chromium/v8/src/libsampler/sampler.cc

// 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"

#include "include/v8-isolate.h"
#include "include/v8-platform.h"
#include "include/v8-unwinder.h"

#ifdef USE_SIGNALS

#include <errno.h>
#include <pthread.h>
#include <signal.h>
#include <sys/time.h>
#include <atomic>

#if !V8_OS_QNX && !V8_OS_AIX && !V8_OS_ZOS
#include <sys/syscall.h>
#endif

#if V8_OS_AIX || V8_TARGET_ARCH_S390X

#include "src/base/platform/time.h"

#elif V8_OS_DARWIN
#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_OPENBSD
#include <ucontext.h>
#endif

#include <unistd.h>

#elif V8_OS_WIN || V8_OS_CYGWIN

#include <windows.h>

#elif V8_OS_FUCHSIA

#include <zircon/process.h>
#include <zircon/syscalls.h>
#include <zircon/syscalls/debug.h>
#include <zircon/types.h>

// TODO(wez): Remove this once the Fuchsia SDK has rolled.
#if defined(ZX_THREAD_STATE_REGSET0)
#define ZX_THREAD_STATE_GENERAL_REGS …
zx_status_t zx_thread_read_state(zx_handle_t h, uint32_t k, void* b, size_t l) {
  uint32_t dummy_out_len = 0;
  return zx_thread_read_state(h, k, b, static_cast<uint32_t>(l),
                              &dummy_out_len);
}
#if defined(__x86_64__)
using zx_thread_state_general_regs_t = zx_x86_64_general_regs_t;
#else
using zx_thread_state_general_regs_t = zx_arm64_general_regs_t;
#endif
#endif  // !defined(ZX_THREAD_STATE_GENERAL_REGS)

#endif

#include <algorithm>
#include <vector>

#include "src/base/atomic-utils.h"
#include "src/base/platform/platform.h"

#if V8_OS_ZOS
// Header from zoslib, for __mcontext_t_:
#include "edcwccwi.h"
#endif

#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__)

using mcontext_t = struct sigcontext;

struct ucontext_t {
  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.
};

#elif defined(__aarch64__)

using mcontext_t = struct sigcontext;

struct ucontext_t {
  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.
};

#elif defined(__mips__)
// MIPS version of sigcontext, for Android bionic.
struct mcontext_t {
  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;
};

struct ucontext_t {
  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.
};

#elif defined(__i386__)
// x86 version for Android.
struct mcontext_t {
  uint32_t gregs[19];
  void* fpregs;
  uint32_t oldmask;
  uint32_t cr2;
};

using kernel_sigset_t = uint32_t[2];  // x86 kernel uses 64-bit signal masks
struct ucontext_t {
  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.
};
enum { REG_EBP = 6, REG_ESP = 7, REG_EIP = 14 };

#elif defined(__x86_64__)
// x64 version for Android.
struct mcontext_t {
  uint64_t gregs[23];
  void* fpregs;
  uint64_t __reserved1[8];
};

struct ucontext_t {
  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.
};
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 defined(USE_SIGNALS)

AtomicGuard::AtomicGuard(AtomicMutex* atomic, bool is_blocking)
    : … { … }

AtomicGuard::~AtomicGuard() { … }

bool AtomicGuard::is_success() const { … }

class Sampler::PlatformData { … };

void SamplerManager::AddSampler(Sampler* sampler) { … }

void SamplerManager::RemoveSampler(Sampler* sampler) { … }

void SamplerManager::DoSample(const v8::RegisterState& state) { … }

SamplerManager* SamplerManager::instance() { … }

#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.
  PlatformData() {
    HANDLE current_process = GetCurrentProcess();
    BOOL result = DuplicateHandle(
        current_process, GetCurrentThread(), current_process, &profiled_thread_,
        THREAD_GET_CONTEXT | THREAD_SUSPEND_RESUME | THREAD_QUERY_INFORMATION,
        FALSE, 0);
    DCHECK(result);
    USE(result);
  }

  ~PlatformData() {
    if (profiled_thread_ != nullptr) {
      CloseHandle(profiled_thread_);
      profiled_thread_ = nullptr;
    }
  }

  HANDLE profiled_thread() { return profiled_thread_; }

 private:
  HANDLE profiled_thread_;
};

#elif V8_OS_FUCHSIA

class Sampler::PlatformData {
 public:
  PlatformData() {
    zx_handle_duplicate(zx_thread_self(), ZX_RIGHT_SAME_RIGHTS,
                        &profiled_thread_);
  }
  ~PlatformData() {
    if (profiled_thread_ != ZX_HANDLE_INVALID) {
      zx_handle_close(profiled_thread_);
      profiled_thread_ = ZX_HANDLE_INVALID;
    }
  }

  zx_handle_t profiled_thread() { return profiled_thread_; }

 private:
  zx_handle_t profiled_thread_ = ZX_HANDLE_INVALID;
};

#endif  // USE_SIGNALS

#if defined(USE_SIGNALS)
class SignalHandler { … };

base::LazyRecursiveMutex SignalHandler::mutex_ = …;

int SignalHandler::client_count_ = …;
struct sigaction SignalHandler::old_signal_handler_;
bool SignalHandler::signal_handler_installed_ = …;

void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
                                         void* context) { … }

void SignalHandler::FillRegisterState(void* context, RegisterState* state) { … }

#endif  // USE_SIGNALS

Sampler::Sampler(Isolate* isolate)
    : … { … }

Sampler::~Sampler() { … }

void Sampler::Start() { … }

void Sampler::Stop() { … }

#if defined(USE_SIGNALS)

void Sampler::DoSample() { … }

#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);
#elif V8_HOST_ARCH_ARM64
    state.pc = reinterpret_cast<void*>(context.Pc);
    state.sp = reinterpret_cast<void*>(context.Sp);
    state.fp = reinterpret_cast<void*>(context.Fp);
#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_FUCHSIA

void Sampler::DoSample() {
  zx_handle_t profiled_thread = platform_data()->profiled_thread();
  if (profiled_thread == ZX_HANDLE_INVALID) return;

  zx_handle_t suspend_token = ZX_HANDLE_INVALID;
  if (zx_task_suspend_token(profiled_thread, &suspend_token) != ZX_OK) return;

  // Wait for the target thread to become suspended, or to exit.
  // TODO(wez): There is currently no suspension count for threads, so there
  // is a risk that some other caller resumes the thread in-between our suspend
  // and wait calls, causing us to miss the SUSPENDED signal. We apply a 100ms
  // deadline to protect against hanging the sampler thread in this case.
  zx_signals_t signals = 0;
  zx_status_t suspended = zx_object_wait_one(
      profiled_thread, ZX_THREAD_SUSPENDED | ZX_THREAD_TERMINATED,
      zx_deadline_after(ZX_MSEC(100)), &signals);
  if (suspended != ZX_OK || (signals & ZX_THREAD_SUSPENDED) == 0) {
    zx_handle_close(suspend_token);
    return;
  }

  // Fetch a copy of its "general register" states.
  zx_thread_state_general_regs_t thread_state = {};
  if (zx_thread_read_state(profiled_thread, ZX_THREAD_STATE_GENERAL_REGS,
                           &thread_state, sizeof(thread_state)) == ZX_OK) {
    v8::RegisterState state;
#if V8_HOST_ARCH_X64
    state.pc = reinterpret_cast<void*>(thread_state.rip);
    state.sp = reinterpret_cast<void*>(thread_state.rsp);
    state.fp = reinterpret_cast<void*>(thread_state.rbp);
#elif V8_HOST_ARCH_ARM64
    state.pc = reinterpret_cast<void*>(thread_state.pc);
    state.sp = reinterpret_cast<void*>(thread_state.sp);
    state.fp = reinterpret_cast<void*>(thread_state.r[29]);
#endif
    SampleStack(state);
  }

  zx_handle_close(suspend_token);
}

// TODO(wez): Remove this once the Fuchsia SDK has rolled.
#if defined(ZX_THREAD_STATE_REGSET0)
#undef ZX_THREAD_STATE_GENERAL_REGS
#endif

#endif  // USE_SIGNALS

}  // namespace sampler
}  // namespace v8