store and potentially set an error number for pretty printing of errors |
| int saved_errno = 0; |
| |
| #ifdef __LP64__ |
| // When requesting low_4g memory and having an expectation, the requested range should fit into |
| // 4GB. |
| if (low_4gb && ( |
| // Start out of bounds. |
| (reinterpret_cast<uintptr_t>(expected) >> 32) != 0 || |
| // End out of bounds. For simplicity, this will fail for the last page of memory. |
| (reinterpret_cast<uintptr_t>(expected + page_aligned_byte_count) >> 32) != 0)) { |
| *error_msg = StringPrintf("The requested address space (%p, %p) cannot fit in low_4gb", |
| expected, expected + page_aligned_byte_count); |
| return nullptr; |
| } |
| #endif |
| |
| // TODO: |
| // A page allocator would be a useful abstraction here, as |
| // 1) It is doubtful that MAP_32BIT on x86_64 is doing the right job for us |
| // 2) The linear scheme, even with simple saving of the last known position, is very crude |
| #if defined(__LP64__) && !defined(__x86_64__) |
| // MAP_32BIT only available on x86_64. |
| void* actual = MAP_FAILED; |
| if (low_4gb && expected == nullptr) { |
| bool first_run = true; |
| |
| for (uintptr_t ptr = next_mem_pos_; ptr < 4 * GB; ptr += kPageSize) { |
| if (4U * GB - ptr < page_aligned_byte_count) { |
| // Not enough memory until 4GB. |
| if (first_run) { |
| // Try another time from the bottom; |
| ptr = LOW_MEM_START - kPageSize; |
| first_run = false; |
| continue; |
| } else { |
| // Second try failed. |
| break; |
| } |
| } |
| |
| uintptr_t tail_ptr; |
| |
| // Check pages are free. |
| bool safe = true; |
| for (tail_ptr = ptr; tail_ptr < ptr + page_aligned_byte_count; tail_ptr += kPageSize) { |
| if (msync(reinterpret_cast<void*>(tail_ptr), kPageSize, 0) == 0) { |
| safe = false; |
| break; |
| } else { |
| DCHECK_EQ(errno, ENOMEM); |
| } |
| } |
| |
| next_mem_pos_ = tail_ptr; // update early, as we break out when we found and mapped a region |
| |
| if (safe == true) { |
| actual = mmap(reinterpret_cast<void*>(ptr), page_aligned_byte_count, prot, flags, fd.get(), |
| 0); |
| if (actual != MAP_FAILED) { |
| // Since we didn't use MAP_FIXED the kernel may have mapped it somewhere not in the low |
| // 4GB. If this is the case, unmap and retry. |
| if (reinterpret_cast<uintptr_t>(actual) + page_aligned_byte_count < 4 * GB) { |
| break; |
| } else { |
| munmap(actual, page_aligned_byte_count); |
| actual = MAP_FAILED; |
| } |
| } |
| } else { |
| // Skip over last page. |
| ptr = tail_ptr; |
| } |
| } |
| |
| if (actual == MAP_FAILED) { |
| LOG(ERROR) << "Could not find contiguous low-memory space."; |
| saved_errno = ENOMEM; |
| } |
| } else { |
| actual = mmap(expected, page_aligned_byte_count, prot, flags, fd.get(), 0); |
| saved_errno = errno; |
| } |
| |
| #else |
| #ifdef __x86_64__ |
| if (low_4gb && expected == nullptr) { |
| flags |= MAP_32BIT; |
| } |
| #endif |
| |
| void* actual = mmap(expected, page_aligned_byte_count, prot, flags, fd.get(), 0); |
| saved_errno = errno; |
| #endif |
| |
| if (actual == MAP_FAILED) { |
| std::string maps; |
| ReadFileToString("/proc/self/maps", &maps); |
| |
| *error_msg = StringPrintf("Failed anonymous mmap(%p, %zd, 0x%x, 0x%x, %d, 0): %s\n%s", |
| expected, page_aligned_byte_count, prot, flags, fd.get(), |
| strerror(saved_errno), maps.c_str()); |
| return nullptr; |
| } |
| std::ostringstream check_map_request_error_msg; |
| if (!CheckMapRequest(expected, actual, page_aligned_byte_count, &check_map_request_error_msg)) { |
| *error_msg = check_map_request_error_msg.str(); |
| return nullptr; |
| } |
| return new MemMap(name, reinterpret_cast<byte*>(actual), byte_count, actual, |
| page_aligned_byte_count, prot); |
| } |
| |
| MemMap* MemMap::MapFileAtAddress(byte* expected, size_t byte_count, int prot, int flags, int fd, |
| off_t start, bool reuse, const char* filename, |
| std::string* error_msg) { |
| CHECK_NE(0, prot); |
| CHECK_NE(0, flags & (MAP_SHARED | MAP_PRIVATE)); |
| if (reuse) { |
| // reuse means it is okay that it overlaps an existing page mapping. |
| // Only use this if you actually made the page reservation yourself. |
| CHECK(expected != nullptr); |
| flags |= MAP_FIXED; |
| } else { |
| CHECK_EQ(0, flags & MAP_FIXED); |
| } |
| |
| if (byte_count == 0) { |
| return new MemMap(filename, nullptr, 0, nullptr, 0, prot); |
| } |
| // Adjust 'offset' to be page-aligned as required by mmap. |
| int page_offset = start % kPageSize; |
| off_t page_aligned_offset = start - page_offset; |
| // Adjust 'byte_count' to be page-aligned as we will map this anyway. |
| size_t page_aligned_byte_count = RoundUp(byte_count + page_offset, kPageSize); |
| // The 'expected' is modified (if specified, ie non-null) to be page aligned to the file but not |
| // necessarily to virtual memory. mmap will page align 'expected' for us. |
| byte* page_aligned_expected = (expected == nullptr) ? nullptr : (expected - page_offset); |
| |
| byte* actual = reinterpret_cast<byte*>(mmap(page_aligned_expected, |
| page_aligned_byte_count, |
| prot, |
| flags, |
| fd, |
| page_aligned_offset)); |
| if (actual == MAP_FAILED) { |
| auto saved_errno = errno; |
| |
| std::string maps; |
| ReadFileToString("/proc/self/maps", &maps); |
| |
| *error_msg = StringPrintf("mmap(%p, %zd, 0x%x, 0x%x, %d, %" PRId64 |
| ") of file '%s' failed: %s\n%s", |
| page_aligned_expected, page_aligned_byte_count, prot, flags, fd, |
| static_cast<int64_t>(page_aligned_offset), filename, |
| strerror(saved_errno), maps.c_str()); |
| return nullptr; |
| } |
| std::ostringstream check_map_request_error_msg; |
| if (!CheckMapRequest(expected, actual, page_aligned_byte_count, &check_map_request_error_msg)) { |
| *error_msg = check_map_request_error_msg.str(); |
| return nullptr; |
| } |
| return new MemMap(filename, actual + page_offset, byte_count, actual, page_aligned_byte_count, |
| prot); |
| } |
| |
| MemMap::~MemMap() { |
| if (base_begin_ == nullptr && base_size_ == 0) { |
| return; |
| } |
| int result = munmap(base_begin_, base_size_); |
| if (result == -1) { |
| PLOG(FATAL) << "munmap failed"; |
| } |
| |
| // Remove it from maps_. |
| MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); |
| bool found = false; |
| for (auto it = maps_.lower_bound(base_begin_), end = maps_.end(); |
| it != end && it->first == base_begin_; ++it) { |
| if (it->second == this) { |
| found = true; |
| maps_.erase(it); |
| break; |
| } |
| } |
| CHECK(found) << "MemMap not found"; |
| } |
| |
| MemMap::MemMap(const std::string& name, byte* begin, size_t size, void* base_begin, |
| size_t base_size, int prot) |
| : name_(name), begin_(begin), size_(size), base_begin_(base_begin), base_size_(base_size), |
| prot_(prot) { |
| if (size_ == 0) { |
| CHECK(begin_ == nullptr); |
| CHECK(base_begin_ == nullptr); |
| CHECK_EQ(base_size_, 0U); |
| } else { |
| CHECK(begin_ != nullptr); |
| CHECK(base_begin_ != nullptr); |
| CHECK_NE(base_size_, 0U); |
| |
| // Add it to maps_. |
| MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); |
| maps_.insert(std::pair<void*, MemMap*>(base_begin_, this)); |
| } |
| }; |
| |
| MemMap* MemMap::RemapAtEnd(byte* new_end, const char* tail_name, int tail_prot, |
| std::string* error_msg) { |
| DCHECK_GE(new_end, Begin()); |
| DCHECK_LE(new_end, End()); |
| DCHECK_LE(begin_ + size_, reinterpret_cast<byte*>(base_begin_) + base_size_); |
| DCHECK(IsAligned<kPageSize>(begin_)); |
| DCHECK(IsAligned<kPageSize>(base_begin_)); |
| DCHECK(IsAligned<kPageSize>(reinterpret_cast<byte*>(base_begin_) + base_size_)); |
| DCHECK(IsAligned<kPageSize>(new_end)); |
| byte* old_end = begin_ + size_; |
| byte* old_base_end = reinterpret_cast<byte*>(base_begin_) + base_size_; |
| byte* new_base_end = new_end; |
| DCHECK_LE(new_base_end, old_base_end); |
| if (new_base_end == old_base_end) { |
| return new MemMap(tail_name, nullptr, 0, nullptr, 0, tail_prot); |
| } |
| size_ = new_end - reinterpret_cast<byte*>(begin_); |
| base_size_ = new_base_end - reinterpret_cast<byte*>(base_begin_); |
| DCHECK_LE(begin_ + size_, reinterpret_cast<byte*>(base_begin_) + base_size_); |
| size_t tail_size = old_end - new_end; |
| byte* tail_base_begin = new_base_end; |
| size_t tail_base_size = old_base_end - new_base_end; |
| DCHECK_EQ(tail_base_begin + tail_base_size, old_base_end); |
| DCHECK(IsAligned<kPageSize>(tail_base_size)); |
| |
| #ifdef USE_ASHMEM |
| // android_os_Debug.cpp read_mapinfo assumes all ashmem regions associated with the VM are |
| // prefixed "dalvik-". |
| std::string debug_friendly_name("dalvik-"); |
| debug_friendly_name += tail_name; |
| ScopedFd fd(ashmem_create_region(debug_friendly_name.c_str(), tail_base_size)); |
| int flags = MAP_PRIVATE | MAP_FIXED; |
| if (fd.get() == -1) { |
| *error_msg = StringPrintf("ashmem_create_region failed for '%s': %s", |
| tail_name, strerror(errno)); |
| return nullptr; |
| } |
| #else |
| ScopedFd fd(-1); |
| int flags = MAP_PRIVATE | MAP_ANONYMOUS; |
| #endif |
| |
| // Unmap/map the tail region. |
| int result = munmap(tail_base_begin, tail_base_size); |
| if (result == -1) { |
| std::string maps; |
| ReadFileToString("/proc/self/maps", &maps); |
| *error_msg = StringPrintf("munmap(%p, %zd) failed for '%s'\n%s", |
| tail_base_begin, tail_base_size, name_.c_str(), |
| maps.c_str()); |
| return nullptr; |
| } |
| // Don't cause memory allocation between the munmap and the mmap |
| // calls. Otherwise, libc (or something else) might take this memory |
| // region. Note this isn't perfect as there's no way to prevent |
| // other threads to try to take this memory region here. |
| byte* actual = reinterpret_cast<byte*>(mmap(tail_base_begin, tail_base_size, tail_prot, |
| flags, fd.get(), 0)); |
| if (actual == MAP_FAILED) { |
| std::string maps; |
| ReadFileToString("/proc/self/maps", &maps); |
| *error_msg = StringPrintf("anonymous mmap(%p, %zd, 0x%x, 0x%x, %d, 0) failed\n%s", |
| tail_base_begin, tail_base_size, tail_prot, flags, fd.get(), |
| maps.c_str()); |
| return nullptr; |
| } |
| return new MemMap(tail_name, actual, tail_size, actual, tail_base_size, tail_prot); |
| } |
| |
| bool MemMap::Protect(int prot) { |
| if (base_begin_ == nullptr && base_size_ == 0) { |
| prot_ = prot; |
| return true; |
| } |
| |
| if (mprotect(base_begin_, base_size_, prot) == 0) { |
| prot_ = prot; |
| return true; |
| } |
| |
| PLOG(ERROR) << "mprotect(" << reinterpret_cast<void*>(base_begin_) << ", " << base_size_ << ", " |
| << prot << ") failed"; |
| return false; |
| } |
| |
| bool MemMap::CheckNoGaps(MemMap* begin_map, MemMap* end_map) { |
| MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); |
| CHECK(begin_map != nullptr); |
| CHECK(end_map != nullptr); |
| CHECK(HasMemMap(begin_map)); |
| CHECK(HasMemMap(end_map)); |
| CHECK_LE(begin_map->BaseBegin(), end_map->BaseBegin()); |
| MemMap* map = begin_map; |
| while (map->BaseBegin() != end_map->BaseBegin()) { |
| MemMap* next_map = GetLargestMemMapAt(map->BaseEnd()); |
| if (next_map == nullptr) { |
| // Found a gap. |
| return false; |
| } |
| map = next_map; |
| } |
| return true; |
| } |
| |
| void MemMap::DumpMaps(std::ostream& os) { |
| DumpMaps(os, maps_); |
| } |
| |
| void MemMap::DumpMaps(std::ostream& os, const std::multimap<void*, MemMap*>& mem_maps) { |
| MutexLock mu(Thread::Current(), *Locks::mem_maps_lock_); |
| DumpMapsLocked(os, mem_maps); |
| } |
| |
| void MemMap::DumpMapsLocked(std::ostream& os, const std::multimap<void*, MemMap*>& mem_maps) { |
| os << mem_maps; |
| } |
| |
| bool MemMap::HasMemMap(MemMap* map) { |
| void* base_begin = map->BaseBegin(); |
| for (auto it = maps_.lower_bound(base_begin), end = maps_.end(); |
| it != end && it->first == base_begin; ++it) { |
| if (it->second == map) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| MemMap* MemMap::GetLargestMemMapAt(void* address) { |
| size_t largest_size = 0; |
| MemMap* largest_map = nullptr; |
| for (auto it = maps_.lower_bound(address), end = maps_.end(); |
| it != end && it->first == address; ++it) { |
| MemMap* map = it->second; |
| CHECK(map != nullptr); |
| if (largest_size < map->BaseSize()) { |
| largest_size = map->BaseSize(); |
| largest_map = map; |
| } |
| } |
| return largest_map; |
| } |
| |
| std::ostream& operator<<(std::ostream& os, const MemMap& mem_map) { |
| os << StringPrintf("[MemMap: %p-%p prot=0x%x %s]", |
| mem_map.BaseBegin(), mem_map.BaseEnd(), mem_map.GetProtect(), |
| mem_map.GetName().c_str()); |
| return os; |
| } |
| |
| } // namespace art |