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ADT arm-eh ast-experimental enum forall-pointer-decay jacob/cs343-translation new-ast-unique-expr pthread-emulation qualifiedEnum

Last change on this file since 5d2db68 was 5afb49a, checked in by Thierry Delisle <tdelisle@…>, 5 years ago
Split thread_leave so backend is called from the kernel once the kernel no longer needs the thread. This hopefully solves the non-deterministic crashes in the build.
Property mode set to `100644`
File size: 22.7 KB

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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 : Mon Aug 31 07:08:20 2020
13	// Update Count : 71
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__ )
77	#define __x87_store
78	#define __x87_load
79
80	#elif defined( __aarch64__ )
81	#define __x87_store \
82	uint32_t __fpcntl[2]; \
83	__asm__ volatile ( \
84	"mrs x9, FPCR\n" \
85	"mrs x10, FPSR\n" \
86	"stp x9, x10, %0\n" \
87	: "=m" (__fpcntl) : : "x9", "x10" \
88	)
89
90	#define __x87_load \
91	__asm__ volatile ( \
92	"ldp x9, x10, %0\n" \
93	"msr FPSR, x10\n" \
94	"msr FPCR, x9\n" \
95	: "=m" (__fpcntl) : : "x9", "x10" \
96	)
97
98	#else
99	#error unsupported hardware architecture
100	#endif
101
102	extern $thread * mainThread;
103	extern processor * mainProcessor;
104
105	//-----------------------------------------------------------------------------
106	// Kernel Scheduling logic
107	static $thread * __next_thread(cluster * this);
108	static $thread * __next_thread_slow(cluster * this);
109	static void __run_thread(processor * this, $thread * dst);
110	static void __wake_one(struct __processor_id_t * id, cluster * cltr);
111
112	static void push (__cluster_idles & idles, processor & proc);
113	static void remove(__cluster_idles & idles, processor & proc);
114	static [unsigned idle, unsigned total, * processor] query( & __cluster_idles idles );
115
116
117	//=============================================================================================
118	// Kernel Scheduling logic
119	//=============================================================================================
120	//Main of the processor contexts
121	void main(processorCtx_t & runner) {
122	// Because of a bug, we couldn't initialized the seed on construction
123	// Do it here
124	kernelTLS.rand_seed ^= rdtscl();
125	kernelTLS.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
126	__tls_rand_advance_bck();
127
128	processor * this = runner.proc;
129	verify(this);
130
131	__cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
132	#if !defined(__CFA_NO_STATISTICS__)
133	if( this->print_halts ) {
134	__cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->id, this->name, (void*)this);
135	}
136	#endif
137
138	{
139	// Setup preemption data
140	preemption_scope scope = { this };
141
142	__cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
143
144	$thread * readyThread = 0p;
145	MAIN_LOOP:
146	for() {
147	// Try to get the next thread
148	readyThread = __next_thread( this->cltr );
149
150	if( !readyThread ) {
151	readyThread = __next_thread_slow( this->cltr );
152	}
153
154	HALT:
155	if( !readyThread ) {
156	// Don't block if we are done
157	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
158
159	#if !defined(__CFA_NO_STATISTICS__)
160	__tls_stats()->ready.sleep.halts++;
161	#endif
162
163	// Push self to idle stack
164	push(this->cltr->idles, * this);
165
166	// Confirm the ready-queue is empty
167	readyThread = __next_thread_slow( this->cltr );
168	if( readyThread ) {
169	// A thread was found, cancel the halt
170	remove(this->cltr->idles, * this);
171
172	#if !defined(__CFA_NO_STATISTICS__)
173	__tls_stats()->ready.sleep.cancels++;
174	#endif
175
176	// continue the mai loop
177	break HALT;
178	}
179
180	#if !defined(__CFA_NO_STATISTICS__)
181	if(this->print_halts) {
182	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->id, rdtscl());
183	}
184	#endif
185
186	wait( this->idle );
187
188	#if !defined(__CFA_NO_STATISTICS__)
189	if(this->print_halts) {
190	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->id, rdtscl());
191	}
192	#endif
193
194	// We were woken up, remove self from idle
195	remove(this->cltr->idles, * this);
196
197	// DON'T just proceed, start looking again
198	continue MAIN_LOOP;
199	}
200
201	/* paranoid */ verify( readyThread );
202
203	// We found a thread run it
204	__run_thread(this, readyThread);
205
206	// Are we done?
207	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
208	}
209
210	__cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
211	}
212
213	V( this->terminated );
214
215	if(this == mainProcessor) {
216	// HACK : the coroutine context switch expects this_thread to be set
217	// and it make sense for it to be set in all other cases except here
218	// fake it
219	kernelTLS.this_thread = mainThread;
220	}
221
222	__cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
223	}
224
225	static int * __volatile_errno() __attribute__((noinline));
226	static int * __volatile_errno() { asm(""); return &errno; }
227
228	// KERNEL ONLY
229	// runThread runs a thread by context switching
230	// from the processor coroutine to the target thread
231	static void __run_thread(processor * this, $thread * thrd_dst) {
232	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
233	/* paranoid */ verifyf( thrd_dst->state == Ready \|\| thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
234	/* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
235	__builtin_prefetch( thrd_dst->context.SP );
236
237	$coroutine * proc_cor = get_coroutine(this->runner);
238
239	// set state of processor coroutine to inactive
240	verify(proc_cor->state == Active);
241	proc_cor->state = Blocked;
242
243	// Actually run the thread
244	RUNNING: while(true) {
245	thrd_dst->preempted = __NO_PREEMPTION;
246	thrd_dst->state = Active;
247
248	// Update global state
249	kernelTLS.this_thread = thrd_dst;
250
251	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
252	/* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
253	/* paranoid */ verify( thrd_dst->context.SP );
254	/* paranoid */ verify( thrd_dst->state != Halted );
255	/* 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
256	/* 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
257	/* paranoid */ verify( 0x0D15EA5E0D15EA5E == thrd_dst->canary );
258
259
260
261	// set context switch to the thread that the processor is executing
262	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
263	// when __cfactx_switch returns we are back in the processor coroutine
264
265	/* paranoid */ verify( 0x0D15EA5E0D15EA5E == thrd_dst->canary );
266	/* 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 );
267	/* 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 );
268	/* paranoid */ verify( thrd_dst->context.SP );
269	/* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
270	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
271
272	// Reset global state
273	kernelTLS.this_thread = 0p;
274
275	// We just finished running a thread, there are a few things that could have happened.
276	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
277	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
278	// 4 - Preempted
279	// In case 1, we may have won a race so we can't write to the state again.
280	// In case 2, we lost the race so we now own the thread.
281
282	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
283	// The thread was preempted, reschedule it and reset the flag
284	__schedule_thread( (__processor_id_t*)this, thrd_dst );
285	break RUNNING;
286	}
287
288	if(unlikely(thrd_dst->state == Halted)) {
289	// The thread has halted, it should never be scheduled/run again
290	// finish the thread
291	__thread_finish( thrd_dst );
292	break RUNNING;
293	}
294
295	/* paranoid */ verify( thrd_dst->state == Active );
296	thrd_dst->state = Blocked;
297
298	// set state of processor coroutine to active and the thread to inactive
299	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
300	switch(old_ticket) {
301	case 1:
302	// This is case 1, the regular case, nothing more is needed
303	break RUNNING;
304	case 2:
305	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
306	// In this case, just run it again.
307	continue RUNNING;
308	default:
309	// This makes no sense, something is wrong abort
310	abort();
311	}
312	}
313
314	// Just before returning to the processor, set the processor coroutine to active
315	proc_cor->state = Active;
316
317	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
318	}
319
320	// KERNEL_ONLY
321	void returnToKernel() {
322	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
323	$coroutine * proc_cor = get_coroutine(kernelTLS.this_processor->runner);
324	$thread * thrd_src = kernelTLS.this_thread;
325
326	#if !defined(__CFA_NO_STATISTICS__)
327	struct processor * last_proc = kernelTLS.this_processor;
328	#endif
329
330	// Run the thread on this processor
331	{
332	int local_errno = *__volatile_errno();
333	#if defined( __i386 ) \|\| defined( __x86_64 )
334	__x87_store;
335	#endif
336	/* paranoid */ verify( proc_cor->context.SP );
337	/* paranoid */ verify( 0x0D15EA5E0D15EA5E == thrd_src->canary );
338	__cfactx_switch( &thrd_src->context, &proc_cor->context );
339	/* paranoid */ verify( 0x0D15EA5E0D15EA5E == thrd_src->canary );
340	#if defined( __i386 ) \|\| defined( __x86_64 )
341	__x87_load;
342	#endif
343	*__volatile_errno() = local_errno;
344	}
345
346	#if !defined(__CFA_NO_STATISTICS__)
347	if(last_proc != kernelTLS.this_processor) {
348	__tls_stats()->ready.threads.migration++;
349	}
350	#endif
351
352	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
353	/* 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 );
354	/* 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 );
355	}
356
357	//-----------------------------------------------------------------------------
358	// Scheduler routines
359	// KERNEL ONLY
360	void __schedule_thread( struct __processor_id_t * id, $thread * thrd ) {
361	/* paranoid */ verify( thrd );
362	/* paranoid */ verify( thrd->state != Halted );
363	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
364	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
365	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
366	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
367	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
368	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
369	/* paranoid */ #endif
370	/* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
371	/* paranoid */ verify( 0x0D15EA5E0D15EA5E == thrd->canary );
372
373
374	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
375
376	ready_schedule_lock ( id );
377	push( thrd->curr_cluster, thrd );
378	__wake_one(id, thrd->curr_cluster);
379	ready_schedule_unlock( id );
380
381	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
382	}
383
384	// KERNEL ONLY
385	static inline $thread * __next_thread(cluster * this) with( *this ) {
386	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
387
388	ready_schedule_lock ( (__processor_id_t*)kernelTLS.this_processor );
389	$thread * thrd = pop( this );
390	ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
391
392	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
393	return thrd;
394	}
395
396	// KERNEL ONLY
397	static inline $thread * __next_thread_slow(cluster * this) with( *this ) {
398	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
399
400	ready_schedule_lock ( (__processor_id_t*)kernelTLS.this_processor );
401	$thread * thrd = pop_slow( this );
402	ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
403
404	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
405	return thrd;
406	}
407
408	// KERNEL ONLY unpark with out disabling interrupts
409	void __unpark( struct __processor_id_t * id, $thread * thrd ) {
410	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
411	switch(old_ticket) {
412	case 1:
413	// Wake won the race, the thread will reschedule/rerun itself
414	break;
415	case 0:
416	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
417	/* paranoid */ verify( thrd->state == Blocked );
418
419	// Wake lost the race,
420	__schedule_thread( id, thrd );
421	break;
422	default:
423	// This makes no sense, something is wrong abort
424	abort();
425	}
426	}
427
428	void unpark( $thread * thrd ) {
429	if( !thrd ) return;
430
431	disable_interrupts();
432	__unpark( (__processor_id_t*)kernelTLS.this_processor, thrd );
433	enable_interrupts( __cfaabi_dbg_ctx );
434	}
435
436	void park( void ) {
437	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
438	disable_interrupts();
439	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
440	/* paranoid */ verify( kernelTLS.this_thread->preempted == __NO_PREEMPTION );
441
442	returnToKernel();
443
444	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
445	enable_interrupts( __cfaabi_dbg_ctx );
446	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
447
448	}
449
450	extern "C" {
451	// Leave the thread monitor
452	// last routine called by a thread.
453	// Should never return
454	void __cfactx_thrd_leave() {
455	$thread * thrd = TL_GET( this_thread );
456	$monitor * this = &thrd->self_mon;
457
458	// Lock the monitor now
459	lock( this->lock __cfaabi_dbg_ctx2 );
460
461	disable_interrupts();
462
463	thrd->state = Halted;
464
465	if( thrd != this->owner \|\| this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
466
467	// Leave the thread
468	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
469	returnToKernel();
470	abort();
471
472	// Control flow should never reach here!
473	}
474	}
475
476	// KERNEL ONLY
477	bool force_yield( __Preemption_Reason reason ) {
478	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
479	disable_interrupts();
480	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
481
482	$thread * thrd = kernelTLS.this_thread;
483	/* paranoid */ verify(thrd->state == Active);
484
485	// SKULLDUGGERY: It is possible that we are preempting this thread just before
486	// it was going to park itself. If that is the case and it is already using the
487	// intrusive fields then we can't use them to preempt the thread
488	// If that is the case, abandon the preemption.
489	bool preempted = false;
490	if(thrd->link.next == 0p) {
491	preempted = true;
492	thrd->preempted = reason;
493	returnToKernel();
494	}
495
496	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
497	enable_interrupts_noPoll();
498	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
499
500	return preempted;
501	}
502
503	//=============================================================================================
504	// Kernel Idle Sleep
505	//=============================================================================================
506	// Wake a thread from the front if there are any
507	static void __wake_one(struct __processor_id_t * id, cluster * this) {
508	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
509	/* paranoid */ verify( ready_schedule_islocked( id ) );
510
511	// Check if there is a sleeping processor
512	processor * p;
513	unsigned idle;
514	unsigned total;
515	[idle, total, p] = query(this->idles);
516
517	// If no one is sleeping, we are done
518	if( idle == 0 ) return;
519
520	// We found a processor, wake it up
521	post( p->idle );
522
523	#if !defined(__CFA_NO_STATISTICS__)
524	__tls_stats()->ready.sleep.wakes++;
525	#endif
526
527	/* paranoid */ verify( ready_schedule_islocked( id ) );
528	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
529
530	return;
531	}
532
533	// Unconditionnaly wake a thread
534	void __wake_proc(processor * this) {
535	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
536
537	disable_interrupts();
538	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
539	post( this->idle );
540	enable_interrupts( __cfaabi_dbg_ctx );
541	}
542
543	static void push (__cluster_idles & this, processor & proc) {
544	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
545	lock( this );
546	this.idle++;
547	/* paranoid */ verify( this.idle <= this.total );
548
549	insert_first(this.list, proc);
550	unlock( this );
551	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
552	}
553
554	static void remove(__cluster_idles & this, processor & proc) {
555	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
556	lock( this );
557	this.idle--;
558	/* paranoid */ verify( this.idle >= 0 );
559
560	remove(proc);
561	unlock( this );
562	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
563	}
564
565	static [unsigned idle, unsigned total, * processor] query( & __cluster_idles this ) {
566	for() {
567	uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
568	if( 1 == (l % 2) ) { Pause(); continue; }
569	unsigned idle = this.idle;
570	unsigned total = this.total;
571	processor * proc = &this.list`first;
572	// Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
573	asm volatile("": : :"memory");
574	if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
575	return [idle, total, proc];
576	}
577	}
578
579	//=============================================================================================
580	// Unexpected Terminating logic
581	//=============================================================================================
582	static __spinlock_t kernel_abort_lock;
583	static bool kernel_abort_called = false;
584
585	void * kernel_abort(void) __attribute__ ((__nothrow__)) {
586	// abort cannot be recursively entered by the same or different processors because all signal handlers return when
587	// the globalAbort flag is true.
588	lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
589
590	// first task to abort ?
591	if ( kernel_abort_called ) { // not first task to abort ?
592	unlock( kernel_abort_lock );
593
594	sigset_t mask;
595	sigemptyset( &mask );
596	sigaddset( &mask, SIGALRM ); // block SIGALRM signals
597	sigaddset( &mask, SIGUSR1 ); // block SIGALRM signals
598	sigsuspend( &mask ); // block the processor to prevent further damage during abort
599	_exit( EXIT_FAILURE ); // if processor unblocks before it is killed, terminate it
600	}
601	else {
602	kernel_abort_called = true;
603	unlock( kernel_abort_lock );
604	}
605
606	return kernelTLS.this_thread;
607	}
608
609	void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
610	$thread * thrd = ( $thread * ) kernel_data;
611
612	if(thrd) {
613	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
614	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
615
616	if ( &thrd->self_cor != thrd->curr_cor ) {
617	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
618	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
619	}
620	else {
621	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
622	}
623	}
624	else {
625	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
626	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
627	}
628	}
629
630	int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
631	return get_coroutine(kernelTLS.this_thread) == get_coroutine(mainThread) ? 4 : 2;
632	}
633
634	static __spinlock_t kernel_debug_lock;
635
636	extern "C" {
637	void __cfaabi_bits_acquire() {
638	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
639	}
640
641	void __cfaabi_bits_release() {
642	unlock( kernel_debug_lock );
643	}
644	}
645
646	//=============================================================================================
647	// Kernel Utilities
648	//=============================================================================================
649	//-----------------------------------------------------------------------------
650	// Locks
651	void ?{}( semaphore & this, int count = 1 ) {
652	(this.lock){};
653	this.count = count;
654	(this.waiting){};
655	}
656	void ^?{}(semaphore & this) {}
657
658	bool P(semaphore & this) with( this ){
659	lock( lock __cfaabi_dbg_ctx2 );
660	count -= 1;
661	if ( count < 0 ) {
662	// queue current task
663	append( waiting, kernelTLS.this_thread );
664
665	// atomically release spin lock and block
666	unlock( lock );
667	park();
668	return true;
669	}
670	else {
671	unlock( lock );
672	return false;
673	}
674	}
675
676	bool V(semaphore & this) with( this ) {
677	$thread * thrd = 0p;
678	lock( lock __cfaabi_dbg_ctx2 );
679	count += 1;
680	if ( count <= 0 ) {
681	// remove task at head of waiting list
682	thrd = pop_head( waiting );
683	}
684
685	unlock( lock );
686
687	// make new owner
688	unpark( thrd );
689
690	return thrd != 0p;
691	}
692
693	bool V(semaphore & this, unsigned diff) with( this ) {
694	$thread * thrd = 0p;
695	lock( lock __cfaabi_dbg_ctx2 );
696	int release = max(-count, (int)diff);
697	count += diff;
698	for(release) {
699	unpark( pop_head( waiting ) );
700	}
701
702	unlock( lock );
703
704	return thrd != 0p;
705	}
706
707	//-----------------------------------------------------------------------------
708	// Debug
709	__cfaabi_dbg_debug_do(
710	extern "C" {
711	void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
712	this.prev_name = prev_name;
713	this.prev_thrd = kernelTLS.this_thread;
714	}
715	}
716	)
717
718	//-----------------------------------------------------------------------------
719	// Debug
720	bool threading_enabled(void) __attribute__((const)) {
721	return true;
722	}
723
724	//-----------------------------------------------------------------------------
725	// Statistics
726	#if !defined(__CFA_NO_STATISTICS__)
727	void print_halts( processor & this ) {
728	this.print_halts = true;
729	}
730	#endif
731	// Local Variables: //
732	// mode: c //
733	// tab-width: 4 //
734	// End: //

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