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/* -*- 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 "ThreadStackHelper.h"
#include "MainThreadUtils.h"
#include "nsJSPrincipals.h"
#include "nsScriptSecurityManager.h"
#include "jsfriendapi.h"
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/IntegerPrintfMacros.h"
#include "mozilla/Move.h"
#include "mozilla/Scoped.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/MemoryChecking.h"
#include "mozilla/Sprintf.h"
#ifdef __GNUC__
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wshadow"
#endif
#if defined(MOZ_VALGRIND)
# include <valgrind/valgrind.h>
#endif
#include <string.h>
#include <vector>
#include <cstdlib>
#ifdef XP_LINUX
#include <ucontext.h>
#include <unistd.h>
#include <sys/syscall.h>
#endif
#ifdef __GNUC__
# pragma GCC diagnostic pop // -Wshadow
#endif
#if defined(XP_LINUX) || defined(XP_MACOSX)
#include <pthread.h>
#endif
namespace mozilla {
void
ThreadStackHelper::Startup()
{
#if defined(XP_LINUX)
MOZ_ASSERT(NS_IsMainThread());
if (!sInitialized) {
// TODO: centralize signal number allocation
sFillStackSignum = SIGRTMIN + 4;
if (sFillStackSignum > SIGRTMAX) {
// Leave uninitialized
MOZ_ASSERT(false);
return;
}
struct sigaction sigact = {};
sigact.sa_sigaction = FillStackHandler;
sigemptyset(&sigact.sa_mask);
sigact.sa_flags = SA_SIGINFO | SA_RESTART;
MOZ_ALWAYS_TRUE(!::sigaction(sFillStackSignum, &sigact, nullptr));
}
sInitialized++;
#endif
}
void
ThreadStackHelper::Shutdown()
{
#if defined(XP_LINUX)
MOZ_ASSERT(NS_IsMainThread());
if (sInitialized == 1) {
struct sigaction sigact = {};
sigact.sa_handler = SIG_DFL;
MOZ_ALWAYS_TRUE(!::sigaction(sFillStackSignum, &sigact, nullptr));
}
sInitialized--;
#endif
}
ThreadStackHelper::ThreadStackHelper()
: mStackToFill(nullptr)
{
#if defined(XP_LINUX)
MOZ_ALWAYS_TRUE(!::sem_init(&mSem, 0, 0));
mThreadID = ::syscall(SYS_gettid);
#elif defined(XP_WIN)
mInitialized = !!::DuplicateHandle(
::GetCurrentProcess(), ::GetCurrentThread(),
::GetCurrentProcess(), &mThreadID,
THREAD_SUSPEND_RESUME
, FALSE, 0);
MOZ_ASSERT(mInitialized);
#elif defined(XP_MACOSX)
mThreadID = mach_thread_self();
#endif
}
ThreadStackHelper::~ThreadStackHelper()
{
#if defined(XP_LINUX)
MOZ_ALWAYS_TRUE(!::sem_destroy(&mSem));
#elif defined(XP_WIN)
if (mInitialized) {
MOZ_ALWAYS_TRUE(!!::CloseHandle(mThreadID));
}
#endif
}
namespace {
template<typename T>
class ScopedSetPtr
{
private:
T*& mPtr;
public:
ScopedSetPtr(T*& p, T* val) : mPtr(p) { mPtr = val; }
~ScopedSetPtr() { mPtr = nullptr; }
};
} // namespace
void
ThreadStackHelper::GetStack(Stack& aStack)
{
// Always run PrepareStackBuffer first to clear aStack
if (!PrepareStackBuffer(aStack)) {
// Skip and return empty aStack
return;
}
ScopedSetPtr<Stack> stackPtr(mStackToFill, &aStack);
#if defined(XP_LINUX)
if (!sInitialized) {
MOZ_ASSERT(false);
return;
}
siginfo_t uinfo = {};
uinfo.si_signo = sFillStackSignum;
uinfo.si_code = SI_QUEUE;
uinfo.si_pid = getpid();
uinfo.si_uid = getuid();
uinfo.si_value.sival_ptr = this;
if (::syscall(SYS_rt_tgsigqueueinfo, uinfo.si_pid,
mThreadID, sFillStackSignum, &uinfo)) {
// rt_tgsigqueueinfo was added in Linux 2.6.31.
// Could have failed because the syscall did not exist.
return;
}
MOZ_ALWAYS_TRUE(!::sem_wait(&mSem));
#elif defined(XP_WIN)
if (!mInitialized) {
MOZ_ASSERT(false);
return;
}
if (::SuspendThread(mThreadID) == DWORD(-1)) {
MOZ_ASSERT(false);
return;
}
// SuspendThread is asynchronous, so the thread may still be running. Use
// GetThreadContext to ensure it's really suspended.
// See https://blogs.msdn.microsoft.com/oldnewthing/20150205-00/?p=44743.
CONTEXT context;
context.ContextFlags = CONTEXT_CONTROL;
if (::GetThreadContext(mThreadID, &context)) {
FillStackBuffer();
FillThreadContext();
}
MOZ_ALWAYS_TRUE(::ResumeThread(mThreadID) != DWORD(-1));
#elif defined(XP_MACOSX)
# if defined(MOZ_VALGRIND) && defined(RUNNING_ON_VALGRIND)
if (RUNNING_ON_VALGRIND) {
/* thread_suspend and thread_resume sometimes hang runs on Valgrind,
for unknown reasons. So, just avoid them. See bug 1100911. */
return;
}
# endif
if (::thread_suspend(mThreadID) != KERN_SUCCESS) {
MOZ_ASSERT(false);
return;
}
FillStackBuffer();
FillThreadContext();
MOZ_ALWAYS_TRUE(::thread_resume(mThreadID) == KERN_SUCCESS);
#endif
}
void
ThreadStackHelper::GetNativeStack(Stack& aStack)
{
/*** STUB ***/
}
#ifdef XP_LINUX
int ThreadStackHelper::sInitialized;
int ThreadStackHelper::sFillStackSignum;
void
ThreadStackHelper::FillStackHandler(int aSignal, siginfo_t* aInfo,
void* aContext)
{
ThreadStackHelper* const helper =
reinterpret_cast<ThreadStackHelper*>(aInfo->si_value.sival_ptr);
helper->FillStackBuffer();
helper->FillThreadContext(aContext);
::sem_post(&helper->mSem);
}
#endif // XP_LINUX
bool
ThreadStackHelper::PrepareStackBuffer(Stack& aStack)
{
// Return false to skip getting the stack and return an empty stack
aStack.clear();
return false;
}
void
ThreadStackHelper::FillStackBuffer()
{
MOZ_ASSERT(mStackToFill->empty());
/*** STUB ***/
}
MOZ_ASAN_BLACKLIST void
ThreadStackHelper::FillThreadContext(void* aContext)
{
/*** STUB ***/
}
} // namespace mozilla
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