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win32_threads.c
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/*
* Copyright (c) 1994 by Xerox Corporation. All rights reserved.
* Copyright (c) 1996 by Silicon Graphics. All rights reserved.
* Copyright (c) 1998 by Fergus Henderson. All rights reserved.
* Copyright (c) 2000-2008 by Hewlett-Packard Development Company.
* All rights reserved.
* Copyright (c) 2008-2022 Ivan Maidanski
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose, provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*/
#include "private/pthread_support.h"
#if defined(GC_WIN32_THREADS)
/* The allocator lock definition. */
# ifndef USE_PTHREAD_LOCKS
# ifdef USE_RWLOCK
GC_INNER SRWLOCK GC_allocate_ml;
# else
GC_INNER CRITICAL_SECTION GC_allocate_ml;
# endif
# endif /* !USE_PTHREAD_LOCKS */
# undef CreateThread
# undef ExitThread
# undef _beginthreadex
# undef _endthreadex
# if !defined(GC_PTHREADS) && !defined(MSWINCE)
# include <errno.h>
# include <process.h> /* for _beginthreadex, _endthreadex */
# endif
static ptr_t copy_ptr_regs(word *regs, const CONTEXT *pcontext);
# ifndef GC_NO_THREADS_DISCOVERY
/* This code operates in two distinct modes, depending on */
/* the setting of GC_win32_dll_threads. */
/* If GC_win32_dll_threads is set, all threads in the process */
/* are implicitly registered with the GC by DllMain. */
/* No explicit registration is required, and attempts at */
/* explicit registration are ignored. This mode is */
/* very different from the Posix operation of the collector. */
/* In this mode access to the thread table is lock-free. */
/* Hence there is a static limit on the number of threads. */
/* GC_DISCOVER_TASK_THREADS should be used if DllMain-based */
/* thread registration is required but it is impossible to */
/* call GC_use_threads_discovery before other GC routines. */
# ifndef GC_DISCOVER_TASK_THREADS
/* GC_win32_dll_threads must be set (if needed) at the */
/* application initialization time, i.e. before any */
/* collector or thread calls. We make it a "dynamic" */
/* option only to avoid multiple library versions. */
GC_INNER GC_bool GC_win32_dll_threads = FALSE;
# endif
# else
/* If GC_win32_dll_threads is FALSE (or the collector is */
/* built without GC_DLL defined), things operate in a way */
/* that is very similar to Posix platforms, and new threads */
/* must be registered with the collector, e.g. by using */
/* preprocessor-based interception of the thread primitives. */
/* In this case, we use a real data structure for the thread */
/* table. Note that there is no equivalent of linker-based */
/* call interception, since we don't have ELF-like */
/* facilities. The Windows analog appears to be "API */
/* hooking", which really seems to be a standard way to */
/* do minor binary rewriting (?). I'd prefer not to have */
/* the basic collector rely on such facilities, but an */
/* optional package that intercepts thread calls this way */
/* would probably be nice. */
# undef MAX_THREADS
/* dll_thread_table[] is always empty. */
# define MAX_THREADS 1
# endif /* GC_NO_THREADS_DISCOVERY */
/* We have two versions of the thread table. Which one */
/* we use depends on whether GC_win32_dll_threads */
/* is set. Note that before initialization, we don't */
/* add any entries to either table, even if DllMain is */
/* called. The main thread will be added on */
/* initialization. */
/* GC_use_threads_discovery() is currently incompatible with pthreads */
/* and WinCE. It might be possible to get DllMain-based thread */
/* registration to work with Cygwin, but if you try it then you are on */
/* your own. */
GC_API void GC_CALL
GC_use_threads_discovery(void)
{
# ifdef GC_NO_THREADS_DISCOVERY
ABORT("GC DllMain-based thread registration unsupported");
# else
/* Turn on GC_win32_dll_threads. */
GC_ASSERT(!GC_is_initialized);
/* Note that GC_use_threads_discovery is expected to be called by */
/* the client application (not from DllMain) at start-up. */
# ifndef GC_DISCOVER_TASK_THREADS
GC_win32_dll_threads = TRUE;
# endif
GC_init();
# ifdef CPPCHECK
GC_noop1((word)(GC_funcptr_uint)(&GC_DllMain));
# endif
# endif
}
# ifndef GC_NO_THREADS_DISCOVERY
/* We track thread attachments while the world is supposed to be */
/* stopped. Unfortunately, we cannot stop them from starting, since */
/* blocking in DllMain seems to cause the world to deadlock. Thus, */
/* we have to recover if we notice this in the middle of marking. */
STATIC volatile AO_t GC_attached_thread = FALSE;
/* We assume that volatile implies memory ordering, at least among */
/* volatiles. This code should consistently use atomic_ops. */
STATIC volatile GC_bool GC_please_stop = FALSE;
# elif defined(GC_ASSERTIONS)
STATIC GC_bool GC_please_stop = FALSE;
# endif /* GC_NO_THREADS_DISCOVERY && GC_ASSERTIONS */
# if defined(WRAP_MARK_SOME) && !defined(GC_PTHREADS)
/* Return TRUE if an thread was attached since we last asked or */
/* since GC_attached_thread was explicitly reset. */
GC_INNER GC_bool
GC_started_thread_while_stopped(void)
{
# ifndef GC_NO_THREADS_DISCOVERY
if (GC_win32_dll_threads) {
# ifdef AO_HAVE_compare_and_swap_release
if (AO_compare_and_swap_release(&GC_attached_thread, TRUE,
FALSE /* stored */))
return TRUE;
# else
/* Prior heap reads need to complete earlier. */
AO_nop_full();
if (AO_load(&GC_attached_thread)) {
AO_store(&GC_attached_thread, FALSE);
return TRUE;
}
# endif
}
# endif
return FALSE;
}
# endif /* WRAP_MARK_SOME */
/* Thread table used if GC_win32_dll_threads is set. */
/* This is a fixed size array. */
/* Since we use runtime conditionals, both versions */
/* are always defined. */
# ifndef MAX_THREADS
# define MAX_THREADS 512
# endif
/* Things may get quite slow for large numbers of threads, */
/* since we look them up with sequential search. */
static volatile struct GC_Thread_Rep dll_thread_table[MAX_THREADS];
# ifndef GC_NO_THREADS_DISCOVERY
static struct GC_StackContext_Rep dll_crtn_table[MAX_THREADS];
# endif
/* Largest index in dll_thread_table that was ever used. */
STATIC volatile LONG GC_max_thread_index = 0;
/* This may be called from DllMain, and hence operates under unusual */
/* constraints. In particular, it must be lock-free if */
/* GC_win32_dll_threads is set. Always called from the thread being */
/* added. If GC_win32_dll_threads is not set, we already hold the */
/* allocator lock except possibly during single-threaded startup code. */
/* Does not initialize thread-local free lists. */
GC_INNER GC_thread
GC_register_my_thread_inner(const struct GC_stack_base *sb,
thread_id_t self_id)
{
GC_thread me;
# ifdef GC_NO_THREADS_DISCOVERY
GC_ASSERT(I_HOLD_LOCK());
# endif
/* The following should be a no-op according to the Win32 */
/* documentation. There is empirical evidence that it */
/* isn't. - HB */
# if defined(MPROTECT_VDB) && !defined(CYGWIN32)
if (GC_auto_incremental
# ifdef GWW_VDB
&& !GC_gww_dirty_init()
# endif
)
GC_set_write_fault_handler();
# endif
# ifndef GC_NO_THREADS_DISCOVERY
if (GC_win32_dll_threads) {
int i;
/* It appears to be unsafe to acquire a lock here, since this */
/* code is apparently not preemptible on some systems. */
/* (This is based on complaints, not on Microsoft's official */
/* documentation, which says this should perform "only simple */
/* initialization tasks".) */
/* Hence we make do with nonblocking synchronization. */
/* It has been claimed that DllMain is really only executed with */
/* a particular system lock held, and thus careful use of locking */
/* around code that doesn't call back into the system libraries */
/* might be OK. But this has not been tested across all Win32 */
/* variants. */
for (i = 0;
InterlockedExchange(&dll_thread_table[i].tm.long_in_use, 1) != 0;
i++) {
/* Compare-and-swap would make this cleaner, but that's not */
/* supported before Windows 98 and NT 4.0. In Windows 2000, */
/* InterlockedExchange is supposed to be replaced by */
/* InterlockedExchangePointer, but that's not really what I */
/* want here. */
/* FIXME: We should eventually declare Windows 95 dead and use */
/* AO_ primitives here. */
if (i == MAX_THREADS - 1)
ABORT("Too many threads");
}
/* Update GC_max_thread_index if necessary. The following is */
/* safe, and unlike CompareExchange-based solutions seems to work */
/* on all Windows 95 and later platforms. Unfortunately, */
/* GC_max_thread_index may be temporarily out of bounds, so */
/* readers have to compensate. */
while (i > GC_max_thread_index) {
InterlockedIncrement((LONG *)&GC_max_thread_index);
/* Cast away volatile for older versions of Win32 headers. */
}
if (EXPECT(GC_max_thread_index >= MAX_THREADS, FALSE)) {
/* We overshot due to simultaneous increments. */
/* Setting it to MAX_THREADS-1 is always safe. */
GC_max_thread_index = MAX_THREADS - 1;
}
me = (GC_thread)(dll_thread_table + i);
me->crtn = &dll_crtn_table[i];
} else
# endif
/* else */ {
/* Not using DllMain. */
me = GC_new_thread(self_id);
}
# ifdef GC_PTHREADS
me->pthread_id = pthread_self();
# endif
# ifndef MSWINCE
/* GetCurrentThread() returns a pseudohandle (a const value). */
if (!DuplicateHandle(GetCurrentProcess(), GetCurrentThread(),
GetCurrentProcess(), (HANDLE *)&me->handle,
0 /* dwDesiredAccess */, FALSE /* bInheritHandle */,
DUPLICATE_SAME_ACCESS)) {
ABORT_ARG1("DuplicateHandle failed", ": errcode= 0x%X",
(unsigned)GetLastError());
}
# endif
# if defined(WOW64_THREAD_CONTEXT_WORKAROUND) && defined(MSWINRT_FLAVOR)
/* Lookup TIB value via a call to NtCurrentTeb() on thread */
/* registration rather than calling GetThreadSelectorEntry() which */
/* is not available on UWP. */
me->tib = (GC_NT_TIB *)NtCurrentTeb();
# endif
me->crtn->last_stack_min = ADDR_LIMIT;
GC_record_stack_base(me->crtn, sb);
/* Up until this point, GC_push_all_stacks considers this thread */
/* invalid. And, up until this point, the entry is viewed by */
/* GC_win32_dll_lookup_thread as reserved but invalid. */
((volatile struct GC_Thread_Rep *)me)->id = self_id;
# ifndef GC_NO_THREADS_DISCOVERY
if (GC_win32_dll_threads) {
if (GC_please_stop) {
AO_store(&GC_attached_thread, TRUE);
AO_nop_full(); /* Later updates must become visible after this. */
}
/* We'd like to wait here, but cannot, since waiting in DllMain */
/* provokes deadlocks. Thus we force marking to be restarted */
/* instead. */
} else
# endif
/* else */ {
/* GC_please_stop is false, otherwise both we and the */
/* thread-stopping code would be holding the allocator lock. */
GC_ASSERT(!GC_please_stop);
}
return me;
}
/* GC_max_thread_index may temporarily be larger than MAX_THREADS. */
/* To avoid subscript errors, we check it on access. */
GC_INLINE LONG
GC_get_max_thread_index(void)
{
LONG my_max = GC_max_thread_index;
if (EXPECT(my_max >= MAX_THREADS, FALSE))
return MAX_THREADS - 1;
return my_max;
}
# ifndef GC_NO_THREADS_DISCOVERY
/* Search in dll_thread_table and return the GC_thread entity */
/* corresponding to the given thread id. */
/* May be called without a lock, but should be called in contexts in */
/* which the requested thread cannot be asynchronously deleted, e.g. */
/* from the thread itself. */
GC_INNER GC_thread
GC_win32_dll_lookup_thread(thread_id_t id)
{
int i;
LONG my_max = GC_get_max_thread_index();
GC_ASSERT(GC_win32_dll_threads);
for (i = 0; i <= my_max; i++) {
if (AO_load_acquire(&dll_thread_table[i].tm.in_use)
&& dll_thread_table[i].id == id) {
/* Must still be in use, since nobody else can store our */
/* thread id. */
break;
}
}
return i <= my_max ? (GC_thread)(dll_thread_table + i) : NULL;
}
# endif /* !GC_NO_THREADS_DISCOVERY */
# ifdef GC_PTHREADS
/* A quick-and-dirty cache of the mapping between pthread_t */
/* and Win32 thread id. */
# define PTHREAD_MAP_SIZE 512
thread_id_t GC_pthread_map_cache[PTHREAD_MAP_SIZE] = { 0 };
/* It appears pthread_t is really a pointer type ... */
# define PTHREAD_MAP_INDEX(pthread_id) \
((NUMERIC_THREAD_ID(pthread_id) >> 5) % PTHREAD_MAP_SIZE)
# define SET_PTHREAD_MAP_CACHE(pthread_id, win32_id) \
(void)(GC_pthread_map_cache[PTHREAD_MAP_INDEX(pthread_id)] = (win32_id))
# define GET_PTHREAD_MAP_CACHE(pthread_id) \
GC_pthread_map_cache[PTHREAD_MAP_INDEX(pthread_id)]
GC_INNER void
GC_win32_cache_self_pthread(thread_id_t self_id)
{
pthread_t self = pthread_self();
GC_ASSERT(I_HOLD_LOCK());
SET_PTHREAD_MAP_CACHE(self, self_id);
}
/* Return a GC_thread corresponding to a given pthread_t, or */
/* NULL if it is not there. We assume that this is only */
/* called for pthread ids that have not yet terminated or are */
/* still joinable, and cannot be terminated concurrently. */
GC_INNER GC_thread
GC_lookup_by_pthread(pthread_t thread)
{
/* TODO: search in dll_thread_table instead when DllMain-based */
/* thread registration is made compatible with pthreads (and */
/* turned on). */
thread_id_t id;
GC_thread p;
int hv;
GC_ASSERT(I_HOLD_READER_LOCK());
id = GET_PTHREAD_MAP_CACHE(thread);
/* We first try the cache. */
for (p = GC_threads[THREAD_TABLE_INDEX(id)]; p != NULL; p = p->tm.next) {
if (EXPECT(THREAD_EQUAL(p->pthread_id, thread), TRUE))
return p;
}
/* If that fails, we use a very slow approach. */
for (hv = 0; hv < THREAD_TABLE_SZ; ++hv) {
for (p = GC_threads[hv]; p != NULL; p = p->tm.next) {
if (THREAD_EQUAL(p->pthread_id, thread))
return p;
}
}
return NULL;
}
# endif /* GC_PTHREADS */
# ifdef WOW64_THREAD_CONTEXT_WORKAROUND
# ifndef CONTEXT_EXCEPTION_ACTIVE
# define CONTEXT_EXCEPTION_ACTIVE 0x08000000
# define CONTEXT_EXCEPTION_REQUEST 0x40000000
# define CONTEXT_EXCEPTION_REPORTING 0x80000000
# endif
/* Is 32-bit code running on Win64? */
static GC_bool isWow64;
# define GET_THREAD_CONTEXT_FLAGS \
(isWow64 ? CONTEXT_INTEGER | CONTEXT_CONTROL \
| CONTEXT_EXCEPTION_REQUEST | CONTEXT_SEGMENTS \
: CONTEXT_INTEGER | CONTEXT_CONTROL)
# elif defined(I386) || defined(XMM_CANT_STORE_PTRS)
# define GET_THREAD_CONTEXT_FLAGS (CONTEXT_INTEGER | CONTEXT_CONTROL)
# else
# define GET_THREAD_CONTEXT_FLAGS \
(CONTEXT_INTEGER | CONTEXT_CONTROL | CONTEXT_FLOATING_POINT)
# endif /* !WOW64_THREAD_CONTEXT_WORKAROUND && !I386 */
/* Suspend the given thread, if it's still active. */
STATIC void
GC_suspend(GC_thread t)
{
# ifndef MSWINCE
DWORD exitCode;
# ifdef RETRY_GET_THREAD_CONTEXT
int retry_cnt;
# define MAX_SUSPEND_THREAD_RETRIES (1000 * 1000)
# endif
# endif
GC_ASSERT(I_HOLD_LOCK());
# ifndef GC_NO_THREADS_DISCOVERY
if (NULL == GC_cptr_load_acquire(&t->handle))
return;
# endif
# if defined(DEBUG_THREADS) && !defined(MSWINCE) \
&& (!defined(MSWIN32) || defined(CONSOLE_LOG))
GC_log_printf("Suspending 0x%x\n", (int)t->id);
# endif
GC_win32_unprotect_thread(t);
GC_acquire_dirty_lock();
# ifdef MSWINCE
/* SuspendThread() will fail if thread is running kernel code. */
while (SuspendThread(THREAD_HANDLE(t)) == (DWORD)-1) {
GC_release_dirty_lock();
Sleep(10); /* in millis */
GC_acquire_dirty_lock();
}
# elif defined(RETRY_GET_THREAD_CONTEXT)
for (retry_cnt = 0;;) {
/* Apparently the Windows 95 GetOpenFileName call creates */
/* a thread that does not properly get cleaned up, and */
/* SuspendThread on its descriptor may provoke a crash. */
/* This reduces the probability of that event, though it still */
/* appears there is a race here. */
if (GetExitCodeThread(t->handle, &exitCode) && exitCode != STILL_ACTIVE) {
GC_release_dirty_lock();
# ifdef GC_PTHREADS
/* Prevent stack from being pushed. */
t->crtn->stack_end = NULL;
# else
/* This breaks pthread_join on Cygwin, which is guaranteed to */
/* only see user threads. */
GC_delete_thread(t);
# endif
return;
}
if (SuspendThread(t->handle) != (DWORD)-1) {
CONTEXT context;
/* Calls to GetThreadContext() may fail. Work around this by */
/* putting access in suspend/resume loop to advance thread */
/* past problematic areas where suspend fails. Capture the */
/* context in per thread structure at the suspend time rather */
/* than at retrieving the context during the push logic. */
context.ContextFlags = GET_THREAD_CONTEXT_FLAGS;
if (GetThreadContext(t->handle, &context)) {
/* TODO: WoW64 extra workaround: if CONTEXT_EXCEPTION_ACTIVE */
/* then Sleep(1) and retry. */
t->context_sp = copy_ptr_regs(t->context_regs, &context);
/* Success; the context pointer registers are saved. */
break;
}
/* Resume the thread, try to suspend it in a better location. */
if (ResumeThread(t->handle) == (DWORD)-1)
ABORT("ResumeThread failed in suspend loop");
} else {
# ifndef GC_NO_THREADS_DISCOVERY
if (NULL == GC_cptr_load_acquire(&t->handle)) {
/* The thread handle is closed asynchronously by GC_DllMain. */
GC_release_dirty_lock();
return;
}
# endif
}
if (retry_cnt > 1) {
GC_release_dirty_lock();
Sleep(0); /* yield */
# ifndef GC_NO_THREADS_DISCOVERY
if (NULL == GC_cptr_load_acquire(&t->handle))
return;
# endif
GC_acquire_dirty_lock();
}
if (++retry_cnt >= MAX_SUSPEND_THREAD_RETRIES) {
/* Something must be wrong. */
ABORT("SuspendThread loop failed");
}
}
# else
if (GetExitCodeThread(t->handle, &exitCode) && exitCode != STILL_ACTIVE) {
GC_release_dirty_lock();
# ifdef GC_PTHREADS
/* Prevent stack from being pushed. */
t->crtn->stack_end = NULL;
# else
GC_delete_thread(t);
# endif
return;
}
if (SuspendThread(t->handle) == (DWORD)-1) {
# ifndef GC_NO_THREADS_DISCOVERY
if (NULL == GC_cptr_load_acquire(&t->handle)) {
GC_release_dirty_lock();
return;
}
# endif
ABORT("SuspendThread failed");
}
# endif
t->flags |= IS_SUSPENDED;
GC_release_dirty_lock();
if (GC_on_thread_event)
GC_on_thread_event(GC_EVENT_THREAD_SUSPENDED, THREAD_HANDLE(t));
}
# if defined(GC_ASSERTIONS) \
&& ((defined(MSWIN32) && !defined(CONSOLE_LOG)) || defined(MSWINCE))
/* Note: set to true only if GC_stop_world() has acquired GC_write_cs. */
GC_INNER GC_bool GC_write_disabled = FALSE;
# endif
GC_INNER void
GC_stop_world(void)
{
thread_id_t self_id = GetCurrentThreadId();
GC_ASSERT(I_HOLD_LOCK());
GC_ASSERT(GC_thr_initialized);
/* This code is the same as in pthread_stop_world.c. */
# ifdef PARALLEL_MARK
if (GC_parallel) {
GC_acquire_mark_lock();
/* We should have previously waited for the count to become zero. */
GC_ASSERT(0 == GC_fl_builder_count);
}
# endif /* PARALLEL_MARK */
# if !defined(GC_NO_THREADS_DISCOVERY) || defined(GC_ASSERTIONS)
GC_please_stop = TRUE;
# endif
# if (defined(MSWIN32) && !defined(CONSOLE_LOG)) || defined(MSWINCE)
GC_ASSERT(!GC_write_disabled);
EnterCriticalSection(&GC_write_cs);
/* It's not allowed to call GC_printf() (and friends) here down to */
/* LeaveCriticalSection (same applies recursively to GC_suspend, */
/* GC_delete_thread, GC_get_max_thread_index, GC_size and */
/* GC_remove_protection). */
# ifdef GC_ASSERTIONS
GC_write_disabled = TRUE;
# endif
# endif
# ifndef GC_NO_THREADS_DISCOVERY
if (GC_win32_dll_threads) {
int i;
int my_max;
/* Any threads being created during this loop will end up setting */
/* GC_attached_thread when they start. This will force marking */
/* to restart. This is not ideal, but hopefully correct. */
AO_store(&GC_attached_thread, FALSE);
my_max = (int)GC_get_max_thread_index();
for (i = 0; i <= my_max; i++) {
GC_thread p = (GC_thread)(dll_thread_table + i);
if (p->crtn->stack_end != NULL && (p->flags & DO_BLOCKING) == 0
&& p->id != self_id) {
GC_suspend(p);
}
}
} else
# endif
/* else */ {
GC_thread p;
int i;
for (i = 0; i < THREAD_TABLE_SZ; i++) {
for (p = GC_threads[i]; p != NULL; p = p->tm.next)
if (p->crtn->stack_end != NULL && p->id != self_id
&& (p->flags & (FINISHED | DO_BLOCKING)) == 0)
GC_suspend(p);
}
}
# if (defined(MSWIN32) && !defined(CONSOLE_LOG)) || defined(MSWINCE)
# ifdef GC_ASSERTIONS
GC_write_disabled = FALSE;
# endif
LeaveCriticalSection(&GC_write_cs);
# endif
# ifdef PARALLEL_MARK
if (GC_parallel)
GC_release_mark_lock();
# endif
}
GC_INNER void
GC_start_world(void)
{
# ifdef GC_ASSERTIONS
thread_id_t self_id = GetCurrentThreadId();
# endif
GC_ASSERT(I_HOLD_LOCK());
if (GC_win32_dll_threads) {
LONG my_max = GC_get_max_thread_index();
int i;
for (i = 0; i <= my_max; i++) {
GC_thread p = (GC_thread)(dll_thread_table + i);
if ((p->flags & IS_SUSPENDED) != 0) {
# ifdef DEBUG_THREADS
GC_log_printf("Resuming 0x%x\n", (int)p->id);
# endif
GC_ASSERT(p->id != self_id);
GC_ASSERT(*(ptr_t *)CAST_AWAY_VOLATILE_PVOID(&p->crtn->stack_end)
!= NULL);
if (ResumeThread(THREAD_HANDLE(p)) == (DWORD)-1)
ABORT("ResumeThread failed");
p->flags &= (unsigned char)~IS_SUSPENDED;
if (GC_on_thread_event)
GC_on_thread_event(GC_EVENT_THREAD_UNSUSPENDED, THREAD_HANDLE(p));
} else {
/* The thread is unregistered or not suspended. */
}
}
} else {
GC_thread p;
int i;
for (i = 0; i < THREAD_TABLE_SZ; i++) {
for (p = GC_threads[i]; p != NULL; p = p->tm.next) {
if ((p->flags & IS_SUSPENDED) != 0) {
# ifdef DEBUG_THREADS
GC_log_printf("Resuming 0x%x\n", (int)p->id);
# endif
GC_ASSERT(p->id != self_id && *(ptr_t *)&p->crtn->stack_end != NULL);
if (ResumeThread(THREAD_HANDLE(p)) == (DWORD)-1)
ABORT("ResumeThread failed");
GC_win32_unprotect_thread(p);
p->flags &= (unsigned char)~IS_SUSPENDED;
if (GC_on_thread_event)
GC_on_thread_event(GC_EVENT_THREAD_UNSUSPENDED, THREAD_HANDLE(p));
} else {
# ifdef DEBUG_THREADS
GC_log_printf("Not resuming thread 0x%x as it is not suspended\n",
(int)p->id);
# endif
}
}
}
}
# if !defined(GC_NO_THREADS_DISCOVERY) || defined(GC_ASSERTIONS)
GC_please_stop = FALSE;
# endif
}
# ifdef MSWINCE
/* The VirtualQuery calls below won't work properly on some old WinCE */
/* versions, but since each stack is restricted to an aligned 64 KiB */
/* region of virtual memory we can just take the next lowest multiple */
/* of 64 KiB. The result of this macro must not be used as its */
/* argument later and must not be used as the lower bound for sp */
/* check (since the stack may be bigger than 64 KiB). */
# define GC_wince_evaluate_stack_min(s) \
(ptr_t)(((word)(s) - (word)1) & ~(word)0xFFFF)
# elif defined(GC_ASSERTIONS)
# define GC_dont_query_stack_min FALSE
# endif
/* A cache holding the results of the recent VirtualQuery call. */
/* Protected by the allocator lock. */
static ptr_t last_address = 0;
static MEMORY_BASIC_INFORMATION last_info;
/* Probe stack memory region (starting at "s") to find out its */
/* lowest address (i.e. stack top). */
/* S must be a mapped address inside the region, NOT the first */
/* unmapped address. */
STATIC ptr_t
GC_get_stack_min(ptr_t s)
{
ptr_t bottom;
GC_ASSERT(I_HOLD_LOCK());
if (s != last_address) {
VirtualQuery(s, &last_info, sizeof(last_info));
last_address = s;
}
do {
bottom = (ptr_t)last_info.BaseAddress;
VirtualQuery(bottom - 1, &last_info, sizeof(last_info));
last_address = bottom - 1;
} while ((last_info.Protect & PAGE_READWRITE)
&& !(last_info.Protect & PAGE_GUARD));
return bottom;
}
/* Return true if the page at s has protections appropriate */
/* for a stack page. */
static GC_bool
may_be_in_stack(ptr_t s)
{
GC_ASSERT(I_HOLD_LOCK());
if (s != last_address) {
VirtualQuery(s, &last_info, sizeof(last_info));
last_address = s;
}
return (last_info.Protect & PAGE_READWRITE)
&& !(last_info.Protect & PAGE_GUARD);
}
/* Copy all registers that might point into the heap. Frame */
/* pointer registers are included in case client code was */
/* compiled with the 'omit frame pointer' optimization. */
/* The context register values are stored to regs argument */
/* which is expected to be of PUSHED_REGS_COUNT length exactly. */
/* The functions returns the context stack pointer value. */
static ptr_t
copy_ptr_regs(word *regs, const CONTEXT *pcontext)
{
ptr_t sp;
int cnt = 0;
# define context (*pcontext)
# define PUSH1(reg) (regs[cnt++] = (word)pcontext->reg)
# define PUSH2(r1, r2) (PUSH1(r1), PUSH1(r2))
# define PUSH4(r1, r2, r3, r4) (PUSH2(r1, r2), PUSH2(r3, r4))
# define PUSH8_LH(r1, r2, r3, r4) \
(PUSH4(r1.Low, r1.High, r2.Low, r2.High), \
PUSH4(r3.Low, r3.High, r4.Low, r4.High))
# if defined(I386)
# ifdef WOW64_THREAD_CONTEXT_WORKAROUND
/* Notes: these should be the first "pushed" registers, exactly */
/* in this order, see the WoW64 logic in GC_push_stack_for(); */
/* these registers do not contain pointers. */
PUSH2(ContextFlags, SegFs);
# endif
PUSH4(Edi, Esi, Ebx, Edx), PUSH2(Ecx, Eax), PUSH1(Ebp);
sp = (ptr_t)context.Esp;
# elif defined(X86_64)
PUSH4(Rax, Rcx, Rdx, Rbx);
PUSH2(Rbp, Rsi);
PUSH1(Rdi);
PUSH4(R8, R9, R10, R11);
PUSH4(R12, R13, R14, R15);
# ifndef XMM_CANT_STORE_PTRS
PUSH8_LH(Xmm0, Xmm1, Xmm2, Xmm3);
PUSH8_LH(Xmm4, Xmm5, Xmm6, Xmm7);
PUSH8_LH(Xmm8, Xmm9, Xmm10, Xmm11);
PUSH8_LH(Xmm12, Xmm13, Xmm14, Xmm15);
# endif
sp = (ptr_t)context.Rsp;
# elif defined(ARM32)
PUSH4(R0, R1, R2, R3), PUSH4(R4, R5, R6, R7), PUSH4(R8, R9, R10, R11);
PUSH1(R12);
sp = (ptr_t)context.Sp;
# elif defined(AARCH64)
PUSH4(X0, X1, X2, X3), PUSH4(X4, X5, X6, X7), PUSH4(X8, X9, X10, X11);
PUSH4(X12, X13, X14, X15), PUSH4(X16, X17, X18, X19),
PUSH4(X20, X21, X22, X23);
PUSH4(X24, X25, X26, X27), PUSH1(X28);
PUSH1(Lr);
sp = (ptr_t)context.Sp;
# elif defined(SHx)
PUSH4(R0, R1, R2, R3), PUSH4(R4, R5, R6, R7), PUSH4(R8, R9, R10, R11);
PUSH2(R12, R13), PUSH1(R14);
sp = (ptr_t)context.R15;
# elif defined(MIPS)
PUSH4(IntAt, IntV0, IntV1, IntA0), PUSH4(IntA1, IntA2, IntA3, IntT0);
PUSH4(IntT1, IntT2, IntT3, IntT4), PUSH4(IntT5, IntT6, IntT7, IntS0);
PUSH4(IntS1, IntS2, IntS3, IntS4), PUSH4(IntS5, IntS6, IntS7, IntT8);
PUSH4(IntT9, IntK0, IntK1, IntS8);
sp = (ptr_t)context.IntSp;
# elif defined(PPC)
PUSH4(Gpr0, Gpr3, Gpr4, Gpr5), PUSH4(Gpr6, Gpr7, Gpr8, Gpr9);
PUSH4(Gpr10, Gpr11, Gpr12, Gpr14), PUSH4(Gpr15, Gpr16, Gpr17, Gpr18);
PUSH4(Gpr19, Gpr20, Gpr21, Gpr22), PUSH4(Gpr23, Gpr24, Gpr25, Gpr26);
PUSH4(Gpr27, Gpr28, Gpr29, Gpr30), PUSH1(Gpr31);
sp = (ptr_t)context.Gpr1;
# elif defined(ALPHA)
PUSH4(IntV0, IntT0, IntT1, IntT2), PUSH4(IntT3, IntT4, IntT5, IntT6);
PUSH4(IntT7, IntS0, IntS1, IntS2), PUSH4(IntS3, IntS4, IntS5, IntFp);
PUSH4(IntA0, IntA1, IntA2, IntA3), PUSH4(IntA4, IntA5, IntT8, IntT9);
PUSH4(IntT10, IntT11, IntT12, IntAt);
sp = (ptr_t)context.IntSp;
# elif defined(CPPCHECK)
GC_noop1_ptr(regs);
sp = (ptr_t)(word)cnt; /* to workaround "cnt not used" false positive */
# else
# error Architecture is not supported
# endif
# undef context
# undef PUSH1
# undef PUSH2
# undef PUSH4
# undef PUSH8_LH
GC_ASSERT(cnt == PUSHED_REGS_COUNT);
return sp;
}
STATIC word
GC_push_stack_for(GC_thread thread, thread_id_t self_id, GC_bool *pfound_me)
{
GC_bool is_self = FALSE;
ptr_t sp, stack_min;
GC_stack_context_t crtn = thread->crtn;
ptr_t stack_end = crtn->stack_end;
struct GC_traced_stack_sect_s *traced_stack_sect = crtn->traced_stack_sect;
GC_ASSERT(I_HOLD_LOCK());
if (EXPECT(NULL == stack_end, FALSE))
return 0;
if (thread->id == self_id) {
GC_ASSERT((thread->flags & DO_BLOCKING) == 0);
sp = GC_approx_sp();
is_self = TRUE;
*pfound_me = TRUE;
} else if ((thread->flags & DO_BLOCKING) != 0) {
/* Use saved sp value for blocked threads. */
sp = crtn->stack_ptr;
} else {
# ifdef RETRY_GET_THREAD_CONTEXT
/* We cache context when suspending the thread since it may */
/* require looping. */
word *regs = thread->context_regs;
if ((thread->flags & IS_SUSPENDED) != 0) {
sp = thread->context_sp;
} else
# else
word regs[PUSHED_REGS_COUNT];
# endif
/* else */ {
CONTEXT context;
/* For unblocked threads call GetThreadContext(). */
context.ContextFlags = GET_THREAD_CONTEXT_FLAGS;
if (GetThreadContext(THREAD_HANDLE(thread), &context)) {
sp = copy_ptr_regs(regs, &context);
} else {
# ifdef RETRY_GET_THREAD_CONTEXT
/* At least, try to use the stale context if saved. */
sp = thread->context_sp;
if (NULL == sp) {
/* Skip the current thread, anyway its stack will */
/* be pushed when the world is stopped. */
return 0;
}
# else
/* This is to avoid "might be uninitialized" compiler warning. */
*(volatile ptr_t *)&sp = NULL;
ABORT("GetThreadContext failed");
# endif
}
}
# ifdef THREAD_LOCAL_ALLOC
GC_ASSERT((thread->flags & IS_SUSPENDED) != 0 || !GC_world_stopped);
# endif
# ifndef WOW64_THREAD_CONTEXT_WORKAROUND
GC_push_many_regs(regs, PUSHED_REGS_COUNT);
# else
GC_push_many_regs(regs + 2, PUSHED_REGS_COUNT - 2);
/* skip ContextFlags and SegFs */
/* WoW64 workaround. */
if (isWow64) {
DWORD ContextFlags = (DWORD)regs[0];
if ((ContextFlags & CONTEXT_EXCEPTION_REPORTING) != 0
&& (ContextFlags
& (CONTEXT_EXCEPTION_ACTIVE
/* | CONTEXT_SERVICE_ACTIVE */))
!= 0) {
GC_NT_TIB *tib;
# ifdef MSWINRT_FLAVOR
tib = thread->tib;
# else
WORD SegFs = (WORD)regs[1];
LDT_ENTRY selector;
if (!GetThreadSelectorEntry(THREAD_HANDLE(thread), SegFs, &selector))
ABORT("GetThreadSelectorEntry failed");
tib = (GC_NT_TIB *)(selector.BaseLow
| (selector.HighWord.Bits.BaseMid << 16)
| (selector.HighWord.Bits.BaseHi << 24));
# endif
# ifdef DEBUG_THREADS
GC_log_printf("TIB stack limit/base: %p .. %p\n",
(void *)tib->StackLimit, (void *)tib->StackBase);
# endif
GC_ASSERT(!HOTTER_THAN((ptr_t)tib->StackBase, stack_end));
if (stack_end != crtn->initial_stack_base
/* We are in a coroutine (old-style way of the support). */
&& (ADDR(stack_end) <= (word)tib->StackLimit
|| (word)tib->StackBase < ADDR(stack_end))) {
/* The coroutine stack is not within TIB stack. */
WARN("GetThreadContext might return stale register values"
" including ESP= %p\n",
sp);
/* TODO: Because of WoW64 bug, there is no guarantee that */
/* sp really points to the stack top but, for now, we do */
/* our best as the TIB stack limit/base cannot be used */
/* while we are inside a coroutine. */
} else {
/* GetThreadContext() might return stale register values, */
/* so we scan the entire stack region (down to the stack */
/* limit). There is no 100% guarantee that all the */
/* registers are pushed but we do our best (the proper */
/* solution would be to fix it inside Windows). */
sp = (ptr_t)tib->StackLimit;
}
} /* else */
# ifdef DEBUG_THREADS
else {
static GC_bool logged;
if (!logged && (ContextFlags & CONTEXT_EXCEPTION_REPORTING) == 0) {
GC_log_printf("CONTEXT_EXCEPTION_REQUEST not supported\n");
logged = TRUE;
}
}
# endif
}
# endif /* WOW64_THREAD_CONTEXT_WORKAROUND */
}
# if defined(STACKPTR_CORRECTOR_AVAILABLE) && defined(GC_PTHREADS)
if (GC_sp_corrector != 0)
GC_sp_corrector((void **)&sp, PTHREAD_TO_VPTR(thread->pthread_id));
# endif
/* Set stack_min to the lowest address in the thread stack, */
/* or to an address in the thread stack no larger than sp, */
/* taking advantage of the old value to avoid slow traversals */
/* of large stacks. */
if (crtn->last_stack_min == ADDR_LIMIT) {
# ifdef MSWINCE
if (GC_dont_query_stack_min) {
stack_min = GC_wince_evaluate_stack_min(
traced_stack_sect != NULL ? (ptr_t)traced_stack_sect : stack_end);
/* Keep last_stack_min value unmodified. */
} else
# endif
/* else */ {
stack_min = GC_get_stack_min(
traced_stack_sect != NULL ? (ptr_t)traced_stack_sect : stack_end);
GC_win32_unprotect_thread(thread);
crtn->last_stack_min = stack_min;
}
} else {
/* First, adjust the latest known minimum stack address if we */
/* are inside GC_call_with_gc_active(). */
if (traced_stack_sect != NULL
&& ADDR_LT((ptr_t)traced_stack_sect, crtn->last_stack_min)) {
GC_win32_unprotect_thread(thread);
crtn->last_stack_min = (ptr_t)traced_stack_sect;
}
if (ADDR_INSIDE(sp, crtn->last_stack_min, stack_end)) {
stack_min = sp;
} else {
/* In the current thread it is always safe to use sp value. */
if (may_be_in_stack(is_self && ADDR_LT(sp, crtn->last_stack_min)
? sp
: crtn->last_stack_min)) {
stack_min = (ptr_t)last_info.BaseAddress;
/* Do not probe rest of the stack if sp is correct. */
if (!ADDR_INSIDE(sp, stack_min, stack_end))
stack_min = GC_get_stack_min(crtn->last_stack_min);
} else {
/* Stack shrunk? Is this possible? */
stack_min = GC_get_stack_min(stack_end);
}
GC_win32_unprotect_thread(thread);
crtn->last_stack_min = stack_min;
}
}
GC_ASSERT(GC_dont_query_stack_min || stack_min == GC_get_stack_min(stack_end)
|| (ADDR_GE(sp, stack_min) && ADDR_LT(stack_min, stack_end)
&& ADDR_LT(GC_get_stack_min(stack_end), stack_min)));
if (ADDR_INSIDE(sp, stack_min, stack_end)) {
# ifdef DEBUG_THREADS
GC_log_printf("Pushing stack for 0x%x from sp %p to %p from 0x%x\n",
(int)thread->id, (void *)sp, (void *)stack_end,
(int)self_id);
# endif