gecko-dev/mozglue/baseprofiler/core/platform-macos.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <unistd.h>
#include <sys/mman.h>
#include <mach/mach_init.h>
#include <mach-o/getsect.h>

#include <AvailabilityMacros.h>

#include <pthread.h>
#include <semaphore.h>
#include <signal.h>
#include <libkern/OSAtomic.h>
#include <mach/mach.h>
#include <mach/semaphore.h>
#include <mach/task.h>
#include <mach/thread_act.h>
#include <mach/vm_statistics.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/sysctl.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <math.h>

// this port is based off of v8 svn revision 9837

namespace mozilla {
namespace baseprofiler {

int profiler_current_process_id() { return getpid(); }

int profiler_current_thread_id() {
  return static_cast<int>(static_cast<pid_t>(syscall(SYS_thread_selfid)));
}

static int64_t MicrosecondsSince1970() {
  struct timeval tv;
  gettimeofday(&tv, NULL);
  return int64_t(tv.tv_sec) * 1000000 + int64_t(tv.tv_usec);
}

void* GetStackTop(void* aGuess) {
  pthread_t thread = pthread_self();
  return pthread_get_stackaddr_np(thread);
}

class PlatformData {
 public:
  explicit PlatformData(int aThreadId) : mProfiledThread(mach_thread_self()) {}

  ~PlatformData() {
    // Deallocate Mach port for thread.
    mach_port_deallocate(mach_task_self(), mProfiledThread);
  }

  thread_act_t ProfiledThread() { return mProfiledThread; }

 private:
  // Note: for mProfiledThread Mach primitives are used instead of pthread's
  // because the latter doesn't provide thread manipulation primitives required.
  // For details, consult "Mac OS X Internals" book, Section 7.3.
  thread_act_t mProfiledThread;
};

////////////////////////////////////////////////////////////////////////
// BEGIN Sampler target specifics

Sampler::Sampler(PSLockRef aLock) {}

void Sampler::Disable(PSLockRef aLock) {}

template <typename Func>
void Sampler::SuspendAndSampleAndResumeThread(
    PSLockRef aLock, const RegisteredThread& aRegisteredThread,
    const TimeStamp& aNow, const Func& aProcessRegs) {
  thread_act_t samplee_thread =
      aRegisteredThread.GetPlatformData()->ProfiledThread();

  //----------------------------------------------------------------//
  // Suspend the samplee thread and get its context.

  // We're using thread_suspend on OS X because pthread_kill (which is what we
  // at one time used on Linux) has less consistent performance and causes
  // strange crashes, see bug 1166778 and bug 1166808.  thread_suspend
  // is also just a lot simpler to use.

  if (KERN_SUCCESS != thread_suspend(samplee_thread)) {
    return;
  }

  //----------------------------------------------------------------//
  // Sample the target thread.

  // WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
  //
  // The profiler's "critical section" begins here.  We must be very careful
  // what we do here, or risk deadlock.  See the corresponding comment in
  // platform-linux-android.cpp for details.

  thread_state_flavor_t flavor = x86_THREAD_STATE64;
  x86_thread_state64_t state;
  mach_msg_type_number_t count = x86_THREAD_STATE64_COUNT;
#if __DARWIN_UNIX03
#  define REGISTER_FIELD(name) __r##name
#else
#  define REGISTER_FIELD(name) r##name
#endif  // __DARWIN_UNIX03

  if (thread_get_state(samplee_thread, flavor,
                       reinterpret_cast<natural_t*>(&state),
                       &count) == KERN_SUCCESS) {
    Registers regs;
    regs.mPC = reinterpret_cast<Address>(state.REGISTER_FIELD(ip));
    regs.mSP = reinterpret_cast<Address>(state.REGISTER_FIELD(sp));
    regs.mFP = reinterpret_cast<Address>(state.REGISTER_FIELD(bp));
    regs.mLR = 0;

    aProcessRegs(regs, aNow);
  }

#undef REGISTER_FIELD

  //----------------------------------------------------------------//
  // Resume the target thread.

  thread_resume(samplee_thread);

  // The profiler's critical section ends here.
  //
  // WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
}

// END Sampler target specifics
////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////
// BEGIN SamplerThread target specifics

static void* ThreadEntry(void* aArg) {
  auto thread = static_cast<SamplerThread*>(aArg);
  thread->Run();
  return nullptr;
}

SamplerThread::SamplerThread(PSLockRef aLock, uint32_t aActivityGeneration,
                             double aIntervalMilliseconds)
    : mSampler(aLock),
      mActivityGeneration(aActivityGeneration),
      mIntervalMicroseconds(
          std::max(1, int(floor(aIntervalMilliseconds * 1000 + 0.5)))),
      mThread{nullptr} {
  pthread_attr_t* attr_ptr = nullptr;
  if (pthread_create(&mThread, attr_ptr, ThreadEntry, this) != 0) {
    MOZ_CRASH("pthread_create failed");
  }
}

SamplerThread::~SamplerThread() { pthread_join(mThread, nullptr); }

void SamplerThread::SleepMicro(uint32_t aMicroseconds) {
  usleep(aMicroseconds);
  // FIXME: the OSX 10.12 page for usleep says "The usleep() function is
  // obsolescent.  Use nanosleep(2) instead."  This implementation could be
  // merged with the linux-android version.  Also, this doesn't handle the
  // case where the usleep call is interrupted by a signal.
}

void SamplerThread::Stop(PSLockRef aLock) { mSampler.Disable(aLock); }

// END SamplerThread target specifics
////////////////////////////////////////////////////////////////////////

static void PlatformInit(PSLockRef aLock) {}

#if defined(HAVE_NATIVE_UNWIND)
void Registers::SyncPopulate() {
  asm(
      // Compute caller's %rsp by adding to %rbp:
      // 8 bytes for previous %rbp, 8 bytes for return address
      "leaq 0x10(%%rbp), %0\n\t"
      // Dereference %rbp to get previous %rbp
      "movq (%%rbp), %1\n\t"
      : "=r"(mSP), "=r"(mFP));
  mPC = reinterpret_cast<Address>(
      __builtin_extract_return_addr(__builtin_return_address(0)));
  mLR = 0;
}
#endif

}  // namespace baseprofiler
}  // namespace mozilla