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kernel.cfa @ 69d1748

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

Last change on this file since 69d1748 was 3ea8ad1, checked in by Thierry Delisle <tdelisle@…>, 4 years ago
Added more checks for thread termination synchronization
Property mode set to `100644`
File size: 23.7 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(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	__cfaabi_tls.rand_seed ^= rdtscl();
125	__cfaabi_tls.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	__cfaabi_tls.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( ! __preemption_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( ! __preemption_enabled() );
252	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
253	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
254	/* paranoid */ verify( thrd_dst->context.SP );
255	/* paranoid */ verify( thrd_dst->state != Halted );
256	/* 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
257	/* 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
258	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
259
260
261
262	// set context switch to the thread that the processor is executing
263	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
264	// when __cfactx_switch returns we are back in the processor coroutine
265
266	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
267	/* 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 );
268	/* 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 );
269	/* paranoid */ verify( thrd_dst->context.SP );
270	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
271	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
272	/* paranoid */ verify( ! __preemption_enabled() );
273
274	// Reset global state
275	kernelTLS().this_thread = 0p;
276
277	// We just finished running a thread, there are a few things that could have happened.
278	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
279	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
280	// 4 - Preempted
281	// In case 1, we may have won a race so we can't write to the state again.
282	// In case 2, we lost the race so we now own the thread.
283
284	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
285	// The thread was preempted, reschedule it and reset the flag
286	__schedule_thread( thrd_dst );
287	break RUNNING;
288	}
289
290	if(unlikely(thrd_dst->state == Halting)) {
291	// The thread has halted, it should never be scheduled/run again
292	// finish the thread
293	__thread_finish( thrd_dst );
294	break RUNNING;
295	}
296
297	/* paranoid */ verify( thrd_dst->state == Active );
298	thrd_dst->state = Blocked;
299
300	// set state of processor coroutine to active and the thread to inactive
301	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
302	switch(old_ticket) {
303	case TICKET_RUNNING:
304	// This is case 1, the regular case, nothing more is needed
305	break RUNNING;
306	case TICKET_UNBLOCK:
307	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
308	// In this case, just run it again.
309	continue RUNNING;
310	default:
311	// This makes no sense, something is wrong abort
312	abort();
313	}
314	}
315
316	// Just before returning to the processor, set the processor coroutine to active
317	proc_cor->state = Active;
318
319	/* paranoid */ verify( ! __preemption_enabled() );
320	}
321
322	// KERNEL_ONLY
323	void returnToKernel() {
324	/* paranoid */ verify( ! __preemption_enabled() );
325	$coroutine * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
326	$thread * thrd_src = kernelTLS().this_thread;
327
328	#if !defined(__CFA_NO_STATISTICS__)
329	struct processor * last_proc = kernelTLS().this_processor;
330	#endif
331
332	// Run the thread on this processor
333	{
334	int local_errno = *__volatile_errno();
335	#if defined( __i386 ) \|\| defined( __x86_64 )
336	__x87_store;
337	#endif
338	/* paranoid */ verify( proc_cor->context.SP );
339	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
340	__cfactx_switch( &thrd_src->context, &proc_cor->context );
341	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
342	#if defined( __i386 ) \|\| defined( __x86_64 )
343	__x87_load;
344	#endif
345	*__volatile_errno() = local_errno;
346	}
347
348	#if !defined(__CFA_NO_STATISTICS__)
349	if(last_proc != kernelTLS().this_processor) {
350	__tls_stats()->ready.threads.migration++;
351	}
352	#endif
353
354	/* paranoid */ verify( ! __preemption_enabled() );
355	/* 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 );
356	/* 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 );
357	}
358
359	//-----------------------------------------------------------------------------
360	// Scheduler routines
361	// KERNEL ONLY
362	void __schedule_thread( $thread * thrd ) {
363	/* paranoid */ verify( ! __preemption_enabled() );
364	/* paranoid */ verify( kernelTLS().this_proc_id );
365	/* paranoid */ verify( thrd );
366	/* paranoid */ verify( thrd->state != Halted );
367	/* paranoid */ verify( thrd->curr_cluster );
368	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
369	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
370	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
371	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
372	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
373	/* paranoid */ #endif
374	/* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
375	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
376
377
378	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
379
380	ready_schedule_lock();
381	push( thrd->curr_cluster, thrd );
382	__wake_one(thrd->curr_cluster);
383	ready_schedule_unlock();
384
385	/* paranoid */ verify( ! __preemption_enabled() );
386	}
387
388	// KERNEL ONLY
389	static inline $thread * __next_thread(cluster * this) with( *this ) {
390	/* paranoid */ verify( ! __preemption_enabled() );
391	/* paranoid */ verify( kernelTLS().this_proc_id );
392
393	ready_schedule_lock();
394	$thread * thrd = pop( this );
395	ready_schedule_unlock();
396
397	/* paranoid */ verify( kernelTLS().this_proc_id );
398	/* paranoid */ verify( ! __preemption_enabled() );
399	return thrd;
400	}
401
402	// KERNEL ONLY
403	static inline $thread * __next_thread_slow(cluster * this) with( *this ) {
404	/* paranoid */ verify( ! __preemption_enabled() );
405	/* paranoid */ verify( kernelTLS().this_proc_id );
406
407	ready_schedule_lock();
408	$thread * thrd = pop_slow( this );
409	ready_schedule_unlock();
410
411	/* paranoid */ verify( kernelTLS().this_proc_id );
412	/* paranoid */ verify( ! __preemption_enabled() );
413	return thrd;
414	}
415
416	void unpark( $thread * thrd ) {
417	if( !thrd ) return;
418
419	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
420	switch(old_ticket) {
421	case TICKET_RUNNING:
422	// Wake won the race, the thread will reschedule/rerun itself
423	break;
424	case TICKET_BLOCKED:
425	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
426	/* paranoid */ verify( thrd->state == Blocked );
427
428	{
429	/* paranoid */ verify( publicTLS_get(this_proc_id) );
430	bool full = publicTLS_get(this_proc_id)->full_proc;
431	if(full) disable_interrupts();
432
433	/* paranoid */ verify( ! __preemption_enabled() );
434
435	// Wake lost the race,
436	__schedule_thread( thrd );
437
438	/* paranoid */ verify( ! __preemption_enabled() );
439
440	if(full) enable_interrupts( __cfaabi_dbg_ctx );
441	/* paranoid */ verify( publicTLS_get(this_proc_id) );
442	}
443
444	break;
445	default:
446	// This makes no sense, something is wrong abort
447	abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
448	}
449	}
450
451	void park( void ) {
452	/* paranoid */ verify( __preemption_enabled() );
453	disable_interrupts();
454	/* paranoid */ verify( ! __preemption_enabled() );
455	/* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
456
457	returnToKernel();
458
459	/* paranoid */ verify( ! __preemption_enabled() );
460	enable_interrupts( __cfaabi_dbg_ctx );
461	/* paranoid */ verify( __preemption_enabled() );
462
463	}
464
465	extern "C" {
466	// Leave the thread monitor
467	// last routine called by a thread.
468	// Should never return
469	void __cfactx_thrd_leave() {
470	$thread * thrd = active_thread();
471	$monitor * this = &thrd->self_mon;
472
473	// Lock the monitor now
474	lock( this->lock __cfaabi_dbg_ctx2 );
475
476	disable_interrupts();
477
478	/* paranoid */ verify( ! __preemption_enabled() );
479	/* paranoid */ verify( thrd->state == Active );
480	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
481	/* paranoid */ verify( kernelTLS().this_thread == thrd );
482	/* paranoid */ verify( thrd->context.SP );
483	/* paranoid */ verifyf( ((uintptr_t)thrd->context.SP) > ((uintptr_t)__get_stack(thrd->curr_cor)->limit), "ERROR : $thread %p has been corrupted.\n StackPointer too large.\n", thrd );
484	/* paranoid */ verifyf( ((uintptr_t)thrd->context.SP) < ((uintptr_t)__get_stack(thrd->curr_cor)->base ), "ERROR : $thread %p has been corrupted.\n StackPointer too small.\n", thrd );
485
486	thrd->state = Halting;
487	if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
488	if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
489	if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
490
491	// Leave the thread
492	returnToKernel();
493
494	// Control flow should never reach here!
495	abort();
496	}
497	}
498
499	// KERNEL ONLY
500	bool force_yield( __Preemption_Reason reason ) {
501	/* paranoid */ verify( __preemption_enabled() );
502	disable_interrupts();
503	/* paranoid */ verify( ! __preemption_enabled() );
504
505	$thread * thrd = kernelTLS().this_thread;
506	/* paranoid */ verify(thrd->state == Active);
507
508	// SKULLDUGGERY: It is possible that we are preempting this thread just before
509	// it was going to park itself. If that is the case and it is already using the
510	// intrusive fields then we can't use them to preempt the thread
511	// If that is the case, abandon the preemption.
512	bool preempted = false;
513	if(thrd->link.next == 0p) {
514	preempted = true;
515	thrd->preempted = reason;
516	returnToKernel();
517	}
518
519	/* paranoid */ verify( ! __preemption_enabled() );
520	enable_interrupts_noPoll();
521	/* paranoid */ verify( __preemption_enabled() );
522
523	return preempted;
524	}
525
526	//=============================================================================================
527	// Kernel Idle Sleep
528	//=============================================================================================
529	// Wake a thread from the front if there are any
530	static void __wake_one(cluster * this) {
531	/* paranoid */ verify( ! __preemption_enabled() );
532	/* paranoid */ verify( ready_schedule_islocked() );
533
534	// Check if there is a sleeping processor
535	processor * p;
536	unsigned idle;
537	unsigned total;
538	[idle, total, p] = query(this->idles);
539
540	// If no one is sleeping, we are done
541	if( idle == 0 ) return;
542
543	// We found a processor, wake it up
544	post( p->idle );
545
546	#if !defined(__CFA_NO_STATISTICS__)
547	__tls_stats()->ready.sleep.wakes++;
548	#endif
549
550	/* paranoid */ verify( ready_schedule_islocked() );
551	/* paranoid */ verify( ! __preemption_enabled() );
552
553	return;
554	}
555
556	// Unconditionnaly wake a thread
557	void __wake_proc(processor * this) {
558	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
559
560	disable_interrupts();
561	/* paranoid */ verify( ! __preemption_enabled() );
562	post( this->idle );
563	enable_interrupts( __cfaabi_dbg_ctx );
564	}
565
566	static void push (__cluster_idles & this, processor & proc) {
567	/* paranoid */ verify( ! __preemption_enabled() );
568	lock( this );
569	this.idle++;
570	/* paranoid */ verify( this.idle <= this.total );
571
572	insert_first(this.list, proc);
573	unlock( this );
574	/* paranoid */ verify( ! __preemption_enabled() );
575	}
576
577	static void remove(__cluster_idles & this, processor & proc) {
578	/* paranoid */ verify( ! __preemption_enabled() );
579	lock( this );
580	this.idle--;
581	/* paranoid */ verify( this.idle >= 0 );
582
583	remove(proc);
584	unlock( this );
585	/* paranoid */ verify( ! __preemption_enabled() );
586	}
587
588	static [unsigned idle, unsigned total, * processor] query( & __cluster_idles this ) {
589	for() {
590	uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
591	if( 1 == (l % 2) ) { Pause(); continue; }
592	unsigned idle = this.idle;
593	unsigned total = this.total;
594	processor * proc = &this.list`first;
595	// Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
596	asm volatile("": : :"memory");
597	if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
598	return [idle, total, proc];
599	}
600	}
601
602	//=============================================================================================
603	// Unexpected Terminating logic
604	//=============================================================================================
605	static __spinlock_t kernel_abort_lock;
606	static bool kernel_abort_called = false;
607
608	void * kernel_abort(void) __attribute__ ((__nothrow__)) {
609	// abort cannot be recursively entered by the same or different processors because all signal handlers return when
610	// the globalAbort flag is true.
611	lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
612
613	// first task to abort ?
614	if ( kernel_abort_called ) { // not first task to abort ?
615	unlock( kernel_abort_lock );
616
617	sigset_t mask;
618	sigemptyset( &mask );
619	sigaddset( &mask, SIGALRM ); // block SIGALRM signals
620	sigaddset( &mask, SIGUSR1 ); // block SIGALRM signals
621	sigsuspend( &mask ); // block the processor to prevent further damage during abort
622	_exit( EXIT_FAILURE ); // if processor unblocks before it is killed, terminate it
623	}
624	else {
625	kernel_abort_called = true;
626	unlock( kernel_abort_lock );
627	}
628
629	return __cfaabi_tls.this_thread;
630	}
631
632	void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
633	$thread * thrd = ( $thread * ) kernel_data;
634
635	if(thrd) {
636	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
637	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
638
639	if ( &thrd->self_cor != thrd->curr_cor ) {
640	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
641	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
642	}
643	else {
644	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
645	}
646	}
647	else {
648	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
649	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
650	}
651	}
652
653	int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
654	return get_coroutine(kernelTLS().this_thread) == get_coroutine(mainThread) ? 4 : 2;
655	}
656
657	static __spinlock_t kernel_debug_lock;
658
659	extern "C" {
660	void __cfaabi_bits_acquire() {
661	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
662	}
663
664	void __cfaabi_bits_release() {
665	unlock( kernel_debug_lock );
666	}
667	}
668
669	//=============================================================================================
670	// Kernel Utilities
671	//=============================================================================================
672	//-----------------------------------------------------------------------------
673	// Locks
674	void ?{}( semaphore & this, int count = 1 ) {
675	(this.lock){};
676	this.count = count;
677	(this.waiting){};
678	}
679	void ^?{}(semaphore & this) {}
680
681	bool P(semaphore & this) with( this ){
682	lock( lock __cfaabi_dbg_ctx2 );
683	count -= 1;
684	if ( count < 0 ) {
685	// queue current task
686	append( waiting, active_thread() );
687
688	// atomically release spin lock and block
689	unlock( lock );
690	park();
691	return true;
692	}
693	else {
694	unlock( lock );
695	return false;
696	}
697	}
698
699	bool V(semaphore & this) with( this ) {
700	$thread * thrd = 0p;
701	lock( lock __cfaabi_dbg_ctx2 );
702	count += 1;
703	if ( count <= 0 ) {
704	// remove task at head of waiting list
705	thrd = pop_head( waiting );
706	}
707
708	unlock( lock );
709
710	// make new owner
711	unpark( thrd );
712
713	return thrd != 0p;
714	}
715
716	bool V(semaphore & this, unsigned diff) with( this ) {
717	$thread * thrd = 0p;
718	lock( lock __cfaabi_dbg_ctx2 );
719	int release = max(-count, (int)diff);
720	count += diff;
721	for(release) {
722	unpark( pop_head( waiting ) );
723	}
724
725	unlock( lock );
726
727	return thrd != 0p;
728	}
729
730	//-----------------------------------------------------------------------------
731	// Debug
732	__cfaabi_dbg_debug_do(
733	extern "C" {
734	void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
735	this.prev_name = prev_name;
736	this.prev_thrd = kernelTLS().this_thread;
737	}
738	}
739	)
740
741	//-----------------------------------------------------------------------------
742	// Debug
743	bool threading_enabled(void) __attribute__((const)) {
744	return true;
745	}
746
747	//-----------------------------------------------------------------------------
748	// Statistics
749	#if !defined(__CFA_NO_STATISTICS__)
750	void print_halts( processor & this ) {
751	this.print_halts = true;
752	}
753
754	void print_stats_now( cluster & this, int flags ) {
755	__print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
756	}
757
758	extern int __print_alarm_stats;
759	void print_alarm_stats() {
760	__print_alarm_stats = -1;
761	}
762	#endif
763	// Local Variables: //
764	// mode: c //
765	// tab-width: 4 //
766	// End: //

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