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#ifdef WIN32_THREADS
#include "gc_priv.h"
#define STRICT
#include <windows.h>
#define MAX_THREADS 64
struct thread_entry {
LONG in_use;
DWORD id;
HANDLE handle;
void *stack; /* The cold end of the stack. */
/* 0 ==> entry not valid. */
/* !in_use ==> stack == 0 */
CONTEXT context;
GC_bool suspended;
};
volatile GC_bool GC_please_stop = FALSE;
volatile struct thread_entry thread_table[MAX_THREADS];
void GC_stop_world()
{
DWORD thread_id = GetCurrentThreadId();
int i;
GC_please_stop = TRUE;
for (i = 0; i < MAX_THREADS; i++)
if (thread_table[i].stack != 0
&& thread_table[i].id != thread_id) {
if (SuspendThread(thread_table[i].handle) == (DWORD)-1)
ABORT("SuspendThread failed");
thread_table[i].suspended = TRUE;
}
}
void GC_start_world()
{
DWORD thread_id = GetCurrentThreadId();
int i;
for (i = 0; i < MAX_THREADS; i++)
if (thread_table[i].stack != 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;
}
ptr_t GC_current_stackbottom()
{
DWORD thread_id = GetCurrentThreadId();
int i;
for (i = 0; i < MAX_THREADS; i++)
if (thread_table[i].stack && thread_table[i].id == thread_id)
return thread_table[i].stack;
ABORT("no thread table entry for current thread");
}
ptr_t GC_get_lo_stack_addr(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);
}
void GC_push_all_stacks()
{
DWORD thread_id = GetCurrentThreadId();
int i;
for (i = 0; i < MAX_THREADS; i++)
if (thread_table[i].stack) {
ptr_t bottom = GC_get_lo_stack_addr(thread_table[i].stack);
if (thread_table[i].id == thread_id)
GC_push_all(&i, thread_table[i].stack);
else {
thread_table[i].context.ContextFlags
= (CONTEXT_INTEGER|CONTEXT_CONTROL);
if (!GetThreadContext(thread_table[i].handle,
&thread_table[i].context))
ABORT("GetThreadContext failed");
if (thread_table[i].context.Esp >= (DWORD)thread_table[i].stack
|| thread_table[i].context.Esp < (DWORD)bottom)
ABORT("Thread stack pointer out of range");
GC_push_one ((word) thread_table[i].context.Edi);
GC_push_one ((word) thread_table[i].context.Esi);
GC_push_one ((word) thread_table[i].context.Ebx);
GC_push_one ((word) thread_table[i].context.Edx);
GC_push_one ((word) thread_table[i].context.Ecx);
GC_push_one ((word) thread_table[i].context.Eax);
GC_push_all_stack(thread_table[i].context.Esp, thread_table[i].stack);
}
}
}
void GC_get_next_stack(char *start, char **lo, char **hi)
{
int i;
# define ADDR_LIMIT (char *)(-1L)
char * current_min = ADDR_LIMIT;
for (i = 0; i < MAX_THREADS; i++) {
char * s = (char *)thread_table[i].stack;
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_lo_stack_addr(current_min);
if (*lo < start) *lo = start;
}
LONG WINAPI GC_write_fault_handler(struct _EXCEPTION_POINTERS *exc_info);
/*
* This isn't generally safe, since DllMain is not premptible.
* If another thread holds the lock while this runs we're in trouble.
* Pontus Rydin suggests wrapping the thread start routine instead.
*/
BOOL WINAPI DllMain(HINSTANCE inst, ULONG reason, LPVOID reserved)
{
switch (reason) {
case DLL_PROCESS_ATTACH:
InitializeCriticalSection(&GC_allocate_ml);
GC_init(); /* Force initialization before thread attach. */
/* fall through */
case DLL_THREAD_ATTACH:
{
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 */
/* inititalization 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 */
# ifndef SMALL_CONFIG
if (GC_incremental) SetUnhandledExceptionFilter(GC_write_fault_handler);
# endif
for (i = 0; InterlockedExchange(&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");
}
thread_table[i].id = GetCurrentThreadId();
if (!DuplicateHandle(GetCurrentProcess(),
GetCurrentThread(),
GetCurrentProcess(),
&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 = GC_get_stack_base();
/* 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);
}
break;
case DLL_PROCESS_DETACH:
case DLL_THREAD_DETACH:
{
int i;
DWORD thread_id = GetCurrentThreadId();
LOCK();
for (i = 0;
thread_table[i].stack == 0 || thread_table[i].id != thread_id;
i++) {
if (i == MAX_THREADS - 1)
ABORT("thread not found on detach");
}
thread_table[i].stack = 0;
thread_table[i].in_use = FALSE;
CloseHandle(thread_table[i].handle);
BZERO(&thread_table[i].context, sizeof(CONTEXT));
UNLOCK();
}
break;
}
return TRUE;
}
#endif /* WIN32_THREADS */
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