The Tor Browser: tools/profiler/platform-linux.cc@97036ab72558 (annotated)

tools/profiler/platform-linux.cc@97036ab72558 (annotated)

tools/profiler/platform-linux.cc

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 // Copyright (c) 2006-2011 The Chromium Authors. All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
 // are met:
 //  * Redistributions of source code must retain the above copyright
 //    notice, this list of conditions and the following disclaimer.
 //  * Redistributions in binary form must reproduce the above copyright
 //    notice, this list of conditions and the following disclaimer in
 //    the documentation and/or other materials provided with the
 //    distribution.
 //  * Neither the name of Google, Inc. nor the names of its contributors
 //    may be used to endorse or promote products derived from this
 //    software without specific prior written permission.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 // FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 // COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 // BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 // OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 // AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 // OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 // SUCH DAMAGE.
 /*
 # vim: sw=2
 */
 #include <stdio.h>
 #include <math.h>
 #include <pthread.h>
 #include <semaphore.h>
 #include <signal.h>
 #include <sys/time.h>
 #include <sys/resource.h>
 #include <sys/syscall.h>
 #include <sys/types.h>
 #include <sys/prctl.h> // set name
 #include <stdlib.h>
 #include <sched.h>
 #ifdef ANDROID
 #include <android/log.h>
 #else
 #define __android_log_print(a, ...)
 #endif
 #include <ucontext.h>
 // Ubuntu Dapper requires memory pages to be marked as
 // executable. Otherwise, OS raises an exception when executing code
 // in that page.
 #include <sys/types.h>  // mmap & munmap
 #include <sys/mman.h>   // mmap & munmap
 #include <sys/stat.h>   // open
 #include <fcntl.h>      // open
 #include <unistd.h>     // sysconf
 #include <semaphore.h>
 #ifdef __GLIBC__
 #include <execinfo.h>   // backtrace, backtrace_symbols
 #endif  // def __GLIBC__
 #include <strings.h>    // index
 #include <errno.h>
 #include <stdarg.h>
 #include "platform.h"
 #include "GeckoProfiler.h"
 #include "mozilla/Mutex.h"
 #include "mozilla/Atomics.h"
 #include "ProfileEntry.h"
 #include "nsThreadUtils.h"
 #include "TableTicker.h"
 #include "UnwinderThread2.h"
 #if defined(__ARM_EABI__) && defined(MOZ_WIDGET_GONK)
  // Should also work on other Android and ARM Linux, but not tested there yet.
 #define USE_EHABI_STACKWALK
 #include "EHABIStackWalk.h"
 #endif
 #include <string.h>
 #include <stdio.h>
 #include <list>
 #ifdef MOZ_NUWA_PROCESS
 #include "ipc/Nuwa.h"
 #endif
 #define SIGNAL_SAVE_PROFILE SIGUSR2
 #if defined(__GLIBC__)
 // glibc doesn't implement gettid(2).
 #include <sys/syscall.h>
 pid_t gettid()
 {
   return (pid_t) syscall(SYS_gettid);
 }
 #endif
 /* static */ Thread::tid_t
 Thread::GetCurrentId()
 {
   return gettid();
 }
 #if !defined(ANDROID)
 // Keep track of when any of our threads calls fork(), so we can
 // temporarily disable signal delivery during the fork() call.  Not
 // doing so appears to cause a kind of race, in which signals keep
 // getting delivered to the thread doing fork(), which keeps causing
 // it to fail and be restarted; hence forward progress is delayed a
 // great deal.  A side effect of this is to permanently disable
 // sampling in the child process.  See bug 837390.
 // Unfortunately this is only doable on non-Android, since Bionic
 // doesn't have pthread_atfork.
 // This records the current state at the time we paused it.
 static bool was_paused = false;
 // In the parent, just before the fork, record the pausedness state,
 // and then pause.
 static void paf_prepare(void) {
   if (Sampler::GetActiveSampler()) {
     was_paused = Sampler::GetActiveSampler()->IsPaused();
     Sampler::GetActiveSampler()->SetPaused(true);
   } else {
     was_paused = false;
   }
 }
 // In the parent, just after the fork, return pausedness to the
 // pre-fork state.
 static void paf_parent(void) {
   if (Sampler::GetActiveSampler())
     Sampler::GetActiveSampler()->SetPaused(was_paused);
 }
 // Set up the fork handlers.
 static void* setup_atfork() {
   pthread_atfork(paf_prepare, paf_parent, NULL);
   return NULL;
 }
 #endif /* !defined(ANDROID) */
 struct SamplerRegistry {
   static void AddActiveSampler(Sampler *sampler) {
     ASSERT(!SamplerRegistry::sampler);
     SamplerRegistry::sampler = sampler;
   }
   static void RemoveActiveSampler(Sampler *sampler) {
     SamplerRegistry::sampler = NULL;
   }
   static Sampler *sampler;
 };
 Sampler *SamplerRegistry::sampler = NULL;
 static mozilla::Atomic<ThreadProfile*> sCurrentThreadProfile;
 static sem_t sSignalHandlingDone;
 static void ProfilerSaveSignalHandler(int signal, siginfo_t* info, void* context) {
   Sampler::GetActiveSampler()->RequestSave();
 }
 static void SetSampleContext(TickSample* sample, void* context)
 {
   // Extracting the sample from the context is extremely machine dependent.
   ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(context);
   mcontext_t& mcontext = ucontext->uc_mcontext;
 #if V8_HOST_ARCH_IA32
   sample->pc = reinterpret_cast<Address>(mcontext.gregs[REG_EIP]);
   sample->sp = reinterpret_cast<Address>(mcontext.gregs[REG_ESP]);
   sample->fp = reinterpret_cast<Address>(mcontext.gregs[REG_EBP]);
 #elif V8_HOST_ARCH_X64
   sample->pc = reinterpret_cast<Address>(mcontext.gregs[REG_RIP]);
   sample->sp = reinterpret_cast<Address>(mcontext.gregs[REG_RSP]);
   sample->fp = reinterpret_cast<Address>(mcontext.gregs[REG_RBP]);
 #elif V8_HOST_ARCH_ARM
 // An undefined macro evaluates to 0, so this applies to Android's Bionic also.
 #if !defined(ANDROID) && (__GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ <= 3))
   sample->pc = reinterpret_cast<Address>(mcontext.gregs[R15]);
   sample->sp = reinterpret_cast<Address>(mcontext.gregs[R13]);
   sample->fp = reinterpret_cast<Address>(mcontext.gregs[R11]);
 #ifdef ENABLE_ARM_LR_SAVING
   sample->lr = reinterpret_cast<Address>(mcontext.gregs[R14]);
 #endif
 #else
   sample->pc = reinterpret_cast<Address>(mcontext.arm_pc);
   sample->sp = reinterpret_cast<Address>(mcontext.arm_sp);
   sample->fp = reinterpret_cast<Address>(mcontext.arm_fp);
 #ifdef ENABLE_ARM_LR_SAVING
   sample->lr = reinterpret_cast<Address>(mcontext.arm_lr);
 #endif
 #endif
 #elif V8_HOST_ARCH_MIPS
   // Implement this on MIPS.
   UNIMPLEMENTED();
 #endif
 }
 #ifdef ANDROID
 #define V8_HOST_ARCH_ARM 1
 #define SYS_gettid __NR_gettid
 #define SYS_tgkill __NR_tgkill
 #else
 #define V8_HOST_ARCH_X64 1
 #endif
 static void ProfilerSignalHandler(int signal, siginfo_t* info, void* context) {
   if (!Sampler::GetActiveSampler()) {
     sem_post(&sSignalHandlingDone);
     return;
   }
   TickSample sample_obj;
   TickSample* sample = &sample_obj;
   sample->context = context;
 #ifdef ENABLE_SPS_LEAF_DATA
   // If profiling, we extract the current pc and sp.
   if (Sampler::GetActiveSampler()->IsProfiling()) {
     SetSampleContext(sample, context);
   }
 #endif
   sample->threadProfile = sCurrentThreadProfile;
   sample->timestamp = mozilla::TimeStamp::Now();
   Sampler::GetActiveSampler()->Tick(sample);
   sCurrentThreadProfile = NULL;
   sem_post(&sSignalHandlingDone);
 }
 // If the Nuwa process is enabled, we need to use the wrapper of tgkill() to
 // perform the mapping of thread ID.
 #ifdef MOZ_NUWA_PROCESS
 extern "C" MFBT_API int tgkill(pid_t tgid, pid_t tid, int signalno);
 #else
 int tgkill(pid_t tgid, pid_t tid, int signalno) {
   return syscall(SYS_tgkill, tgid, tid, signalno);
 }
 #endif
 class PlatformData : public Malloced {
  public:
   PlatformData()
   {}
 };
 /* static */ PlatformData*
 Sampler::AllocPlatformData(int aThreadId)
 {
   return new PlatformData;
 }
 /* static */ void
 Sampler::FreePlatformData(PlatformData* aData)
 {
   delete aData;
 }
 static void* SignalSender(void* arg) {
   // Taken from platform_thread_posix.cc
   prctl(PR_SET_NAME, "SamplerThread", 0, 0, 0);
 #ifdef MOZ_NUWA_PROCESS
   // If the Nuwa process is enabled, we need to mark and freeze the sampler
   // thread in the Nuwa process and have this thread recreated in the spawned
   // child.
   if(IsNuwaProcess()) {
     NuwaMarkCurrentThread(nullptr, nullptr);
     // Freeze the thread here so the spawned child will get the correct tgid
     // from the getpid() call below.
     NuwaFreezeCurrentThread();
   }
 #endif
   int vm_tgid_ = getpid();
   while (SamplerRegistry::sampler->IsActive()) {
     SamplerRegistry::sampler->HandleSaveRequest();
     if (!SamplerRegistry::sampler->IsPaused()) {
       mozilla::MutexAutoLock lock(*Sampler::sRegisteredThreadsMutex);
       std::vector<ThreadInfo*> threads =
         SamplerRegistry::sampler->GetRegisteredThreads();
       for (uint32_t i = 0; i < threads.size(); i++) {
         ThreadInfo* info = threads[i];
         // This will be null if we're not interested in profiling this thread.
         if (!info->Profile())
           continue;
         PseudoStack::SleepState sleeping = info->Stack()->observeSleeping();
         if (sleeping == PseudoStack::SLEEPING_AGAIN) {
           info->Profile()->DuplicateLastSample();
           //XXX: This causes flushes regardless of jank-only mode
           info->Profile()->flush();
           continue;
         }
         // We use sCurrentThreadProfile the ThreadProfile for the
         // thread we're profiling to the signal handler
         sCurrentThreadProfile = info->Profile();
         int threadId = info->ThreadId();
         if (tgkill(vm_tgid_, threadId, SIGPROF) != 0) {
           printf_stderr("profiler failed to signal tid=%d\n", threadId);
 #ifdef DEBUG
           abort();
 #endif
           continue;
         }
         // Wait for the signal handler to run before moving on to the next one
         sem_wait(&sSignalHandlingDone);
       }
     }
     // Convert ms to us and subtract 100 us to compensate delays
     // occuring during signal delivery.
     // TODO measure and confirm this.
     int interval = floor(SamplerRegistry::sampler->interval() * 1000 + 0.5) - 100;
     if (interval <= 0) {
       interval = 1;
     }
     OS::SleepMicro(interval);
   }
   return 0;
 }
 Sampler::Sampler(double interval, bool profiling, int entrySize)
     : interval_(interval),
       profiling_(profiling),
       paused_(false),
       active_(false),
       entrySize_(entrySize) {
 }
 Sampler::~Sampler() {
   ASSERT(!signal_sender_launched_);
 }
 void Sampler::Start() {
   LOG("Sampler started");
 #ifdef USE_EHABI_STACKWALK
   mozilla::EHABIStackWalkInit();
 #endif
   SamplerRegistry::AddActiveSampler(this);
   // Initialize signal handler communication
   sCurrentThreadProfile = NULL;
   if (sem_init(&sSignalHandlingDone, /* pshared: */ 0, /* value: */ 0) != 0) {
     LOG("Error initializing semaphore");
     return;
   }
   // Request profiling signals.
   LOG("Request signal");
   struct sigaction sa;
   sa.sa_sigaction = ProfilerSignalHandler;
   sigemptyset(&sa.sa_mask);
   sa.sa_flags = SA_RESTART | SA_SIGINFO;
   if (sigaction(SIGPROF, &sa, &old_sigprof_signal_handler_) != 0) {
     LOG("Error installing signal");
     return;
   }
   // Request save profile signals
   struct sigaction sa2;
   sa2.sa_sigaction = ProfilerSaveSignalHandler;
   sigemptyset(&sa2.sa_mask);
   sa2.sa_flags = SA_RESTART | SA_SIGINFO;
   if (sigaction(SIGNAL_SAVE_PROFILE, &sa2, &old_sigsave_signal_handler_) != 0) {
     LOG("Error installing start signal");
     return;
   }
   LOG("Signal installed");
   signal_handler_installed_ = true;
   // Start a thread that sends SIGPROF signal to VM thread.
   // Sending the signal ourselves instead of relying on itimer provides
   // much better accuracy.
   SetActive(true);
   if (pthread_create(
         &signal_sender_thread_, NULL, SignalSender, NULL) == 0) {
     signal_sender_launched_ = true;
   }
   LOG("Profiler thread started");
 }
 void Sampler::Stop() {
   SetActive(false);
   // Wait for signal sender termination (it will exit after setting
   // active_ to false).
   if (signal_sender_launched_) {
     pthread_join(signal_sender_thread_, NULL);
     signal_sender_launched_ = false;
   }
   SamplerRegistry::RemoveActiveSampler(this);
   // Restore old signal handler
   if (signal_handler_installed_) {
     sigaction(SIGNAL_SAVE_PROFILE, &old_sigsave_signal_handler_, 0);
     sigaction(SIGPROF, &old_sigprof_signal_handler_, 0);
     signal_handler_installed_ = false;
   }
 }
 bool Sampler::RegisterCurrentThread(const char* aName,
                                     PseudoStack* aPseudoStack,
                                     bool aIsMainThread, void* stackTop)
 {
   if (!Sampler::sRegisteredThreadsMutex)
     return false;
   mozilla::MutexAutoLock lock(*Sampler::sRegisteredThreadsMutex);
   int id = gettid();
   for (uint32_t i = 0; i < sRegisteredThreads->size(); i++) {
     ThreadInfo* info = sRegisteredThreads->at(i);
     if (info->ThreadId() == id) {
       // Thread already registered. This means the first unregister will be
       // too early.
       ASSERT(false);
       return false;
     }
   }
   set_tls_stack_top(stackTop);
   ThreadInfo* info = new ThreadInfo(aName, id,
     aIsMainThread, aPseudoStack, stackTop);
   if (sActiveSampler) {
     sActiveSampler->RegisterThread(info);
   }
   sRegisteredThreads->push_back(info);
   uwt__register_thread_for_profiling(stackTop);
   return true;
 }
 void Sampler::UnregisterCurrentThread()
 {
   if (!Sampler::sRegisteredThreadsMutex)
     return;
   tlsStackTop.set(nullptr);
   mozilla::MutexAutoLock lock(*Sampler::sRegisteredThreadsMutex);
   int id = gettid();
   for (uint32_t i = 0; i < sRegisteredThreads->size(); i++) {
     ThreadInfo* info = sRegisteredThreads->at(i);
     if (info->ThreadId() == id) {
       delete info;
       sRegisteredThreads->erase(sRegisteredThreads->begin() + i);
       break;
     }
   }
   uwt__unregister_thread_for_profiling();
 }
 #ifdef ANDROID
 static struct sigaction old_sigstart_signal_handler;
 const int SIGSTART = SIGUSR2;
 static void freeArray(const char** array, int size) {
   for (int i = 0; i < size; i++) {
     free((void*) array[i]);
   }
 }
 static uint32_t readCSVArray(char* csvList, const char** buffer) {
   uint32_t count;
   char* savePtr;
   int newlinePos = strlen(csvList) - 1;
   if (csvList[newlinePos] == '\n') {
     csvList[newlinePos] = '\0';
   }
   char* item = strtok_r(csvList, ",", &savePtr);
   for (count = 0; item; item = strtok_r(NULL, ",", &savePtr)) {
     int length = strlen(item) + 1;  // Include \0
     char* newBuf = (char*) malloc(sizeof(char) * length);
     buffer[count] = newBuf;
     strncpy(newBuf, item, length);
     count++;
   }
   return count;
 }
 // Currently support only the env variables
 // reported in read_profiler_env
 static void ReadProfilerVars(const char* fileName, const char** features,
                             uint32_t* featureCount, const char** threadNames, uint32_t* threadCount) {
   FILE* file = fopen(fileName, "r");
   const int bufferSize = 1024;
   char line[bufferSize];
   char* feature;
   char* value;
   char* savePtr;
   if (file) {
     while (fgets(line, bufferSize, file) != NULL) {
       feature = strtok_r(line, "=", &savePtr);
       value = strtok_r(NULL, "", &savePtr);
       if (strncmp(feature, PROFILER_MODE, bufferSize) == 0) {
         set_profiler_mode(value);
       } else if (strncmp(feature, PROFILER_INTERVAL, bufferSize) == 0) {
         set_profiler_interval(value);
       } else if (strncmp(feature, PROFILER_ENTRIES, bufferSize) == 0) {
         set_profiler_entries(value);
       } else if (strncmp(feature, PROFILER_STACK, bufferSize) == 0) {
         set_profiler_scan(value);
       } else if (strncmp(feature, PROFILER_FEATURES, bufferSize) == 0) {
         *featureCount = readCSVArray(value, features);
       } else if (strncmp(feature, "threads", bufferSize) == 0) {
         *threadCount = readCSVArray(value, threadNames);
       }
     }
     fclose(file);
   }
 }
 static void StartSignalHandler(int signal, siginfo_t* info, void* context) {
   // XXX: Everything we do here is NOT async signal safe. We risk nasty things
   // like deadlocks but we typically only do this once so it tends to be ok.
   // See bug 909403
   uint32_t featureCount = 0;
   uint32_t threadCount = 0;
   // Just allocate 10 features for now
   // FIXME: these don't really point to const chars*
   // So we free them later, but we don't want to change the const char**
   // declaration in profiler_start. Annoying but ok for now.
   const char* threadNames[10];
   const char* features[10];
   const char* profilerConfigFile = "/data/local/tmp/profiler.options";
   ReadProfilerVars(profilerConfigFile, features, &featureCount, threadNames, &threadCount);
   MOZ_ASSERT(featureCount < 10);
   MOZ_ASSERT(threadCount < 10);
   profiler_start(PROFILE_DEFAULT_ENTRY, 1,
       features, featureCount,
       threadNames, threadCount);
   freeArray(threadNames, threadCount);
   freeArray(features, featureCount);
 }
 void OS::Startup()
 {
   LOG("Registering start signal");
   struct sigaction sa;
   sa.sa_sigaction = StartSignalHandler;
   sigemptyset(&sa.sa_mask);
   sa.sa_flags = SA_RESTART | SA_SIGINFO;
   if (sigaction(SIGSTART, &sa, &old_sigstart_signal_handler) != 0) {
     LOG("Error installing signal");
   }
 }
 #else
 void OS::Startup() {
   // Set up the fork handlers.
   setup_atfork();
 }
 #endif
 void TickSample::PopulateContext(void* aContext)
 {
   MOZ_ASSERT(aContext);
   ucontext_t* pContext = reinterpret_cast<ucontext_t*>(aContext);
   if (!getcontext(pContext)) {
     context = pContext;
     SetSampleContext(this, aContext);
   }
 }
 // WARNING: Works with values up to 1 second
 void OS::SleepMicro(int microseconds)
 {
   struct timespec ts;
   ts.tv_sec  = 0;
   ts.tv_nsec = microseconds * 1000UL;
   while (true) {
     // in the case of interrupt we keep waiting
     // nanosleep puts the remaining to back into ts
     if (!nanosleep(&ts, &ts) || errno != EINTR) {
       return;
     }
   }
 }

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tools/profiler/platform-linux.cc@97036ab72558 (annotated)

tools/profiler/platform-linux.cc