1// Copyright 2013 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "src/sampler.h"
6
7#if V8_OS_POSIX && !V8_OS_CYGWIN
8
9#define USE_SIGNALS
10
11#include <errno.h>
12#include <pthread.h>
13#include <signal.h>
14#include <sys/time.h>
15
16#if !V8_OS_QNX
17#include <sys/syscall.h>
18#endif
19
20#if V8_OS_MACOSX
21#include <mach/mach.h>
22// OpenBSD doesn't have <ucontext.h>. ucontext_t lives in <signal.h>
23// and is a typedef for struct sigcontext. There is no uc_mcontext.
24#elif(!V8_OS_ANDROID || defined(__BIONIC_HAVE_UCONTEXT_T)) \
25    && !V8_OS_OPENBSD
26#include <ucontext.h>
27#endif
28
29#include <unistd.h>
30
31// GLibc on ARM defines mcontext_t has a typedef for 'struct sigcontext'.
32// Old versions of the C library <signal.h> didn't define the type.
33#if V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T) && \
34    (defined(__arm__) || defined(__aarch64__)) && \
35    !defined(__BIONIC_HAVE_STRUCT_SIGCONTEXT)
36#include <asm/sigcontext.h>
37#endif
38
39#elif V8_OS_WIN || V8_OS_CYGWIN
40
41#include "src/base/win32-headers.h"
42
43#endif
44
45#include "src/v8.h"
46
47#include "src/cpu-profiler-inl.h"
48#include "src/flags.h"
49#include "src/frames-inl.h"
50#include "src/log.h"
51#include "src/platform.h"
52#include "src/simulator.h"
53#include "src/v8threads.h"
54#include "src/vm-state-inl.h"
55
56
57#if V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T)
58
59// Not all versions of Android's C library provide ucontext_t.
60// Detect this and provide custom but compatible definitions. Note that these
61// follow the GLibc naming convention to access register values from
62// mcontext_t.
63//
64// See http://code.google.com/p/android/issues/detail?id=34784
65
66#if defined(__arm__)
67
68typedef struct sigcontext mcontext_t;
69
70typedef struct ucontext {
71  uint32_t uc_flags;
72  struct ucontext* uc_link;
73  stack_t uc_stack;
74  mcontext_t uc_mcontext;
75  // Other fields are not used by V8, don't define them here.
76} ucontext_t;
77
78#elif defined(__aarch64__)
79
80typedef struct sigcontext mcontext_t;
81
82typedef struct ucontext {
83  uint64_t uc_flags;
84  struct ucontext *uc_link;
85  stack_t uc_stack;
86  mcontext_t uc_mcontext;
87  // Other fields are not used by V8, don't define them here.
88} ucontext_t;
89
90#elif defined(__mips__)
91// MIPS version of sigcontext, for Android bionic.
92typedef struct {
93  uint32_t regmask;
94  uint32_t status;
95  uint64_t pc;
96  uint64_t gregs[32];
97  uint64_t fpregs[32];
98  uint32_t acx;
99  uint32_t fpc_csr;
100  uint32_t fpc_eir;
101  uint32_t used_math;
102  uint32_t dsp;
103  uint64_t mdhi;
104  uint64_t mdlo;
105  uint32_t hi1;
106  uint32_t lo1;
107  uint32_t hi2;
108  uint32_t lo2;
109  uint32_t hi3;
110  uint32_t lo3;
111} mcontext_t;
112
113typedef struct ucontext {
114  uint32_t uc_flags;
115  struct ucontext* uc_link;
116  stack_t uc_stack;
117  mcontext_t uc_mcontext;
118  // Other fields are not used by V8, don't define them here.
119} ucontext_t;
120
121#elif defined(__i386__)
122// x86 version for Android.
123typedef struct {
124  uint32_t gregs[19];
125  void* fpregs;
126  uint32_t oldmask;
127  uint32_t cr2;
128} mcontext_t;
129
130typedef uint32_t kernel_sigset_t[2];  // x86 kernel uses 64-bit signal masks
131typedef struct ucontext {
132  uint32_t uc_flags;
133  struct ucontext* uc_link;
134  stack_t uc_stack;
135  mcontext_t uc_mcontext;
136  // Other fields are not used by V8, don't define them here.
137} ucontext_t;
138enum { REG_EBP = 6, REG_ESP = 7, REG_EIP = 14 };
139
140#elif defined(__x86_64__)
141// x64 version for Android.
142typedef struct {
143  uint64_t gregs[23];
144  void* fpregs;
145  uint64_t __reserved1[8];
146} mcontext_t;
147
148typedef struct ucontext {
149  uint64_t uc_flags;
150  struct ucontext *uc_link;
151  stack_t uc_stack;
152  mcontext_t uc_mcontext;
153  // Other fields are not used by V8, don't define them here.
154} ucontext_t;
155enum { REG_RBP = 10, REG_RSP = 15, REG_RIP = 16 };
156#endif
157
158#endif  // V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T)
159
160
161namespace v8 {
162namespace internal {
163
164namespace {
165
166class PlatformDataCommon : public Malloced {
167 public:
168  PlatformDataCommon() : profiled_thread_id_(ThreadId::Current()) {}
169  ThreadId profiled_thread_id() { return profiled_thread_id_; }
170
171 protected:
172  ~PlatformDataCommon() {}
173
174 private:
175  ThreadId profiled_thread_id_;
176};
177
178}  // namespace
179
180#if defined(USE_SIGNALS)
181
182class Sampler::PlatformData : public PlatformDataCommon {
183 public:
184  PlatformData() : vm_tid_(pthread_self()) {}
185  pthread_t vm_tid() const { return vm_tid_; }
186
187 private:
188  pthread_t vm_tid_;
189};
190
191#elif V8_OS_WIN || V8_OS_CYGWIN
192
193// ----------------------------------------------------------------------------
194// Win32 profiler support. On Cygwin we use the same sampler implementation as
195// on Win32.
196
197class Sampler::PlatformData : public PlatformDataCommon {
198 public:
199  // Get a handle to the calling thread. This is the thread that we are
200  // going to profile. We need to make a copy of the handle because we are
201  // going to use it in the sampler thread. Using GetThreadHandle() will
202  // not work in this case. We're using OpenThread because DuplicateHandle
203  // for some reason doesn't work in Chrome's sandbox.
204  PlatformData()
205      : profiled_thread_(OpenThread(THREAD_GET_CONTEXT |
206                                    THREAD_SUSPEND_RESUME |
207                                    THREAD_QUERY_INFORMATION,
208                                    false,
209                                    GetCurrentThreadId())) {}
210
211  ~PlatformData() {
212    if (profiled_thread_ != NULL) {
213      CloseHandle(profiled_thread_);
214      profiled_thread_ = NULL;
215    }
216  }
217
218  HANDLE profiled_thread() { return profiled_thread_; }
219
220 private:
221  HANDLE profiled_thread_;
222};
223#endif
224
225
226#if defined(USE_SIMULATOR)
227class SimulatorHelper {
228 public:
229  inline bool Init(Sampler* sampler, Isolate* isolate) {
230    simulator_ = isolate->thread_local_top()->simulator_;
231    // Check if there is active simulator.
232    return simulator_ != NULL;
233  }
234
235  inline void FillRegisters(RegisterState* state) {
236#if V8_TARGET_ARCH_ARM
237    state->pc = reinterpret_cast<Address>(simulator_->get_pc());
238    state->sp = reinterpret_cast<Address>(simulator_->get_register(
239        Simulator::sp));
240    state->fp = reinterpret_cast<Address>(simulator_->get_register(
241        Simulator::r11));
242#elif V8_TARGET_ARCH_ARM64
243    if (simulator_->sp() == 0 || simulator_->fp() == 0) {
244      // It possible that the simulator is interrupted while it is updating
245      // the sp or fp register. ARM64 simulator does this in two steps:
246      // first setting it to zero and then setting it to the new value.
247      // Bailout if sp/fp doesn't contain the new value.
248      return;
249    }
250    state->pc = reinterpret_cast<Address>(simulator_->pc());
251    state->sp = reinterpret_cast<Address>(simulator_->sp());
252    state->fp = reinterpret_cast<Address>(simulator_->fp());
253#elif V8_TARGET_ARCH_MIPS
254    state->pc = reinterpret_cast<Address>(simulator_->get_pc());
255    state->sp = reinterpret_cast<Address>(simulator_->get_register(
256        Simulator::sp));
257    state->fp = reinterpret_cast<Address>(simulator_->get_register(
258        Simulator::fp));
259#endif
260  }
261
262 private:
263  Simulator* simulator_;
264};
265#endif  // USE_SIMULATOR
266
267
268#if defined(USE_SIGNALS)
269
270class SignalHandler : public AllStatic {
271 public:
272  static void SetUp() { if (!mutex_) mutex_ = new Mutex(); }
273  static void TearDown() { delete mutex_; }
274
275  static void IncreaseSamplerCount() {
276    LockGuard<Mutex> lock_guard(mutex_);
277    if (++client_count_ == 1) Install();
278  }
279
280  static void DecreaseSamplerCount() {
281    LockGuard<Mutex> lock_guard(mutex_);
282    if (--client_count_ == 0) Restore();
283  }
284
285  static bool Installed() {
286    return signal_handler_installed_;
287  }
288
289 private:
290  static void Install() {
291    struct sigaction sa;
292    sa.sa_sigaction = &HandleProfilerSignal;
293    sigemptyset(&sa.sa_mask);
294#if V8_OS_QNX
295    sa.sa_flags = SA_SIGINFO;
296#else
297    sa.sa_flags = SA_RESTART | SA_SIGINFO;
298#endif
299    signal_handler_installed_ =
300        (sigaction(SIGPROF, &sa, &old_signal_handler_) == 0);
301  }
302
303  static void Restore() {
304    if (signal_handler_installed_) {
305      sigaction(SIGPROF, &old_signal_handler_, 0);
306      signal_handler_installed_ = false;
307    }
308  }
309
310  static void HandleProfilerSignal(int signal, siginfo_t* info, void* context);
311  // Protects the process wide state below.
312  static Mutex* mutex_;
313  static int client_count_;
314  static bool signal_handler_installed_;
315  static struct sigaction old_signal_handler_;
316};
317
318
319Mutex* SignalHandler::mutex_ = NULL;
320int SignalHandler::client_count_ = 0;
321struct sigaction SignalHandler::old_signal_handler_;
322bool SignalHandler::signal_handler_installed_ = false;
323
324
325void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
326                                         void* context) {
327#if V8_OS_NACL
328  // As Native Client does not support signal handling, profiling
329  // is disabled.
330  return;
331#else
332  USE(info);
333  if (signal != SIGPROF) return;
334  Isolate* isolate = Isolate::UncheckedCurrent();
335  if (isolate == NULL || !isolate->IsInitialized() || !isolate->IsInUse()) {
336    // We require a fully initialized and entered isolate.
337    return;
338  }
339  if (v8::Locker::IsActive() &&
340      !isolate->thread_manager()->IsLockedByCurrentThread()) {
341    return;
342  }
343
344  Sampler* sampler = isolate->logger()->sampler();
345  if (sampler == NULL) return;
346
347  RegisterState state;
348
349#if defined(USE_SIMULATOR)
350  SimulatorHelper helper;
351  if (!helper.Init(sampler, isolate)) return;
352  helper.FillRegisters(&state);
353  // It possible that the simulator is interrupted while it is updating
354  // the sp or fp register. ARM64 simulator does this in two steps:
355  // first setting it to zero and then setting it to the new value.
356  // Bailout if sp/fp doesn't contain the new value.
357  if (state.sp == 0 || state.fp == 0) return;
358#else
359  // Extracting the sample from the context is extremely machine dependent.
360  ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(context);
361#if !V8_OS_OPENBSD
362  mcontext_t& mcontext = ucontext->uc_mcontext;
363#endif
364#if V8_OS_LINUX
365#if V8_HOST_ARCH_IA32
366  state.pc = reinterpret_cast<Address>(mcontext.gregs[REG_EIP]);
367  state.sp = reinterpret_cast<Address>(mcontext.gregs[REG_ESP]);
368  state.fp = reinterpret_cast<Address>(mcontext.gregs[REG_EBP]);
369#elif V8_HOST_ARCH_X64
370  state.pc = reinterpret_cast<Address>(mcontext.gregs[REG_RIP]);
371  state.sp = reinterpret_cast<Address>(mcontext.gregs[REG_RSP]);
372  state.fp = reinterpret_cast<Address>(mcontext.gregs[REG_RBP]);
373#elif V8_HOST_ARCH_ARM
374#if defined(__GLIBC__) && !defined(__UCLIBC__) && \
375    (__GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ <= 3))
376  // Old GLibc ARM versions used a gregs[] array to access the register
377  // values from mcontext_t.
378  state.pc = reinterpret_cast<Address>(mcontext.gregs[R15]);
379  state.sp = reinterpret_cast<Address>(mcontext.gregs[R13]);
380  state.fp = reinterpret_cast<Address>(mcontext.gregs[R11]);
381#else
382  state.pc = reinterpret_cast<Address>(mcontext.arm_pc);
383  state.sp = reinterpret_cast<Address>(mcontext.arm_sp);
384  state.fp = reinterpret_cast<Address>(mcontext.arm_fp);
385#endif  // defined(__GLIBC__) && !defined(__UCLIBC__) &&
386        // (__GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ <= 3))
387#elif V8_HOST_ARCH_ARM64
388  state.pc = reinterpret_cast<Address>(mcontext.pc);
389  state.sp = reinterpret_cast<Address>(mcontext.sp);
390  // FP is an alias for x29.
391  state.fp = reinterpret_cast<Address>(mcontext.regs[29]);
392#elif V8_HOST_ARCH_MIPS
393  state.pc = reinterpret_cast<Address>(mcontext.pc);
394  state.sp = reinterpret_cast<Address>(mcontext.gregs[29]);
395  state.fp = reinterpret_cast<Address>(mcontext.gregs[30]);
396#endif  // V8_HOST_ARCH_*
397#elif V8_OS_MACOSX
398#if V8_HOST_ARCH_X64
399#if __DARWIN_UNIX03
400  state.pc = reinterpret_cast<Address>(mcontext->__ss.__rip);
401  state.sp = reinterpret_cast<Address>(mcontext->__ss.__rsp);
402  state.fp = reinterpret_cast<Address>(mcontext->__ss.__rbp);
403#else  // !__DARWIN_UNIX03
404  state.pc = reinterpret_cast<Address>(mcontext->ss.rip);
405  state.sp = reinterpret_cast<Address>(mcontext->ss.rsp);
406  state.fp = reinterpret_cast<Address>(mcontext->ss.rbp);
407#endif  // __DARWIN_UNIX03
408#elif V8_HOST_ARCH_IA32
409#if __DARWIN_UNIX03
410  state.pc = reinterpret_cast<Address>(mcontext->__ss.__eip);
411  state.sp = reinterpret_cast<Address>(mcontext->__ss.__esp);
412  state.fp = reinterpret_cast<Address>(mcontext->__ss.__ebp);
413#else  // !__DARWIN_UNIX03
414  state.pc = reinterpret_cast<Address>(mcontext->ss.eip);
415  state.sp = reinterpret_cast<Address>(mcontext->ss.esp);
416  state.fp = reinterpret_cast<Address>(mcontext->ss.ebp);
417#endif  // __DARWIN_UNIX03
418#endif  // V8_HOST_ARCH_IA32
419#elif V8_OS_FREEBSD
420#if V8_HOST_ARCH_IA32
421  state.pc = reinterpret_cast<Address>(mcontext.mc_eip);
422  state.sp = reinterpret_cast<Address>(mcontext.mc_esp);
423  state.fp = reinterpret_cast<Address>(mcontext.mc_ebp);
424#elif V8_HOST_ARCH_X64
425  state.pc = reinterpret_cast<Address>(mcontext.mc_rip);
426  state.sp = reinterpret_cast<Address>(mcontext.mc_rsp);
427  state.fp = reinterpret_cast<Address>(mcontext.mc_rbp);
428#elif V8_HOST_ARCH_ARM
429  state.pc = reinterpret_cast<Address>(mcontext.mc_r15);
430  state.sp = reinterpret_cast<Address>(mcontext.mc_r13);
431  state.fp = reinterpret_cast<Address>(mcontext.mc_r11);
432#endif  // V8_HOST_ARCH_*
433#elif V8_OS_NETBSD
434#if V8_HOST_ARCH_IA32
435  state.pc = reinterpret_cast<Address>(mcontext.__gregs[_REG_EIP]);
436  state.sp = reinterpret_cast<Address>(mcontext.__gregs[_REG_ESP]);
437  state.fp = reinterpret_cast<Address>(mcontext.__gregs[_REG_EBP]);
438#elif V8_HOST_ARCH_X64
439  state.pc = reinterpret_cast<Address>(mcontext.__gregs[_REG_RIP]);
440  state.sp = reinterpret_cast<Address>(mcontext.__gregs[_REG_RSP]);
441  state.fp = reinterpret_cast<Address>(mcontext.__gregs[_REG_RBP]);
442#endif  // V8_HOST_ARCH_*
443#elif V8_OS_OPENBSD
444#if V8_HOST_ARCH_IA32
445  state.pc = reinterpret_cast<Address>(ucontext->sc_eip);
446  state.sp = reinterpret_cast<Address>(ucontext->sc_esp);
447  state.fp = reinterpret_cast<Address>(ucontext->sc_ebp);
448#elif V8_HOST_ARCH_X64
449  state.pc = reinterpret_cast<Address>(ucontext->sc_rip);
450  state.sp = reinterpret_cast<Address>(ucontext->sc_rsp);
451  state.fp = reinterpret_cast<Address>(ucontext->sc_rbp);
452#endif  // V8_HOST_ARCH_*
453#elif V8_OS_SOLARIS
454  state.pc = reinterpret_cast<Address>(mcontext.gregs[REG_PC]);
455  state.sp = reinterpret_cast<Address>(mcontext.gregs[REG_SP]);
456  state.fp = reinterpret_cast<Address>(mcontext.gregs[REG_FP]);
457#elif V8_OS_QNX
458#if V8_HOST_ARCH_IA32
459  state.pc = reinterpret_cast<Address>(mcontext.cpu.eip);
460  state.sp = reinterpret_cast<Address>(mcontext.cpu.esp);
461  state.fp = reinterpret_cast<Address>(mcontext.cpu.ebp);
462#elif V8_HOST_ARCH_ARM
463  state.pc = reinterpret_cast<Address>(mcontext.cpu.gpr[ARM_REG_PC]);
464  state.sp = reinterpret_cast<Address>(mcontext.cpu.gpr[ARM_REG_SP]);
465  state.fp = reinterpret_cast<Address>(mcontext.cpu.gpr[ARM_REG_FP]);
466#endif  // V8_HOST_ARCH_*
467#endif  // V8_OS_QNX
468#endif  // USE_SIMULATOR
469  sampler->SampleStack(state);
470#endif  // V8_OS_NACL
471}
472
473#endif
474
475
476class SamplerThread : public Thread {
477 public:
478  static const int kSamplerThreadStackSize = 64 * KB;
479
480  explicit SamplerThread(int interval)
481      : Thread(Thread::Options("SamplerThread", kSamplerThreadStackSize)),
482        interval_(interval) {}
483
484  static void SetUp() { if (!mutex_) mutex_ = new Mutex(); }
485  static void TearDown() { delete mutex_; mutex_ = NULL; }
486
487  static void AddActiveSampler(Sampler* sampler) {
488    bool need_to_start = false;
489    LockGuard<Mutex> lock_guard(mutex_);
490    if (instance_ == NULL) {
491      // Start a thread that will send SIGPROF signal to VM threads,
492      // when CPU profiling will be enabled.
493      instance_ = new SamplerThread(sampler->interval());
494      need_to_start = true;
495    }
496
497    ASSERT(sampler->IsActive());
498    ASSERT(!instance_->active_samplers_.Contains(sampler));
499    ASSERT(instance_->interval_ == sampler->interval());
500    instance_->active_samplers_.Add(sampler);
501
502    if (need_to_start) instance_->StartSynchronously();
503  }
504
505  static void RemoveActiveSampler(Sampler* sampler) {
506    SamplerThread* instance_to_remove = NULL;
507    {
508      LockGuard<Mutex> lock_guard(mutex_);
509
510      ASSERT(sampler->IsActive());
511      bool removed = instance_->active_samplers_.RemoveElement(sampler);
512      ASSERT(removed);
513      USE(removed);
514
515      // We cannot delete the instance immediately as we need to Join() the
516      // thread but we are holding mutex_ and the thread may try to acquire it.
517      if (instance_->active_samplers_.is_empty()) {
518        instance_to_remove = instance_;
519        instance_ = NULL;
520      }
521    }
522
523    if (!instance_to_remove) return;
524    instance_to_remove->Join();
525    delete instance_to_remove;
526  }
527
528  // Implement Thread::Run().
529  virtual void Run() {
530    while (true) {
531      {
532        LockGuard<Mutex> lock_guard(mutex_);
533        if (active_samplers_.is_empty()) break;
534        // When CPU profiling is enabled both JavaScript and C++ code is
535        // profiled. We must not suspend.
536        for (int i = 0; i < active_samplers_.length(); ++i) {
537          Sampler* sampler = active_samplers_.at(i);
538          if (!sampler->isolate()->IsInitialized()) continue;
539          if (!sampler->IsProfiling()) continue;
540          sampler->DoSample();
541        }
542      }
543      OS::Sleep(interval_);
544    }
545  }
546
547 private:
548  // Protects the process wide state below.
549  static Mutex* mutex_;
550  static SamplerThread* instance_;
551
552  const int interval_;
553  List<Sampler*> active_samplers_;
554
555  DISALLOW_COPY_AND_ASSIGN(SamplerThread);
556};
557
558
559Mutex* SamplerThread::mutex_ = NULL;
560SamplerThread* SamplerThread::instance_ = NULL;
561
562
563//
564// StackTracer implementation
565//
566DISABLE_ASAN void TickSample::Init(Isolate* isolate,
567                                   const RegisterState& regs) {
568  ASSERT(isolate->IsInitialized());
569  timestamp = TimeTicks::HighResolutionNow();
570  pc = regs.pc;
571  state = isolate->current_vm_state();
572
573  // Avoid collecting traces while doing GC.
574  if (state == GC) return;
575
576  Address js_entry_sp = isolate->js_entry_sp();
577  if (js_entry_sp == 0) {
578    // Not executing JS now.
579    return;
580  }
581
582  ExternalCallbackScope* scope = isolate->external_callback_scope();
583  Address handler = Isolate::handler(isolate->thread_local_top());
584  // If there is a handler on top of the external callback scope then
585  // we have already entrered JavaScript again and the external callback
586  // is not the top function.
587  if (scope && scope->scope_address() < handler) {
588    external_callback = scope->callback();
589    has_external_callback = true;
590  } else {
591    // Sample potential return address value for frameless invocation of
592    // stubs (we'll figure out later, if this value makes sense).
593    tos = Memory::Address_at(regs.sp);
594    has_external_callback = false;
595  }
596
597  SafeStackFrameIterator it(isolate, regs.fp, regs.sp, js_entry_sp);
598  top_frame_type = it.top_frame_type();
599  int i = 0;
600  while (!it.done() && i < TickSample::kMaxFramesCount) {
601    stack[i++] = it.frame()->pc();
602    it.Advance();
603  }
604  frames_count = i;
605}
606
607
608void Sampler::SetUp() {
609#if defined(USE_SIGNALS)
610  SignalHandler::SetUp();
611#endif
612  SamplerThread::SetUp();
613}
614
615
616void Sampler::TearDown() {
617  SamplerThread::TearDown();
618#if defined(USE_SIGNALS)
619  SignalHandler::TearDown();
620#endif
621}
622
623
624Sampler::Sampler(Isolate* isolate, int interval)
625    : isolate_(isolate),
626      interval_(interval),
627      profiling_(false),
628      has_processing_thread_(false),
629      active_(false),
630      is_counting_samples_(false),
631      js_and_external_sample_count_(0) {
632  data_ = new PlatformData;
633}
634
635
636Sampler::~Sampler() {
637  ASSERT(!IsActive());
638  delete data_;
639}
640
641
642void Sampler::Start() {
643  ASSERT(!IsActive());
644  SetActive(true);
645  SamplerThread::AddActiveSampler(this);
646}
647
648
649void Sampler::Stop() {
650  ASSERT(IsActive());
651  SamplerThread::RemoveActiveSampler(this);
652  SetActive(false);
653}
654
655
656void Sampler::IncreaseProfilingDepth() {
657  base::NoBarrier_AtomicIncrement(&profiling_, 1);
658#if defined(USE_SIGNALS)
659  SignalHandler::IncreaseSamplerCount();
660#endif
661}
662
663
664void Sampler::DecreaseProfilingDepth() {
665#if defined(USE_SIGNALS)
666  SignalHandler::DecreaseSamplerCount();
667#endif
668  base::NoBarrier_AtomicIncrement(&profiling_, -1);
669}
670
671
672void Sampler::SampleStack(const RegisterState& state) {
673  TickSample* sample = isolate_->cpu_profiler()->StartTickSample();
674  TickSample sample_obj;
675  if (sample == NULL) sample = &sample_obj;
676  sample->Init(isolate_, state);
677  if (is_counting_samples_) {
678    if (sample->state == JS || sample->state == EXTERNAL) {
679      ++js_and_external_sample_count_;
680    }
681  }
682  Tick(sample);
683  if (sample != &sample_obj) {
684    isolate_->cpu_profiler()->FinishTickSample();
685  }
686}
687
688
689#if defined(USE_SIGNALS)
690
691void Sampler::DoSample() {
692  if (!SignalHandler::Installed()) return;
693  pthread_kill(platform_data()->vm_tid(), SIGPROF);
694}
695
696#elif V8_OS_WIN || V8_OS_CYGWIN
697
698void Sampler::DoSample() {
699  HANDLE profiled_thread = platform_data()->profiled_thread();
700  if (profiled_thread == NULL) return;
701
702#if defined(USE_SIMULATOR)
703  SimulatorHelper helper;
704  if (!helper.Init(this, isolate())) return;
705#endif
706
707  const DWORD kSuspendFailed = static_cast<DWORD>(-1);
708  if (SuspendThread(profiled_thread) == kSuspendFailed) return;
709
710  // Context used for sampling the register state of the profiled thread.
711  CONTEXT context;
712  memset(&context, 0, sizeof(context));
713  context.ContextFlags = CONTEXT_FULL;
714  if (GetThreadContext(profiled_thread, &context) != 0) {
715    RegisterState state;
716#if defined(USE_SIMULATOR)
717    helper.FillRegisters(&state);
718#else
719#if V8_HOST_ARCH_X64
720    state.pc = reinterpret_cast<Address>(context.Rip);
721    state.sp = reinterpret_cast<Address>(context.Rsp);
722    state.fp = reinterpret_cast<Address>(context.Rbp);
723#else
724    state.pc = reinterpret_cast<Address>(context.Eip);
725    state.sp = reinterpret_cast<Address>(context.Esp);
726    state.fp = reinterpret_cast<Address>(context.Ebp);
727#endif
728#endif  // USE_SIMULATOR
729    SampleStack(state);
730  }
731  ResumeThread(profiled_thread);
732}
733
734#endif  // USE_SIGNALS
735
736
737} }  // namespace v8::internal
738