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// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/libsampler/sampler.h"
#if V8_OS_POSIX && !V8_OS_CYGWIN
#define USE_SIGNALS
#include <errno.h>
#include <pthread.h>
#include <signal.h>
#include <sys/time.h>
#if !V8_OS_QNX && !V8_OS_FUCHSIA && !V8_OS_AIX
#include <sys/syscall.h> // NOLINT
#endif
#if V8_OS_MACOSX
#include <mach/mach.h>
// OpenBSD doesn't have <ucontext.h>. ucontext_t lives in <signal.h>
// and is a typedef for struct sigcontext. There is no uc_mcontext.
#elif(!V8_OS_ANDROID || defined(__BIONIC_HAVE_UCONTEXT_T)) && !V8_OS_OPENBSD
#include <ucontext.h>
#endif
#include <unistd.h>
// GLibc on ARM defines mcontext_t has a typedef for 'struct sigcontext'.
// Old versions of the C library <signal.h> didn't define the type.
#if V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T) && \
(defined(__arm__) || defined(__aarch64__)) && \
!defined(__BIONIC_HAVE_STRUCT_SIGCONTEXT)
#include <asm/sigcontext.h> // NOLINT
#endif
#elif V8_OS_WIN || V8_OS_CYGWIN
#include "src/base/win32-headers.h"
#endif
#include <algorithm>
#include <vector>
#include <map>
#include "src/base/atomic-utils.h"
#include "src/base/hashmap.h"
#include "src/base/platform/platform.h"
#if V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T)
// Not all versions of Android's C library provide ucontext_t.
// Detect this and provide custom but compatible definitions. Note that these
// follow the GLibc naming convention to access register values from
// mcontext_t.
//
// See http://code.google.com/p/android/issues/detail?id=34784
#if defined(__arm__)
typedef struct sigcontext mcontext_t;
typedef struct ucontext {
uint32_t uc_flags;
struct ucontext* uc_link;
stack_t uc_stack;
mcontext_t uc_mcontext;
// Other fields are not used by V8, don't define them here.
} ucontext_t;
#elif defined(__aarch64__)
typedef struct sigcontext mcontext_t;
typedef struct ucontext {
uint64_t uc_flags;
struct ucontext *uc_link;
stack_t uc_stack;
mcontext_t uc_mcontext;
// Other fields are not used by V8, don't define them here.
} ucontext_t;
#elif defined(__mips__)
// MIPS version of sigcontext, for Android bionic.
typedef struct {
uint32_t regmask;
uint32_t status;
uint64_t pc;
uint64_t gregs[32];
uint64_t fpregs[32];
uint32_t acx;
uint32_t fpc_csr;
uint32_t fpc_eir;
uint32_t used_math;
uint32_t dsp;
uint64_t mdhi;
uint64_t mdlo;
uint32_t hi1;
uint32_t lo1;
uint32_t hi2;
uint32_t lo2;
uint32_t hi3;
uint32_t lo3;
} mcontext_t;
typedef struct ucontext {
uint32_t uc_flags;
struct ucontext* uc_link;
stack_t uc_stack;
mcontext_t uc_mcontext;
// Other fields are not used by V8, don't define them here.
} ucontext_t;
#elif defined(__i386__)
// x86 version for Android.
typedef struct {
uint32_t gregs[19];
void* fpregs;
uint32_t oldmask;
uint32_t cr2;
} mcontext_t;
typedef uint32_t kernel_sigset_t[2]; // x86 kernel uses 64-bit signal masks
typedef struct ucontext {
uint32_t uc_flags;
struct ucontext* uc_link;
stack_t uc_stack;
mcontext_t uc_mcontext;
// Other fields are not used by V8, don't define them here.
} ucontext_t;
enum { REG_EBP = 6, REG_ESP = 7, REG_EIP = 14 };
#elif defined(__x86_64__)
// x64 version for Android.
typedef struct {
uint64_t gregs[23];
void* fpregs;
uint64_t __reserved1[8];
} mcontext_t;
typedef struct ucontext {
uint64_t uc_flags;
struct ucontext *uc_link;
stack_t uc_stack;
mcontext_t uc_mcontext;
// Other fields are not used by V8, don't define them here.
} ucontext_t;
enum { REG_RBP = 10, REG_RSP = 15, REG_RIP = 16 };
#endif
#endif // V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T)
namespace v8 {
namespace sampler {
#if V8_OS_STARBOARD
class Sampler::PlatformData {
public:
PlatformData() = default;
};
#endif
namespace {
#if defined(USE_SIGNALS)
typedef std::vector<Sampler*> SamplerList;
typedef SamplerList::iterator SamplerListIterator;
typedef base::AtomicValue<bool> AtomicMutex;
class AtomicGuard {
public:
explicit AtomicGuard(AtomicMutex* atomic, bool is_blocking = true)
: atomic_(atomic), is_success_(false) {
do {
// Use Acquire_Load to gain mutual exclusion.
USE(atomic_->Value());
is_success_ = atomic_->TrySetValue(false, true);
} while (is_blocking && !is_success_);
}
bool is_success() const { return is_success_; }
~AtomicGuard() {
if (!is_success_) return;
atomic_->SetValue(false);
}
private:
AtomicMutex* const atomic_;
bool is_success_;
};
// Returns key for hash map.
void* ThreadKey(pthread_t thread_id) {
return reinterpret_cast<void*>(thread_id);
}
// Returns hash value for hash map.
uint32_t ThreadHash(pthread_t thread_id) {
#if V8_OS_BSD
return static_cast<uint32_t>(reinterpret_cast<intptr_t>(thread_id));
#else
return static_cast<uint32_t>(thread_id);
#endif
}
#endif // USE_SIGNALS
} // namespace
#if defined(USE_SIGNALS)
class Sampler::PlatformData {
public:
PlatformData() : vm_tid_(pthread_self()) {}
pthread_t vm_tid() const { return vm_tid_; }
private:
pthread_t vm_tid_;
};
class SamplerManager {
public:
SamplerManager() : sampler_map_() {}
void AddSampler(Sampler* sampler) {
AtomicGuard atomic_guard(&samplers_access_counter_);
DCHECK(sampler->IsActive() || !sampler->IsRegistered());
// Add sampler into map if needed.
pthread_t thread_id = sampler->platform_data()->vm_tid();
base::HashMap::Entry* entry =
sampler_map_.LookupOrInsert(ThreadKey(thread_id),
ThreadHash(thread_id));
DCHECK_NOT_NULL(entry);
if (entry->value == nullptr) {
SamplerList* samplers = new SamplerList();
samplers->push_back(sampler);
entry->value = samplers;
} else {
SamplerList* samplers = reinterpret_cast<SamplerList*>(entry->value);
bool exists = false;
for (SamplerListIterator iter = samplers->begin();
iter != samplers->end(); ++iter) {
if (*iter == sampler) {
exists = true;
break;
}
}
if (!exists) {
samplers->push_back(sampler);
}
}
}
void RemoveSampler(Sampler* sampler) {
AtomicGuard atomic_guard(&samplers_access_counter_);
DCHECK(sampler->IsActive() || sampler->IsRegistered());
// Remove sampler from map.
pthread_t thread_id = sampler->platform_data()->vm_tid();
void* thread_key = ThreadKey(thread_id);
uint32_t thread_hash = ThreadHash(thread_id);
base::HashMap::Entry* entry = sampler_map_.Lookup(thread_key, thread_hash);
DCHECK_NOT_NULL(entry);
SamplerList* samplers = reinterpret_cast<SamplerList*>(entry->value);
for (SamplerListIterator iter = samplers->begin(); iter != samplers->end();
++iter) {
if (*iter == sampler) {
samplers->erase(iter);
break;
}
}
if (samplers->empty()) {
sampler_map_.Remove(thread_key, thread_hash);
delete samplers;
}
}
#if defined(USE_SIGNALS)
void DoSample(const v8::RegisterState& state) {
AtomicGuard atomic_guard(&SamplerManager::samplers_access_counter_, false);
if (!atomic_guard.is_success()) return;
pthread_t thread_id = pthread_self();
base::HashMap::Entry* entry =
sampler_map_.Lookup(ThreadKey(thread_id), ThreadHash(thread_id));
if (!entry) return;
SamplerList& samplers = *static_cast<SamplerList*>(entry->value);
for (size_t i = 0; i < samplers.size(); ++i) {
Sampler* sampler = samplers[i];
Isolate* isolate = sampler->isolate();
// We require a fully initialized and entered isolate.
if (isolate == nullptr || !isolate->IsInUse()) continue;
if (v8::Locker::IsActive() && !Locker::IsLocked(isolate)) continue;
sampler->SampleStack(state);
}
}
#endif
static SamplerManager* instance() { return instance_.Pointer(); }
private:
base::HashMap sampler_map_;
static AtomicMutex samplers_access_counter_;
static base::LazyInstance<SamplerManager>::type instance_;
};
AtomicMutex SamplerManager::samplers_access_counter_;
base::LazyInstance<SamplerManager>::type SamplerManager::instance_ =
LAZY_INSTANCE_INITIALIZER;
#elif V8_OS_WIN || V8_OS_CYGWIN
// ----------------------------------------------------------------------------
// Win32 profiler support. On Cygwin we use the same sampler implementation as
// on Win32.
class Sampler::PlatformData {
public:
// Get a handle to the calling thread. This is the thread that we are
// going to profile. We need to make a copy of the handle because we are
// going to use it in the sampler thread. Using GetThreadHandle() will
// not work in this case. We're using OpenThread because DuplicateHandle
// for some reason doesn't work in Chrome's sandbox.
PlatformData()
: profiled_thread_(OpenThread(THREAD_GET_CONTEXT |
THREAD_SUSPEND_RESUME |
THREAD_QUERY_INFORMATION,
false,
GetCurrentThreadId())) {}
~PlatformData() {
if (profiled_thread_ != nullptr) {
CloseHandle(profiled_thread_);
profiled_thread_ = nullptr;
}
}
HANDLE profiled_thread() { return profiled_thread_; }
private:
HANDLE profiled_thread_;
};
#endif // USE_SIGNALS
#if defined(USE_SIGNALS)
class SignalHandler {
public:
static void SetUp() { if (!mutex_) mutex_ = new base::Mutex(); }
static void TearDown() {
delete mutex_;
mutex_ = nullptr;
}
static void IncreaseSamplerCount() {
base::LockGuard<base::Mutex> lock_guard(mutex_);
if (++client_count_ == 1) Install();
}
static void DecreaseSamplerCount() {
base::LockGuard<base::Mutex> lock_guard(mutex_);
if (--client_count_ == 0) Restore();
}
static bool Installed() {
base::LockGuard<base::Mutex> lock_guard(mutex_);
return signal_handler_installed_;
}
private:
static void Install() {
struct sigaction sa;
sa.sa_sigaction = &HandleProfilerSignal;
sigemptyset(&sa.sa_mask);
#if V8_OS_QNX
sa.sa_flags = SA_SIGINFO;
#else
sa.sa_flags = SA_RESTART | SA_SIGINFO;
#endif
signal_handler_installed_ =
(sigaction(SIGPROF, &sa, &old_signal_handler_) == 0);
}
static void Restore() {
if (signal_handler_installed_) {
sigaction(SIGPROF, &old_signal_handler_, 0);
signal_handler_installed_ = false;
}
}
static void FillRegisterState(void* context, RegisterState* regs);
static void HandleProfilerSignal(int signal, siginfo_t* info, void* context);
// Protects the process wide state below.
static base::Mutex* mutex_;
static int client_count_;
static bool signal_handler_installed_;
static struct sigaction old_signal_handler_;
};
base::Mutex* SignalHandler::mutex_ = nullptr;
int SignalHandler::client_count_ = 0;
struct sigaction SignalHandler::old_signal_handler_;
bool SignalHandler::signal_handler_installed_ = false;
void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
void* context) {
USE(info);
if (signal != SIGPROF) return;
v8::RegisterState state;
FillRegisterState(context, &state);
SamplerManager::instance()->DoSample(state);
}
void SignalHandler::FillRegisterState(void* context, RegisterState* state) {
// Extracting the sample from the context is extremely machine dependent.
ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(context);
#if !(V8_OS_OPENBSD || (V8_OS_LINUX && (V8_HOST_ARCH_PPC || V8_HOST_ARCH_S390)))
mcontext_t& mcontext = ucontext->uc_mcontext;
#endif
#if V8_OS_LINUX || V8_OS_FUCHSIA
#if V8_HOST_ARCH_IA32
state->pc = reinterpret_cast<void*>(mcontext.gregs[REG_EIP]);
state->sp = reinterpret_cast<void*>(mcontext.gregs[REG_ESP]);
state->fp = reinterpret_cast<void*>(mcontext.gregs[REG_EBP]);
#elif V8_HOST_ARCH_X64
state->pc = reinterpret_cast<void*>(mcontext.gregs[REG_RIP]);
state->sp = reinterpret_cast<void*>(mcontext.gregs[REG_RSP]);
state->fp = reinterpret_cast<void*>(mcontext.gregs[REG_RBP]);
#elif V8_HOST_ARCH_ARM
#if V8_LIBC_GLIBC && !V8_GLIBC_PREREQ(2, 4)
// Old GLibc ARM versions used a gregs[] array to access the register
// values from mcontext_t.
state->pc = reinterpret_cast<void*>(mcontext.gregs[R15]);
state->sp = reinterpret_cast<void*>(mcontext.gregs[R13]);
state->fp = reinterpret_cast<void*>(mcontext.gregs[R11]);
#else
state->pc = reinterpret_cast<void*>(mcontext.arm_pc);
state->sp = reinterpret_cast<void*>(mcontext.arm_sp);
state->fp = reinterpret_cast<void*>(mcontext.arm_fp);
#endif // V8_LIBC_GLIBC && !V8_GLIBC_PREREQ(2, 4)
#elif V8_HOST_ARCH_ARM64
state->pc = reinterpret_cast<void*>(mcontext.pc);
state->sp = reinterpret_cast<void*>(mcontext.sp);
// FP is an alias for x29.
state->fp = reinterpret_cast<void*>(mcontext.regs[29]);
#elif V8_HOST_ARCH_MIPS
state->pc = reinterpret_cast<void*>(mcontext.pc);
state->sp = reinterpret_cast<void*>(mcontext.gregs[29]);
state->fp = reinterpret_cast<void*>(mcontext.gregs[30]);
#elif V8_HOST_ARCH_MIPS64
state->pc = reinterpret_cast<void*>(mcontext.pc);
state->sp = reinterpret_cast<void*>(mcontext.gregs[29]);
state->fp = reinterpret_cast<void*>(mcontext.gregs[30]);
#elif V8_HOST_ARCH_PPC
#if V8_LIBC_GLIBC
state->pc = reinterpret_cast<void*>(ucontext->uc_mcontext.regs->nip);
state->sp =
reinterpret_cast<void*>(ucontext->uc_mcontext.regs->gpr[PT_R1]);
state->fp =
reinterpret_cast<void*>(ucontext->uc_mcontext.regs->gpr[PT_R31]);
#else
// Some C libraries, notably Musl, define the regs member as a void pointer
state->pc = reinterpret_cast<void*>(ucontext->uc_mcontext.gp_regs[32]);
state->sp = reinterpret_cast<void*>(ucontext->uc_mcontext.gp_regs[1]);
state->fp = reinterpret_cast<void*>(ucontext->uc_mcontext.gp_regs[31]);
#endif
#elif V8_HOST_ARCH_S390
#if V8_TARGET_ARCH_32_BIT
// 31-bit target will have bit 0 (MSB) of the PSW set to denote addressing
// mode. This bit needs to be masked out to resolve actual address.
state->pc =
reinterpret_cast<void*>(ucontext->uc_mcontext.psw.addr & 0x7FFFFFFF);
#else
state->pc = reinterpret_cast<void*>(ucontext->uc_mcontext.psw.addr);
#endif // V8_TARGET_ARCH_32_BIT
state->sp = reinterpret_cast<void*>(ucontext->uc_mcontext.gregs[15]);
state->fp = reinterpret_cast<void*>(ucontext->uc_mcontext.gregs[11]);
#endif // V8_HOST_ARCH_*
#elif V8_OS_MACOSX
#if V8_HOST_ARCH_X64
#if __DARWIN_UNIX03
state->pc = reinterpret_cast<void*>(mcontext->__ss.__rip);
state->sp = reinterpret_cast<void*>(mcontext->__ss.__rsp);
state->fp = reinterpret_cast<void*>(mcontext->__ss.__rbp);
#else // !__DARWIN_UNIX03
state->pc = reinterpret_cast<void*>(mcontext->ss.rip);
state->sp = reinterpret_cast<void*>(mcontext->ss.rsp);
state->fp = reinterpret_cast<void*>(mcontext->ss.rbp);
#endif // __DARWIN_UNIX03
#elif V8_HOST_ARCH_IA32
#if __DARWIN_UNIX03
state->pc = reinterpret_cast<void*>(mcontext->__ss.__eip);
state->sp = reinterpret_cast<void*>(mcontext->__ss.__esp);
state->fp = reinterpret_cast<void*>(mcontext->__ss.__ebp);
#else // !__DARWIN_UNIX03
state->pc = reinterpret_cast<void*>(mcontext->ss.eip);
state->sp = reinterpret_cast<void*>(mcontext->ss.esp);
state->fp = reinterpret_cast<void*>(mcontext->ss.ebp);
#endif // __DARWIN_UNIX03
#endif // V8_HOST_ARCH_IA32
#elif V8_OS_FREEBSD
#if V8_HOST_ARCH_IA32
state->pc = reinterpret_cast<void*>(mcontext.mc_eip);
state->sp = reinterpret_cast<void*>(mcontext.mc_esp);
state->fp = reinterpret_cast<void*>(mcontext.mc_ebp);
#elif V8_HOST_ARCH_X64
state->pc = reinterpret_cast<void*>(mcontext.mc_rip);
state->sp = reinterpret_cast<void*>(mcontext.mc_rsp);
state->fp = reinterpret_cast<void*>(mcontext.mc_rbp);
#elif V8_HOST_ARCH_ARM
state->pc = reinterpret_cast<void*>(mcontext.mc_r15);
state->sp = reinterpret_cast<void*>(mcontext.mc_r13);
state->fp = reinterpret_cast<void*>(mcontext.mc_r11);
#endif // V8_HOST_ARCH_*
#elif V8_OS_NETBSD
#if V8_HOST_ARCH_IA32
state->pc = reinterpret_cast<void*>(mcontext.__gregs[_REG_EIP]);
state->sp = reinterpret_cast<void*>(mcontext.__gregs[_REG_ESP]);
state->fp = reinterpret_cast<void*>(mcontext.__gregs[_REG_EBP]);
#elif V8_HOST_ARCH_X64
state->pc = reinterpret_cast<void*>(mcontext.__gregs[_REG_RIP]);
state->sp = reinterpret_cast<void*>(mcontext.__gregs[_REG_RSP]);
state->fp = reinterpret_cast<void*>(mcontext.__gregs[_REG_RBP]);
#endif // V8_HOST_ARCH_*
#elif V8_OS_OPENBSD
#if V8_HOST_ARCH_IA32
state->pc = reinterpret_cast<void*>(ucontext->sc_eip);
state->sp = reinterpret_cast<void*>(ucontext->sc_esp);
state->fp = reinterpret_cast<void*>(ucontext->sc_ebp);
#elif V8_HOST_ARCH_X64
state->pc = reinterpret_cast<void*>(ucontext->sc_rip);
state->sp = reinterpret_cast<void*>(ucontext->sc_rsp);
state->fp = reinterpret_cast<void*>(ucontext->sc_rbp);
#endif // V8_HOST_ARCH_*
#elif V8_OS_SOLARIS
state->pc = reinterpret_cast<void*>(mcontext.gregs[REG_PC]);
state->sp = reinterpret_cast<void*>(mcontext.gregs[REG_SP]);
state->fp = reinterpret_cast<void*>(mcontext.gregs[REG_FP]);
#elif V8_OS_QNX
#if V8_HOST_ARCH_IA32
state->pc = reinterpret_cast<void*>(mcontext.cpu.eip);
state->sp = reinterpret_cast<void*>(mcontext.cpu.esp);
state->fp = reinterpret_cast<void*>(mcontext.cpu.ebp);
#elif V8_HOST_ARCH_ARM
state->pc = reinterpret_cast<void*>(mcontext.cpu.gpr[ARM_REG_PC]);
state->sp = reinterpret_cast<void*>(mcontext.cpu.gpr[ARM_REG_SP]);
state->fp = reinterpret_cast<void*>(mcontext.cpu.gpr[ARM_REG_FP]);
#endif // V8_HOST_ARCH_*
#elif V8_OS_AIX
state->pc = reinterpret_cast<void*>(mcontext.jmp_context.iar);
state->sp = reinterpret_cast<void*>(mcontext.jmp_context.gpr[1]);
state->fp = reinterpret_cast<void*>(mcontext.jmp_context.gpr[31]);
#endif // V8_OS_AIX
}
#endif // USE_SIGNALS
void Sampler::SetUp() {
#if defined(USE_SIGNALS)
SignalHandler::SetUp();
#endif
}
void Sampler::TearDown() {
#if defined(USE_SIGNALS)
SignalHandler::TearDown();
#endif
}
Sampler::Sampler(Isolate* isolate)
: is_counting_samples_(false),
js_sample_count_(0),
external_sample_count_(0),
isolate_(isolate),
profiling_(false),
has_processing_thread_(false),
active_(false),
registered_(false) {
data_ = new PlatformData;
}
Sampler::~Sampler() {
DCHECK(!IsActive());
#if defined(USE_SIGNALS)
if (IsRegistered()) {
SamplerManager::instance()->RemoveSampler(this);
}
#endif
delete data_;
}
void Sampler::Start() {
DCHECK(!IsActive());
SetActive(true);
#if defined(USE_SIGNALS)
SamplerManager::instance()->AddSampler(this);
#endif
}
void Sampler::Stop() {
#if defined(USE_SIGNALS)
SamplerManager::instance()->RemoveSampler(this);
#endif
DCHECK(IsActive());
SetActive(false);
SetRegistered(false);
}
void Sampler::IncreaseProfilingDepth() {
base::Relaxed_AtomicIncrement(&profiling_, 1);
#if defined(USE_SIGNALS)
SignalHandler::IncreaseSamplerCount();
#endif
}
void Sampler::DecreaseProfilingDepth() {
#if defined(USE_SIGNALS)
SignalHandler::DecreaseSamplerCount();
#endif
base::Relaxed_AtomicIncrement(&profiling_, -1);
}
#if defined(USE_SIGNALS)
void Sampler::DoSample() {
if (!SignalHandler::Installed()) return;
if (!IsActive() && !IsRegistered()) {
SamplerManager::instance()->AddSampler(this);
SetRegistered(true);
}
pthread_kill(platform_data()->vm_tid(), SIGPROF);
}
#elif V8_OS_WIN || V8_OS_CYGWIN
void Sampler::DoSample() {
HANDLE profiled_thread = platform_data()->profiled_thread();
if (profiled_thread == nullptr) return;
const DWORD kSuspendFailed = static_cast<DWORD>(-1);
if (SuspendThread(profiled_thread) == kSuspendFailed) return;
// Context used for sampling the register state of the profiled thread.
CONTEXT context;
memset(&context, 0, sizeof(context));
context.ContextFlags = CONTEXT_FULL;
if (GetThreadContext(profiled_thread, &context) != 0) {
v8::RegisterState state;
#if V8_HOST_ARCH_X64
state.pc = reinterpret_cast<void*>(context.Rip);
state.sp = reinterpret_cast<void*>(context.Rsp);
state.fp = reinterpret_cast<void*>(context.Rbp);
#else
state.pc = reinterpret_cast<void*>(context.Eip);
state.sp = reinterpret_cast<void*>(context.Esp);
state.fp = reinterpret_cast<void*>(context.Ebp);
#endif
SampleStack(state);
}
ResumeThread(profiled_thread);
}
#elif V8_OS_STARBOARD
void Sampler::DoSample() {
SB_NOTIMPLEMENTED();
}
#endif // USE_SIGNALS
} // namespace sampler
} // namespace v8