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kernel.cfa @ 2fafe7e

ADTarm-ehast-experimentalenumforall-pointer-decayjacob/cs343-translationnew-astnew-ast-unique-exprpthread-emulationqualifiedEnum

Last change on this file since 2fafe7e was 7fdae38, checked in by Thierry Delisle <tdelisle@…>, 4 years ago
Replaced unnecessary thread fence with sufficient compiler fence
Property mode set to `100644`
File size: 22.1 KB

Line
1	//
2	// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
3	//
4	// The contents of this file are covered under the licence agreement in the
5	// file "LICENCE" distributed with Cforall.
6	//
7	// kernel.c --
8	//
9	// Author : Thierry Delisle
10	// Created On : Tue Jan 17 12:27:26 2017
11	// Last Modified By : Peter A. Buhr
12	// Last Modified On : Thu Jul 9 06:22:54 2020
13	// Update Count : 66
14	//
15
16	#define __cforall_thread__
17	// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
18
19	//C Includes
20	#include <errno.h>
21	#include <stdio.h>
22	#include <signal.h>
23	#include <unistd.h>
24
25	//CFA Includes
26	#include "kernel_private.hfa"
27	#include "preemption.hfa"
28
29	//Private includes
30	#define __CFA_INVOKE_PRIVATE__
31	#include "invoke.h"
32
33
34	//-----------------------------------------------------------------------------
35	// Some assembly required
36	#if defined( __i386 )
37	// mxcr : SSE Status and Control bits (control bits are preserved across function calls)
38	// fcw : X87 FPU control word (preserved across function calls)
39	#define __x87_store \
40	uint32_t __mxcr; \
41	uint16_t __fcw; \
42	__asm__ volatile ( \
43	"stmxcsr %0\n" \
44	"fnstcw %1\n" \
45	: "=m" (__mxcr),\
46	"=m" (__fcw) \
47	)
48
49	#define __x87_load \
50	__asm__ volatile ( \
51	"fldcw %1\n" \
52	"ldmxcsr %0\n" \
53	::"m" (__mxcr),\
54	"m" (__fcw) \
55	)
56
57	#elif defined( __x86_64 )
58	#define __x87_store \
59	uint32_t __mxcr; \
60	uint16_t __fcw; \
61	__asm__ volatile ( \
62	"stmxcsr %0\n" \
63	"fnstcw %1\n" \
64	: "=m" (__mxcr),\
65	"=m" (__fcw) \
66	)
67
68	#define __x87_load \
69	__asm__ volatile ( \
70	"fldcw %1\n" \
71	"ldmxcsr %0\n" \
72	:: "m" (__mxcr),\
73	"m" (__fcw) \
74	)
75
76
77	#elif defined( __ARM_ARCH )
78	#else
79	#error unknown hardware architecture
80	#endif
81
82	extern $thread * mainThread;
83	extern processor * mainProcessor;
84
85	//-----------------------------------------------------------------------------
86	// Kernel Scheduling logic
87	static $thread * __next_thread(cluster * this);
88	static $thread * __next_thread_slow(cluster * this);
89	static void __run_thread(processor * this, $thread * dst);
90	static void __wake_one(struct __processor_id_t * id, cluster * cltr);
91
92	static void push (__cluster_idles & idles, processor & proc);
93	static void remove(__cluster_idles & idles, processor & proc);
94	static [unsigned idle, unsigned total, * processor] query( & __cluster_idles idles );
95
96
97	//=============================================================================================
98	// Kernel Scheduling logic
99	//=============================================================================================
100	//Main of the processor contexts
101	void main(processorCtx_t & runner) {
102	// Because of a bug, we couldn't initialized the seed on construction
103	// Do it here
104	kernelTLS.rand_seed ^= rdtscl();
105
106	processor * this = runner.proc;
107	verify(this);
108
109	__cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
110	#if !defined(__CFA_NO_STATISTICS__)
111	if( this->print_halts ) {
112	__cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->id, this->name, (void*)this);
113	}
114	#endif
115
116	{
117	// Setup preemption data
118	preemption_scope scope = { this };
119
120	__cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
121
122	$thread * readyThread = 0p;
123	MAIN_LOOP:
124	for() {
125	// Try to get the next thread
126	readyThread = __next_thread( this->cltr );
127
128	if( !readyThread ) {
129	readyThread = __next_thread_slow( this->cltr );
130	}
131
132	HALT:
133	if( !readyThread ) {
134	// Don't block if we are done
135	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
136
137	#if !defined(__CFA_NO_STATISTICS__)
138	__tls_stats()->ready.sleep.halts++;
139	#endif
140
141	// Push self to idle stack
142	push(this->cltr->idles, * this);
143
144	// Confirm the ready-queue is empty
145	readyThread = __next_thread_slow( this->cltr );
146	if( readyThread ) {
147	// A thread was found, cancel the halt
148	remove(this->cltr->idles, * this);
149
150	#if !defined(__CFA_NO_STATISTICS__)
151	__tls_stats()->ready.sleep.cancels++;
152	#endif
153
154	// continue the mai loop
155	break HALT;
156	}
157
158	#if !defined(__CFA_NO_STATISTICS__)
159	if(this->print_halts) {
160	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->id, rdtscl());
161	}
162	#endif
163
164	wait( this->idle );
165
166	#if !defined(__CFA_NO_STATISTICS__)
167	if(this->print_halts) {
168	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->id, rdtscl());
169	}
170	#endif
171
172	// We were woken up, remove self from idle
173	remove(this->cltr->idles, * this);
174
175	// DON'T just proceed, start looking again
176	continue MAIN_LOOP;
177	}
178
179	/* paranoid */ verify( readyThread );
180
181	// We found a thread run it
182	__run_thread(this, readyThread);
183
184	// Are we done?
185	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
186	}
187
188	__cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
189	}
190
191	V( this->terminated );
192
193	if(this == mainProcessor) {
194	// HACK : the coroutine context switch expects this_thread to be set
195	// and it make sense for it to be set in all other cases except here
196	// fake it
197	kernelTLS.this_thread = mainThread;
198	}
199
200	__cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
201	}
202
203	static int * __volatile_errno() __attribute__((noinline));
204	static int * __volatile_errno() { asm(""); return &errno; }
205
206	// KERNEL ONLY
207	// runThread runs a thread by context switching
208	// from the processor coroutine to the target thread
209	static void __run_thread(processor * this, $thread * thrd_dst) {
210	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
211	/* paranoid */ verifyf( thrd_dst->state == Ready \|\| thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
212	/* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
213	__builtin_prefetch( thrd_dst->context.SP );
214
215	$coroutine * proc_cor = get_coroutine(this->runner);
216
217	// Update global state
218	kernelTLS.this_thread = thrd_dst;
219
220	// set state of processor coroutine to inactive
221	verify(proc_cor->state == Active);
222	proc_cor->state = Blocked;
223
224	// Actually run the thread
225	RUNNING: while(true) {
226	thrd_dst->preempted = __NO_PREEMPTION;
227	thrd_dst->state = Active;
228
229	__cfaabi_dbg_debug_do(
230	thrd_dst->park_stale = true;
231	thrd_dst->unpark_stale = true;
232	)
233
234	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
235	/* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
236	/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ) \|\| thrd_dst->curr_cor == proc_cor, "ERROR : Destination $thread %p has been corrupted.\n StackPointer too small.\n", thrd_dst ); // add escape condition if we are setting up the processor
237	/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit) \|\| thrd_dst->curr_cor == proc_cor, "ERROR : Destination $thread %p has been corrupted.\n StackPointer too large.\n", thrd_dst ); // add escape condition if we are setting up the processor
238
239	// set context switch to the thread that the processor is executing
240	verify( thrd_dst->context.SP );
241	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
242	// when __cfactx_switch returns we are back in the processor coroutine
243
244	/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit), "ERROR : Destination $thread %p has been corrupted.\n StackPointer too large.\n", thrd_dst );
245	/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ), "ERROR : Destination $thread %p has been corrupted.\n StackPointer too small.\n", thrd_dst );
246	/* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
247	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
248
249
250	// We just finished running a thread, there are a few things that could have happened.
251	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
252	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
253	// 4 - Preempted
254	// In case 1, we may have won a race so we can't write to the state again.
255	// In case 2, we lost the race so we now own the thread.
256
257	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
258	// The thread was preempted, reschedule it and reset the flag
259	__schedule_thread( (__processor_id_t*)this, thrd_dst );
260	break RUNNING;
261	}
262
263	if(unlikely(thrd_dst->state == Halted)) {
264	// The thread has halted, it should never be scheduled/run again
265	// We may need to wake someone up here since
266	unpark( this->destroyer __cfaabi_dbg_ctx2 );
267	this->destroyer = 0p;
268	break RUNNING;
269	}
270
271	/* paranoid */ verify( thrd_dst->state == Active );
272	thrd_dst->state = Blocked;
273
274	// set state of processor coroutine to active and the thread to inactive
275	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
276	__cfaabi_dbg_debug_do( thrd_dst->park_result = old_ticket; )
277	switch(old_ticket) {
278	case 1:
279	// This is case 1, the regular case, nothing more is needed
280	break RUNNING;
281	case 2:
282	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
283	// In this case, just run it again.
284	continue RUNNING;
285	default:
286	// This makes no sense, something is wrong abort
287	abort();
288	}
289	}
290
291	// Just before returning to the processor, set the processor coroutine to active
292	proc_cor->state = Active;
293	kernelTLS.this_thread = 0p;
294
295	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
296	}
297
298	// KERNEL_ONLY
299	void returnToKernel() {
300	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
301	$coroutine * proc_cor = get_coroutine(kernelTLS.this_processor->runner);
302	$thread * thrd_src = kernelTLS.this_thread;
303
304	#if !defined(__CFA_NO_STATISTICS__)
305	struct processor * last_proc = kernelTLS.this_processor;
306	#endif
307
308	// Run the thread on this processor
309	{
310	int local_errno = *__volatile_errno();
311	#if defined( __i386 ) \|\| defined( __x86_64 )
312	__x87_store;
313	#endif
314	verify( proc_cor->context.SP );
315	__cfactx_switch( &thrd_src->context, &proc_cor->context );
316	#if defined( __i386 ) \|\| defined( __x86_64 )
317	__x87_load;
318	#endif
319	*__volatile_errno() = local_errno;
320	}
321
322	#if !defined(__CFA_NO_STATISTICS__)
323	if(last_proc != kernelTLS.this_processor) {
324	__tls_stats()->ready.threads.migration++;
325	}
326	#endif
327
328	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
329	/* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) < ((uintptr_t)__get_stack(thrd_src->curr_cor)->base ), "ERROR : Returning $thread %p has been corrupted.\n StackPointer too small.\n", thrd_src );
330	/* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) > ((uintptr_t)__get_stack(thrd_src->curr_cor)->limit), "ERROR : Returning $thread %p has been corrupted.\n StackPointer too large.\n", thrd_src );
331	}
332
333	//-----------------------------------------------------------------------------
334	// Scheduler routines
335	// KERNEL ONLY
336	void __schedule_thread( struct __processor_id_t * id, $thread * thrd ) {
337	/* paranoid */ verify( thrd );
338	/* paranoid */ verify( thrd->state != Halted );
339	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
340	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
341	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
342	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
343	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
344	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
345	/* paranoid */ #endif
346	/* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
347
348	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
349
350	ready_schedule_lock ( id );
351	push( thrd->curr_cluster, thrd );
352	__wake_one(id, thrd->curr_cluster);
353	ready_schedule_unlock( id );
354
355	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
356	}
357
358	// KERNEL ONLY
359	static inline $thread * __next_thread(cluster * this) with( *this ) {
360	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
361
362	ready_schedule_lock ( (__processor_id_t*)kernelTLS.this_processor );
363	$thread * thrd = pop( this );
364	ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
365
366	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
367	return thrd;
368	}
369
370	// KERNEL ONLY
371	static inline $thread * __next_thread_slow(cluster * this) with( *this ) {
372	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
373
374	ready_schedule_lock ( (__processor_id_t*)kernelTLS.this_processor );
375	$thread * thrd = pop_slow( this );
376	ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
377
378	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
379	return thrd;
380	}
381
382	// KERNEL ONLY unpark with out disabling interrupts
383	void __unpark( struct __processor_id_t * id, $thread * thrd __cfaabi_dbg_ctx_param2 ) {
384	// record activity
385	__cfaabi_dbg_record_thrd( *thrd, false, caller );
386
387	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
388	__cfaabi_dbg_debug_do( thrd->unpark_result = old_ticket; thrd->unpark_state = thrd->state; )
389	switch(old_ticket) {
390	case 1:
391	// Wake won the race, the thread will reschedule/rerun itself
392	break;
393	case 0:
394	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
395	/* paranoid */ verify( thrd->state == Blocked );
396
397	// Wake lost the race,
398	__schedule_thread( id, thrd );
399	break;
400	default:
401	// This makes no sense, something is wrong abort
402	abort();
403	}
404	}
405
406	void unpark( $thread * thrd __cfaabi_dbg_ctx_param2 ) {
407	if( !thrd ) return;
408
409	disable_interrupts();
410	__unpark( (__processor_id_t*)kernelTLS.this_processor, thrd __cfaabi_dbg_ctx_fwd2 );
411	enable_interrupts( __cfaabi_dbg_ctx );
412	}
413
414	void park( __cfaabi_dbg_ctx_param ) {
415	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
416	disable_interrupts();
417	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
418	/* paranoid */ verify( kernelTLS.this_thread->preempted == __NO_PREEMPTION );
419
420	// record activity
421	__cfaabi_dbg_record_thrd( *kernelTLS.this_thread, true, caller );
422
423	returnToKernel();
424
425	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
426	enable_interrupts( __cfaabi_dbg_ctx );
427	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
428
429	}
430
431	// KERNEL ONLY
432	void __leave_thread() {
433	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
434	returnToKernel();
435	abort();
436	}
437
438	// KERNEL ONLY
439	bool force_yield( __Preemption_Reason reason ) {
440	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
441	disable_interrupts();
442	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
443
444	$thread * thrd = kernelTLS.this_thread;
445	/* paranoid */ verify(thrd->state == Active);
446
447	// SKULLDUGGERY: It is possible that we are preempting this thread just before
448	// it was going to park itself. If that is the case and it is already using the
449	// intrusive fields then we can't use them to preempt the thread
450	// If that is the case, abandon the preemption.
451	bool preempted = false;
452	if(thrd->link.next == 0p) {
453	preempted = true;
454	thrd->preempted = reason;
455	returnToKernel();
456	}
457
458	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
459	enable_interrupts_noPoll();
460	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
461
462	return preempted;
463	}
464
465	//=============================================================================================
466	// Kernel Idle Sleep
467	//=============================================================================================
468	// Wake a thread from the front if there are any
469	static void __wake_one(struct __processor_id_t * id, cluster * this) {
470	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
471	/* paranoid */ verify( ready_schedule_islocked( id ) );
472
473	// Check if there is a sleeping processor
474	processor * p;
475	unsigned idle;
476	unsigned total;
477	[idle, total, p] = query(this->idles);
478
479	// If no one is sleeping, we are done
480	if( idle == 0 ) return;
481
482	// We found a processor, wake it up
483	post( p->idle );
484
485	#if !defined(__CFA_NO_STATISTICS__)
486	__tls_stats()->ready.sleep.wakes++;
487	#endif
488
489	/* paranoid */ verify( ready_schedule_islocked( id ) );
490	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
491
492	return;
493	}
494
495	// Unconditionnaly wake a thread
496	void __wake_proc(processor * this) {
497	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
498
499	disable_interrupts();
500	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
501	bool ret = post( this->idle );
502	enable_interrupts( __cfaabi_dbg_ctx );
503	}
504
505	static void push (__cluster_idles & this, processor & proc) {
506	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
507	lock( this );
508	this.idle++;
509	/* paranoid */ verify( this.idle <= this.total );
510
511	insert_first(this.list, proc);
512	unlock( this );
513	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
514	}
515
516	static void remove(__cluster_idles & this, processor & proc) {
517	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
518	lock( this );
519	this.idle--;
520	/* paranoid */ verify( this.idle >= 0 );
521
522	remove(proc);
523	unlock( this );
524	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
525	}
526
527	static [unsigned idle, unsigned total, * processor] query( & __cluster_idles this ) {
528	for() {
529	uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
530	if( 1 == (l % 2) ) { Pause(); continue; }
531	unsigned idle = this.idle;
532	unsigned total = this.total;
533	processor * proc = &this.list`first;
534	// Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
535	asm volatile("": : :"memory");
536	if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
537	return [idle, total, proc];
538	}
539	}
540
541	//=============================================================================================
542	// Unexpected Terminating logic
543	//=============================================================================================
544	static __spinlock_t kernel_abort_lock;
545	static bool kernel_abort_called = false;
546
547	void * kernel_abort(void) __attribute__ ((__nothrow__)) {
548	// abort cannot be recursively entered by the same or different processors because all signal handlers return when
549	// the globalAbort flag is true.
550	lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
551
552	// first task to abort ?
553	if ( kernel_abort_called ) { // not first task to abort ?
554	unlock( kernel_abort_lock );
555
556	sigset_t mask;
557	sigemptyset( &mask );
558	sigaddset( &mask, SIGALRM ); // block SIGALRM signals
559	sigaddset( &mask, SIGUSR1 ); // block SIGALRM signals
560	sigsuspend( &mask ); // block the processor to prevent further damage during abort
561	_exit( EXIT_FAILURE ); // if processor unblocks before it is killed, terminate it
562	}
563	else {
564	kernel_abort_called = true;
565	unlock( kernel_abort_lock );
566	}
567
568	return kernelTLS.this_thread;
569	}
570
571	void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
572	$thread * thrd = ( $thread * ) kernel_data;
573
574	if(thrd) {
575	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
576	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
577
578	if ( &thrd->self_cor != thrd->curr_cor ) {
579	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
580	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
581	}
582	else {
583	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
584	}
585	}
586	else {
587	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
588	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
589	}
590	}
591
592	int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
593	return get_coroutine(kernelTLS.this_thread) == get_coroutine(mainThread) ? 4 : 2;
594	}
595
596	static __spinlock_t kernel_debug_lock;
597
598	extern "C" {
599	void __cfaabi_bits_acquire() {
600	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
601	}
602
603	void __cfaabi_bits_release() {
604	unlock( kernel_debug_lock );
605	}
606	}
607
608	//=============================================================================================
609	// Kernel Utilities
610	//=============================================================================================
611	//-----------------------------------------------------------------------------
612	// Locks
613	void ?{}( semaphore & this, int count = 1 ) {
614	(this.lock){};
615	this.count = count;
616	(this.waiting){};
617	}
618	void ^?{}(semaphore & this) {}
619
620	bool P(semaphore & this) with( this ){
621	lock( lock __cfaabi_dbg_ctx2 );
622	count -= 1;
623	if ( count < 0 ) {
624	// queue current task
625	append( waiting, kernelTLS.this_thread );
626
627	// atomically release spin lock and block
628	unlock( lock );
629	park( __cfaabi_dbg_ctx );
630	return true;
631	}
632	else {
633	unlock( lock );
634	return false;
635	}
636	}
637
638	bool V(semaphore & this) with( this ) {
639	$thread * thrd = 0p;
640	lock( lock __cfaabi_dbg_ctx2 );
641	count += 1;
642	if ( count <= 0 ) {
643	// remove task at head of waiting list
644	thrd = pop_head( waiting );
645	}
646
647	unlock( lock );
648
649	// make new owner
650	unpark( thrd __cfaabi_dbg_ctx2 );
651
652	return thrd != 0p;
653	}
654
655	bool V(semaphore & this, unsigned diff) with( this ) {
656	$thread * thrd = 0p;
657	lock( lock __cfaabi_dbg_ctx2 );
658	int release = max(-count, (int)diff);
659	count += diff;
660	for(release) {
661	unpark( pop_head( waiting ) __cfaabi_dbg_ctx2 );
662	}
663
664	unlock( lock );
665
666	return thrd != 0p;
667	}
668
669	//-----------------------------------------------------------------------------
670	// Debug
671	__cfaabi_dbg_debug_do(
672	extern "C" {
673	void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
674	this.prev_name = prev_name;
675	this.prev_thrd = kernelTLS.this_thread;
676	}
677
678	void __cfaabi_dbg_record_thrd($thread & this, bool park, const char prev_name[]) {
679	if(park) {
680	this.park_caller = prev_name;
681	this.park_stale = false;
682	}
683	else {
684	this.unpark_caller = prev_name;
685	this.unpark_stale = false;
686	}
687	}
688	}
689	)
690
691	//-----------------------------------------------------------------------------
692	// Debug
693	bool threading_enabled(void) __attribute__((const)) {
694	return true;
695	}
696
697	//-----------------------------------------------------------------------------
698	// Statistics
699	#if !defined(__CFA_NO_STATISTICS__)
700	void print_halts( processor & this ) {
701	this.print_halts = true;
702	}
703	#endif
704	// Local Variables: //
705	// mode: c //
706	// tab-width: 4 //
707	// End: //

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