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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) 2008-2021 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/gc_priv.h"
#if defined(GC_WIN32_THREADS)
#ifdef THREAD_LOCAL_ALLOC
# include "private/thread_local_alloc.h"
#endif /* THREAD_LOCAL_ALLOC */
/* Allocation lock declarations. */
#if !defined(USE_PTHREAD_LOCKS)
GC_INNER CRITICAL_SECTION GC_allocate_ml;
# ifdef GC_ASSERTIONS
GC_INNER DWORD GC_lock_holder = NO_THREAD;
/* Thread id for current holder of allocation lock */
# endif
#else
GC_INNER pthread_mutex_t GC_allocate_ml = PTHREAD_MUTEX_INITIALIZER;
# ifdef GC_ASSERTIONS
GC_INNER unsigned long GC_lock_holder = NO_THREAD;
# endif
#endif
#undef CreateThread
#undef ExitThread
#undef _beginthreadex
#undef _endthreadex
#ifdef GC_PTHREADS
# include <errno.h> /* for EAGAIN */
/* Cygwin-specific forward decls */
# undef pthread_create
# undef pthread_join
# undef pthread_detach
# ifndef GC_NO_PTHREAD_SIGMASK
# undef pthread_sigmask
# endif
STATIC void * GC_pthread_start(void * arg);
STATIC void GC_thread_exit_proc(void *arg);
# include <pthread.h>
# ifdef CAN_CALL_ATFORK
# include <unistd.h>
# endif
#elif !defined(MSWINCE)
# include <process.h> /* For _beginthreadex, _endthreadex */
# include <errno.h> /* for errno, EAGAIN */
#endif /* !GC_PTHREADS && !MSWINCE */
/* PUSHED_REGS_COUNT is the number of copied registers in copy_ptr_regs. */
static ptr_t copy_ptr_regs(word *regs, const CONTEXT *pcontext);
#if defined(I386)
# ifdef WOW64_THREAD_CONTEXT_WORKAROUND
# define PUSHED_REGS_COUNT 9
# else
# define PUSHED_REGS_COUNT 7
# endif
#elif defined(X86_64) || defined(SHx)
# define PUSHED_REGS_COUNT 15
#elif defined(ARM32)
# define PUSHED_REGS_COUNT 13
#elif defined(AARCH64)
# define PUSHED_REGS_COUNT 30
#elif defined(MIPS) || defined(ALPHA)
# define PUSHED_REGS_COUNT 28
#elif defined(PPC)
# define PUSHED_REGS_COUNT 29
#endif
/* DllMain-based thread registration is currently incompatible */
/* with thread-local allocation, pthreads and WinCE. */
#if (defined(GC_DLL) || defined(GC_INSIDE_DLL)) && !defined(NO_CRT) \
&& !defined(GC_NO_THREADS_DISCOVERY) && !defined(MSWINCE) \
&& !defined(THREAD_LOCAL_ALLOC) && !defined(GC_PTHREADS)
/* 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. */
# ifdef GC_DISCOVER_TASK_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. */
# define GC_win32_dll_threads TRUE
# else
STATIC GC_bool GC_win32_dll_threads = FALSE;
/* 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. */
# 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. */
# ifndef GC_NO_THREADS_DISCOVERY
# define GC_NO_THREADS_DISCOVERY
# endif
# define GC_win32_dll_threads FALSE
# undef MAX_THREADS
# define MAX_THREADS 1 /* dll_thread_table[] is always empty. */
#endif /* GC_NO_THREADS_DISCOVERY */
/* We have two versions of the thread table. Which one */
/* we us depends on whether or not 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. */
/* The type of the first argument to InterlockedExchange. */
/* Documented to be LONG volatile *, but at least gcc likes */
/* this better. */
typedef LONG * IE_t;
STATIC GC_bool GC_thr_initialized = FALSE;
#ifndef GC_ALWAYS_MULTITHREADED
GC_INNER GC_bool GC_need_to_lock = FALSE;
#endif
static GC_bool parallel_initialized = FALSE;
/* 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(!parallel_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_parallel();
# endif
}
#define ADDR_LIMIT ((ptr_t)GC_WORD_MAX)
struct GC_Thread_Rep {
union {
# ifndef GC_NO_THREADS_DISCOVERY
volatile AO_t in_use;
/* Updated without lock. */
/* We assert that unused */
/* entries have invalid ids of */
/* zero and zero stack fields. */
/* Used only with GC_win32_dll_threads. */
LONG long_in_use; /* The same but of the type that */
/* matches the first argument of */
/* InterlockedExchange(); volatile is */
/* omitted because the ancient version */
/* of the prototype lacks the qualifier.*/
# endif
struct GC_Thread_Rep * next;
/* Hash table link without */
/* GC_win32_dll_threads. */
/* More recently allocated threads */
/* with a given pthread id come */
/* first. (All but the first are */
/* guaranteed to be dead, but we may */
/* not yet have registered the join.) */
} tm; /* table_management */
DWORD id;
# ifdef MSWINCE
/* According to MSDN specs for WinCE targets: */
/* - DuplicateHandle() is not applicable to thread handles; and */
/* - the value returned by GetCurrentThreadId() could be used as */
/* a "real" thread handle (for SuspendThread(), ResumeThread() and */
/* GetThreadContext()). */
# define THREAD_HANDLE(t) (HANDLE)(word)(t)->id
# else
HANDLE handle;
# define THREAD_HANDLE(t) (t)->handle
# endif
ptr_t stack_base; /* The cold end of the stack. */
/* 0 ==> entry not valid. */
/* !in_use ==> stack_base == 0 */
ptr_t last_stack_min; /* Last known minimum (hottest) address */
/* in stack or ADDR_LIMIT if unset */
# ifdef IA64
ptr_t backing_store_end;
ptr_t backing_store_ptr;
# elif defined(I386)
ptr_t initial_stack_base;
/* The cold end of the stack saved by */
/* GC_record_stack_base (never modified */
/* by GC_set_stackbottom). */
# endif
ptr_t thread_blocked_sp; /* Protected by GC lock. */
/* NULL value means thread unblocked. */
/* If set to non-NULL, thread will */
/* acquire GC lock before doing any */
/* pointer manipulations. Thus it does */
/* not need to stop this thread. */
struct GC_traced_stack_sect_s *traced_stack_sect;
/* Points to the "stack section" data */
/* held in stack by the innermost */
/* GC_call_with_gc_active() of this */
/* thread. May be NULL. */
unsigned short finalizer_skipped;
unsigned char finalizer_nested;
/* Used by GC_check_finalizer_nested() */
/* to minimize the level of recursion */
/* when a client finalizer allocates */
/* memory (initially both are 0). */
unsigned char suspended; /* really of GC_bool type */
# ifdef GC_PTHREADS
unsigned char flags; /* Protected by GC lock. */
# define FINISHED 1 /* Thread has exited. */
# define DETACHED 2 /* Thread is intended to be detached. */
# define KNOWN_FINISHED(t) (((t) -> flags) & FINISHED)
pthread_t pthread_id;
void *status; /* hold exit value until join in case it's a pointer */
# else
# define KNOWN_FINISHED(t) 0
# endif
# ifdef THREAD_LOCAL_ALLOC
struct thread_local_freelists tlfs;
# endif
# ifdef RETRY_GET_THREAD_CONTEXT
ptr_t context_sp;
word context_regs[PUSHED_REGS_COUNT];
/* Populated as part of GC_suspend() as */
/* resume/suspend loop may be needed for the */
/* call to GetThreadContext() to succeed. */
# endif
};
typedef struct GC_Thread_Rep * GC_thread;
typedef volatile struct GC_Thread_Rep * GC_vthread;
#ifndef GC_NO_THREADS_DISCOVERY
STATIC DWORD GC_main_thread = 0;
/* 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 assumed that volatile ==> 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
AO_nop_full(); /* Prior heap reads need to complete earlier. */
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. */
volatile struct GC_Thread_Rep dll_thread_table[MAX_THREADS];
STATIC volatile LONG GC_max_thread_index = 0;
/* Largest index in dll_thread_table */
/* that was ever used. */
/* And now the version used if GC_win32_dll_threads is not set. */
/* This is a chained hash table, with much of the code borrowed */
/* from the Posix implementation. */
#ifndef THREAD_TABLE_SZ
# define THREAD_TABLE_SZ 256 /* Power of 2 (for speed). */
#endif
#define THREAD_TABLE_INDEX(id) /* id is of DWORD type */ \
(int)((((id) >> 8) ^ (id)) % THREAD_TABLE_SZ)
STATIC GC_thread GC_threads[THREAD_TABLE_SZ];
/* It may not be safe to allocate when we register the first thread. */
/* Thus we allocated one statically. It does not contain any pointer */
/* field we need to push ("next" and "status" fields are unused). */
static struct GC_Thread_Rep first_thread;
static GC_bool first_thread_used = FALSE;
/* Add a thread to GC_threads. We assume it wasn't already there. */
/* Caller holds allocation lock. */
/* Unlike the pthreads version, the id field is set by the caller. */
STATIC GC_thread GC_new_thread(DWORD id)
{
int hv = THREAD_TABLE_INDEX(id);
GC_thread result;
# ifdef DEBUG_THREADS
GC_log_printf("Creating thread 0x%lx\n", (long)id);
if (GC_threads[hv] != NULL)
GC_log_printf("Hash collision at GC_threads[%d]\n", hv);
# endif
GC_ASSERT(I_HOLD_LOCK());
if (!EXPECT(first_thread_used, TRUE)) {
result = &first_thread;
first_thread_used = TRUE;
GC_ASSERT(NULL == GC_threads[hv]);
} else {
GC_ASSERT(!GC_win32_dll_threads);
result = (struct GC_Thread_Rep *)
GC_INTERNAL_MALLOC(sizeof(struct GC_Thread_Rep), NORMAL);
if (result == 0) return(0);
}
/* result -> id = id; Done by caller. */
result -> tm.next = GC_threads[hv];
GC_threads[hv] = result;
# ifdef GC_PTHREADS
GC_ASSERT(result -> flags == 0);
# endif
GC_ASSERT(result -> thread_blocked_sp == NULL);
if (EXPECT(result != &first_thread, TRUE))
GC_dirty(result);
return(result);
}
GC_INNER GC_bool GC_in_thread_creation = FALSE;
/* Protected by allocation lock. */
GC_INLINE void GC_record_stack_base(GC_vthread me,
const struct GC_stack_base *sb)
{
me -> stack_base = (ptr_t)sb->mem_base;
# ifdef IA64
me -> backing_store_end = (ptr_t)sb->reg_base;
# elif defined(I386)
me -> initial_stack_base = (ptr_t)sb->mem_base;
# endif
if (me -> stack_base == NULL)
ABORT("Bad stack base in GC_register_my_thread");
}
/* 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 */
/* allocation lock except possibly during single-threaded startup code. */
STATIC GC_thread GC_register_my_thread_inner(const struct GC_stack_base *sb,
DWORD thread_id)
{
GC_vthread me;
/* 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 hasn't 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 Win95 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 Windows95 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((IE_t)&GC_max_thread_index);
}
if (GC_max_thread_index >= MAX_THREADS) {
/* We overshot due to simultaneous increments. */
/* Setting it to MAX_THREADS-1 is always safe. */
GC_max_thread_index = MAX_THREADS - 1;
}
me = dll_thread_table + i;
} else
# endif
/* else */ /* Not using DllMain */ {
GC_ASSERT(I_HOLD_LOCK());
GC_in_thread_creation = TRUE; /* OK to collect from unknown thread. */
me = GC_new_thread(thread_id);
GC_in_thread_creation = FALSE;
if (me == 0)
ABORT("Failed to allocate memory for thread registering");
}
# ifdef GC_PTHREADS
/* me can be NULL -> segfault */
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
me -> last_stack_min = ADDR_LIMIT;
GC_record_stack_base(me, sb);
/* Up until this point, GC_push_all_stacks considers this thread */
/* invalid. */
/* Up until this point, this entry is viewed as reserved but invalid */
/* by GC_delete_thread. */
me -> id = thread_id;
# if defined(THREAD_LOCAL_ALLOC)
GC_init_thread_local((GC_tlfs)(&(me->tlfs)));
# endif
# 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 can't, since waiting in DllMain */
/* provokes deadlocks. */
/* Thus we force marking to be restarted instead. */
} else
# endif
/* else */ {
GC_ASSERT(!GC_please_stop);
/* Otherwise both we and the thread stopping code would be */
/* holding the allocation lock. */
}
return (GC_thread)(me);
}
/*
* GC_max_thread_index may temporarily be larger than MAX_THREADS.
* To avoid subscript errors, we check on access.
*/
GC_INLINE LONG GC_get_max_thread_index(void)
{
LONG my_max = GC_max_thread_index;
if (my_max >= MAX_THREADS) return MAX_THREADS - 1;
return my_max;
}
/* Return the GC_thread corresponding to a 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. */
/* This version assumes that either GC_win32_dll_threads is set, or */
/* we hold the allocator lock. */
/* Also used (for assertion checking only) from thread_local_alloc.c. */
STATIC GC_thread GC_lookup_thread_inner(DWORD thread_id)
{
# ifndef GC_NO_THREADS_DISCOVERY
if (GC_win32_dll_threads) {
int i;
LONG my_max = GC_get_max_thread_index();
for (i = 0; i <= my_max &&
(!AO_load_acquire(&dll_thread_table[i].tm.in_use)
|| dll_thread_table[i].id != thread_id);
/* Must still be in_use, since nobody else can store our */
/* thread_id. */
i++) {
/* empty */
}
return i <= my_max ? (GC_thread)(dll_thread_table + i) : NULL;
} else
# endif
/* else */ {
GC_thread p = GC_threads[THREAD_TABLE_INDEX(thread_id)];
GC_ASSERT(I_HOLD_LOCK());
while (p != 0 && p -> id != thread_id) p = p -> tm.next;
return(p);
}
}
#ifdef LINT2
# define CHECK_LOOKUP_MY_THREAD(me) \
if (!(me)) ABORT("GC_lookup_thread_inner(GetCurrentThreadId) failed")
#else
# define CHECK_LOOKUP_MY_THREAD(me) /* empty */
#endif
/* Called by GC_finalize() (in case of an allocation failure observed). */
/* GC_reset_finalizer_nested() is the same as in pthread_support.c. */
GC_INNER void GC_reset_finalizer_nested(void)
{
GC_thread me = GC_lookup_thread_inner(GetCurrentThreadId());
CHECK_LOOKUP_MY_THREAD(me);
me->finalizer_nested = 0;
}
/* Checks and updates the thread-local level of finalizers recursion. */
/* Returns NULL if GC_invoke_finalizers() should not be called by the */
/* collector (to minimize the risk of a deep finalizers recursion), */
/* otherwise returns a pointer to the thread-local finalizer_nested. */
/* Called by GC_notify_or_invoke_finalizers() only (the lock is held). */
/* GC_check_finalizer_nested() is the same as in pthread_support.c. */
GC_INNER unsigned char *GC_check_finalizer_nested(void)
{
GC_thread me = GC_lookup_thread_inner(GetCurrentThreadId());
unsigned nesting_level;
CHECK_LOOKUP_MY_THREAD(me);
nesting_level = me->finalizer_nested;
if (nesting_level) {
/* We are inside another GC_invoke_finalizers(). */
/* Skip some implicitly-called GC_invoke_finalizers() */
/* depending on the nesting (recursion) level. */
if (++me->finalizer_skipped < (1U << nesting_level)) return NULL;
me->finalizer_skipped = 0;
}
me->finalizer_nested = (unsigned char)(nesting_level + 1);
return &me->finalizer_nested;
}
#if defined(GC_ASSERTIONS) && defined(THREAD_LOCAL_ALLOC)
/* This is called from thread-local GC_malloc(). */
GC_bool GC_is_thread_tsd_valid(void *tsd)
{
GC_thread me;
DCL_LOCK_STATE;
LOCK();
me = GC_lookup_thread_inner(GetCurrentThreadId());
UNLOCK();
return (word)tsd >= (word)(&me->tlfs)
&& (word)tsd < (word)(&me->tlfs) + sizeof(me->tlfs);
}
#endif /* GC_ASSERTIONS && THREAD_LOCAL_ALLOC */
GC_API int GC_CALL GC_thread_is_registered(void)
{
DWORD thread_id = GetCurrentThreadId();
GC_thread me;
DCL_LOCK_STATE;
LOCK();
me = GC_lookup_thread_inner(thread_id);
UNLOCK();
return me != NULL;
}
GC_API void GC_CALL GC_register_altstack(void *stack GC_ATTR_UNUSED,
GC_word stack_size GC_ATTR_UNUSED,
void *altstack GC_ATTR_UNUSED,
GC_word altstack_size GC_ATTR_UNUSED)
{
/* TODO: Implement */
}
/* Make sure thread descriptor t is not protected by the VDB */
/* implementation. */
/* Used to prevent write faults when the world is (partially) stopped, */
/* since it may have been stopped with a system lock held, and that */
/* lock may be required for fault handling. */
#if defined(MPROTECT_VDB)
# define UNPROTECT_THREAD(t) \
if (!GC_win32_dll_threads && GC_auto_incremental \
&& t != &first_thread) { \
GC_ASSERT(SMALL_OBJ(GC_size(t))); \
GC_remove_protection(HBLKPTR(t), 1, FALSE); \
} else (void)0
#else
# define UNPROTECT_THREAD(t) (void)0
#endif
#ifdef CYGWIN32
# define GC_PTHREAD_PTRVAL(pthread_id) pthread_id
#elif defined(GC_WIN32_PTHREADS) || defined(GC_PTHREADS_PARAMARK)
# include <pthread.h> /* to check for winpthreads */
# if defined(__WINPTHREADS_VERSION_MAJOR)
# define GC_PTHREAD_PTRVAL(pthread_id) pthread_id
# else
# define GC_PTHREAD_PTRVAL(pthread_id) pthread_id.p
# endif
#endif
/* If a thread has been joined, but we have not yet */
/* been notified, then there may be more than one thread */
/* in the table with the same win32 id. */
/* This is OK, but we need a way to delete a specific one. */
/* Assumes we hold the allocation lock unless */
/* GC_win32_dll_threads is set. Does not actually free */
/* GC_thread entry (only unlinks it). */
/* If GC_win32_dll_threads is set it should be called from the */
/* thread being deleted. */
STATIC void GC_delete_gc_thread_no_free(GC_vthread t)
{
# ifndef MSWINCE
CloseHandle(t->handle);
# endif
# ifndef GC_NO_THREADS_DISCOVERY
if (GC_win32_dll_threads) {
/* This is intended to be lock-free. */
/* It is either called synchronously from the thread being */
/* deleted, or by the joining thread. */
/* In this branch asynchronous changes to (*t) are possible. */
/* It's not allowed to call GC_printf (and the friends) here, */
/* see GC_stop_world() for the information. */
t -> stack_base = 0;
t -> id = 0;
t -> suspended = FALSE;
# ifdef RETRY_GET_THREAD_CONTEXT
t -> context_sp = NULL;
# endif
AO_store_release(&t->tm.in_use, FALSE);
} else
# endif
/* else */ {
DWORD id = ((GC_thread)t) -> id;
/* Cast away volatile qualifier, since we have lock. */
int hv = THREAD_TABLE_INDEX(id);
GC_thread p = GC_threads[hv];
GC_thread prev = NULL;
GC_ASSERT(I_HOLD_LOCK());
while (p != (GC_thread)t) {
prev = p;
p = p -> tm.next;
}
if (prev == 0) {
GC_threads[hv] = p -> tm.next;
} else {
GC_ASSERT(prev != &first_thread);
prev -> tm.next = p -> tm.next;
GC_dirty(prev);
}
}
}
/* Delete a thread from GC_threads. We assume it is there. */
/* (The code intentionally traps if it wasn't.) Assumes we */
/* hold the allocation lock unless GC_win32_dll_threads is set. */
/* If GC_win32_dll_threads is set then it should be called from */
/* the thread being deleted. It is also safe to delete the */
/* main thread (unless GC_win32_dll_threads). */
STATIC void GC_delete_thread(DWORD id)
{
if (GC_win32_dll_threads) {
GC_vthread t = GC_lookup_thread_inner(id);
if (0 == t) {
WARN("Removing nonexistent thread, id= %" WARN_PRIdPTR "\n", id);
} else {
GC_delete_gc_thread_no_free(t);
}
} else {
int hv = THREAD_TABLE_INDEX(id);
GC_thread p = GC_threads[hv];
GC_thread prev = NULL;
GC_ASSERT(I_HOLD_LOCK());
while (p -> id != id) {
prev = p;
p = p -> tm.next;
}
# ifndef MSWINCE
CloseHandle(p->handle);
# endif
if (prev == 0) {
GC_threads[hv] = p -> tm.next;
} else {
GC_ASSERT(prev != &first_thread);
prev -> tm.next = p -> tm.next;
GC_dirty(prev);
}
if (EXPECT(p != &first_thread, TRUE)) {
GC_INTERNAL_FREE(p);
}
}
}
GC_API void GC_CALL GC_allow_register_threads(void)
{
/* Check GC is initialized and the current thread is registered. */
GC_ASSERT(GC_lookup_thread_inner(GetCurrentThreadId()) != 0);
# if !defined(GC_ALWAYS_MULTITHREADED) && !defined(PARALLEL_MARK) \
&& !defined(GC_NO_THREADS_DISCOVERY)
/* GC_init() does not call GC_init_parallel() in this case. */
parallel_initialized = TRUE;
# endif
set_need_to_lock();
}
GC_API int GC_CALL GC_register_my_thread(const struct GC_stack_base *sb)
{
GC_thread me;
DWORD thread_id = GetCurrentThreadId();
DCL_LOCK_STATE;
if (GC_need_to_lock == FALSE)
ABORT("Threads explicit registering is not previously enabled");
/* We lock here, since we want to wait for an ongoing GC. */
LOCK();
me = GC_lookup_thread_inner(thread_id);
if (me == 0) {
# ifdef GC_PTHREADS
me = GC_register_my_thread_inner(sb, thread_id);
# if defined(CPPCHECK)
GC_noop1(me->flags);
# endif
me -> flags |= DETACHED;
/* Treat as detached, since we do not need to worry about */
/* pointer results. */
# else
GC_register_my_thread_inner(sb, thread_id);
# endif
UNLOCK();
return GC_SUCCESS;
} else
# ifdef GC_PTHREADS
/* else */ if ((me -> flags & FINISHED) != 0) {
GC_record_stack_base(me, sb);
me -> flags &= ~FINISHED; /* but not DETACHED */
# ifdef THREAD_LOCAL_ALLOC
GC_init_thread_local((GC_tlfs)(&me->tlfs));
# endif
UNLOCK();
return GC_SUCCESS;
} else
# endif
/* else */ {
UNLOCK();
return GC_DUPLICATE;
}
}
#ifdef GC_DISABLE_INCREMENTAL
# define GC_wait_for_gc_completion(wait_for_all) (void)(wait_for_all)
#else
/* Similar to that in pthread_support.c. */
STATIC void GC_wait_for_gc_completion(GC_bool wait_for_all)
{
GC_ASSERT(I_HOLD_LOCK());
if (GC_incremental && GC_collection_in_progress()) {
word old_gc_no = GC_gc_no;
/* Make sure that no part of our stack is still on the mark stack, */
/* since it's about to be unmapped. */
do {
ENTER_GC();
GC_in_thread_creation = TRUE;
GC_collect_a_little_inner(1);
GC_in_thread_creation = FALSE;
EXIT_GC();
UNLOCK();
Sleep(0); /* yield */
LOCK();
} while (GC_incremental && GC_collection_in_progress()
&& (wait_for_all || old_gc_no == GC_gc_no));
}
}
#endif /* !GC_DISABLE_INCREMENTAL */
GC_API int GC_CALL GC_unregister_my_thread(void)
{
DCL_LOCK_STATE;
# ifdef DEBUG_THREADS
GC_log_printf("Unregistering thread 0x%lx\n", (long)GetCurrentThreadId());
# endif
if (GC_win32_dll_threads) {
# if defined(THREAD_LOCAL_ALLOC)
/* Can't happen: see GC_use_threads_discovery(). */
GC_ASSERT(FALSE);
# else
/* FIXME: Should we just ignore this? */
GC_delete_thread(GetCurrentThreadId());
# endif
} else {
# if defined(THREAD_LOCAL_ALLOC) || defined(GC_PTHREADS)
GC_thread me;
# endif
DWORD thread_id = GetCurrentThreadId();
LOCK();
GC_wait_for_gc_completion(FALSE);
# if defined(THREAD_LOCAL_ALLOC) || defined(GC_PTHREADS)
me = GC_lookup_thread_inner(thread_id);
CHECK_LOOKUP_MY_THREAD(me);
GC_ASSERT(!KNOWN_FINISHED(me));
# endif
# if defined(THREAD_LOCAL_ALLOC)
GC_ASSERT(GC_getspecific(GC_thread_key) == &me->tlfs);
GC_destroy_thread_local(&(me->tlfs));
# endif
# ifdef GC_PTHREADS
if ((me -> flags & DETACHED) == 0) {
me -> flags |= FINISHED;
} else
# endif
/* else */ {
GC_delete_thread(thread_id);
}
# if defined(THREAD_LOCAL_ALLOC)
/* It is required to call remove_specific defined in specific.c. */
GC_remove_specific(GC_thread_key);
# endif
UNLOCK();
}
return GC_SUCCESS;
}
/* Wrapper for functions that are likely to block for an appreciable */
/* length of time. */
/* GC_do_blocking_inner() is nearly the same as in pthread_support.c */
GC_INNER void GC_do_blocking_inner(ptr_t data, void * context GC_ATTR_UNUSED)
{
struct blocking_data * d = (struct blocking_data *) data;
DWORD thread_id = GetCurrentThreadId();
GC_thread me;
# ifdef IA64
ptr_t stack_ptr = GC_save_regs_in_stack();
# endif
DCL_LOCK_STATE;
LOCK();
me = GC_lookup_thread_inner(thread_id);
CHECK_LOOKUP_MY_THREAD(me);
GC_ASSERT(me -> thread_blocked_sp == NULL);
# ifdef IA64
me -> backing_store_ptr = stack_ptr;
# endif
me -> thread_blocked_sp = (ptr_t) &d; /* save approx. sp */
/* Save context here if we want to support precise stack marking */
UNLOCK();
d -> client_data = (d -> fn)(d -> client_data);
LOCK(); /* This will block if the world is stopped. */
# if defined(CPPCHECK)
GC_noop1((word)me->thread_blocked_sp);
# endif
me -> thread_blocked_sp = NULL;
UNLOCK();
}
/* GC_call_with_gc_active() has the opposite to GC_do_blocking() */
/* functionality. It might be called from a user function invoked by */
/* GC_do_blocking() to temporarily back allow calling any GC function */
/* and/or manipulating pointers to the garbage collected heap. */
GC_API void * GC_CALL GC_call_with_gc_active(GC_fn_type fn,
void * client_data)
{
struct GC_traced_stack_sect_s stacksect;
DWORD thread_id = GetCurrentThreadId();
GC_thread me;
DCL_LOCK_STATE;
LOCK(); /* This will block if the world is stopped. */
me = GC_lookup_thread_inner(thread_id);
CHECK_LOOKUP_MY_THREAD(me);
/* Adjust our stack bottom pointer (this could happen unless */
/* GC_get_stack_base() was used which returned GC_SUCCESS). */
GC_ASSERT(me -> stack_base != NULL);
if ((word)me->stack_base < (word)(&stacksect)) {
me -> stack_base = (ptr_t)(&stacksect);
# if defined(I386)
me -> initial_stack_base = me -> stack_base;
# endif
}
if (me -> thread_blocked_sp == NULL) {
/* We are not inside GC_do_blocking() - do nothing more. */
UNLOCK();
client_data = fn(client_data);
/* Prevent treating the above as a tail call. */
GC_noop1(COVERT_DATAFLOW(&stacksect));
return client_data; /* result */
}
/* Setup new "stack section". */
stacksect.saved_stack_ptr = me -> thread_blocked_sp;
# ifdef IA64
/* This is the same as in GC_call_with_stack_base(). */
stacksect.backing_store_end = GC_save_regs_in_stack();
/* Unnecessarily flushes register stack, */
/* but that probably doesn't hurt. */
stacksect.saved_backing_store_ptr = me -> backing_store_ptr;
# endif
stacksect.prev = me -> traced_stack_sect;
me -> thread_blocked_sp = NULL;
me -> traced_stack_sect = &stacksect;
UNLOCK();
client_data = fn(client_data);
GC_ASSERT(me -> thread_blocked_sp == NULL);
GC_ASSERT(me -> traced_stack_sect == &stacksect);
/* Restore original "stack section". */
LOCK();
# if defined(CPPCHECK)
GC_noop1((word)me->traced_stack_sect);
# endif
me -> traced_stack_sect = stacksect.prev;
# ifdef IA64
me -> backing_store_ptr = stacksect.saved_backing_store_ptr;
# endif
me -> thread_blocked_sp = stacksect.saved_stack_ptr;
UNLOCK();
return client_data; /* result */