runtime/jit/debugger_interface.cc - LeafOS-Project/android_art - Gitiles

 /*
  * Copyright (C) 2015 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 "debugger_interface.h"

 #include <android-base/logging.h>

 #include "base/array_ref.h"
 #include "base/mutex.h"
 #include "base/time_utils.h"
 #include "thread-current-inl.h"
 #include "thread.h"

 #include <atomic>
 #include <unordered_map>
 #include <cstddef>

 //
 // Debug interface for native tools (gdb, lldb, libunwind, simpleperf).
 //
 // See http://sourceware.org/gdb/onlinedocs/gdb/Declarations.html
 //
 // There are two ways for native tools to access the debug data safely:
 //
 // 1) Synchronously, by setting a breakpoint in the __*_debug_register_code
 //    method, which is called after every modification of the linked list.
 //    GDB does this, but it is complex to set up and it stops the process.
 //
 // 2) Asynchronously, by monitoring the action_seqlock_.
 //   * The seqlock is a monotonically increasing counter which is incremented
 //     before and after every modification of the linked list. Odd value of
 //     the counter means the linked list is being modified (it is locked).
 //   * The tool should read the value of the seqlock both before and after
 //     copying the linked list.  If the seqlock values match and are even,
 //     the copy is consistent.  Otherwise, the reader should try again.
 //     * Note that using the data directly while is it being modified
 //       might crash the tool.  Therefore, the only safe way is to make
 //       a copy and use the copy only after the seqlock has been checked.
 //     * Note that the process might even free and munmap the data while
 //       it is being copied, therefore the reader should either handle
 //       SEGV or use OS calls to read the memory (e.g. process_vm_readv).
 //   * The seqlock can be used to determine the number of modifications of
 //     the linked list, which can be used to intelligently cache the data.
 //     Note the possible overflow of the seqlock.  It is intentionally
 //     32-bit, since 64-bit atomics can be tricky on some architectures.
 //   * The timestamps on the entry record the time when the entry was
 //     created which is relevant if the unwinding is not live and is
 //     postponed until much later.  All timestamps must be unique.
 //   * Memory barriers are used to make it possible to reason about
 //     the data even when it is being modified (e.g. the process crashed
 //     while that data was locked, and thus it will be never unlocked).
 //     * In particular, it should be possible to:
 //       1) read the seqlock and then the linked list head pointer.
 //       2) copy the entry and check that seqlock has not changed.
 //       3) copy the symfile and check that seqlock has not changed.
 //       4) go back to step 2 using the next pointer (if non-null).
 //       This safely creates copy of all symfiles, although other data
 //       might be inconsistent/unusable (e.g. prev_, action_timestamp_).
 //   * For full conformance with the C++ memory model, all seqlock
 //     protected accesses should be atomic. We currently do this in the
 //     more critical cases. The rest will have to be fixed before
 //     attempting to run TSAN on this code.
 //

 namespace art {
 extern "C" {
   enum JITAction {
     JIT_NOACTION = 0,
     JIT_REGISTER_FN,
     JIT_UNREGISTER_FN
   };

   struct JITCodeEntry {
     // Atomic to ensure the reader can always iterate over the linked list
     // (e.g. the process could crash in the middle of writing this field).
     std::atomic<JITCodeEntry*> next_;
     // Non-atomic. The reader should not use it. It is only used for deletion.
     JITCodeEntry* prev_;
     const uint8_t* symfile_addr_;
     uint64_t symfile_size_;  // Beware of the offset (12 on x86; but 16 on ARM32).

     // Android-specific fields:
     uint64_t register_timestamp_;  // CLOCK_MONOTONIC time of entry registration.
   };

   struct JITDescriptor {
     uint32_t version_ = 1;                      // NB: GDB supports only version 1.
     uint32_t action_flag_ = JIT_NOACTION;       // One of the JITAction enum values.
     JITCodeEntry* relevant_entry_ = nullptr;    // The entry affected by the action.
     std::atomic<JITCodeEntry*> head_{nullptr};  // Head of link list of all entries.

     // Android-specific fields:
     uint8_t magic_[8] = {'A', 'n', 'd', 'r', 'o', 'i', 'd', '1'};
     uint32_t flags_ = 0;  // Reserved for future use. Must be 0.
     uint32_t sizeof_descriptor = sizeof(JITDescriptor);
     uint32_t sizeof_entry = sizeof(JITCodeEntry);
     std::atomic_uint32_t action_seqlock_{0};  // Incremented before and after any modification.
     uint64_t action_timestamp_ = 1;           // CLOCK_MONOTONIC time of last action.
   };

   // Check that std::atomic has the expected layout.
   static_assert(alignof(std::atomic_uint32_t) == alignof(uint32_t), "Weird alignment");
   static_assert(sizeof(std::atomic_uint32_t) == sizeof(uint32_t), "Weird size");
   static_assert(alignof(std::atomic<void*>) == alignof(void*), "Weird alignment");
   static_assert(sizeof(std::atomic<void*>) == sizeof(void*), "Weird size");

   // GDB may set breakpoint here. We must ensure it is not removed or deduplicated.
   void __attribute__((noinline)) __jit_debug_register_code() {
     __asm__("");
   }

   // Alternatively, native tools may overwrite this field to execute custom handler.
   void (*__jit_debug_register_code_ptr)() = __jit_debug_register_code;

   // The root data structure describing of all JITed methods.
   JITDescriptor __jit_debug_descriptor {};

   // The following globals mirror the ones above, but are used to register dex files.
   void __attribute__((noinline)) __dex_debug_register_code() {
     __asm__("");
   }
   void (*__dex_debug_register_code_ptr)() = __dex_debug_register_code;
   JITDescriptor __dex_debug_descriptor {};
 }

 // Mark the descriptor as "locked", so native tools know the data is being modified.
 static void ActionSeqlock(JITDescriptor& descriptor) {
   DCHECK_EQ(descriptor.action_seqlock_.load() & 1, 0u) << "Already locked";
   descriptor.action_seqlock_.fetch_add(1, std::memory_order_relaxed);
   // Ensure that any writes within the locked section cannot be reordered before the increment.
   std::atomic_thread_fence(std::memory_order_release);
 }

 // Mark the descriptor as "unlocked", so native tools know the data is safe to read.
 static void ActionSequnlock(JITDescriptor& descriptor) {
   DCHECK_EQ(descriptor.action_seqlock_.load() & 1, 1u) << "Already unlocked";
   // Ensure that any writes within the locked section cannot be reordered after the increment.
   std::atomic_thread_fence(std::memory_order_release);
   descriptor.action_seqlock_.fetch_add(1, std::memory_order_relaxed);
 }

 static JITCodeEntry* CreateJITCodeEntryInternal(
     JITDescriptor& descriptor,
     void (*register_code_ptr)(),
     const ArrayRef<const uint8_t>& symfile)
     REQUIRES(Locks::native_debug_interface_lock_) {
   // Ensure the timestamp is monotonically increasing even in presence of low
   // granularity system timer.  This ensures each entry has unique timestamp.
   uint64_t timestamp = std::max(descriptor.action_timestamp_ + 1, NanoTime());

   JITCodeEntry* head = descriptor.head_.load(std::memory_order_relaxed);
   JITCodeEntry* entry = new JITCodeEntry;
   CHECK(entry != nullptr);
   entry->symfile_addr_ = symfile.data();
   entry->symfile_size_ = symfile.size();
   entry->prev_ = nullptr;
   entry->next_.store(head, std::memory_order_relaxed);
   entry->register_timestamp_ = timestamp;

   // We are going to modify the linked list, so take the seqlock.
   ActionSeqlock(descriptor);
   if (head != nullptr) {
     head->prev_ = entry;
   }
   descriptor.head_.store(entry, std::memory_order_relaxed);
   descriptor.relevant_entry_ = entry;
   descriptor.action_flag_ = JIT_REGISTER_FN;
   descriptor.action_timestamp_ = timestamp;
   ActionSequnlock(descriptor);

   (*register_code_ptr)();
   return entry;
 }

 static void DeleteJITCodeEntryInternal(
     JITDescriptor& descriptor,
     void (*register_code_ptr)(),
     JITCodeEntry* entry)
     REQUIRES(Locks::native_debug_interface_lock_) {
   CHECK(entry != nullptr);

   // Ensure the timestamp is monotonically increasing even in presence of low
   // granularity system timer.  This ensures each entry has unique timestamp.
   uint64_t timestamp = std::max(descriptor.action_timestamp_ + 1, NanoTime());

   // We are going to modify the linked list, so take the seqlock.
   ActionSeqlock(descriptor);
   JITCodeEntry* next = entry->next_.load(std::memory_order_relaxed);
   if (entry->prev_ != nullptr) {
     entry->prev_->next_.store(next, std::memory_order_relaxed);
   } else {
     descriptor.head_.store(next, std::memory_order_relaxed);
   }
   if (next != nullptr) {
     next->prev_ = entry->prev_;
   }
   descriptor.relevant_entry_ = entry;
   descriptor.action_flag_ = JIT_UNREGISTER_FN;
   descriptor.action_timestamp_ = timestamp;
   ActionSequnlock(descriptor);

   (*register_code_ptr)();

   // Ensure that clear below can not be reordered above the unlock above.
   std::atomic_thread_fence(std::memory_order_release);

   // Aggressively clear the entry as an extra check of the synchronisation.
   memset(entry, 0, sizeof(*entry));

   delete entry;
 }

 static std::unordered_map<const void*, JITCodeEntry*> __dex_debug_entries
     GUARDED_BY(Locks::native_debug_interface_lock_);

 void AddNativeDebugInfoForDex(Thread* current_thread, ArrayRef<const uint8_t> dexfile) {
   MutexLock mu(current_thread, *Locks::native_debug_interface_lock_);
   DCHECK(dexfile.data() != nullptr);
   // This is just defensive check. The class linker should not register the dex file twice.
   if (__dex_debug_entries.count(dexfile.data()) == 0) {
     JITCodeEntry* entry = CreateJITCodeEntryInternal(__dex_debug_descriptor,
                                                      __dex_debug_register_code_ptr,
                                                      dexfile);
     __dex_debug_entries.emplace(dexfile.data(), entry);
   }
 }

 void RemoveNativeDebugInfoForDex(Thread* current_thread, ArrayRef<const uint8_t> dexfile) {
   MutexLock mu(current_thread, *Locks::native_debug_interface_lock_);
   auto it = __dex_debug_entries.find(dexfile.data());
   // We register dex files in the class linker and free them in DexFile_closeDexFile, but
   // there might be cases where we load the dex file without using it in the class linker.
   if (it != __dex_debug_entries.end()) {
     DeleteJITCodeEntryInternal(__dex_debug_descriptor,
                                __dex_debug_register_code_ptr,
                                it->second);
     __dex_debug_entries.erase(it);
   }
 }

 static size_t __jit_debug_mem_usage
     GUARDED_BY(Locks::native_debug_interface_lock_) = 0;

 // Mapping from handle to entry. Used to manage life-time of the entries.
 static std::unordered_map<const void*, JITCodeEntry*> __jit_debug_entries
     GUARDED_BY(Locks::native_debug_interface_lock_);

 void AddNativeDebugInfoForJit(const void* handle, const std::vector<uint8_t>& symfile) {
   DCHECK_NE(symfile.size(), 0u);

   // Make a copy of the buffer to shrink it and to pass ownership to JITCodeEntry.
   uint8_t* copy = new uint8_t[symfile.size()];
   CHECK(copy != nullptr);
   memcpy(copy, symfile.data(), symfile.size());

   JITCodeEntry* entry = CreateJITCodeEntryInternal(
       __jit_debug_descriptor,
       __jit_debug_register_code_ptr,
       ArrayRef<const uint8_t>(copy, symfile.size()));
   __jit_debug_mem_usage += sizeof(JITCodeEntry) + entry->symfile_size_;

   // We don't provide handle for type debug info, which means we cannot free it later.
   // (this only happens when --generate-debug-info flag is enabled for the purpose
   // of being debugged with gdb; it does not happen for debuggable apps by default).
   bool ok = handle == nullptr || __jit_debug_entries.emplace(handle, entry).second;
   DCHECK(ok) << "Native debug entry already exists for " << std::hex << handle;
 }

 void RemoveNativeDebugInfoForJit(const void* handle) {
   auto it = __jit_debug_entries.find(handle);
   // We generate JIT native debug info only if the right runtime flags are enabled,
   // but we try to remove it unconditionally whenever code is freed from JIT cache.
   if (it != __jit_debug_entries.end()) {
     JITCodeEntry* entry = it->second;
     const uint8_t* symfile_addr = entry->symfile_addr_;
     uint64_t symfile_size = entry->symfile_size_;
     DeleteJITCodeEntryInternal(__jit_debug_descriptor,
                                __jit_debug_register_code_ptr,
                                entry);
     __jit_debug_entries.erase(it);
     __jit_debug_mem_usage -= sizeof(JITCodeEntry) + symfile_size;
     delete[] symfile_addr;
   }
 }

 size_t GetJitNativeDebugInfoMemUsage() {
   return __jit_debug_mem_usage + __jit_debug_entries.size() * 2 * sizeof(void*);
 }

 }  // namespace art
	/*
	* Copyright (C) 2015 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 "debugger_interface.h"

	#include <android-base/logging.h>

	#include "base/array_ref.h"
	#include "base/mutex.h"
	#include "base/time_utils.h"
	#include "thread-current-inl.h"
	#include "thread.h"

	#include <atomic>
	#include <unordered_map>
	#include <cstddef>

	//
	// Debug interface for native tools (gdb, lldb, libunwind, simpleperf).
	//
	// See http://sourceware.org/gdb/onlinedocs/gdb/Declarations.html
	//
	// There are two ways for native tools to access the debug data safely:
	//
	// 1) Synchronously, by setting a breakpoint in the __*_debug_register_code
	// method, which is called after every modification of the linked list.
	// GDB does this, but it is complex to set up and it stops the process.
	//
	// 2) Asynchronously, by monitoring the action_seqlock_.
	// * The seqlock is a monotonically increasing counter which is incremented
	// before and after every modification of the linked list. Odd value of
	// the counter means the linked list is being modified (it is locked).
	// * The tool should read the value of the seqlock both before and after
	// copying the linked list. If the seqlock values match and are even,
	// the copy is consistent. Otherwise, the reader should try again.
	// * Note that using the data directly while is it being modified
	// might crash the tool. Therefore, the only safe way is to make
	// a copy and use the copy only after the seqlock has been checked.
	// * Note that the process might even free and munmap the data while
	// it is being copied, therefore the reader should either handle
	// SEGV or use OS calls to read the memory (e.g. process_vm_readv).
	// * The seqlock can be used to determine the number of modifications of
	// the linked list, which can be used to intelligently cache the data.
	// Note the possible overflow of the seqlock. It is intentionally
	// 32-bit, since 64-bit atomics can be tricky on some architectures.
	// * The timestamps on the entry record the time when the entry was
	// created which is relevant if the unwinding is not live and is
	// postponed until much later. All timestamps must be unique.
	// * Memory barriers are used to make it possible to reason about
	// the data even when it is being modified (e.g. the process crashed
	// while that data was locked, and thus it will be never unlocked).
	// * In particular, it should be possible to:
	// 1) read the seqlock and then the linked list head pointer.
	// 2) copy the entry and check that seqlock has not changed.
	// 3) copy the symfile and check that seqlock has not changed.
	// 4) go back to step 2 using the next pointer (if non-null).
	// This safely creates copy of all symfiles, although other data
	// might be inconsistent/unusable (e.g. prev_, action_timestamp_).
	// * For full conformance with the C++ memory model, all seqlock
	// protected accesses should be atomic. We currently do this in the
	// more critical cases. The rest will have to be fixed before
	// attempting to run TSAN on this code.
	//

	namespace art {
	extern "C" {
	enum JITAction {
	JIT_NOACTION = 0,
	JIT_REGISTER_FN,
	JIT_UNREGISTER_FN
	};

	struct JITCodeEntry {
	// Atomic to ensure the reader can always iterate over the linked list
	// (e.g. the process could crash in the middle of writing this field).
	std::atomic<JITCodeEntry*> next_;
	// Non-atomic. The reader should not use it. It is only used for deletion.
	JITCodeEntry* prev_;
	const uint8_t* symfile_addr_;
	uint64_t symfile_size_; // Beware of the offset (12 on x86; but 16 on ARM32).

	// Android-specific fields:
	uint64_t register_timestamp_; // CLOCK_MONOTONIC time of entry registration.
	};

	struct JITDescriptor {
	uint32_t version_ = 1; // NB: GDB supports only version 1.
	uint32_t action_flag_ = JIT_NOACTION; // One of the JITAction enum values.
	JITCodeEntry* relevant_entry_ = nullptr; // The entry affected by the action.
	std::atomic<JITCodeEntry*> head_{nullptr}; // Head of link list of all entries.

	// Android-specific fields:
	uint8_t magic_[8] = {'A', 'n', 'd', 'r', 'o', 'i', 'd', '1'};
	uint32_t flags_ = 0; // Reserved for future use. Must be 0.
	uint32_t sizeof_descriptor = sizeof(JITDescriptor);
	uint32_t sizeof_entry = sizeof(JITCodeEntry);
	std::atomic_uint32_t action_seqlock_{0}; // Incremented before and after any modification.
	uint64_t action_timestamp_ = 1; // CLOCK_MONOTONIC time of last action.
	};

	// Check that std::atomic has the expected layout.
	static_assert(alignof(std::atomic_uint32_t) == alignof(uint32_t), "Weird alignment");
	static_assert(sizeof(std::atomic_uint32_t) == sizeof(uint32_t), "Weird size");
	static_assert(alignof(std::atomic<void>) == alignof(void), "Weird alignment");
	static_assert(sizeof(std::atomic<void>) == sizeof(void), "Weird size");

	// GDB may set breakpoint here. We must ensure it is not removed or deduplicated.
	void __attribute__((noinline)) __jit_debug_register_code() {
	__asm__("");
	}

	// Alternatively, native tools may overwrite this field to execute custom handler.
	void (*__jit_debug_register_code_ptr)() = __jit_debug_register_code;

	// The root data structure describing of all JITed methods.
	JITDescriptor __jit_debug_descriptor {};

	// The following globals mirror the ones above, but are used to register dex files.
	void __attribute__((noinline)) __dex_debug_register_code() {
	__asm__("");
	}
	void (*__dex_debug_register_code_ptr)() = __dex_debug_register_code;
	JITDescriptor __dex_debug_descriptor {};
	}

	// Mark the descriptor as "locked", so native tools know the data is being modified.
	static void ActionSeqlock(JITDescriptor& descriptor) {
	DCHECK_EQ(descriptor.action_seqlock_.load() & 1, 0u) << "Already locked";
	descriptor.action_seqlock_.fetch_add(1, std::memory_order_relaxed);
	// Ensure that any writes within the locked section cannot be reordered before the increment.
	std::atomic_thread_fence(std::memory_order_release);
	}

	// Mark the descriptor as "unlocked", so native tools know the data is safe to read.
	static void ActionSequnlock(JITDescriptor& descriptor) {
	DCHECK_EQ(descriptor.action_seqlock_.load() & 1, 1u) << "Already unlocked";
	// Ensure that any writes within the locked section cannot be reordered after the increment.
	std::atomic_thread_fence(std::memory_order_release);
	descriptor.action_seqlock_.fetch_add(1, std::memory_order_relaxed);
	}

	static JITCodeEntry* CreateJITCodeEntryInternal(
	JITDescriptor& descriptor,
	void (*register_code_ptr)(),
	const ArrayRef<const uint8_t>& symfile)
	REQUIRES(Locks::native_debug_interface_lock_) {
	// Ensure the timestamp is monotonically increasing even in presence of low
	// granularity system timer. This ensures each entry has unique timestamp.
	uint64_t timestamp = std::max(descriptor.action_timestamp_ + 1, NanoTime());

	JITCodeEntry* head = descriptor.head_.load(std::memory_order_relaxed);
	JITCodeEntry* entry = new JITCodeEntry;
	CHECK(entry != nullptr);
	entry->symfile_addr_ = symfile.data();
	entry->symfile_size_ = symfile.size();
	entry->prev_ = nullptr;
	entry->next_.store(head, std::memory_order_relaxed);
	entry->register_timestamp_ = timestamp;

	// We are going to modify the linked list, so take the seqlock.
	ActionSeqlock(descriptor);
	if (head != nullptr) {
	head->prev_ = entry;
	}
	descriptor.head_.store(entry, std::memory_order_relaxed);
	descriptor.relevant_entry_ = entry;
	descriptor.action_flag_ = JIT_REGISTER_FN;
	descriptor.action_timestamp_ = timestamp;
	ActionSequnlock(descriptor);

	(*register_code_ptr)();
	return entry;
	}

	static void DeleteJITCodeEntryInternal(
	JITDescriptor& descriptor,
	void (*register_code_ptr)(),
	JITCodeEntry* entry)
	REQUIRES(Locks::native_debug_interface_lock_) {
	CHECK(entry != nullptr);

	// Ensure the timestamp is monotonically increasing even in presence of low
	// granularity system timer. This ensures each entry has unique timestamp.
	uint64_t timestamp = std::max(descriptor.action_timestamp_ + 1, NanoTime());

	// We are going to modify the linked list, so take the seqlock.
	ActionSeqlock(descriptor);
	JITCodeEntry* next = entry->next_.load(std::memory_order_relaxed);
	if (entry->prev_ != nullptr) {
	entry->prev_->next_.store(next, std::memory_order_relaxed);
	} else {
	descriptor.head_.store(next, std::memory_order_relaxed);
	}
	if (next != nullptr) {
	next->prev_ = entry->prev_;
	}
	descriptor.relevant_entry_ = entry;
	descriptor.action_flag_ = JIT_UNREGISTER_FN;
	descriptor.action_timestamp_ = timestamp;
	ActionSequnlock(descriptor);

	(*register_code_ptr)();

	// Ensure that clear below can not be reordered above the unlock above.
	std::atomic_thread_fence(std::memory_order_release);

	// Aggressively clear the entry as an extra check of the synchronisation.
	memset(entry, 0, sizeof(*entry));

	delete entry;
	}

	static std::unordered_map<const void, JITCodeEntry> __dex_debug_entries
	GUARDED_BY(Locks::native_debug_interface_lock_);

	void AddNativeDebugInfoForDex(Thread* current_thread, ArrayRef<const uint8_t> dexfile) {
	MutexLock mu(current_thread, *Locks::native_debug_interface_lock_);
	DCHECK(dexfile.data() != nullptr);
	// This is just defensive check. The class linker should not register the dex file twice.
	if (__dex_debug_entries.count(dexfile.data()) == 0) {
	JITCodeEntry* entry = CreateJITCodeEntryInternal(__dex_debug_descriptor,
	__dex_debug_register_code_ptr,
	dexfile);
	__dex_debug_entries.emplace(dexfile.data(), entry);
	}
	}

	void RemoveNativeDebugInfoForDex(Thread* current_thread, ArrayRef<const uint8_t> dexfile) {
	MutexLock mu(current_thread, *Locks::native_debug_interface_lock_);
	auto it = __dex_debug_entries.find(dexfile.data());
	// We register dex files in the class linker and free them in DexFile_closeDexFile, but
	// there might be cases where we load the dex file without using it in the class linker.
	if (it != __dex_debug_entries.end()) {
	DeleteJITCodeEntryInternal(__dex_debug_descriptor,
	__dex_debug_register_code_ptr,
	it->second);
	__dex_debug_entries.erase(it);
	}
	}

	static size_t __jit_debug_mem_usage
	GUARDED_BY(Locks::native_debug_interface_lock_) = 0;

	// Mapping from handle to entry. Used to manage life-time of the entries.
	static std::unordered_map<const void, JITCodeEntry> __jit_debug_entries
	GUARDED_BY(Locks::native_debug_interface_lock_);

	void AddNativeDebugInfoForJit(const void* handle, const std::vector<uint8_t>& symfile) {
	DCHECK_NE(symfile.size(), 0u);

	// Make a copy of the buffer to shrink it and to pass ownership to JITCodeEntry.
	uint8_t* copy = new uint8_t[symfile.size()];
	CHECK(copy != nullptr);
	memcpy(copy, symfile.data(), symfile.size());

	JITCodeEntry* entry = CreateJITCodeEntryInternal(
	__jit_debug_descriptor,
	__jit_debug_register_code_ptr,
	ArrayRef<const uint8_t>(copy, symfile.size()));
	__jit_debug_mem_usage += sizeof(JITCodeEntry) + entry->symfile_size_;

	// We don't provide handle for type debug info, which means we cannot free it later.
	// (this only happens when --generate-debug-info flag is enabled for the purpose
	// of being debugged with gdb; it does not happen for debuggable apps by default).
	bool ok = handle == nullptr \|\| __jit_debug_entries.emplace(handle, entry).second;
	DCHECK(ok) << "Native debug entry already exists for " << std::hex << handle;
	}

	void RemoveNativeDebugInfoForJit(const void* handle) {
	auto it = __jit_debug_entries.find(handle);
	// We generate JIT native debug info only if the right runtime flags are enabled,
	// but we try to remove it unconditionally whenever code is freed from JIT cache.
	if (it != __jit_debug_entries.end()) {
	JITCodeEntry* entry = it->second;
	const uint8_t* symfile_addr = entry->symfile_addr_;
	uint64_t symfile_size = entry->symfile_size_;
	DeleteJITCodeEntryInternal(__jit_debug_descriptor,
	__jit_debug_register_code_ptr,
	entry);
	__jit_debug_entries.erase(it);
	__jit_debug_mem_usage -= sizeof(JITCodeEntry) + symfile_size;
	delete[] symfile_addr;
	}
	}

	size_t GetJitNativeDebugInfoMemUsage() {
	return __jit_debug_mem_usage + __jit_debug_entries.size() * 2 * sizeof(void*);
	}

	} // namespace art