#include "private/gc_priv.h" #if defined(GC_WIN32_THREADS) #include <windows.h> #ifdef CYGWIN32 # include <errno.h> /* Cygwin-specific forward decls */ # undef pthread_create # undef pthread_sigmask # undef pthread_join # undef pthread_detach # undef dlopen # define DEBUG_CYGWIN_THREADS 0 void * GC_start_routine(void * arg); void GC_thread_exit_proc(void *arg); #endif /* The type of the first argument to InterlockedExchange. */ /* Documented to be LONG volatile *, but at least gcc likes */ /* this better. */ typedef LONG * IE_t; #ifndef MAX_THREADS # define MAX_THREADS 256 /* FIXME: */ /* Things may get quite slow for large numbers of threads, */ /* since we look them up with sequential search. */ #endif GC_bool GC_thr_initialized = FALSE; DWORD GC_main_thread = 0; struct GC_thread_Rep { LONG in_use; /* Updated without lock. */ /* We assert that unused */ /* entries have invalid ids of */ /* zero and zero stack fields. */ DWORD id; HANDLE handle; ptr_t stack_base; /* The cold end of the stack. */ /* 0 ==> entry not valid. */ /* !in_use ==> stack_base == 0 */ GC_bool suspended; # ifdef CYGWIN32 void *status; /* hold exit value until join in case it's a pointer */ pthread_t pthread_id; short flags; /* Protected by GC lock. */ # define FINISHED 1 /* Thread has exited. */ # define DETACHED 2 /* Thread is intended to be detached. */ # endif }; typedef volatile struct GC_thread_Rep * GC_thread; /* * We generally assume that volatile ==> memory ordering, at least among * volatiles. */ volatile GC_bool GC_please_stop = FALSE; volatile struct GC_thread_Rep thread_table[MAX_THREADS]; volatile LONG GC_max_thread_index = 0; /* Largest index in thread_table */ /* that was ever used. */ extern LONG WINAPI GC_write_fault_handler(struct _EXCEPTION_POINTERS *exc_info); /* * This may be called from DllMain, and hence operates under unusual * constraints. */ static GC_thread GC_new_thread(void) { int i; /* It appears to be unsafe to acquire a lock here, since this */ /* code is apparently not preeemptible 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. */ /* The following should be a noop according to the win32 */ /* documentation. There is empirical evidence that it */ /* isn't. - HB */ # if defined(MPROTECT_VDB) if (GC_incremental) SetUnhandledExceptionFilter(GC_write_fault_handler); # endif /* cast away volatile qualifier */ for (i = 0; InterlockedExchange((IE_t)&thread_table[i].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. */ 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; } # ifdef CYGWIN32 thread_table[i].pthread_id = pthread_self(); # endif if (!DuplicateHandle(GetCurrentProcess(), GetCurrentThread(), GetCurrentProcess(), (HANDLE*)&thread_table[i].handle, 0, 0, DUPLICATE_SAME_ACCESS)) { DWORD last_error = GetLastError(); GC_printf1("Last error code: %lx\n", last_error); ABORT("DuplicateHandle failed"); } thread_table[i].stack_base = GC_get_stack_base(); /* Up until this point, GC_push_all_stacks considers this thread */ /* invalid. */ if (thread_table[i].stack_base == NULL) ABORT("Failed to find stack base in GC_new_thread"); /* Up until this point, this entry is viewed as reserved but invalid */ /* by GC_delete_thread. */ thread_table[i].id = GetCurrentThreadId(); /* If this thread is being created while we are trying to stop */ /* the world, wait here. Hopefully this can't happen on any */ /* systems that don't allow us to block here. */ while (GC_please_stop) Sleep(20); return thread_table + i; } /* * GC_max_thread_index may temporarily be larger than MAX_THREADS. * To avoid subscript errors, we check on access. */ #ifdef __GNUC__ __inline__ #endif LONG GC_get_max_thread_index() { LONG my_max = GC_max_thread_index; if (my_max >= MAX_THREADS) return MAX_THREADS-1; return my_max; } /* This is intended to be lock-free, though that */ /* assumes that the CloseHandle becomes visible before the */ /* in_use assignment. */ static void GC_delete_gc_thread(GC_thread thr) { CloseHandle(thr->handle); /* cast away volatile qualifier */ thr->stack_base = 0; thr->id = 0; # ifdef CYGWIN32 thr->pthread_id = 0; # endif /* CYGWIN32 */ thr->in_use = FALSE; } static void GC_delete_thread(DWORD thread_id) { int i; LONG my_max = GC_get_max_thread_index(); for (i = 0; i <= my_max && (!thread_table[i].in_use || thread_table[i].id != thread_id); /* Must still be in_use, since nobody else can store our thread_id. */ i++) {} if (i > my_max) { WARN("Removing nonexistent thread %ld\n", (GC_word)thread_id); } else { GC_delete_gc_thread(thread_table+i); } } #ifdef CYGWIN32 /* Return a GC_thread corresponding to a given pthread_t. */ /* Returns 0 if it's not there. */ /* We assume that this is only called for pthread ids that */ /* have not yet terminated or are still joinable. */ static GC_thread GC_lookup_thread(pthread_t id) { int i; LONG my_max = GC_get_max_thread_index(); for (i = 0; i <= my_max && (!thread_table[i].in_use || thread_table[i].pthread_id != id || !thread_table[i].in_use); /* Must still be in_use, since nobody else can store our thread_id. */ i++); if (i > my_max) return 0; return thread_table + i; } #endif /* CYGWIN32 */ void GC_push_thread_structures GC_PROTO((void)) { /* Unlike the other threads implementations, the thread table here */ /* contains no pointers to the collectable heap. Thus we have */ /* no private structures we need to preserve. */ # ifdef CYGWIN32 { int i; /* pthreads may keep a pointer in the thread exit value */ LONG my_max = GC_get_max_thread_index(); for (i = 0; i <= my_max; i++) if (thread_table[i].in_use) GC_push_all((ptr_t)&(thread_table[i].status), (ptr_t)(&(thread_table[i].status)+1)); } # endif } /* Defined in misc.c */ extern CRITICAL_SECTION GC_write_cs; void GC_stop_world() { DWORD thread_id = GetCurrentThreadId(); int i; if (!GC_thr_initialized) ABORT("GC_stop_world() called before GC_thr_init()"); GC_please_stop = TRUE; # ifndef CYGWIN32 EnterCriticalSection(&GC_write_cs); # endif /* !CYGWIN32 */ for (i = 0; i <= GC_get_max_thread_index(); i++) if (thread_table[i].stack_base != 0 && thread_table[i].id != thread_id) { # ifdef MSWINCE /* SuspendThread will fail if thread is running kernel code */ while (SuspendThread(thread_table[i].handle) == (DWORD)-1) Sleep(10); # else /* 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's a race here. */ DWORD exitCode; if (GetExitCodeThread(thread_table[i].handle,&exitCode) && exitCode != STILL_ACTIVE) { thread_table[i].stack_base = 0; /* prevent stack from being pushed */ # ifndef CYGWIN32 /* this breaks pthread_join on Cygwin, which is guaranteed to */ /* only see user pthreads */ thread_table[i].in_use = FALSE; CloseHandle(thread_table[i].handle); # endif continue; } if (SuspendThread(thread_table[i].handle) == (DWORD)-1) ABORT("SuspendThread failed"); # endif thread_table[i].suspended = TRUE; } # ifndef CYGWIN32 LeaveCriticalSection(&GC_write_cs); # endif /* !CYGWIN32 */ } void GC_start_world() { DWORD thread_id = GetCurrentThreadId(); int i; LONG my_max = GC_get_max_thread_index(); for (i = 0; i <= my_max; i++) if (thread_table[i].stack_base != 0 && thread_table[i].suspended && thread_table[i].id != thread_id) { if (ResumeThread(thread_table[i].handle) == (DWORD)-1) ABORT("ResumeThread failed"); thread_table[i].suspended = FALSE; } GC_please_stop = FALSE; } # ifdef _MSC_VER # pragma warning(disable:4715) # endif ptr_t GC_current_stackbottom() { DWORD thread_id = GetCurrentThreadId(); int i; LONG my_max = GC_get_max_thread_index(); for (i = 0; i <= my_max; i++) if (thread_table[i].stack_base && thread_table[i].id == thread_id) return thread_table[i].stack_base; ABORT("no thread table entry for current thread"); } # ifdef _MSC_VER # pragma warning(default:4715) # endif # ifdef MSWINCE /* The VirtualQuery calls below won't work properly on WinCE, but */ /* since each stack is restricted to an aligned 64K region of */ /* virtual memory we can just take the next lowest multiple of 64K. */ # define GC_get_stack_min(s) \ ((ptr_t)(((DWORD)(s) - 1) & 0xFFFF0000)) # else static ptr_t GC_get_stack_min(ptr_t s) { ptr_t bottom; MEMORY_BASIC_INFORMATION info; VirtualQuery(s, &info, sizeof(info)); do { bottom = info.BaseAddress; VirtualQuery(bottom - 1, &info, sizeof(info)); } while ((info.Protect & PAGE_READWRITE) && !(info.Protect & PAGE_GUARD)); return(bottom); } # endif void GC_push_all_stacks() { DWORD thread_id = GetCurrentThreadId(); GC_bool found_me = FALSE; int i; int dummy; ptr_t sp, stack_min; GC_thread thread; LONG my_max = GC_get_max_thread_index(); for (i = 0; i <= my_max; i++) { thread = thread_table + i; if (thread -> in_use && thread -> stack_base) { if (thread -> id == thread_id) { sp = (ptr_t) &dummy; found_me = TRUE; } else { CONTEXT context; context.ContextFlags = CONTEXT_INTEGER|CONTEXT_CONTROL; if (!GetThreadContext(thread_table[i].handle, &context)) ABORT("GetThreadContext failed"); /* Push all registers that might point into the heap. Frame */ /* pointer registers are included in case client code was */ /* compiled with the 'omit frame pointer' optimisation. */ # define PUSH1(reg) GC_push_one((word)context.reg) # define PUSH2(r1,r2) PUSH1(r1), PUSH1(r2) # define PUSH4(r1,r2,r3,r4) PUSH2(r1,r2), PUSH2(r3,r4) # if defined(I386) PUSH4(Edi,Esi,Ebx,Edx), PUSH2(Ecx,Eax), PUSH1(Ebp); sp = (ptr_t)context.Esp; # 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(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; # else # error "architecture is not supported" # endif } stack_min = GC_get_stack_min(thread->stack_base); if (sp >= stack_min && sp < thread->stack_base) GC_push_all_stack(sp, thread->stack_base); else { WARN("Thread stack pointer 0x%lx out of range, pushing everything\n", (unsigned long)sp); GC_push_all_stack(stack_min, thread->stack_base); } } } if (!found_me) ABORT("Collecting from unknown thread."); } void GC_get_next_stack(char *start, char **lo, char **hi) { int i; # define ADDR_LIMIT (char *)(-1L) char * current_min = ADDR_LIMIT; LONG my_max = GC_get_max_thread_index(); for (i = 0; i <= my_max; i++) { char * s = (char *)thread_table[i].stack_base; if (0 != s && s > start && s < current_min) { current_min = s; } } *hi = current_min; if (current_min == ADDR_LIMIT) { *lo = ADDR_LIMIT; return; } *lo = GC_get_stack_min(current_min); if (*lo < start) *lo = start; } #if !defined(CYGWIN32) #if !defined(MSWINCE) && defined(GC_DLL) /* We register threads from DllMain */ GC_API HANDLE WINAPI GC_CreateThread( LPSECURITY_ATTRIBUTES lpThreadAttributes, DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress, LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId ) { return CreateThread(lpThreadAttributes, dwStackSize, lpStartAddress, lpParameter, dwCreationFlags, lpThreadId); } #else /* defined(MSWINCE) || !defined(GC_DLL)) */ /* We have no DllMain to take care of new threads. Thus we */ /* must properly intercept thread creation. */ typedef struct { LPTHREAD_START_ROUTINE start; LPVOID param; } thread_args; static DWORD WINAPI thread_start(LPVOID arg); GC_API HANDLE WINAPI GC_CreateThread( LPSECURITY_ATTRIBUTES lpThreadAttributes, DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress, LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId ) { HANDLE thread_h = NULL; thread_args *args; if (!GC_is_initialized) GC_init(); /* make sure GC is initialized (i.e. main thread is attached) */ args = GC_malloc_uncollectable(sizeof(thread_args)); /* Handed off to and deallocated by child thread. */ if (0 == args) { SetLastError(ERROR_NOT_ENOUGH_MEMORY); return NULL; } /* set up thread arguments */ args -> start = lpStartAddress; args -> param = lpParameter; thread_h = CreateThread(lpThreadAttributes, dwStackSize, thread_start, args, dwCreationFlags, lpThreadId); return thread_h; } static DWORD WINAPI thread_start(LPVOID arg) { DWORD ret = 0; thread_args *args = (thread_args *)arg; GC_new_thread(); /* Clear the thread entry even if we exit with an exception. */ /* This is probably pointless, since an uncaught exception is */ /* supposed to result in the process being killed. */ #ifndef __GNUC__ __try { #endif /* __GNUC__ */ ret = args->start (args->param); #ifndef __GNUC__ } __finally { #endif /* __GNUC__ */ GC_free(args); GC_delete_thread(GetCurrentThreadId()); #ifndef __GNUC__ } #endif /* __GNUC__ */ return ret; } #endif /* !defined(MSWINCE) && !(defined(__MINGW32__) && !defined(_DLL)) */ #endif /* !CYGWIN32 */ #ifdef MSWINCE typedef struct { HINSTANCE hInstance; HINSTANCE hPrevInstance; LPWSTR lpCmdLine; int nShowCmd; } main_thread_args; DWORD WINAPI main_thread_start(LPVOID arg); int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int nShowCmd) { DWORD exit_code = 1; main_thread_args args = { hInstance, hPrevInstance, lpCmdLine, nShowCmd }; HANDLE thread_h; DWORD thread_id; /* initialize everything */ GC_init(); /* start the main thread */ thread_h = GC_CreateThread( NULL, 0, main_thread_start, &args, 0, &thread_id); if (thread_h != NULL) { WaitForSingleObject (thread_h, INFINITE); GetExitCodeThread (thread_h, &exit_code); CloseHandle (thread_h); } GC_deinit(); DeleteCriticalSection(&GC_allocate_ml); return (int) exit_code; } DWORD WINAPI main_thread_start(LPVOID arg) { main_thread_args * args = (main_thread_args *) arg; return (DWORD) GC_WinMain (args->hInstance, args->hPrevInstance, args->lpCmdLine, args->nShowCmd); } # else /* !MSWINCE */ /* Called by GC_init() - we hold the allocation lock. */ void GC_thr_init() { if (GC_thr_initialized) return; GC_main_thread = GetCurrentThreadId(); GC_thr_initialized = TRUE; /* Add the initial thread, so we can stop it. */ GC_new_thread(); } #ifdef CYGWIN32 struct start_info { void *(*start_routine)(void *); void *arg; GC_bool detached; }; int GC_pthread_join(pthread_t pthread_id, void **retval) { int result; int i; GC_thread me; # if DEBUG_CYGWIN_THREADS GC_printf3("thread 0x%x(0x%x) is joining thread 0x%x.\n", (int)pthread_self(), GetCurrentThreadId(), (int)pthread_id); # endif /* Thread being joined might not have registered itself yet. */ /* After the join,thread id may have been recycled. */ /* FIXME: It would be better if this worked more like */ /* pthread_support.c. */ while ((me = GC_lookup_thread(pthread_id)) == 0) Sleep(10); result = pthread_join(pthread_id, retval); GC_delete_gc_thread(me); # if DEBUG_CYGWIN_THREADS GC_printf3("thread 0x%x(0x%x) completed join with thread 0x%x.\n", (int)pthread_self(), GetCurrentThreadId(), (int)pthread_id); # endif return result; } /* Cygwin-pthreads calls CreateThread internally, but it's not * easily interceptible by us.. * so intercept pthread_create instead */ int GC_pthread_create(pthread_t *new_thread, const pthread_attr_t *attr, void *(*start_routine)(void *), void *arg) { int result; struct start_info * si; if (!GC_is_initialized) GC_init(); /* make sure GC is initialized (i.e. main thread is attached) */ /* This is otherwise saved only in an area mmapped by the thread */ /* library, which isn't visible to the collector. */ si = GC_malloc_uncollectable(sizeof(struct start_info)); if (0 == si) return(EAGAIN); si -> start_routine = start_routine; si -> arg = arg; if (attr != 0 && pthread_attr_getdetachstate(attr, &si->detached) == PTHREAD_CREATE_DETACHED) { si->detached = TRUE; } # if DEBUG_CYGWIN_THREADS GC_printf2("About to create a thread from 0x%x(0x%x)\n", (int)pthread_self(), GetCurrentThreadId); # endif result = pthread_create(new_thread, attr, GC_start_routine, si); if (result) { /* failure */ GC_free(si); } return(result); } void * GC_start_routine(void * arg) { struct start_info * si = arg; void * result; void *(*start)(void *); void *start_arg; pthread_t pthread_id; GC_thread me; GC_bool detached; int i; # if DEBUG_CYGWIN_THREADS GC_printf2("thread 0x%x(0x%x) starting...\n",(int)pthread_self(), GetCurrentThreadId()); # endif /* If a GC occurs before the thread is registered, that GC will */ /* ignore this thread. That's fine, since it will block trying to */ /* acquire the allocation lock, and won't yet hold interesting */ /* pointers. */ LOCK(); /* We register the thread here instead of in the parent, so that */ /* we don't need to hold the allocation lock during pthread_create. */ me = GC_new_thread(); UNLOCK(); start = si -> start_routine; start_arg = si -> arg; if (si-> detached) me -> flags |= DETACHED; me -> pthread_id = pthread_id = pthread_self(); GC_free(si); /* was allocated uncollectable */ pthread_cleanup_push(GC_thread_exit_proc, (void *)me); result = (*start)(start_arg); me -> status = result; pthread_cleanup_pop(0); # if DEBUG_CYGWIN_THREADS GC_printf2("thread 0x%x(0x%x) returned from start routine.\n", (int)pthread_self(),GetCurrentThreadId()); # endif return(result); } void GC_thread_exit_proc(void *arg) { GC_thread me = (GC_thread)arg; int i; # if DEBUG_CYGWIN_THREADS GC_printf2("thread 0x%x(0x%x) called pthread_exit().\n", (int)pthread_self(),GetCurrentThreadId()); # endif LOCK(); if (me -> flags & DETACHED) { GC_delete_thread(GetCurrentThreadId()); } else { /* deallocate it as part of join */ me -> flags |= FINISHED; } UNLOCK(); } /* nothing required here... */ int GC_pthread_sigmask(int how, const sigset_t *set, sigset_t *oset) { return pthread_sigmask(how, set, oset); } int GC_pthread_detach(pthread_t thread) { int result; GC_thread thread_gc_id; LOCK(); thread_gc_id = GC_lookup_thread(thread); UNLOCK(); result = pthread_detach(thread); if (result == 0) { LOCK(); thread_gc_id -> flags |= DETACHED; /* Here the pthread thread id may have been recycled. */ if (thread_gc_id -> flags & FINISHED) { GC_delete_gc_thread(thread_gc_id); } UNLOCK(); } return result; } #else /* !CYGWIN32 */ /* * We avoid acquiring locks here, since this doesn't seem to be preemptable. * Pontus Rydin suggests wrapping the thread start routine instead. */ #ifdef GC_DLL BOOL WINAPI DllMain(HINSTANCE inst, ULONG reason, LPVOID reserved) { switch (reason) { case DLL_PROCESS_ATTACH: GC_init(); /* Force initialization before thread attach. */ /* fall through */ case DLL_THREAD_ATTACH: GC_ASSERT(GC_thr_initialized); if (GC_main_thread != GetCurrentThreadId()) { GC_new_thread(); } /* o.w. we already did it during GC_thr_init(), called by GC_init() */ break; case DLL_THREAD_DETACH: GC_delete_thread(GetCurrentThreadId()); break; case DLL_PROCESS_DETACH: { int i; LOCK(); for (i = 0; i <= GC_get_max_thread_index(); ++i) { if (thread_table[i].in_use) GC_delete_gc_thread(thread_table + i); } UNLOCK(); GC_deinit(); DeleteCriticalSection(&GC_allocate_ml); } break; } return TRUE; } #endif /* GC_DLL */ #endif /* !CYGWIN32 */ # endif /* !MSWINCE */ #endif /* GC_WIN32_THREADS */