in imgdiag/imgdiag.cc [283:831]
bool DumpImageDiffMap(pid_t image_diff_pid,
pid_t zygote_diff_pid,
const backtrace_map_t& boot_map)
SHARED_REQUIRES(Locks::mutator_lock_) {
std::ostream& os = *os_;
const size_t pointer_size = InstructionSetPointerSize(
Runtime::Current()->GetInstructionSet());
std::string file_name =
StringPrintf("/proc/%ld/mem", static_cast<long>(image_diff_pid)); // NOLINT [runtime/int]
size_t boot_map_size = boot_map.end - boot_map.start;
// Open /proc/$pid/mem as a file
auto map_file = std::unique_ptr<File>(OS::OpenFileForReading(file_name.c_str()));
if (map_file == nullptr) {
os << "Failed to open " << file_name << " for reading";
return false;
}
// Memory-map /proc/$pid/mem subset from the boot map
CHECK(boot_map.end >= boot_map.start);
std::string error_msg;
// Walk the bytes and diff against our boot image
const ImageHeader& boot_image_header = image_header_;
os << "\nObserving boot image header at address "
<< reinterpret_cast<const void*>(&boot_image_header)
<< "\n\n";
const uint8_t* image_begin_unaligned = boot_image_header.GetImageBegin();
const uint8_t* image_mirror_end_unaligned = image_begin_unaligned +
boot_image_header.GetImageSection(ImageHeader::kSectionObjects).Size();
const uint8_t* image_end_unaligned = image_begin_unaligned + boot_image_header.GetImageSize();
// Adjust range to nearest page
const uint8_t* image_begin = AlignDown(image_begin_unaligned, kPageSize);
const uint8_t* image_end = AlignUp(image_end_unaligned, kPageSize);
ptrdiff_t page_off_begin = boot_image_header.GetImageBegin() - image_begin;
if (reinterpret_cast<uintptr_t>(image_begin) > boot_map.start ||
reinterpret_cast<uintptr_t>(image_end) < boot_map.end) {
// Sanity check that we aren't trying to read a completely different boot image
os << "Remote boot map is out of range of local boot map: " <<
"local begin " << reinterpret_cast<const void*>(image_begin) <<
", local end " << reinterpret_cast<const void*>(image_end) <<
", remote begin " << reinterpret_cast<const void*>(boot_map.start) <<
", remote end " << reinterpret_cast<const void*>(boot_map.end);
return false;
// If we wanted even more validation we could map the ImageHeader from the file
}
std::vector<uint8_t> remote_contents(boot_map_size);
if (!map_file->PreadFully(&remote_contents[0], boot_map_size, boot_map.start)) {
os << "Could not fully read file " << file_name;
return false;
}
std::vector<uint8_t> zygote_contents;
std::unique_ptr<File> zygote_map_file;
if (zygote_diff_pid != -1) {
std::string zygote_file_name =
StringPrintf("/proc/%ld/mem", static_cast<long>(zygote_diff_pid)); // NOLINT [runtime/int]
zygote_map_file.reset(OS::OpenFileForReading(zygote_file_name.c_str()));
// The boot map should be at the same address.
zygote_contents.resize(boot_map_size);
if (!zygote_map_file->PreadFully(&zygote_contents[0], boot_map_size, boot_map.start)) {
LOG(WARNING) << "Could not fully read zygote file " << zygote_file_name;
zygote_contents.clear();
}
}
std::string page_map_file_name = StringPrintf(
"/proc/%ld/pagemap", static_cast<long>(image_diff_pid)); // NOLINT [runtime/int]
auto page_map_file = std::unique_ptr<File>(OS::OpenFileForReading(page_map_file_name.c_str()));
if (page_map_file == nullptr) {
os << "Failed to open " << page_map_file_name << " for reading: " << strerror(errno);
return false;
}
// Not truly clean, mmap-ing boot.art again would be more pristine, but close enough
const char* clean_page_map_file_name = "/proc/self/pagemap";
auto clean_page_map_file = std::unique_ptr<File>(
OS::OpenFileForReading(clean_page_map_file_name));
if (clean_page_map_file == nullptr) {
os << "Failed to open " << clean_page_map_file_name << " for reading: " << strerror(errno);
return false;
}
auto kpage_flags_file = std::unique_ptr<File>(OS::OpenFileForReading("/proc/kpageflags"));
if (kpage_flags_file == nullptr) {
os << "Failed to open /proc/kpageflags for reading: " << strerror(errno);
return false;
}
auto kpage_count_file = std::unique_ptr<File>(OS::OpenFileForReading("/proc/kpagecount"));
if (kpage_count_file == nullptr) {
os << "Failed to open /proc/kpagecount for reading:" << strerror(errno);
return false;
}
// Set of the remote virtual page indices that are dirty
std::set<size_t> dirty_page_set_remote;
// Set of the local virtual page indices that are dirty
std::set<size_t> dirty_page_set_local;
size_t different_int32s = 0;
size_t different_bytes = 0;
size_t different_pages = 0;
size_t virtual_page_idx = 0; // Virtual page number (for an absolute memory address)
size_t page_idx = 0; // Page index relative to 0
size_t previous_page_idx = 0; // Previous page index relative to 0
size_t dirty_pages = 0;
size_t private_pages = 0;
size_t private_dirty_pages = 0;
// Iterate through one page at a time. Boot map begin/end already implicitly aligned.
for (uintptr_t begin = boot_map.start; begin != boot_map.end; begin += kPageSize) {
ptrdiff_t offset = begin - boot_map.start;
// We treat the image header as part of the memory map for now
// If we wanted to change this, we could pass base=start+sizeof(ImageHeader)
// But it might still be interesting to see if any of the ImageHeader data mutated
const uint8_t* local_ptr = reinterpret_cast<const uint8_t*>(&boot_image_header) + offset;
uint8_t* remote_ptr = &remote_contents[offset];
if (memcmp(local_ptr, remote_ptr, kPageSize) != 0) {
different_pages++;
// Count the number of 32-bit integers that are different.
for (size_t i = 0; i < kPageSize / sizeof(uint32_t); ++i) {
uint32_t* remote_ptr_int32 = reinterpret_cast<uint32_t*>(remote_ptr);
const uint32_t* local_ptr_int32 = reinterpret_cast<const uint32_t*>(local_ptr);
if (remote_ptr_int32[i] != local_ptr_int32[i]) {
different_int32s++;
}
}
}
}
// Iterate through one byte at a time.
for (uintptr_t begin = boot_map.start; begin != boot_map.end; ++begin) {
previous_page_idx = page_idx;
ptrdiff_t offset = begin - boot_map.start;
// We treat the image header as part of the memory map for now
// If we wanted to change this, we could pass base=start+sizeof(ImageHeader)
// But it might still be interesting to see if any of the ImageHeader data mutated
const uint8_t* local_ptr = reinterpret_cast<const uint8_t*>(&boot_image_header) + offset;
uint8_t* remote_ptr = &remote_contents[offset];
virtual_page_idx = reinterpret_cast<uintptr_t>(local_ptr) / kPageSize;
// Calculate the page index, relative to the 0th page where the image begins
page_idx = (offset + page_off_begin) / kPageSize;
if (*local_ptr != *remote_ptr) {
// Track number of bytes that are different
different_bytes++;
}
// Independently count the # of dirty pages on the remote side
size_t remote_virtual_page_idx = begin / kPageSize;
if (previous_page_idx != page_idx) {
uint64_t page_count = 0xC0FFEE;
// TODO: virtual_page_idx needs to be from the same process
int dirtiness = (IsPageDirty(page_map_file.get(), // Image-diff-pid procmap
clean_page_map_file.get(), // Self procmap
kpage_flags_file.get(),
kpage_count_file.get(),
remote_virtual_page_idx, // potentially "dirty" page
virtual_page_idx, // true "clean" page
&page_count,
&error_msg));
if (dirtiness < 0) {
os << error_msg;
return false;
} else if (dirtiness > 0) {
dirty_pages++;
dirty_page_set_remote.insert(dirty_page_set_remote.end(), remote_virtual_page_idx);
dirty_page_set_local.insert(dirty_page_set_local.end(), virtual_page_idx);
}
bool is_dirty = dirtiness > 0;
bool is_private = page_count == 1;
if (page_count == 1) {
private_pages++;
}
if (is_dirty && is_private) {
private_dirty_pages++;
}
}
}
std::map<mirror::Class*, ClassData> class_data;
// Walk each object in the remote image space and compare it against ours
size_t different_objects = 0;
std::map<off_t /* field offset */, int /* count */> art_method_field_dirty_count;
std::vector<ArtMethod*> art_method_dirty_objects;
std::map<off_t /* field offset */, int /* count */> class_field_dirty_count;
std::vector<mirror::Class*> class_dirty_objects;
// List of local objects that are clean, but located on dirty pages.
std::vector<mirror::Object*> false_dirty_objects;
size_t false_dirty_object_bytes = 0;
// Look up remote classes by their descriptor
std::map<std::string, mirror::Class*> remote_class_map;
// Look up local classes by their descriptor
std::map<std::string, mirror::Class*> local_class_map;
// Objects that are dirty against the image (possibly shared or private dirty).
std::set<mirror::Object*> image_dirty_objects;
// Objects that are dirty against the zygote (probably private dirty).
std::set<mirror::Object*> zygote_dirty_objects;
size_t dirty_object_bytes = 0;
const uint8_t* begin_image_ptr = image_begin_unaligned;
const uint8_t* end_image_ptr = image_mirror_end_unaligned;
const uint8_t* current = begin_image_ptr + RoundUp(sizeof(ImageHeader), kObjectAlignment);
while (reinterpret_cast<uintptr_t>(current) < reinterpret_cast<uintptr_t>(end_image_ptr)) {
CHECK_ALIGNED(current, kObjectAlignment);
mirror::Object* obj = reinterpret_cast<mirror::Object*>(const_cast<uint8_t*>(current));
// Sanity check that we are reading a real object
CHECK(obj->GetClass() != nullptr) << "Image object at address " << obj << " has null class";
if (kUseBakerOrBrooksReadBarrier) {
obj->AssertReadBarrierPointer();
}
// Iterate every page this object belongs to
bool on_dirty_page = false;
size_t page_off = 0;
size_t current_page_idx;
uintptr_t object_address;
do {
object_address = reinterpret_cast<uintptr_t>(current);
current_page_idx = object_address / kPageSize + page_off;
if (dirty_page_set_local.find(current_page_idx) != dirty_page_set_local.end()) {
// This object is on a dirty page
on_dirty_page = true;
}
page_off++;
} while ((current_page_idx * kPageSize) <
RoundUp(object_address + obj->SizeOf(), kObjectAlignment));
mirror::Class* klass = obj->GetClass();
// Check against the other object and see if they are different
ptrdiff_t offset = current - begin_image_ptr;
const uint8_t* current_remote = &remote_contents[offset];
mirror::Object* remote_obj = reinterpret_cast<mirror::Object*>(
const_cast<uint8_t*>(current_remote));
bool different_image_object = memcmp(current, current_remote, obj->SizeOf()) != 0;
if (different_image_object) {
bool different_zygote_object = false;
if (!zygote_contents.empty()) {
const uint8_t* zygote_ptr = &zygote_contents[offset];
different_zygote_object = memcmp(current, zygote_ptr, obj->SizeOf()) != 0;
}
if (different_zygote_object) {
// Different from zygote.
zygote_dirty_objects.insert(obj);
} else {
// Just different from iamge.
image_dirty_objects.insert(obj);
}
different_objects++;
dirty_object_bytes += obj->SizeOf();
++class_data[klass].dirty_object_count;
// Go byte-by-byte and figure out what exactly got dirtied
size_t dirty_byte_count_per_object = 0;
for (size_t i = 0; i < obj->SizeOf(); ++i) {
if (current[i] != current_remote[i]) {
dirty_byte_count_per_object++;
}
}
class_data[klass].dirty_object_byte_count += dirty_byte_count_per_object;
class_data[klass].dirty_object_size_in_bytes += obj->SizeOf();
class_data[klass].dirty_objects.push_back(remote_obj);
} else {
++class_data[klass].clean_object_count;
}
std::string descriptor = GetClassDescriptor(klass);
if (different_image_object) {
if (klass->IsClassClass()) {
// this is a "Class"
mirror::Class* obj_as_class = reinterpret_cast<mirror::Class*>(remote_obj);
// print the fields that are dirty
for (size_t i = 0; i < obj->SizeOf(); ++i) {
if (current[i] != current_remote[i]) {
class_field_dirty_count[i]++;
}
}
class_dirty_objects.push_back(obj_as_class);
} else if (strcmp(descriptor.c_str(), "Ljava/lang/reflect/ArtMethod;") == 0) {
// this is an ArtMethod
ArtMethod* art_method = reinterpret_cast<ArtMethod*>(remote_obj);
// print the fields that are dirty
for (size_t i = 0; i < obj->SizeOf(); ++i) {
if (current[i] != current_remote[i]) {
art_method_field_dirty_count[i]++;
}
}
art_method_dirty_objects.push_back(art_method);
}
} else if (on_dirty_page) {
// This object was either never mutated or got mutated back to the same value.
// TODO: Do I want to distinguish a "different" vs a "dirty" page here?
false_dirty_objects.push_back(obj);
class_data[klass].false_dirty_objects.push_back(obj);
false_dirty_object_bytes += obj->SizeOf();
class_data[obj->GetClass()].false_dirty_byte_count += obj->SizeOf();
class_data[obj->GetClass()].false_dirty_object_count += 1;
}
if (strcmp(descriptor.c_str(), "Ljava/lang/Class;") == 0) {
local_class_map[descriptor] = reinterpret_cast<mirror::Class*>(obj);
remote_class_map[descriptor] = reinterpret_cast<mirror::Class*>(remote_obj);
}
// Unconditionally store the class descriptor in case we need it later
class_data[klass].descriptor = descriptor;
current += RoundUp(obj->SizeOf(), kObjectAlignment);
}
// Looking at only dirty pages, figure out how many of those bytes belong to dirty objects.
float true_dirtied_percent = dirty_object_bytes * 1.0f / (dirty_pages * kPageSize);
size_t false_dirty_pages = dirty_pages - different_pages;
os << "Mapping at [" << reinterpret_cast<void*>(boot_map.start) << ", "
<< reinterpret_cast<void*>(boot_map.end) << ") had: \n "
<< different_bytes << " differing bytes, \n "
<< different_int32s << " differing int32s, \n "
<< different_objects << " different objects, \n "
<< dirty_object_bytes << " different object [bytes], \n "
<< false_dirty_objects.size() << " false dirty objects,\n "
<< false_dirty_object_bytes << " false dirty object [bytes], \n "
<< true_dirtied_percent << " different objects-vs-total in a dirty page;\n "
<< different_pages << " different pages; \n "
<< dirty_pages << " pages are dirty; \n "
<< false_dirty_pages << " pages are false dirty; \n "
<< private_pages << " pages are private; \n "
<< private_dirty_pages << " pages are Private_Dirty\n "
<< "";
// vector of pairs (int count, Class*)
auto dirty_object_class_values = SortByValueDesc<mirror::Class*, int, ClassData>(
class_data, [](const ClassData& d) { return d.dirty_object_count; });
auto clean_object_class_values = SortByValueDesc<mirror::Class*, int, ClassData>(
class_data, [](const ClassData& d) { return d.clean_object_count; });
if (!zygote_dirty_objects.empty()) {
os << "\n" << " Dirty objects compared to zygote (probably private dirty): "
<< zygote_dirty_objects.size() << "\n";
for (mirror::Object* obj : zygote_dirty_objects) {
const uint8_t* obj_bytes = reinterpret_cast<const uint8_t*>(obj);
ptrdiff_t offset = obj_bytes - begin_image_ptr;
uint8_t* remote_bytes = &zygote_contents[offset];
DiffObjectContents(obj, remote_bytes, os);
}
}
os << "\n" << " Dirty objects compared to image (private or shared dirty): "
<< image_dirty_objects.size() << "\n";
for (mirror::Object* obj : image_dirty_objects) {
const uint8_t* obj_bytes = reinterpret_cast<const uint8_t*>(obj);
ptrdiff_t offset = obj_bytes - begin_image_ptr;
uint8_t* remote_bytes = &remote_contents[offset];
DiffObjectContents(obj, remote_bytes, os);
}
os << "\n" << " Dirty object count by class:\n";
for (const auto& vk_pair : dirty_object_class_values) {
int dirty_object_count = vk_pair.first;
mirror::Class* klass = vk_pair.second;
int object_sizes = class_data[klass].dirty_object_size_in_bytes;
float avg_dirty_bytes_per_class =
class_data[klass].dirty_object_byte_count * 1.0f / object_sizes;
float avg_object_size = object_sizes * 1.0f / dirty_object_count;
const std::string& descriptor = class_data[klass].descriptor;
os << " " << PrettyClass(klass) << " ("
<< "objects: " << dirty_object_count << ", "
<< "avg dirty bytes: " << avg_dirty_bytes_per_class << ", "
<< "avg object size: " << avg_object_size << ", "
<< "class descriptor: '" << descriptor << "'"
<< ")\n";
constexpr size_t kMaxAddressPrint = 5;
if (strcmp(descriptor.c_str(), "Ljava/lang/reflect/ArtMethod;") == 0) {
os << " sample object addresses: ";
for (size_t i = 0; i < art_method_dirty_objects.size() && i < kMaxAddressPrint; ++i) {
auto art_method = art_method_dirty_objects[i];
os << reinterpret_cast<void*>(art_method) << ", ";
}
os << "\n";
os << " dirty byte +offset:count list = ";
auto art_method_field_dirty_count_sorted =
SortByValueDesc<off_t, int, int>(art_method_field_dirty_count);
for (auto pair : art_method_field_dirty_count_sorted) {
off_t offset = pair.second;
int count = pair.first;
os << "+" << offset << ":" << count << ", ";
}
os << "\n";
os << " field contents:\n";
const auto& dirty_objects_list = class_data[klass].dirty_objects;
for (mirror::Object* obj : dirty_objects_list) {
// remote method
auto art_method = reinterpret_cast<ArtMethod*>(obj);
// remote class
mirror::Class* remote_declaring_class =
FixUpRemotePointer(art_method->GetDeclaringClass(), remote_contents, boot_map);
// local class
mirror::Class* declaring_class =
RemoteContentsPointerToLocal(remote_declaring_class,
remote_contents,
boot_image_header);
os << " " << reinterpret_cast<void*>(obj) << " ";
os << " entryPointFromJni: "
<< reinterpret_cast<const void*>(
art_method->GetEntryPointFromJniPtrSize(pointer_size)) << ", ";
os << " entryPointFromQuickCompiledCode: "
<< reinterpret_cast<const void*>(
art_method->GetEntryPointFromQuickCompiledCodePtrSize(pointer_size))
<< ", ";
os << " isNative? " << (art_method->IsNative() ? "yes" : "no") << ", ";
os << " class_status (local): " << declaring_class->GetStatus();
os << " class_status (remote): " << remote_declaring_class->GetStatus();
os << "\n";
}
}
if (strcmp(descriptor.c_str(), "Ljava/lang/Class;") == 0) {
os << " sample object addresses: ";
for (size_t i = 0; i < class_dirty_objects.size() && i < kMaxAddressPrint; ++i) {
auto class_ptr = class_dirty_objects[i];
os << reinterpret_cast<void*>(class_ptr) << ", ";
}
os << "\n";
os << " dirty byte +offset:count list = ";
auto class_field_dirty_count_sorted =
SortByValueDesc<off_t, int, int>(class_field_dirty_count);
for (auto pair : class_field_dirty_count_sorted) {
off_t offset = pair.second;
int count = pair.first;
os << "+" << offset << ":" << count << ", ";
}
os << "\n";
os << " field contents:\n";
const auto& dirty_objects_list = class_data[klass].dirty_objects;
for (mirror::Object* obj : dirty_objects_list) {
// remote class object
auto remote_klass = reinterpret_cast<mirror::Class*>(obj);
// local class object
auto local_klass = RemoteContentsPointerToLocal(remote_klass,
remote_contents,
boot_image_header);
os << " " << reinterpret_cast<void*>(obj) << " ";
os << " class_status (remote): " << remote_klass->GetStatus() << ", ";
os << " class_status (local): " << local_klass->GetStatus();
os << "\n";
}
}
}
auto false_dirty_object_class_values = SortByValueDesc<mirror::Class*, int, ClassData>(
class_data, [](const ClassData& d) { return d.false_dirty_object_count; });
os << "\n" << " False-dirty object count by class:\n";
for (const auto& vk_pair : false_dirty_object_class_values) {
int object_count = vk_pair.first;
mirror::Class* klass = vk_pair.second;
int object_sizes = class_data[klass].false_dirty_byte_count;
float avg_object_size = object_sizes * 1.0f / object_count;
const std::string& descriptor = class_data[klass].descriptor;
os << " " << PrettyClass(klass) << " ("
<< "objects: " << object_count << ", "
<< "avg object size: " << avg_object_size << ", "
<< "total bytes: " << object_sizes << ", "
<< "class descriptor: '" << descriptor << "'"
<< ")\n";
if (strcmp(descriptor.c_str(), "Ljava/lang/reflect/ArtMethod;") == 0) {
auto& art_method_false_dirty_objects = class_data[klass].false_dirty_objects;
os << " field contents:\n";
for (mirror::Object* obj : art_method_false_dirty_objects) {
// local method
auto art_method = reinterpret_cast<ArtMethod*>(obj);
// local class
mirror::Class* declaring_class = art_method->GetDeclaringClass();
os << " " << reinterpret_cast<void*>(obj) << " ";
os << " entryPointFromJni: "
<< reinterpret_cast<const void*>(
art_method->GetEntryPointFromJniPtrSize(pointer_size)) << ", ";
os << " entryPointFromQuickCompiledCode: "
<< reinterpret_cast<const void*>(
art_method->GetEntryPointFromQuickCompiledCodePtrSize(pointer_size))
<< ", ";
os << " isNative? " << (art_method->IsNative() ? "yes" : "no") << ", ";
os << " class_status (local): " << declaring_class->GetStatus();
os << "\n";
}
}
}
os << "\n" << " Clean object count by class:\n";
for (const auto& vk_pair : clean_object_class_values) {
os << " " << PrettyClass(vk_pair.second) << " (" << vk_pair.first << ")\n";
}
return true;
}