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kernel.cfa @ b8b0de0c

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

Last change on this file since b8b0de0c was 325e6ea, checked in by Thierry Delisle <tdelisle@…>, 4 years ago
Kernel now tallies stats regularly
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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	#if !defined(__CFA_NO_STATISTICS__)
143	unsigned long long last_tally = rdtscl();
144	#endif
145
146
147	__cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
148
149	$thread * readyThread = 0p;
150	MAIN_LOOP:
151	for() {
152	// Try to get the next thread
153	readyThread = __next_thread( this->cltr );
154
155	if( !readyThread ) {
156	readyThread = __next_thread_slow( this->cltr );
157	}
158
159	HALT:
160	if( !readyThread ) {
161	// Don't block if we are done
162	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
163
164	#if !defined(__CFA_NO_STATISTICS__)
165	__tls_stats()->ready.sleep.halts++;
166	#endif
167
168	// Push self to idle stack
169	push(this->cltr->idles, * this);
170
171	// Confirm the ready-queue is empty
172	readyThread = __next_thread_slow( this->cltr );
173	if( readyThread ) {
174	// A thread was found, cancel the halt
175	remove(this->cltr->idles, * this);
176
177	#if !defined(__CFA_NO_STATISTICS__)
178	__tls_stats()->ready.sleep.cancels++;
179	#endif
180
181	// continue the mai loop
182	break HALT;
183	}
184
185	#if !defined(__CFA_NO_STATISTICS__)
186	if(this->print_halts) {
187	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->id, rdtscl());
188	}
189	#endif
190
191	wait( this->idle );
192
193	#if !defined(__CFA_NO_STATISTICS__)
194	if(this->print_halts) {
195	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->id, rdtscl());
196	}
197	#endif
198
199	// We were woken up, remove self from idle
200	remove(this->cltr->idles, * this);
201
202	// DON'T just proceed, start looking again
203	continue MAIN_LOOP;
204	}
205
206	/* paranoid */ verify( readyThread );
207
208	// We found a thread run it
209	__run_thread(this, readyThread);
210
211	// Are we done?
212	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
213
214	#if !defined(__CFA_NO_STATISTICS__)
215	unsigned long long curr = rdtscl();
216	if(curr > (last_tally + 500000000)) {
217	__tally_stats(this->cltr->stats, __cfaabi_tls.this_stats);
218	last_tally = curr;
219	}
220	#endif
221	}
222
223	__cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
224	}
225
226	V( this->terminated );
227
228	if(this == mainProcessor) {
229	// HACK : the coroutine context switch expects this_thread to be set
230	// and it make sense for it to be set in all other cases except here
231	// fake it
232	__cfaabi_tls.this_thread = mainThread;
233	}
234
235	__cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
236	}
237
238	static int * __volatile_errno() __attribute__((noinline));
239	static int * __volatile_errno() { asm(""); return &errno; }
240
241	// KERNEL ONLY
242	// runThread runs a thread by context switching
243	// from the processor coroutine to the target thread
244	static void __run_thread(processor * this, $thread * thrd_dst) {
245	/* paranoid */ verify( ! __preemption_enabled() );
246	/* paranoid */ verifyf( thrd_dst->state == Ready \|\| thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
247	/* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
248	__builtin_prefetch( thrd_dst->context.SP );
249
250	$coroutine * proc_cor = get_coroutine(this->runner);
251
252	// set state of processor coroutine to inactive
253	verify(proc_cor->state == Active);
254	proc_cor->state = Blocked;
255
256	// Actually run the thread
257	RUNNING: while(true) {
258	thrd_dst->preempted = __NO_PREEMPTION;
259	thrd_dst->state = Active;
260
261	// Update global state
262	kernelTLS().this_thread = thrd_dst;
263
264	/* paranoid */ verify( ! __preemption_enabled() );
265	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
266	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
267	/* paranoid */ verify( thrd_dst->context.SP );
268	/* paranoid */ verify( thrd_dst->state != Halted );
269	/* 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
270	/* 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
271	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
272
273
274
275	// set context switch to the thread that the processor is executing
276	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
277	// when __cfactx_switch returns we are back in the processor coroutine
278
279	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
280	/* 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 );
281	/* 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 );
282	/* paranoid */ verify( thrd_dst->context.SP );
283	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
284	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
285	/* paranoid */ verify( ! __preemption_enabled() );
286
287	// Reset global state
288	kernelTLS().this_thread = 0p;
289
290	// We just finished running a thread, there are a few things that could have happened.
291	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
292	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
293	// 4 - Preempted
294	// In case 1, we may have won a race so we can't write to the state again.
295	// In case 2, we lost the race so we now own the thread.
296
297	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
298	// The thread was preempted, reschedule it and reset the flag
299	__schedule_thread( thrd_dst );
300	break RUNNING;
301	}
302
303	if(unlikely(thrd_dst->state == Halting)) {
304	// The thread has halted, it should never be scheduled/run again
305	// finish the thread
306	__thread_finish( thrd_dst );
307	break RUNNING;
308	}
309
310	/* paranoid */ verify( thrd_dst->state == Active );
311	thrd_dst->state = Blocked;
312
313	// set state of processor coroutine to active and the thread to inactive
314	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
315	switch(old_ticket) {
316	case TICKET_RUNNING:
317	// This is case 1, the regular case, nothing more is needed
318	break RUNNING;
319	case TICKET_UNBLOCK:
320	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
321	// In this case, just run it again.
322	continue RUNNING;
323	default:
324	// This makes no sense, something is wrong abort
325	abort();
326	}
327	}
328
329	// Just before returning to the processor, set the processor coroutine to active
330	proc_cor->state = Active;
331
332	/* paranoid */ verify( ! __preemption_enabled() );
333	}
334
335	// KERNEL_ONLY
336	void returnToKernel() {
337	/* paranoid */ verify( ! __preemption_enabled() );
338	$coroutine * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
339	$thread * thrd_src = kernelTLS().this_thread;
340
341	#if !defined(__CFA_NO_STATISTICS__)
342	struct processor * last_proc = kernelTLS().this_processor;
343	#endif
344
345	// Run the thread on this processor
346	{
347	int local_errno = *__volatile_errno();
348	#if defined( __i386 ) \|\| defined( __x86_64 )
349	__x87_store;
350	#endif
351	/* paranoid */ verify( proc_cor->context.SP );
352	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
353	__cfactx_switch( &thrd_src->context, &proc_cor->context );
354	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
355	#if defined( __i386 ) \|\| defined( __x86_64 )
356	__x87_load;
357	#endif
358	*__volatile_errno() = local_errno;
359	}
360
361	#if !defined(__CFA_NO_STATISTICS__)
362	if(last_proc != kernelTLS().this_processor) {
363	__tls_stats()->ready.threads.migration++;
364	}
365	#endif
366
367	/* paranoid */ verify( ! __preemption_enabled() );
368	/* 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 );
369	/* 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 );
370	}
371
372	//-----------------------------------------------------------------------------
373	// Scheduler routines
374	// KERNEL ONLY
375	void __schedule_thread( $thread * thrd ) {
376	/* paranoid */ verify( ! __preemption_enabled() );
377	/* paranoid */ verify( kernelTLS().this_proc_id );
378	/* paranoid */ verify( thrd );
379	/* paranoid */ verify( thrd->state != Halted );
380	/* paranoid */ verify( thrd->curr_cluster );
381	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
382	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
383	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
384	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
385	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
386	/* paranoid */ #endif
387	/* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
388	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
389
390
391	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
392
393	ready_schedule_lock();
394	// Dereference the thread now because once we push it, there is not guaranteed it's still valid.
395	struct cluster * cl = thrd->curr_cluster;
396
397	// push the thread to the cluster ready-queue
398	push( cl, thrd );
399
400	// variable thrd is no longer safe to use
401
402	// wake the cluster using the save variable.
403	__wake_one( cl );
404	ready_schedule_unlock();
405
406	/* paranoid */ verify( ! __preemption_enabled() );
407	}
408
409	// KERNEL ONLY
410	static inline $thread * __next_thread(cluster * this) with( *this ) {
411	/* paranoid */ verify( ! __preemption_enabled() );
412	/* paranoid */ verify( kernelTLS().this_proc_id );
413
414	ready_schedule_lock();
415	$thread * thrd = pop( this );
416	ready_schedule_unlock();
417
418	/* paranoid */ verify( kernelTLS().this_proc_id );
419	/* paranoid */ verify( ! __preemption_enabled() );
420	return thrd;
421	}
422
423	// KERNEL ONLY
424	static inline $thread * __next_thread_slow(cluster * this) with( *this ) {
425	/* paranoid */ verify( ! __preemption_enabled() );
426	/* paranoid */ verify( kernelTLS().this_proc_id );
427
428	ready_schedule_lock();
429	$thread * thrd = pop_slow( this );
430	ready_schedule_unlock();
431
432	/* paranoid */ verify( kernelTLS().this_proc_id );
433	/* paranoid */ verify( ! __preemption_enabled() );
434	return thrd;
435	}
436
437	void unpark( $thread * thrd ) {
438	if( !thrd ) return;
439
440	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
441	switch(old_ticket) {
442	case TICKET_RUNNING:
443	// Wake won the race, the thread will reschedule/rerun itself
444	break;
445	case TICKET_BLOCKED:
446	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
447	/* paranoid */ verify( thrd->state == Blocked );
448
449	{
450	/* paranoid */ verify( publicTLS_get(this_proc_id) );
451	bool full = publicTLS_get(this_proc_id)->full_proc;
452	if(full) disable_interrupts();
453
454	/* paranoid */ verify( ! __preemption_enabled() );
455
456	// Wake lost the race,
457	__schedule_thread( thrd );
458
459	/* paranoid */ verify( ! __preemption_enabled() );
460
461	if(full) enable_interrupts( __cfaabi_dbg_ctx );
462	/* paranoid */ verify( publicTLS_get(this_proc_id) );
463	}
464
465	break;
466	default:
467	// This makes no sense, something is wrong abort
468	abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
469	}
470	}
471
472	void park( void ) {
473	/* paranoid */ verify( __preemption_enabled() );
474	disable_interrupts();
475	/* paranoid */ verify( ! __preemption_enabled() );
476	/* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
477
478	returnToKernel();
479
480	/* paranoid */ verify( ! __preemption_enabled() );
481	enable_interrupts( __cfaabi_dbg_ctx );
482	/* paranoid */ verify( __preemption_enabled() );
483
484	}
485
486	extern "C" {
487	// Leave the thread monitor
488	// last routine called by a thread.
489	// Should never return
490	void __cfactx_thrd_leave() {
491	$thread * thrd = active_thread();
492	$monitor * this = &thrd->self_mon;
493
494	// Lock the monitor now
495	lock( this->lock __cfaabi_dbg_ctx2 );
496
497	disable_interrupts();
498
499	/* paranoid */ verify( ! __preemption_enabled() );
500	/* paranoid */ verify( thrd->state == Active );
501	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
502	/* paranoid */ verify( kernelTLS().this_thread == thrd );
503	/* paranoid */ verify( thrd->context.SP );
504	/* 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 );
505	/* 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 );
506
507	thrd->state = Halting;
508	if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
509	if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
510	if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
511
512	// Leave the thread
513	returnToKernel();
514
515	// Control flow should never reach here!
516	abort();
517	}
518	}
519
520	// KERNEL ONLY
521	bool force_yield( __Preemption_Reason reason ) {
522	/* paranoid */ verify( __preemption_enabled() );
523	disable_interrupts();
524	/* paranoid */ verify( ! __preemption_enabled() );
525
526	$thread * thrd = kernelTLS().this_thread;
527	/* paranoid */ verify(thrd->state == Active);
528
529	// SKULLDUGGERY: It is possible that we are preempting this thread just before
530	// it was going to park itself. If that is the case and it is already using the
531	// intrusive fields then we can't use them to preempt the thread
532	// If that is the case, abandon the preemption.
533	bool preempted = false;
534	if(thrd->link.next == 0p) {
535	preempted = true;
536	thrd->preempted = reason;
537	returnToKernel();
538	}
539
540	/* paranoid */ verify( ! __preemption_enabled() );
541	enable_interrupts_noPoll();
542	/* paranoid */ verify( __preemption_enabled() );
543
544	return preempted;
545	}
546
547	//=============================================================================================
548	// Kernel Idle Sleep
549	//=============================================================================================
550	// Wake a thread from the front if there are any
551	static void __wake_one(cluster * this) {
552	/* paranoid */ verify( ! __preemption_enabled() );
553	/* paranoid */ verify( ready_schedule_islocked() );
554
555	// Check if there is a sleeping processor
556	processor * p;
557	unsigned idle;
558	unsigned total;
559	[idle, total, p] = query(this->idles);
560
561	// If no one is sleeping, we are done
562	if( idle == 0 ) return;
563
564	// We found a processor, wake it up
565	post( p->idle );
566
567	#if !defined(__CFA_NO_STATISTICS__)
568	__tls_stats()->ready.sleep.wakes++;
569	#endif
570
571	/* paranoid */ verify( ready_schedule_islocked() );
572	/* paranoid */ verify( ! __preemption_enabled() );
573
574	return;
575	}
576
577	// Unconditionnaly wake a thread
578	void __wake_proc(processor * this) {
579	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
580
581	disable_interrupts();
582	/* paranoid */ verify( ! __preemption_enabled() );
583	post( this->idle );
584	enable_interrupts( __cfaabi_dbg_ctx );
585	}
586
587	static void push (__cluster_idles & this, processor & proc) {
588	/* paranoid */ verify( ! __preemption_enabled() );
589	lock( this );
590	this.idle++;
591	/* paranoid */ verify( this.idle <= this.total );
592
593	insert_first(this.list, proc);
594	unlock( this );
595	/* paranoid */ verify( ! __preemption_enabled() );
596	}
597
598	static void remove(__cluster_idles & this, processor & proc) {
599	/* paranoid */ verify( ! __preemption_enabled() );
600	lock( this );
601	this.idle--;
602	/* paranoid */ verify( this.idle >= 0 );
603
604	remove(proc);
605	unlock( this );
606	/* paranoid */ verify( ! __preemption_enabled() );
607	}
608
609	static [unsigned idle, unsigned total, * processor] query( & __cluster_idles this ) {
610	for() {
611	uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
612	if( 1 == (l % 2) ) { Pause(); continue; }
613	unsigned idle = this.idle;
614	unsigned total = this.total;
615	processor * proc = &this.list`first;
616	// Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
617	asm volatile("": : :"memory");
618	if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
619	return [idle, total, proc];
620	}
621	}
622
623	//=============================================================================================
624	// Unexpected Terminating logic
625	//=============================================================================================
626	static __spinlock_t kernel_abort_lock;
627	static bool kernel_abort_called = false;
628
629	void * kernel_abort(void) __attribute__ ((__nothrow__)) {
630	// abort cannot be recursively entered by the same or different processors because all signal handlers return when
631	// the globalAbort flag is true.
632	lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
633
634	// disable interrupts, it no longer makes sense to try to interrupt this processor
635	disable_interrupts();
636
637	// first task to abort ?
638	if ( kernel_abort_called ) { // not first task to abort ?
639	unlock( kernel_abort_lock );
640
641	sigset_t mask;
642	sigemptyset( &mask );
643	sigaddset( &mask, SIGALRM ); // block SIGALRM signals
644	sigaddset( &mask, SIGUSR1 ); // block SIGALRM signals
645	sigsuspend( &mask ); // block the processor to prevent further damage during abort
646	_exit( EXIT_FAILURE ); // if processor unblocks before it is killed, terminate it
647	}
648	else {
649	kernel_abort_called = true;
650	unlock( kernel_abort_lock );
651	}
652
653	return __cfaabi_tls.this_thread;
654	}
655
656	void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
657	$thread * thrd = ( $thread * ) kernel_data;
658
659	if(thrd) {
660	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
661	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
662
663	if ( &thrd->self_cor != thrd->curr_cor ) {
664	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
665	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
666	}
667	else {
668	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
669	}
670	}
671	else {
672	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
673	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
674	}
675	}
676
677	int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
678	return get_coroutine(kernelTLS().this_thread) == get_coroutine(mainThread) ? 4 : 2;
679	}
680
681	static __spinlock_t kernel_debug_lock;
682
683	extern "C" {
684	void __cfaabi_bits_acquire() {
685	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
686	}
687
688	void __cfaabi_bits_release() {
689	unlock( kernel_debug_lock );
690	}
691	}
692
693	//=============================================================================================
694	// Kernel Utilities
695	//=============================================================================================
696	//-----------------------------------------------------------------------------
697	// Locks
698	void ?{}( semaphore & this, int count = 1 ) {
699	(this.lock){};
700	this.count = count;
701	(this.waiting){};
702	}
703	void ^?{}(semaphore & this) {}
704
705	bool P(semaphore & this) with( this ){
706	lock( lock __cfaabi_dbg_ctx2 );
707	count -= 1;
708	if ( count < 0 ) {
709	// queue current task
710	append( waiting, active_thread() );
711
712	// atomically release spin lock and block
713	unlock( lock );
714	park();
715	return true;
716	}
717	else {
718	unlock( lock );
719	return false;
720	}
721	}
722
723	bool V(semaphore & this) with( this ) {
724	$thread * thrd = 0p;
725	lock( lock __cfaabi_dbg_ctx2 );
726	count += 1;
727	if ( count <= 0 ) {
728	// remove task at head of waiting list
729	thrd = pop_head( waiting );
730	}
731
732	unlock( lock );
733
734	// make new owner
735	unpark( thrd );
736
737	return thrd != 0p;
738	}
739
740	bool V(semaphore & this, unsigned diff) with( this ) {
741	$thread * thrd = 0p;
742	lock( lock __cfaabi_dbg_ctx2 );
743	int release = max(-count, (int)diff);
744	count += diff;
745	for(release) {
746	unpark( pop_head( waiting ) );
747	}
748
749	unlock( lock );
750
751	return thrd != 0p;
752	}
753
754	//-----------------------------------------------------------------------------
755	// Debug
756	__cfaabi_dbg_debug_do(
757	extern "C" {
758	void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
759	this.prev_name = prev_name;
760	this.prev_thrd = kernelTLS().this_thread;
761	}
762	}
763	)
764
765	//-----------------------------------------------------------------------------
766	// Debug
767	bool threading_enabled(void) __attribute__((const)) {
768	return true;
769	}
770
771	//-----------------------------------------------------------------------------
772	// Statistics
773	#if !defined(__CFA_NO_STATISTICS__)
774	void print_halts( processor & this ) {
775	this.print_halts = true;
776	}
777
778	void print_stats_now( cluster & this, int flags ) {
779	__print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
780	}
781
782	extern int __print_alarm_stats;
783	void print_alarm_stats() {
784	__print_alarm_stats = -1;
785	}
786	#endif
787	// Local Variables: //
788	// mode: c //
789	// tab-width: 4 //
790	// End: //

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