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kernel.cfa @ b7fe2e6

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

Last change on this file since b7fe2e6 was e67a82d, checked in by Peter A. Buhr <pabuhr@…>, 4 years ago
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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 : Fri Aug 14 15:23:00 2020
13	// Update Count : 69
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	#elif defined( __ARM_ARCH )
77	#define __x87_store \
78	uint32_t __fpcntl[2]; \
79	__asm__ volatile ( \
80	"mrs x9, FPCR\n" \
81	"mrs x10, FPSR\n" \
82	"stp x9, x10, %0\n" \
83	: "=m" (__fpcntl) : : "x9", "x10" \
84	)
85
86	#define __x87_load \
87	__asm__ volatile ( \
88	"ldp x9, x10, %0\n" \
89	"msr FPSR, x10\n" \
90	"msr FPCR, x9\n" \
91	: "=m" (__fpcntl) : : "x9", "x10" \
92	)
93
94	#else
95	#error unknown hardware architecture
96	#endif
97
98	extern $thread * mainThread;
99	extern processor * mainProcessor;
100
101	//-----------------------------------------------------------------------------
102	// Kernel Scheduling logic
103	static $thread * __next_thread(cluster * this);
104	static $thread * __next_thread_slow(cluster * this);
105	static void __run_thread(processor * this, $thread * dst);
106	static void __wake_one(struct __processor_id_t * id, cluster * cltr);
107
108	static void push (__cluster_idles & idles, processor & proc);
109	static void remove(__cluster_idles & idles, processor & proc);
110	static [unsigned idle, unsigned total, * processor] query( & __cluster_idles idles );
111
112
113	//=============================================================================================
114	// Kernel Scheduling logic
115	//=============================================================================================
116	//Main of the processor contexts
117	void main(processorCtx_t & runner) {
118	// Because of a bug, we couldn't initialized the seed on construction
119	// Do it here
120	kernelTLS.rand_seed ^= rdtscl();
121	kernelTLS.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
122	__tls_rand_advance_bck();
123
124	processor * this = runner.proc;
125	verify(this);
126
127	__cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
128	#if !defined(__CFA_NO_STATISTICS__)
129	if( this->print_halts ) {
130	__cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->id, this->name, (void*)this);
131	}
132	#endif
133
134	{
135	// Setup preemption data
136	preemption_scope scope = { this };
137
138	__cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
139
140	$thread * readyThread = 0p;
141	MAIN_LOOP:
142	for() {
143	// Try to get the next thread
144	readyThread = __next_thread( this->cltr );
145
146	if( !readyThread ) {
147	readyThread = __next_thread_slow( this->cltr );
148	}
149
150	HALT:
151	if( !readyThread ) {
152	// Don't block if we are done
153	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
154
155	#if !defined(__CFA_NO_STATISTICS__)
156	__tls_stats()->ready.sleep.halts++;
157	#endif
158
159	// Push self to idle stack
160	push(this->cltr->idles, * this);
161
162	// Confirm the ready-queue is empty
163	readyThread = __next_thread_slow( this->cltr );
164	if( readyThread ) {
165	// A thread was found, cancel the halt
166	remove(this->cltr->idles, * this);
167
168	#if !defined(__CFA_NO_STATISTICS__)
169	__tls_stats()->ready.sleep.cancels++;
170	#endif
171
172	// continue the mai loop
173	break HALT;
174	}
175
176	#if !defined(__CFA_NO_STATISTICS__)
177	if(this->print_halts) {
178	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->id, rdtscl());
179	}
180	#endif
181
182	wait( this->idle );
183
184	#if !defined(__CFA_NO_STATISTICS__)
185	if(this->print_halts) {
186	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->id, rdtscl());
187	}
188	#endif
189
190	// We were woken up, remove self from idle
191	remove(this->cltr->idles, * this);
192
193	// DON'T just proceed, start looking again
194	continue MAIN_LOOP;
195	}
196
197	/* paranoid */ verify( readyThread );
198
199	// We found a thread run it
200	__run_thread(this, readyThread);
201
202	// Are we done?
203	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
204	}
205
206	__cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
207	}
208
209	V( this->terminated );
210
211	if(this == mainProcessor) {
212	// HACK : the coroutine context switch expects this_thread to be set
213	// and it make sense for it to be set in all other cases except here
214	// fake it
215	kernelTLS.this_thread = mainThread;
216	}
217
218	__cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
219	}
220
221	static int * __volatile_errno() __attribute__((noinline));
222	static int * __volatile_errno() { asm(""); return &errno; }
223
224	// KERNEL ONLY
225	// runThread runs a thread by context switching
226	// from the processor coroutine to the target thread
227	static void __run_thread(processor * this, $thread * thrd_dst) {
228	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
229	/* paranoid */ verifyf( thrd_dst->state == Ready \|\| thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
230	/* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
231	__builtin_prefetch( thrd_dst->context.SP );
232
233	$coroutine * proc_cor = get_coroutine(this->runner);
234
235	// Update global state
236	kernelTLS.this_thread = thrd_dst;
237
238	// set state of processor coroutine to inactive
239	verify(proc_cor->state == Active);
240	proc_cor->state = Blocked;
241
242	// Actually run the thread
243	RUNNING: while(true) {
244	thrd_dst->preempted = __NO_PREEMPTION;
245	thrd_dst->state = Active;
246
247	__cfaabi_dbg_debug_do(
248	thrd_dst->park_stale = true;
249	thrd_dst->unpark_stale = true;
250	)
251
252	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
253	/* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
254	/* 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
255	/* 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
256
257	// set context switch to the thread that the processor is executing
258	verify( thrd_dst->context.SP );
259	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
260	// when __cfactx_switch returns we are back in the processor coroutine
261
262	/* 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 );
263	/* 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 );
264	/* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
265	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
266
267
268	// We just finished running a thread, there are a few things that could have happened.
269	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
270	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
271	// 4 - Preempted
272	// In case 1, we may have won a race so we can't write to the state again.
273	// In case 2, we lost the race so we now own the thread.
274
275	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
276	// The thread was preempted, reschedule it and reset the flag
277	__schedule_thread( (__processor_id_t*)this, thrd_dst );
278	break RUNNING;
279	}
280
281	if(unlikely(thrd_dst->state == Halted)) {
282	// The thread has halted, it should never be scheduled/run again
283	// We may need to wake someone up here since
284	unpark( this->destroyer __cfaabi_dbg_ctx2 );
285	this->destroyer = 0p;
286	break RUNNING;
287	}
288
289	/* paranoid */ verify( thrd_dst->state == Active );
290	thrd_dst->state = Blocked;
291
292	// set state of processor coroutine to active and the thread to inactive
293	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
294	__cfaabi_dbg_debug_do( thrd_dst->park_result = old_ticket; )
295	switch(old_ticket) {
296	case 1:
297	// This is case 1, the regular case, nothing more is needed
298	break RUNNING;
299	case 2:
300	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
301	// In this case, just run it again.
302	continue RUNNING;
303	default:
304	// This makes no sense, something is wrong abort
305	abort();
306	}
307	}
308
309	// Just before returning to the processor, set the processor coroutine to active
310	proc_cor->state = Active;
311	kernelTLS.this_thread = 0p;
312
313	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
314	}
315
316	// KERNEL_ONLY
317	void returnToKernel() {
318	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
319	$coroutine * proc_cor = get_coroutine(kernelTLS.this_processor->runner);
320	$thread * thrd_src = kernelTLS.this_thread;
321
322	#if !defined(__CFA_NO_STATISTICS__)
323	struct processor * last_proc = kernelTLS.this_processor;
324	#endif
325
326	// Run the thread on this processor
327	{
328	int local_errno = *__volatile_errno();
329	#if defined( __i386 ) \|\| defined( __x86_64 )
330	__x87_store;
331	#endif
332	verify( proc_cor->context.SP );
333	__cfactx_switch( &thrd_src->context, &proc_cor->context );
334	#if defined( __i386 ) \|\| defined( __x86_64 )
335	__x87_load;
336	#endif
337	*__volatile_errno() = local_errno;
338	}
339
340	#if !defined(__CFA_NO_STATISTICS__)
341	if(last_proc != kernelTLS.this_processor) {
342	__tls_stats()->ready.threads.migration++;
343	}
344	#endif
345
346	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
347	/* 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 );
348	/* 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 );
349	}
350
351	//-----------------------------------------------------------------------------
352	// Scheduler routines
353	// KERNEL ONLY
354	void __schedule_thread( struct __processor_id_t * id, $thread * thrd ) {
355	/* paranoid */ verify( thrd );
356	/* paranoid */ verify( thrd->state != Halted );
357	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
358	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
359	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
360	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
361	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
362	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
363	/* paranoid */ #endif
364	/* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
365
366	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
367
368	ready_schedule_lock ( id );
369	push( thrd->curr_cluster, thrd );
370	__wake_one(id, thrd->curr_cluster);
371	ready_schedule_unlock( id );
372
373	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
374	}
375
376	// KERNEL ONLY
377	static inline $thread * __next_thread(cluster * this) with( *this ) {
378	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
379
380	ready_schedule_lock ( (__processor_id_t*)kernelTLS.this_processor );
381	$thread * thrd = pop( this );
382	ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
383
384	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
385	return thrd;
386	}
387
388	// KERNEL ONLY
389	static inline $thread * __next_thread_slow(cluster * this) with( *this ) {
390	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
391
392	ready_schedule_lock ( (__processor_id_t*)kernelTLS.this_processor );
393	$thread * thrd = pop_slow( this );
394	ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
395
396	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
397	return thrd;
398	}
399
400	// KERNEL ONLY unpark with out disabling interrupts
401	void __unpark( struct __processor_id_t * id, $thread * thrd __cfaabi_dbg_ctx_param2 ) {
402	// record activity
403	__cfaabi_dbg_record_thrd( *thrd, false, caller );
404
405	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
406	__cfaabi_dbg_debug_do( thrd->unpark_result = old_ticket; thrd->unpark_state = thrd->state; )
407	switch(old_ticket) {
408	case 1:
409	// Wake won the race, the thread will reschedule/rerun itself
410	break;
411	case 0:
412	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
413	/* paranoid */ verify( thrd->state == Blocked );
414
415	// Wake lost the race,
416	__schedule_thread( id, thrd );
417	break;
418	default:
419	// This makes no sense, something is wrong abort
420	abort();
421	}
422	}
423
424	void unpark( $thread * thrd __cfaabi_dbg_ctx_param2 ) {
425	if( !thrd ) return;
426
427	disable_interrupts();
428	__unpark( (__processor_id_t*)kernelTLS.this_processor, thrd __cfaabi_dbg_ctx_fwd2 );
429	enable_interrupts( __cfaabi_dbg_ctx );
430	}
431
432	void park( __cfaabi_dbg_ctx_param ) {
433	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
434	disable_interrupts();
435	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
436	/* paranoid */ verify( kernelTLS.this_thread->preempted == __NO_PREEMPTION );
437
438	// record activity
439	__cfaabi_dbg_record_thrd( *kernelTLS.this_thread, true, caller );
440
441	returnToKernel();
442
443	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
444	enable_interrupts( __cfaabi_dbg_ctx );
445	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
446
447	}
448
449	// KERNEL ONLY
450	void __leave_thread() {
451	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
452	returnToKernel();
453	abort();
454	}
455
456	// KERNEL ONLY
457	bool force_yield( __Preemption_Reason reason ) {
458	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
459	disable_interrupts();
460	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
461
462	$thread * thrd = kernelTLS.this_thread;
463	/* paranoid */ verify(thrd->state == Active);
464
465	// SKULLDUGGERY: It is possible that we are preempting this thread just before
466	// it was going to park itself. If that is the case and it is already using the
467	// intrusive fields then we can't use them to preempt the thread
468	// If that is the case, abandon the preemption.
469	bool preempted = false;
470	if(thrd->link.next == 0p) {
471	preempted = true;
472	thrd->preempted = reason;
473	returnToKernel();
474	}
475
476	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
477	enable_interrupts_noPoll();
478	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
479
480	return preempted;
481	}
482
483	//=============================================================================================
484	// Kernel Idle Sleep
485	//=============================================================================================
486	// Wake a thread from the front if there are any
487	static void __wake_one(struct __processor_id_t * id, cluster * this) {
488	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
489	/* paranoid */ verify( ready_schedule_islocked( id ) );
490
491	// Check if there is a sleeping processor
492	processor * p;
493	unsigned idle;
494	unsigned total;
495	[idle, total, p] = query(this->idles);
496
497	// If no one is sleeping, we are done
498	if( idle == 0 ) return;
499
500	// We found a processor, wake it up
501	post( p->idle );
502
503	#if !defined(__CFA_NO_STATISTICS__)
504	__tls_stats()->ready.sleep.wakes++;
505	#endif
506
507	/* paranoid */ verify( ready_schedule_islocked( id ) );
508	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
509
510	return;
511	}
512
513	// Unconditionnaly wake a thread
514	void __wake_proc(processor * this) {
515	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
516
517	disable_interrupts();
518	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
519	bool ret = post( this->idle );
520	enable_interrupts( __cfaabi_dbg_ctx );
521	}
522
523	static void push (__cluster_idles & this, processor & proc) {
524	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
525	lock( this );
526	this.idle++;
527	/* paranoid */ verify( this.idle <= this.total );
528
529	insert_first(this.list, proc);
530	unlock( this );
531	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
532	}
533
534	static void remove(__cluster_idles & this, processor & proc) {
535	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
536	lock( this );
537	this.idle--;
538	/* paranoid */ verify( this.idle >= 0 );
539
540	remove(proc);
541	unlock( this );
542	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
543	}
544
545	static [unsigned idle, unsigned total, * processor] query( & __cluster_idles this ) {
546	for() {
547	uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
548	if( 1 == (l % 2) ) { Pause(); continue; }
549	unsigned idle = this.idle;
550	unsigned total = this.total;
551	processor * proc = &this.list`first;
552	// Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
553	asm volatile("": : :"memory");
554	if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
555	return [idle, total, proc];
556	}
557	}
558
559	//=============================================================================================
560	// Unexpected Terminating logic
561	//=============================================================================================
562	static __spinlock_t kernel_abort_lock;
563	static bool kernel_abort_called = false;
564
565	void * kernel_abort(void) __attribute__ ((__nothrow__)) {
566	// abort cannot be recursively entered by the same or different processors because all signal handlers return when
567	// the globalAbort flag is true.
568	lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
569
570	// first task to abort ?
571	if ( kernel_abort_called ) { // not first task to abort ?
572	unlock( kernel_abort_lock );
573
574	sigset_t mask;
575	sigemptyset( &mask );
576	sigaddset( &mask, SIGALRM ); // block SIGALRM signals
577	sigaddset( &mask, SIGUSR1 ); // block SIGALRM signals
578	sigsuspend( &mask ); // block the processor to prevent further damage during abort
579	_exit( EXIT_FAILURE ); // if processor unblocks before it is killed, terminate it
580	}
581	else {
582	kernel_abort_called = true;
583	unlock( kernel_abort_lock );
584	}
585
586	return kernelTLS.this_thread;
587	}
588
589	void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
590	$thread * thrd = ( $thread * ) kernel_data;
591
592	if(thrd) {
593	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
594	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
595
596	if ( &thrd->self_cor != thrd->curr_cor ) {
597	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
598	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
599	}
600	else {
601	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
602	}
603	}
604	else {
605	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
606	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
607	}
608	}
609
610	int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
611	return get_coroutine(kernelTLS.this_thread) == get_coroutine(mainThread) ? 4 : 2;
612	}
613
614	static __spinlock_t kernel_debug_lock;
615
616	extern "C" {
617	void __cfaabi_bits_acquire() {
618	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
619	}
620
621	void __cfaabi_bits_release() {
622	unlock( kernel_debug_lock );
623	}
624	}
625
626	//=============================================================================================
627	// Kernel Utilities
628	//=============================================================================================
629	//-----------------------------------------------------------------------------
630	// Locks
631	void ?{}( semaphore & this, int count = 1 ) {
632	(this.lock){};
633	this.count = count;
634	(this.waiting){};
635	}
636	void ^?{}(semaphore & this) {}
637
638	bool P(semaphore & this) with( this ){
639	lock( lock __cfaabi_dbg_ctx2 );
640	count -= 1;
641	if ( count < 0 ) {
642	// queue current task
643	append( waiting, kernelTLS.this_thread );
644
645	// atomically release spin lock and block
646	unlock( lock );
647	park( __cfaabi_dbg_ctx );
648	return true;
649	}
650	else {
651	unlock( lock );
652	return false;
653	}
654	}
655
656	bool V(semaphore & this) with( this ) {
657	$thread * thrd = 0p;
658	lock( lock __cfaabi_dbg_ctx2 );
659	count += 1;
660	if ( count <= 0 ) {
661	// remove task at head of waiting list
662	thrd = pop_head( waiting );
663	}
664
665	unlock( lock );
666
667	// make new owner
668	unpark( thrd __cfaabi_dbg_ctx2 );
669
670	return thrd != 0p;
671	}
672
673	bool V(semaphore & this, unsigned diff) with( this ) {
674	$thread * thrd = 0p;
675	lock( lock __cfaabi_dbg_ctx2 );
676	int release = max(-count, (int)diff);
677	count += diff;
678	for(release) {
679	unpark( pop_head( waiting ) __cfaabi_dbg_ctx2 );
680	}
681
682	unlock( lock );
683
684	return thrd != 0p;
685	}
686
687	//-----------------------------------------------------------------------------
688	// Debug
689	__cfaabi_dbg_debug_do(
690	extern "C" {
691	void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
692	this.prev_name = prev_name;
693	this.prev_thrd = kernelTLS.this_thread;
694	}
695
696	void __cfaabi_dbg_record_thrd($thread & this, bool park, const char prev_name[]) {
697	if(park) {
698	this.park_caller = prev_name;
699	this.park_stale = false;
700	}
701	else {
702	this.unpark_caller = prev_name;
703	this.unpark_stale = false;
704	}
705	}
706	}
707	)
708
709	//-----------------------------------------------------------------------------
710	// Debug
711	bool threading_enabled(void) __attribute__((const)) {
712	return true;
713	}
714
715	//-----------------------------------------------------------------------------
716	// Statistics
717	#if !defined(__CFA_NO_STATISTICS__)
718	void print_halts( processor & this ) {
719	this.print_halts = true;
720	}
721	#endif
722	// Local Variables: //
723	// mode: c //
724	// tab-width: 4 //
725	// End: //

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