[apple/javascriptcore.git] / heap / MachineStackMarker.cpp

/*
 *  Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 *  Copyright (C) 2007 Eric Seidel <eric@webkit.org>
 *  Copyright (C) 2009 Acision BV. All rights reserved.
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#include "config.h"
#include "MachineStackMarker.h"

#include "ConservativeRoots.h"
#include "Heap.h"
#include "JSArray.h"
#include "VM.h"
#include <setjmp.h>
#include <stdlib.h>
#include <wtf/StdLibExtras.h>

#if OS(DARWIN)

#include <mach/mach_init.h>
#include <mach/mach_port.h>
#include <mach/task.h>
#include <mach/thread_act.h>
#include <mach/vm_map.h>

#elif OS(WINDOWS)

#include <windows.h>
#include <malloc.h>

#elif OS(UNIX)

#include <sys/mman.h>
#include <unistd.h>

#if OS(SOLARIS)
#include <thread.h>
#else
#include <pthread.h>
#endif

#if HAVE(PTHREAD_NP_H)
#include <pthread_np.h>
#endif

#if OS(QNX)
#include <fcntl.h>
#include <sys/procfs.h>
#include <stdio.h>
#include <errno.h>
#endif

#if USE(PTHREADS) && !OS(WINDOWS) && !OS(DARWIN)
#include <signal.h>
#endif

#endif

using namespace WTF;

namespace JSC {

static inline void swapIfBackwards(void*& begin, void*& end)
{
#if OS(WINCE)
    if (begin <= end)
        return;
    std::swap(begin, end);
#else
UNUSED_PARAM(begin);
UNUSED_PARAM(end);
#endif
}

#if OS(DARWIN)
typedef mach_port_t PlatformThread;
#elif OS(WINDOWS)
typedef HANDLE PlatformThread;
#elif USE(PTHREADS)
typedef pthread_t PlatformThread;
static const int SigThreadSuspendResume = SIGUSR2;

#if defined(SA_RESTART)
static void pthreadSignalHandlerSuspendResume(int)
{
    sigset_t signalSet;
    sigemptyset(&signalSet);
    sigaddset(&signalSet, SigThreadSuspendResume);
    sigsuspend(&signalSet);
}
#endif
#endif

class MachineThreads::Thread {
    WTF_MAKE_FAST_ALLOCATED;
public:
    Thread(const PlatformThread& platThread, void* base)
        : platformThread(platThread)
        , stackBase(base)
    {
#if USE(PTHREADS) && !OS(WINDOWS) && !OS(DARWIN) && defined(SA_RESTART)
        // if we have SA_RESTART, enable SIGUSR2 debugging mechanism
        struct sigaction action;
        action.sa_handler = pthreadSignalHandlerSuspendResume;
        sigemptyset(&action.sa_mask);
        action.sa_flags = SA_RESTART;
        sigaction(SigThreadSuspendResume, &action, 0);

        sigset_t mask;
        sigemptyset(&mask);
        sigaddset(&mask, SigThreadSuspendResume);
        pthread_sigmask(SIG_UNBLOCK, &mask, 0);
#endif
    }

    Thread* next;
    PlatformThread platformThread;
    void* stackBase;
};

MachineThreads::MachineThreads(Heap* heap)
    : m_registeredThreads(0)
    , m_threadSpecific(0)
#if !ASSERT_DISABLED
    , m_heap(heap)
#endif
{
    UNUSED_PARAM(heap);
}

MachineThreads::~MachineThreads()
{
    if (m_threadSpecific)
        threadSpecificKeyDelete(m_threadSpecific);

    MutexLocker registeredThreadsLock(m_registeredThreadsMutex);
    for (Thread* t = m_registeredThreads; t;) {
        Thread* next = t->next;
        delete t;
        t = next;
    }
}

static inline PlatformThread getCurrentPlatformThread()
{
#if OS(DARWIN)
    return pthread_mach_thread_np(pthread_self());
#elif OS(WINDOWS)
    return GetCurrentThread();
#elif USE(PTHREADS)
    return pthread_self();
#endif
}

static inline bool equalThread(const PlatformThread& first, const PlatformThread& second)
{
#if OS(DARWIN) || OS(WINDOWS)
    return first == second;
#elif USE(PTHREADS)
    return !!pthread_equal(first, second);
#else
#error Need a way to compare threads on this platform
#endif
}

void MachineThreads::makeUsableFromMultipleThreads()
{
    if (m_threadSpecific)
        return;

    threadSpecificKeyCreate(&m_threadSpecific, removeThread);
}

void MachineThreads::addCurrentThread()
{
    ASSERT(!m_heap->vm()->exclusiveThread || m_heap->vm()->exclusiveThread == currentThread());

    if (!m_threadSpecific || threadSpecificGet(m_threadSpecific))
        return;

    threadSpecificSet(m_threadSpecific, this);
    Thread* thread = new Thread(getCurrentPlatformThread(), wtfThreadData().stack().origin());

    MutexLocker lock(m_registeredThreadsMutex);

    thread->next = m_registeredThreads;
    m_registeredThreads = thread;
}

void MachineThreads::removeThread(void* p)
{
    if (p)
        static_cast<MachineThreads*>(p)->removeCurrentThread();
}

void MachineThreads::removeCurrentThread()
{
    PlatformThread currentPlatformThread = getCurrentPlatformThread();

    MutexLocker lock(m_registeredThreadsMutex);

    if (equalThread(currentPlatformThread, m_registeredThreads->platformThread)) {
        Thread* t = m_registeredThreads;
        m_registeredThreads = m_registeredThreads->next;
        delete t;
    } else {
        Thread* last = m_registeredThreads;
        Thread* t;
        for (t = m_registeredThreads->next; t; t = t->next) {
            if (equalThread(t->platformThread, currentPlatformThread)) {
                last->next = t->next;
                break;
            }
            last = t;
        }
        ASSERT(t); // If t is NULL, we never found ourselves in the list.
        delete t;
    }
}

#if COMPILER(GCC)
#define REGISTER_BUFFER_ALIGNMENT __attribute__ ((aligned (sizeof(void*))))
#else
#define REGISTER_BUFFER_ALIGNMENT
#endif

void MachineThreads::gatherFromCurrentThread(ConservativeRoots& conservativeRoots, void* stackCurrent)
{
    // setjmp forces volatile registers onto the stack
    jmp_buf registers REGISTER_BUFFER_ALIGNMENT;
#if COMPILER(MSVC)
#pragma warning(push)
#pragma warning(disable: 4611)
#endif
    setjmp(registers);
#if COMPILER(MSVC)
#pragma warning(pop)
#endif

    void* registersBegin = &registers;
    void* registersEnd = reinterpret_cast<void*>(roundUpToMultipleOf<sizeof(void*)>(reinterpret_cast<uintptr_t>(&registers + 1)));
    swapIfBackwards(registersBegin, registersEnd);
    conservativeRoots.add(registersBegin, registersEnd);

    void* stackBegin = stackCurrent;
    void* stackEnd = wtfThreadData().stack().origin();
    swapIfBackwards(stackBegin, stackEnd);
    conservativeRoots.add(stackBegin, stackEnd);
}

static inline void suspendThread(const PlatformThread& platformThread)
{
#if OS(DARWIN)
    thread_suspend(platformThread);
#elif OS(WINDOWS)
    SuspendThread(platformThread);
#elif USE(PTHREADS)
    pthread_kill(platformThread, SigThreadSuspendResume);
#else
#error Need a way to suspend threads on this platform
#endif
}

static inline void resumeThread(const PlatformThread& platformThread)
{
#if OS(DARWIN)
    thread_resume(platformThread);
#elif OS(WINDOWS)
    ResumeThread(platformThread);
#elif USE(PTHREADS)
    pthread_kill(platformThread, SigThreadSuspendResume);
#else
#error Need a way to resume threads on this platform
#endif
}

typedef unsigned long usword_t; // word size, assumed to be either 32 or 64 bit

#if OS(DARWIN)

#if CPU(X86)
typedef i386_thread_state_t PlatformThreadRegisters;
#elif CPU(X86_64)
typedef x86_thread_state64_t PlatformThreadRegisters;
#elif CPU(PPC)
typedef ppc_thread_state_t PlatformThreadRegisters;
#elif CPU(PPC64)
typedef ppc_thread_state64_t PlatformThreadRegisters;
#elif CPU(ARM)
typedef arm_thread_state_t PlatformThreadRegisters;
#elif CPU(ARM64)
typedef arm_thread_state64_t PlatformThreadRegisters;
#else
#error Unknown Architecture
#endif

#elif OS(WINDOWS)
typedef CONTEXT PlatformThreadRegisters;
#elif OS(QNX)
typedef struct _debug_thread_info PlatformThreadRegisters;
#elif USE(PTHREADS)
typedef pthread_attr_t PlatformThreadRegisters;
#else
#error Need a thread register struct for this platform
#endif

static size_t getPlatformThreadRegisters(const PlatformThread& platformThread, PlatformThreadRegisters& regs)
{
#if OS(DARWIN)

#if CPU(X86)
    unsigned user_count = sizeof(regs)/sizeof(int);
    thread_state_flavor_t flavor = i386_THREAD_STATE;
#elif CPU(X86_64)
    unsigned user_count = x86_THREAD_STATE64_COUNT;
    thread_state_flavor_t flavor = x86_THREAD_STATE64;
#elif CPU(PPC) 
    unsigned user_count = PPC_THREAD_STATE_COUNT;
    thread_state_flavor_t flavor = PPC_THREAD_STATE;
#elif CPU(PPC64)
    unsigned user_count = PPC_THREAD_STATE64_COUNT;
    thread_state_flavor_t flavor = PPC_THREAD_STATE64;
#elif CPU(ARM)
    unsigned user_count = ARM_THREAD_STATE_COUNT;
    thread_state_flavor_t flavor = ARM_THREAD_STATE;
#elif CPU(ARM64)
    unsigned user_count = ARM_THREAD_STATE64_COUNT;
    thread_state_flavor_t flavor = ARM_THREAD_STATE64;
#else
#error Unknown Architecture
#endif

    kern_return_t result = thread_get_state(platformThread, flavor, (thread_state_t)&regs, &user_count);
    if (result != KERN_SUCCESS) {
        WTFReportFatalError(__FILE__, __LINE__, WTF_PRETTY_FUNCTION, 
                            "JavaScript garbage collection failed because thread_get_state returned an error (%d). This is probably the result of running inside Rosetta, which is not supported.", result);
        CRASH();
    }
    return user_count * sizeof(usword_t);
// end OS(DARWIN)

#elif OS(WINDOWS)
    regs.ContextFlags = CONTEXT_INTEGER | CONTEXT_CONTROL;
    GetThreadContext(platformThread, &regs);
    return sizeof(CONTEXT);
#elif OS(QNX)
    memset(&regs, 0, sizeof(regs));
    regs.tid = platformThread;
    // FIXME: If we find this hurts performance, we can consider caching the fd and keeping it open.
    int fd = open("/proc/self/as", O_RDONLY);
    if (fd == -1) {
        LOG_ERROR("Unable to open /proc/self/as (errno: %d)", errno);
        CRASH();
    }
    int rc = devctl(fd, DCMD_PROC_TIDSTATUS, &regs, sizeof(regs), 0);
    if (rc != EOK) {
        LOG_ERROR("devctl(DCMD_PROC_TIDSTATUS) failed (error: %d)", rc);
        CRASH();
    }
    close(fd);
    return sizeof(struct _debug_thread_info);
#elif USE(PTHREADS)
    pthread_attr_init(&regs);
#if HAVE(PTHREAD_NP_H) || OS(NETBSD)
    // e.g. on FreeBSD 5.4, neundorf@kde.org
    pthread_attr_get_np(platformThread, &regs);
#else
    // FIXME: this function is non-portable; other POSIX systems may have different np alternatives
    pthread_getattr_np(platformThread, &regs);
#endif
    return 0;
#else
#error Need a way to get thread registers on this platform
#endif
}

static inline void* otherThreadStackPointer(const PlatformThreadRegisters& regs)
{
#if OS(DARWIN)

#if __DARWIN_UNIX03

#if CPU(X86)
    return reinterpret_cast<void*>(regs.__esp);
#elif CPU(X86_64)
    return reinterpret_cast<void*>(regs.__rsp);
#elif CPU(PPC) || CPU(PPC64)
    return reinterpret_cast<void*>(regs.__r1);
#elif CPU(ARM)
    return reinterpret_cast<void*>(regs.__sp);
#elif CPU(ARM64)
    return reinterpret_cast<void*>(regs.__sp);
#else
#error Unknown Architecture
#endif

#else // !__DARWIN_UNIX03

#if CPU(X86)
    return reinterpret_cast<void*>(regs.esp);
#elif CPU(X86_64)
    return reinterpret_cast<void*>(regs.rsp);
#elif CPU(PPC) || CPU(PPC64)
    return reinterpret_cast<void*>(regs.r1);
#else
#error Unknown Architecture
#endif

#endif // __DARWIN_UNIX03

// end OS(DARWIN)
#elif OS(WINDOWS)

#if CPU(ARM)
    return reinterpret_cast<void*>((uintptr_t) regs.Sp);
#elif CPU(MIPS)
    return reinterpret_cast<void*>((uintptr_t) regs.IntSp);
#elif CPU(X86)
    return reinterpret_cast<void*>((uintptr_t) regs.Esp);
#elif CPU(X86_64)
    return reinterpret_cast<void*>((uintptr_t) regs.Rsp);
#else
#error Unknown Architecture
#endif

#elif OS(QNX)
    return reinterpret_cast<void*>((uintptr_t) regs.sp);

#elif USE(PTHREADS)
    void* stackBase = 0;
    size_t stackSize = 0;
    int rc = pthread_attr_getstack(&regs, &stackBase, &stackSize);
    (void)rc; // FIXME: Deal with error code somehow? Seems fatal.
    ASSERT(stackBase);
    return static_cast<char*>(stackBase) + stackSize;
#else
#error Need a way to get the stack pointer for another thread on this platform
#endif
}

static void freePlatformThreadRegisters(PlatformThreadRegisters& regs)
{
#if USE(PTHREADS) && !OS(WINDOWS) && !OS(DARWIN) && !OS(QNX)
    pthread_attr_destroy(&regs);
#else
    UNUSED_PARAM(regs);
#endif
}

void MachineThreads::gatherFromOtherThread(ConservativeRoots& conservativeRoots, Thread* thread)
{
    PlatformThreadRegisters regs;
    size_t regSize = getPlatformThreadRegisters(thread->platformThread, regs);

    conservativeRoots.add(static_cast<void*>(&regs), static_cast<void*>(reinterpret_cast<char*>(&regs) + regSize));

    void* stackPointer = otherThreadStackPointer(regs);
    void* stackBase = thread->stackBase;
    swapIfBackwards(stackPointer, stackBase);
    conservativeRoots.add(stackPointer, stackBase);

    freePlatformThreadRegisters(regs);
}

void MachineThreads::gatherConservativeRoots(ConservativeRoots& conservativeRoots, void* stackCurrent)
{
    gatherFromCurrentThread(conservativeRoots, stackCurrent);

    if (m_threadSpecific) {
        PlatformThread currentPlatformThread = getCurrentPlatformThread();

        MutexLocker lock(m_registeredThreadsMutex);

#ifndef NDEBUG
        // Forbid malloc during the gather phase. The gather phase suspends
        // threads, so a malloc during gather would risk a deadlock with a
        // thread that had been suspended while holding the malloc lock.
        fastMallocForbid();
#endif
        for (Thread* thread = m_registeredThreads; thread; thread = thread->next) {
            if (!equalThread(thread->platformThread, currentPlatformThread))
                suspendThread(thread->platformThread);
        }

        // It is safe to access the registeredThreads list, because we earlier asserted that locks are being held,
        // and since this is a shared heap, they are real locks.
        for (Thread* thread = m_registeredThreads; thread; thread = thread->next) {
            if (!equalThread(thread->platformThread, currentPlatformThread))
                gatherFromOtherThread(conservativeRoots, thread);
        }

        for (Thread* thread = m_registeredThreads; thread; thread = thread->next) {
            if (!equalThread(thread->platformThread, currentPlatformThread))
                resumeThread(thread->platformThread);
        }

#ifndef NDEBUG
        fastMallocAllow();
#endif
    }
}

} // namespace JSC
Commit	Line	Data
14957cd0 A	1	/*
	2	* Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
	3	* Copyright (C) 2007 Eric Seidel <eric@webkit.org>
	4	* Copyright (C) 2009 Acision BV. All rights reserved.
	5	*
	6	* This library is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU Lesser General Public
	8	* License as published by the Free Software Foundation; either
	9	* version 2 of the License, or (at your option) any later version.
	10	*
	11	* This library is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	14	* Lesser General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU Lesser General Public
	17	* License along with this library; if not, write to the Free Software
	18	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	19	*
	20	*/
	21
	22	#include "config.h"
	23	#include "MachineStackMarker.h"
	24
	25	#include "ConservativeRoots.h"
	26	#include "Heap.h"
	27	#include "JSArray.h"
93a37866	28	#include "VM.h"
14957cd0 A	29	#include <setjmp.h>
	30	#include <stdlib.h>
	31	#include <wtf/StdLibExtras.h>
	32
14957cd0 A	33	#if OS(DARWIN)
	34
	35	#include <mach/mach_init.h>
	36	#include <mach/mach_port.h>
	37	#include <mach/task.h>
	38	#include <mach/thread_act.h>
	39	#include <mach/vm_map.h>
	40
	41	#elif OS(WINDOWS)
	42
	43	#include <windows.h>
	44	#include <malloc.h>
	45
14957cd0 A	46	#elif OS(UNIX)
14957cd0 A	47
14957cd0	48	#include <sys/mman.h>
14957cd0 A	49	#include <unistd.h>
	50
	51	#if OS(SOLARIS)
	52	#include <thread.h>
	53	#else
	54	#include <pthread.h>
	55	#endif
	56
	57	#if HAVE(PTHREAD_NP_H)
	58	#include <pthread_np.h>
	59	#endif
	60
	61	#if OS(QNX)
	62	#include <fcntl.h>
	63	#include <sys/procfs.h>
	64	#include <stdio.h>
	65	#include <errno.h>
	66	#endif
	67
	68	#if USE(PTHREADS) && !OS(WINDOWS) && !OS(DARWIN)
	69	#include <signal.h>
14957cd0 A	70	#endif
	71
	72	#endif
	73
	74	using namespace WTF;
	75
	76	namespace JSC {
	77
	78	static inline void swapIfBackwards(void& begin, void& end)
	79	{
	80	#if OS(WINCE)
	81	if (begin <= end)
	82	return;
	83	std::swap(begin, end);
	84	#else
	85	UNUSED_PARAM(begin);
	86	UNUSED_PARAM(end);
	87	#endif
	88	}
	89
14957cd0 A	90	#if OS(DARWIN)
	91	typedef mach_port_t PlatformThread;
	92	#elif OS(WINDOWS)
	93	typedef HANDLE PlatformThread;
	94	#elif USE(PTHREADS)
	95	typedef pthread_t PlatformThread;
	96	static const int SigThreadSuspendResume = SIGUSR2;
	97
6fe7ccc8	98	#if defined(SA_RESTART)
93a37866	99	static void pthreadSignalHandlerSuspendResume(int)
14957cd0 A	100	{
	101	sigset_t signalSet;
	102	sigemptyset(&signalSet);
	103	sigaddset(&signalSet, SigThreadSuspendResume);
	104	sigsuspend(&signalSet);
	105	}
	106	#endif
6fe7ccc8	107	#endif
14957cd0 A	108
14957cd0 A	109	class MachineThreads::Thread {
93a37866	110	WTF_MAKE_FAST_ALLOCATED;
14957cd0	111	public:
6fe7ccc8 A	112	Thread(const PlatformThread& platThread, void* base)
6fe7ccc8 A	113	: platformThread(platThread)
14957cd0 A	114	, stackBase(base)
14957cd0 A	115	{
6fe7ccc8 A	116	#if USE(PTHREADS) && !OS(WINDOWS) && !OS(DARWIN) && defined(SA_RESTART)
6fe7ccc8 A	117	// if we have SA_RESTART, enable SIGUSR2 debugging mechanism
14957cd0 A	118	struct sigaction action;
	119	action.sa_handler = pthreadSignalHandlerSuspendResume;
	120	sigemptyset(&action.sa_mask);
	121	action.sa_flags = SA_RESTART;
	122	sigaction(SigThreadSuspendResume, &action, 0);
	123
	124	sigset_t mask;
	125	sigemptyset(&mask);
	126	sigaddset(&mask, SigThreadSuspendResume);
	127	pthread_sigmask(SIG_UNBLOCK, &mask, 0);
	128	#endif
	129	}
	130
	131	Thread* next;
14957cd0 A	132	PlatformThread platformThread;
	133	void* stackBase;
	134	};
	135
14957cd0	136	MachineThreads::MachineThreads(Heap* heap)
93a37866	137	: m_registeredThreads(0)
14957cd0	138	, m_threadSpecific(0)
93a37866 A	139	#if !ASSERT_DISABLED
	140	, m_heap(heap)
	141	#endif
14957cd0	142	{
93a37866	143	UNUSED_PARAM(heap);
14957cd0 A	144	}
	145
	146	MachineThreads::~MachineThreads()
	147	{
93a37866 A	148	if (m_threadSpecific)
93a37866 A	149	threadSpecificKeyDelete(m_threadSpecific);
14957cd0 A	150
	151	MutexLocker registeredThreadsLock(m_registeredThreadsMutex);
	152	for (Thread* t = m_registeredThreads; t;) {
	153	Thread* next = t->next;
	154	delete t;
	155	t = next;
	156	}
14957cd0 A	157	}
14957cd0 A	158
14957cd0 A	159	static inline PlatformThread getCurrentPlatformThread()
	160	{
	161	#if OS(DARWIN)
	162	return pthread_mach_thread_np(pthread_self());
	163	#elif OS(WINDOWS)
6fe7ccc8	164	return GetCurrentThread();
14957cd0 A	165	#elif USE(PTHREADS)
	166	return pthread_self();
	167	#endif
	168	}
	169
6fe7ccc8 A	170	static inline bool equalThread(const PlatformThread& first, const PlatformThread& second)
	171	{
	172	#if OS(DARWIN) \|\| OS(WINDOWS)
	173	return first == second;
	174	#elif USE(PTHREADS)
	175	return !!pthread_equal(first, second);
	176	#else
	177	#error Need a way to compare threads on this platform
	178	#endif
	179	}
	180
14957cd0 A	181	void MachineThreads::makeUsableFromMultipleThreads()
	182	{
	183	if (m_threadSpecific)
	184	return;
	185
93a37866	186	threadSpecificKeyCreate(&m_threadSpecific, removeThread);
14957cd0 A	187	}
	188
	189	void MachineThreads::addCurrentThread()
	190	{
93a37866	191	ASSERT(!m_heap->vm()->exclusiveThread \|\| m_heap->vm()->exclusiveThread == currentThread());
14957cd0	192
93a37866	193	if (!m_threadSpecific \|\| threadSpecificGet(m_threadSpecific))
14957cd0 A	194	return;
14957cd0 A	195
93a37866	196	threadSpecificSet(m_threadSpecific, this);
6fe7ccc8	197	Thread* thread = new Thread(getCurrentPlatformThread(), wtfThreadData().stack().origin());
14957cd0 A	198
	199	MutexLocker lock(m_registeredThreadsMutex);
	200
	201	thread->next = m_registeredThreads;
	202	m_registeredThreads = thread;
	203	}
	204
	205	void MachineThreads::removeThread(void* p)
	206	{
	207	if (p)
	208	static_cast<MachineThreads*>(p)->removeCurrentThread();
	209	}
	210
	211	void MachineThreads::removeCurrentThread()
	212	{
6fe7ccc8	213	PlatformThread currentPlatformThread = getCurrentPlatformThread();
14957cd0 A	214
	215	MutexLocker lock(m_registeredThreadsMutex);
	216
6fe7ccc8	217	if (equalThread(currentPlatformThread, m_registeredThreads->platformThread)) {
14957cd0 A	218	Thread* t = m_registeredThreads;
	219	m_registeredThreads = m_registeredThreads->next;
	220	delete t;
	221	} else {
	222	Thread* last = m_registeredThreads;
	223	Thread* t;
	224	for (t = m_registeredThreads->next; t; t = t->next) {
6fe7ccc8	225	if (equalThread(t->platformThread, currentPlatformThread)) {
14957cd0 A	226	last->next = t->next;
	227	break;
	228	}
	229	last = t;
	230	}
	231	ASSERT(t); // If t is NULL, we never found ourselves in the list.
	232	delete t;
	233	}
	234	}
	235
14957cd0 A	236	#if COMPILER(GCC)
	237	#define REGISTER_BUFFER_ALIGNMENT __attribute__ ((aligned (sizeof(void*))))
	238	#else
	239	#define REGISTER_BUFFER_ALIGNMENT
	240	#endif
	241
	242	void MachineThreads::gatherFromCurrentThread(ConservativeRoots& conservativeRoots, void* stackCurrent)
	243	{
	244	// setjmp forces volatile registers onto the stack
	245	jmp_buf registers REGISTER_BUFFER_ALIGNMENT;
	246	#if COMPILER(MSVC)
	247	#pragma warning(push)
	248	#pragma warning(disable: 4611)
	249	#endif
	250	setjmp(registers);
	251	#if COMPILER(MSVC)
	252	#pragma warning(pop)
	253	#endif
	254
	255	void* registersBegin = &registers;
	256	void* registersEnd = reinterpret_cast<void>(roundUpToMultipleOf<sizeof(void)>(reinterpret_cast<uintptr_t>(&registers + 1)));
	257	swapIfBackwards(registersBegin, registersEnd);
	258	conservativeRoots.add(registersBegin, registersEnd);
	259
	260	void* stackBegin = stackCurrent;
6fe7ccc8	261	void* stackEnd = wtfThreadData().stack().origin();
14957cd0 A	262	swapIfBackwards(stackBegin, stackEnd);
	263	conservativeRoots.add(stackBegin, stackEnd);
	264	}
	265
14957cd0 A	266	static inline void suspendThread(const PlatformThread& platformThread)
	267	{
	268	#if OS(DARWIN)
	269	thread_suspend(platformThread);
	270	#elif OS(WINDOWS)
	271	SuspendThread(platformThread);
	272	#elif USE(PTHREADS)
	273	pthread_kill(platformThread, SigThreadSuspendResume);
	274	#else
	275	#error Need a way to suspend threads on this platform
	276	#endif
	277	}
	278
	279	static inline void resumeThread(const PlatformThread& platformThread)
	280	{
	281	#if OS(DARWIN)
	282	thread_resume(platformThread);
	283	#elif OS(WINDOWS)
	284	ResumeThread(platformThread);
	285	#elif USE(PTHREADS)
	286	pthread_kill(platformThread, SigThreadSuspendResume);
	287	#else
	288	#error Need a way to resume threads on this platform
	289	#endif
	290	}
	291
	292	typedef unsigned long usword_t; // word size, assumed to be either 32 or 64 bit
	293
	294	#if OS(DARWIN)
	295
	296	#if CPU(X86)
	297	typedef i386_thread_state_t PlatformThreadRegisters;
	298	#elif CPU(X86_64)
	299	typedef x86_thread_state64_t PlatformThreadRegisters;
	300	#elif CPU(PPC)
	301	typedef ppc_thread_state_t PlatformThreadRegisters;
	302	#elif CPU(PPC64)
	303	typedef ppc_thread_state64_t PlatformThreadRegisters;
	304	#elif CPU(ARM)
	305	typedef arm_thread_state_t PlatformThreadRegisters;
93a37866 A	306	#elif CPU(ARM64)
93a37866 A	307	typedef arm_thread_state64_t PlatformThreadRegisters;
14957cd0 A	308	#else
	309	#error Unknown Architecture
	310	#endif
	311
	312	#elif OS(WINDOWS)
	313	typedef CONTEXT PlatformThreadRegisters;
6fe7ccc8 A	314	#elif OS(QNX)
6fe7ccc8 A	315	typedef struct _debug_thread_info PlatformThreadRegisters;
14957cd0 A	316	#elif USE(PTHREADS)
	317	typedef pthread_attr_t PlatformThreadRegisters;
	318	#else
	319	#error Need a thread register struct for this platform
	320	#endif
	321
	322	static size_t getPlatformThreadRegisters(const PlatformThread& platformThread, PlatformThreadRegisters& regs)
	323	{
	324	#if OS(DARWIN)
	325
	326	#if CPU(X86)
	327	unsigned user_count = sizeof(regs)/sizeof(int);
	328	thread_state_flavor_t flavor = i386_THREAD_STATE;
	329	#elif CPU(X86_64)
	330	unsigned user_count = x86_THREAD_STATE64_COUNT;
	331	thread_state_flavor_t flavor = x86_THREAD_STATE64;
	332	#elif CPU(PPC)
	333	unsigned user_count = PPC_THREAD_STATE_COUNT;
	334	thread_state_flavor_t flavor = PPC_THREAD_STATE;
	335	#elif CPU(PPC64)
	336	unsigned user_count = PPC_THREAD_STATE64_COUNT;
	337	thread_state_flavor_t flavor = PPC_THREAD_STATE64;
	338	#elif CPU(ARM)
	339	unsigned user_count = ARM_THREAD_STATE_COUNT;
	340	thread_state_flavor_t flavor = ARM_THREAD_STATE;
93a37866 A	341	#elif CPU(ARM64)
	342	unsigned user_count = ARM_THREAD_STATE64_COUNT;
	343	thread_state_flavor_t flavor = ARM_THREAD_STATE64;
14957cd0 A	344	#else
	345	#error Unknown Architecture
	346	#endif
	347
	348	kern_return_t result = thread_get_state(platformThread, flavor, (thread_state_t)&regs, &user_count);
	349	if (result != KERN_SUCCESS) {
	350	WTFReportFatalError(__FILE__, __LINE__, WTF_PRETTY_FUNCTION,
	351	"JavaScript garbage collection failed because thread_get_state returned an error (%d). This is probably the result of running inside Rosetta, which is not supported.", result);
	352	CRASH();
	353	}
	354	return user_count * sizeof(usword_t);
	355	// end OS(DARWIN)
	356
	357	#elif OS(WINDOWS)
6fe7ccc8	358	regs.ContextFlags = CONTEXT_INTEGER \| CONTEXT_CONTROL;
14957cd0 A	359	GetThreadContext(platformThread, &regs);
14957cd0 A	360	return sizeof(CONTEXT);
6fe7ccc8 A	361	#elif OS(QNX)
6fe7ccc8 A	362	memset(&regs, 0, sizeof(regs));
93a37866 A	363	regs.tid = platformThread;
	364	// FIXME: If we find this hurts performance, we can consider caching the fd and keeping it open.
	365	int fd = open("/proc/self/as", O_RDONLY);
6fe7ccc8	366	if (fd == -1) {
93a37866 A	367	LOG_ERROR("Unable to open /proc/self/as (errno: %d)", errno);
	368	CRASH();
	369	}
	370	int rc = devctl(fd, DCMD_PROC_TIDSTATUS, &regs, sizeof(regs), 0);
	371	if (rc != EOK) {
	372	LOG_ERROR("devctl(DCMD_PROC_TIDSTATUS) failed (error: %d)", rc);
6fe7ccc8 A	373	CRASH();
6fe7ccc8 A	374	}
6fe7ccc8	375	close(fd);
93a37866	376	return sizeof(struct _debug_thread_info);
14957cd0 A	377	#elif USE(PTHREADS)
	378	pthread_attr_init(&regs);
	379	#if HAVE(PTHREAD_NP_H) \|\| OS(NETBSD)
	380	// e.g. on FreeBSD 5.4, neundorf@kde.org
	381	pthread_attr_get_np(platformThread, &regs);
	382	#else
	383	// FIXME: this function is non-portable; other POSIX systems may have different np alternatives
	384	pthread_getattr_np(platformThread, &regs);
	385	#endif
	386	return 0;
	387	#else
	388	#error Need a way to get thread registers on this platform
	389	#endif
	390	}
	391
	392	static inline void* otherThreadStackPointer(const PlatformThreadRegisters& regs)
	393	{
	394	#if OS(DARWIN)
	395
	396	#if __DARWIN_UNIX03
	397
	398	#if CPU(X86)
	399	return reinterpret_cast<void*>(regs.__esp);
	400	#elif CPU(X86_64)
	401	return reinterpret_cast<void*>(regs.__rsp);
	402	#elif CPU(PPC) \|\| CPU(PPC64)
	403	return reinterpret_cast<void*>(regs.__r1);
	404	#elif CPU(ARM)
	405	return reinterpret_cast<void*>(regs.__sp);
93a37866 A	406	#elif CPU(ARM64)
93a37866 A	407	return reinterpret_cast<void*>(regs.__sp);
14957cd0 A	408	#else
	409	#error Unknown Architecture
	410	#endif
	411
	412	#else // !__DARWIN_UNIX03
	413
	414	#if CPU(X86)
	415	return reinterpret_cast<void*>(regs.esp);
	416	#elif CPU(X86_64)
	417	return reinterpret_cast<void*>(regs.rsp);
	418	#elif CPU(PPC) \|\| CPU(PPC64)
	419	return reinterpret_cast<void*>(regs.r1);
	420	#else
	421	#error Unknown Architecture
	422	#endif
	423
	424	#endif // __DARWIN_UNIX03
	425
	426	// end OS(DARWIN)
6fe7ccc8 A	427	#elif OS(WINDOWS)
	428
	429	#if CPU(ARM)
	430	return reinterpret_cast<void*>((uintptr_t) regs.Sp);
	431	#elif CPU(MIPS)
	432	return reinterpret_cast<void*>((uintptr_t) regs.IntSp);
	433	#elif CPU(X86)
14957cd0	434	return reinterpret_cast<void*>((uintptr_t) regs.Esp);
6fe7ccc8	435	#elif CPU(X86_64)
14957cd0	436	return reinterpret_cast<void*>((uintptr_t) regs.Rsp);
6fe7ccc8 A	437	#else
	438	#error Unknown Architecture
	439	#endif
	440
	441	#elif OS(QNX)
	442	return reinterpret_cast<void*>((uintptr_t) regs.sp);
	443
14957cd0 A	444	#elif USE(PTHREADS)
	445	void* stackBase = 0;
	446	size_t stackSize = 0;
	447	int rc = pthread_attr_getstack(&regs, &stackBase, &stackSize);
	448	(void)rc; // FIXME: Deal with error code somehow? Seems fatal.
	449	ASSERT(stackBase);
	450	return static_cast<char*>(stackBase) + stackSize;
	451	#else
	452	#error Need a way to get the stack pointer for another thread on this platform
	453	#endif
	454	}
	455
	456	static void freePlatformThreadRegisters(PlatformThreadRegisters& regs)
	457	{
6fe7ccc8	458	#if USE(PTHREADS) && !OS(WINDOWS) && !OS(DARWIN) && !OS(QNX)
14957cd0 A	459	pthread_attr_destroy(&regs);
	460	#else
	461	UNUSED_PARAM(regs);
	462	#endif
	463	}
	464
	465	void MachineThreads::gatherFromOtherThread(ConservativeRoots& conservativeRoots, Thread* thread)
	466	{
14957cd0 A	467	PlatformThreadRegisters regs;
	468	size_t regSize = getPlatformThreadRegisters(thread->platformThread, regs);
	469
	470	conservativeRoots.add(static_cast<void>(&regs), static_cast<void>(reinterpret_cast<char*>(&regs) + regSize));
	471
	472	void* stackPointer = otherThreadStackPointer(regs);
	473	void* stackBase = thread->stackBase;
	474	swapIfBackwards(stackPointer, stackBase);
	475	conservativeRoots.add(stackPointer, stackBase);
	476
14957cd0 A	477	freePlatformThreadRegisters(regs);
	478	}
	479
14957cd0 A	480	void MachineThreads::gatherConservativeRoots(ConservativeRoots& conservativeRoots, void* stackCurrent)
	481	{
	482	gatherFromCurrentThread(conservativeRoots, stackCurrent);
	483
14957cd0	484	if (m_threadSpecific) {
6fe7ccc8	485	PlatformThread currentPlatformThread = getCurrentPlatformThread();
14957cd0 A	486
	487	MutexLocker lock(m_registeredThreadsMutex);
	488
	489	#ifndef NDEBUG
	490	// Forbid malloc during the gather phase. The gather phase suspends
	491	// threads, so a malloc during gather would risk a deadlock with a
	492	// thread that had been suspended while holding the malloc lock.
	493	fastMallocForbid();
	494	#endif
93a37866 A	495	for (Thread* thread = m_registeredThreads; thread; thread = thread->next) {
	496	if (!equalThread(thread->platformThread, currentPlatformThread))
	497	suspendThread(thread->platformThread);
	498	}
	499
14957cd0 A	500	// It is safe to access the registeredThreads list, because we earlier asserted that locks are being held,
	501	// and since this is a shared heap, they are real locks.
	502	for (Thread* thread = m_registeredThreads; thread; thread = thread->next) {
6fe7ccc8	503	if (!equalThread(thread->platformThread, currentPlatformThread))
14957cd0 A	504	gatherFromOtherThread(conservativeRoots, thread);
14957cd0 A	505	}
93a37866 A	506
	507	for (Thread* thread = m_registeredThreads; thread; thread = thread->next) {
	508	if (!equalThread(thread->platformThread, currentPlatformThread))
	509	resumeThread(thread->platformThread);
	510	}
	511
14957cd0 A	512	#ifndef NDEBUG
	513	fastMallocAllow();
	514	#endif
	515	}
14957cd0 A	516	}
	517
	518	} // namespace JSC