// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/profiler/libunwindstack_unwinder_android.h"
#include <sys/mman.h>
#include <string>
#include <vector>
#include "third_party/libunwindstack/src/libunwindstack/include/unwindstack/Elf.h"
#include "third_party/libunwindstack/src/libunwindstack/include/unwindstack/Error.h"
#include "third_party/libunwindstack/src/libunwindstack/include/unwindstack/Maps.h"
#include "third_party/libunwindstack/src/libunwindstack/include/unwindstack/Memory.h"
#include "third_party/libunwindstack/src/libunwindstack/include/unwindstack/Regs.h"
#include "third_party/libunwindstack/src/libunwindstack/include/unwindstack/Unwinder.h"
#include "base/logging.h"
#include "base/memory/ptr_util.h"
#include "base/notreached.h"
#include "base/profiler/module_cache.h"
#include "base/profiler/native_unwinder_android.h"
#include "base/profiler/profile_builder.h"
#include "base/trace_event/base_tracing.h"
#include "build/build_config.h"
#if defined(ARCH_CPU_ARM_FAMILY) && defined(ARCH_CPU_32_BITS)
#include "third_party/libunwindstack/src/libunwindstack/include/unwindstack/MachineArm.h"
#include "third_party/libunwindstack/src/libunwindstack/include/unwindstack/RegsArm.h"
#elif defined(ARCH_CPU_ARM_FAMILY) && defined(ARCH_CPU_64_BITS)
#include "third_party/libunwindstack/src/libunwindstack/include/unwindstack/MachineArm64.h"
#include "third_party/libunwindstack/src/libunwindstack/include/unwindstack/RegsArm64.h"
#endif // #if defined(ARCH_CPU_ARM_FAMILY) && defined(ARCH_CPU_32_BITS)
namespace base {
namespace {
class NonElfModule : public ModuleCache::Module {
public:
explicit NonElfModule(unwindstack::MapInfo* map_info)
: start_(map_info->start()),
size_(map_info->end() - start_),
map_info_name_(map_info->name()) {}
~NonElfModule() override = default;
uintptr_t GetBaseAddress() const override { return start_; }
std::string GetId() const override { return std::string(); }
FilePath GetDebugBasename() const override {
return FilePath(map_info_name_);
}
size_t GetSize() const override { return size_; }
bool IsNative() const override { return true; }
private:
const uintptr_t start_;
const size_t size_;
const std::string map_info_name_;
};
std::unique_ptr<unwindstack::Regs> CreateFromRegisterContext(
RegisterContext* thread_context) {
#if defined(ARCH_CPU_ARM_FAMILY) && defined(ARCH_CPU_32_BITS)
return base::WrapUnique<unwindstack::Regs>(unwindstack::RegsArm::Read(
reinterpret_cast<void*>(&thread_context->arm_r0)));
#elif defined(ARCH_CPU_ARM_FAMILY) && defined(ARCH_CPU_64_BITS)
return base::WrapUnique<unwindstack::Regs>(unwindstack::RegsArm64::Read(
reinterpret_cast<void*>(&thread_context->regs[0])));
#else // #if defined(ARCH_CPU_ARM_FAMILY) && defined(ARCH_CPU_32_BITS)
NOTREACHED();
#endif // #if defined(ARCH_CPU_ARM_FAMILY) && defined(ARCH_CPU_32_BITS)
}
void WriteLibunwindstackTraceEventArgs(unwindstack::ErrorCode error_code,
std::optional<int> num_frames,
perfetto::EventContext& ctx) {
auto* track_event = ctx.event<perfetto::protos::pbzero::ChromeTrackEvent>();
auto* libunwindstack_unwinder = track_event->set_libunwindstack_unwinder();
using ProtoEnum = perfetto::protos::pbzero::LibunwindstackUnwinder::ErrorCode;
libunwindstack_unwinder->set_error_code(static_cast<ProtoEnum>(error_code));
if (num_frames.has_value()) {
libunwindstack_unwinder->set_num_frames(*num_frames);
}
}
bool IsJavaModule(const base::ModuleCache::Module* module) {
if (!module) {
return false;
}
const auto path = module->GetDebugBasename();
const std::string& debug_basename = path.value();
return debug_basename.find("chrome.apk") != std::string::npos ||
debug_basename.find("base.apk") != std::string::npos;
}
} // namespace
LibunwindstackUnwinderAndroid::LibunwindstackUnwinderAndroid()
: memory_regions_map_(
static_cast<NativeUnwinderAndroidMemoryRegionsMapImpl*>(
NativeUnwinderAndroid::CreateMemoryRegionsMap(
/*use_updatable_maps=*/false)
.release())) {
TRACE_EVENT_INSTANT(
TRACE_DISABLED_BY_DEFAULT("cpu_profiler"),
"LibunwindstackUnwinderAndroid::LibunwindstackUnwinderAndroid");
}
LibunwindstackUnwinderAndroid::~LibunwindstackUnwinderAndroid() = default;
void LibunwindstackUnwinderAndroid::InitializeModules() {}
bool LibunwindstackUnwinderAndroid::CanUnwindFrom(
const Frame& current_frame) const {
return true;
}
unwindstack::JitDebug* LibunwindstackUnwinderAndroid::GetOrCreateJitDebug(
unwindstack::ArchEnum arch) {
if (!jit_debug_) {
jit_debug_ = unwindstack::CreateJitDebug(
arch, memory_regions_map_->memory(), search_libs_);
}
return jit_debug_.get();
}
unwindstack::DexFiles* LibunwindstackUnwinderAndroid::GetOrCreateDexFiles(
unwindstack::ArchEnum arch) {
if (!dex_files_) {
dex_files_ = unwindstack::CreateDexFiles(
arch, memory_regions_map_->memory(), search_libs_);
}
return dex_files_.get();
}
UnwindResult LibunwindstackUnwinderAndroid::TryUnwind(
UnwinderStateCapture* capture_state,
RegisterContext* thread_context,
uintptr_t stack_top,
std::vector<Frame>* stack) {
TRACE_EVENT(TRACE_DISABLED_BY_DEFAULT("cpu_profiler.debug"),
"LibunwindstackUnwinderAndroid::TryUnwind");
// 500 is taken from traced_perf's own limit:
// https://cs.android.com/android/platform/superproject/+/master:external/perfetto/src/profiling/memory/unwinding.cc;l=64;drc=5860970a8606bb48059aa31ee506328286b9bf92
const int kMaxFrames = 500;
// We use a struct and lambda here to cleanly express the result of an attempt
// to unwind. Sometimes when we fail we can succeed if we reparse maps and so
// we will call |attempt_unwind| twice.
struct UnwindValues {
unwindstack::ErrorCode error_code;
uint64_t warnings;
std::vector<unwindstack::FrameData> frames;
};
std::unique_ptr<unwindstack::Regs> regs =
CreateFromRegisterContext(thread_context);
DCHECK(regs);
TRACE_EVENT_BEGIN(TRACE_DISABLED_BY_DEFAULT("cpu_profiler.debug"),
"libunwindstack::Unwind");
unwindstack::Unwinder unwinder(kMaxFrames, memory_regions_map_->maps(),
regs.get(), memory_regions_map_->memory());
unwinder.SetJitDebug(GetOrCreateJitDebug(regs->Arch()));
unwinder.SetDexFiles(GetOrCreateDexFiles(regs->Arch()));
unwinder.Unwind(/*initial_map_names_to_skip=*/nullptr,
/*map_suffixes_to_ignore=*/nullptr);
TRACE_EVENT_END(TRACE_DISABLED_BY_DEFAULT("cpu_profiler.debug"));
// Currently libunwindstack doesn't support warnings.
UnwindValues values =
UnwindValues{unwinder.LastErrorCode(), /*unwinder.warnings()*/ 0,
unwinder.ConsumeFrames()};
if (values.error_code != unwindstack::ERROR_NONE) {
TRACE_EVENT_INSTANT(TRACE_DISABLED_BY_DEFAULT("cpu_profiler.debug"),
"Libunwindstack Failure",
[&values](perfetto::EventContext& ctx) {
WriteLibunwindstackTraceEventArgs(
values.error_code, values.frames.size(), ctx);
});
}
if (values.frames.empty()) {
return UnwindResult::kCompleted;
}
// The list of frames provided by Libunwindstack's Unwind() contains the
// executing frame. The executing frame is also added by
// StackSamplerImpl::WalkStack(). Ignore the frame from the latter to avoid
// duplication. In case a java method was being interpreted libunwindstack
// adds a dummy frame for it and then writes the corresponding native frame.
// In such a scenario we want to prefer the frames produced by
// libunwindstack.
DCHECK_EQ(stack->size(), 1u);
stack->clear();
for (const unwindstack::FrameData& frame : values.frames) {
const ModuleCache::Module* module =
module_cache()->GetModuleForAddress(frame.pc);
if (module == nullptr && frame.map_info != nullptr) {
// Try searching for the module with same module start.
module = module_cache()->GetModuleForAddress(frame.map_info->start());
if (module == nullptr) {
auto module_for_caching =
std::make_unique<NonElfModule>(frame.map_info.get());
module = module_for_caching.get();
module_cache()->AddCustomNativeModule(std::move(module_for_caching));
}
if (frame.pc < frame.map_info->start() ||
frame.pc >= frame.map_info->end()) {
TRACE_EVENT_INSTANT(TRACE_DISABLED_BY_DEFAULT("cpu_profiler"),
"PC out of map range",
[&values](perfetto::EventContext& ctx) {
WriteLibunwindstackTraceEventArgs(
values.error_code, std::nullopt, ctx);
});
}
}
std::string function_name = IsJavaModule(module) ? frame.function_name : "";
stack->emplace_back(frame.pc, module, std::move(function_name));
}
return UnwindResult::kCompleted;
}
} // namespace base
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