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kernel.cfa@ 89c2a77b

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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 89c2a77b was 73f4d08, checked in by Thierry Delisle <tdelisle@…>, 4 years ago
Added stats implementation for dumping a big array of timestamped values. Disabled by default. I might not keep it but committing it for now.
Property mode set to `100644`
File size: 24.8 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	extern "C" {
25	#include <sys/eventfd.h>
26	}
27
28	//CFA Includes
29	#include "kernel_private.hfa"
30	#include "preemption.hfa"
31
32	//Private includes
33	#define __CFA_INVOKE_PRIVATE__
34	#include "invoke.h"
35
36
37	//-----------------------------------------------------------------------------
38	// Some assembly required
39	#if defined( __i386 )
40	// mxcr : SSE Status and Control bits (control bits are preserved across function calls)
41	// fcw : X87 FPU control word (preserved across function calls)
42	#define __x87_store \
43	uint32_t __mxcr; \
44	uint16_t __fcw; \
45	__asm__ volatile ( \
46	"stmxcsr %0\n" \
47	"fnstcw %1\n" \
48	: "=m" (__mxcr),\
49	"=m" (__fcw) \
50	)
51
52	#define __x87_load \
53	__asm__ volatile ( \
54	"fldcw %1\n" \
55	"ldmxcsr %0\n" \
56	::"m" (__mxcr),\
57	"m" (__fcw) \
58	)
59
60	#elif defined( __x86_64 )
61	#define __x87_store \
62	uint32_t __mxcr; \
63	uint16_t __fcw; \
64	__asm__ volatile ( \
65	"stmxcsr %0\n" \
66	"fnstcw %1\n" \
67	: "=m" (__mxcr),\
68	"=m" (__fcw) \
69	)
70
71	#define __x87_load \
72	__asm__ volatile ( \
73	"fldcw %1\n" \
74	"ldmxcsr %0\n" \
75	:: "m" (__mxcr),\
76	"m" (__fcw) \
77	)
78
79	#elif defined( __arm__ )
80	#define __x87_store
81	#define __x87_load
82
83	#elif defined( __aarch64__ )
84	#define __x87_store \
85	uint32_t __fpcntl[2]; \
86	__asm__ volatile ( \
87	"mrs x9, FPCR\n" \
88	"mrs x10, FPSR\n" \
89	"stp x9, x10, %0\n" \
90	: "=m" (__fpcntl) : : "x9", "x10" \
91	)
92
93	#define __x87_load \
94	__asm__ volatile ( \
95	"ldp x9, x10, %0\n" \
96	"msr FPSR, x10\n" \
97	"msr FPCR, x9\n" \
98	: "=m" (__fpcntl) : : "x9", "x10" \
99	)
100
101	#else
102	#error unsupported hardware architecture
103	#endif
104
105	extern $thread * mainThread;
106	extern processor * mainProcessor;
107
108	//-----------------------------------------------------------------------------
109	// Kernel Scheduling logic
110	static $thread * __next_thread(cluster * this);
111	static $thread * __next_thread_slow(cluster * this);
112	static void __run_thread(processor * this, $thread * dst);
113	static void __wake_one(cluster * cltr);
114
115	static void push (__cluster_idles & idles, processor & proc);
116	static void remove(__cluster_idles & idles, processor & proc);
117	static [unsigned idle, unsigned total, * processor] query( & __cluster_idles idles );
118
119	extern void __cfa_io_start( processor * );
120	extern void __cfa_io_drain( processor * );
121	extern void __cfa_io_flush( processor * );
122	extern void __cfa_io_stop ( processor * );
123	static inline void __maybe_io_drain( processor * );
124
125	extern void __disable_interrupts_hard();
126	extern void __enable_interrupts_hard();
127
128	//=============================================================================================
129	// Kernel Scheduling logic
130	//=============================================================================================
131	//Main of the processor contexts
132	void main(processorCtx_t & runner) {
133	// Because of a bug, we couldn't initialized the seed on construction
134	// Do it here
135	__cfaabi_tls.rand_seed ^= rdtscl();
136	__cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
137	__tls_rand_advance_bck();
138
139	processor * this = runner.proc;
140	verify(this);
141
142	__cfa_io_start( this );
143
144	__cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
145	#if !defined(__CFA_NO_STATISTICS__)
146	if( this->print_halts ) {
147	__cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->id, this->name, (void*)this);
148	}
149	#endif
150
151	{
152	// Setup preemption data
153	preemption_scope scope = { this };
154
155	#if !defined(__CFA_NO_STATISTICS__)
156	unsigned long long last_tally = rdtscl();
157	#endif
158
159	// if we need to run some special setup, now is the time to do it.
160	if(this->init.thrd) {
161	this->init.thrd->curr_cluster = this->cltr;
162	__run_thread(this, this->init.thrd);
163	}
164
165	__cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
166
167	$thread * readyThread = 0p;
168	MAIN_LOOP:
169	for() {
170	// Check if there is pending io
171	__maybe_io_drain( this );
172
173	// Try to get the next thread
174	readyThread = __next_thread( this->cltr );
175
176	if( !readyThread ) {
177	__cfa_io_flush( this );
178	readyThread = __next_thread_slow( this->cltr );
179	}
180
181	HALT:
182	if( !readyThread ) {
183	// Don't block if we are done
184	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
185
186	#if !defined(__CFA_NO_STATISTICS__)
187	__tls_stats()->ready.sleep.halts++;
188	#endif
189
190	// Push self to idle stack
191	push(this->cltr->idles, * this);
192
193	// Confirm the ready-queue is empty
194	readyThread = __next_thread_slow( this->cltr );
195	if( readyThread ) {
196	// A thread was found, cancel the halt
197	remove(this->cltr->idles, * this);
198
199	#if !defined(__CFA_NO_STATISTICS__)
200	__tls_stats()->ready.sleep.cancels++;
201	#endif
202
203	// continue the mai loop
204	break HALT;
205	}
206
207	#if !defined(__CFA_NO_STATISTICS__)
208	if(this->print_halts) {
209	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->id, rdtscl());
210	}
211	#endif
212
213	__cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
214
215	__disable_interrupts_hard();
216	eventfd_t val;
217	eventfd_read( this->idle, &val );
218	__enable_interrupts_hard();
219
220	#if !defined(__CFA_NO_STATISTICS__)
221	if(this->print_halts) {
222	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->id, rdtscl());
223	}
224	#endif
225
226	// We were woken up, remove self from idle
227	remove(this->cltr->idles, * this);
228
229	// DON'T just proceed, start looking again
230	continue MAIN_LOOP;
231	}
232
233	/* paranoid */ verify( readyThread );
234
235	// Reset io dirty bit
236	this->io.dirty = false;
237
238	// We found a thread run it
239	__run_thread(this, readyThread);
240
241	// Are we done?
242	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
243
244	#if !defined(__CFA_NO_STATISTICS__)
245	unsigned long long curr = rdtscl();
246	if(curr > (last_tally + 500000000)) {
247	__tally_stats(this->cltr->stats, __cfaabi_tls.this_stats);
248	last_tally = curr;
249	}
250	#endif
251
252	if(this->io.pending && !this->io.dirty) {
253	__cfa_io_flush( this );
254	}
255	}
256
257	__cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
258	}
259
260	__cfa_io_stop( this );
261
262	post( this->terminated );
263
264
265	if(this == mainProcessor) {
266	// HACK : the coroutine context switch expects this_thread to be set
267	// and it make sense for it to be set in all other cases except here
268	// fake it
269	__cfaabi_tls.this_thread = mainThread;
270	}
271
272	__cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
273	}
274
275	static int * __volatile_errno() __attribute__((noinline));
276	static int * __volatile_errno() { asm(""); return &errno; }
277
278	// KERNEL ONLY
279	// runThread runs a thread by context switching
280	// from the processor coroutine to the target thread
281	static void __run_thread(processor * this, $thread * thrd_dst) {
282	/* paranoid */ verify( ! __preemption_enabled() );
283	/* paranoid */ verifyf( thrd_dst->state == Ready \|\| thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
284	/* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
285	__builtin_prefetch( thrd_dst->context.SP );
286
287	__cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
288
289	$coroutine * proc_cor = get_coroutine(this->runner);
290
291	// set state of processor coroutine to inactive
292	verify(proc_cor->state == Active);
293	proc_cor->state = Blocked;
294
295	// Actually run the thread
296	RUNNING: while(true) {
297	thrd_dst->preempted = __NO_PREEMPTION;
298	thrd_dst->state = Active;
299
300	// Update global state
301	kernelTLS().this_thread = thrd_dst;
302
303	/* paranoid */ verify( ! __preemption_enabled() );
304	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
305	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
306	/* paranoid */ verify( thrd_dst->context.SP );
307	/* paranoid */ verify( thrd_dst->state != Halted );
308	/* 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
309	/* 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
310	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
311
312
313
314	// set context switch to the thread that the processor is executing
315	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
316	// when __cfactx_switch returns we are back in the processor coroutine
317
318	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
319	/* 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 );
320	/* 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 );
321	/* paranoid */ verify( thrd_dst->context.SP );
322	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
323	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
324	/* paranoid */ verify( ! __preemption_enabled() );
325
326	// Reset global state
327	kernelTLS().this_thread = 0p;
328
329	// We just finished running a thread, there are a few things that could have happened.
330	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
331	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
332	// 4 - Preempted
333	// In case 1, we may have won a race so we can't write to the state again.
334	// In case 2, we lost the race so we now own the thread.
335
336	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
337	// The thread was preempted, reschedule it and reset the flag
338	__schedule_thread( thrd_dst );
339	break RUNNING;
340	}
341
342	if(unlikely(thrd_dst->state == Halting)) {
343	// The thread has halted, it should never be scheduled/run again
344	// finish the thread
345	__thread_finish( thrd_dst );
346	break RUNNING;
347	}
348
349	/* paranoid */ verify( thrd_dst->state == Active );
350	thrd_dst->state = Blocked;
351
352	// set state of processor coroutine to active and the thread to inactive
353	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
354	switch(old_ticket) {
355	case TICKET_RUNNING:
356	// This is case 1, the regular case, nothing more is needed
357	break RUNNING;
358	case TICKET_UNBLOCK:
359	#if !defined(__CFA_NO_STATISTICS__)
360	__tls_stats()->ready.threads.threads++;
361	__push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", this );
362	#endif
363	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
364	// In this case, just run it again.
365	continue RUNNING;
366	default:
367	// This makes no sense, something is wrong abort
368	abort();
369	}
370	}
371
372	// Just before returning to the processor, set the processor coroutine to active
373	proc_cor->state = Active;
374
375	__cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
376
377	#if !defined(__CFA_NO_STATISTICS__)
378	__tls_stats()->ready.threads.threads--;
379	__push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", this );
380	#endif
381
382	/* paranoid */ verify( ! __preemption_enabled() );
383	}
384
385	// KERNEL_ONLY
386	void returnToKernel() {
387	/* paranoid */ verify( ! __preemption_enabled() );
388	$coroutine * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
389	$thread * thrd_src = kernelTLS().this_thread;
390
391	#if !defined(__CFA_NO_STATISTICS__)
392	struct processor * last_proc = kernelTLS().this_processor;
393	#endif
394
395	// Run the thread on this processor
396	{
397	int local_errno = *__volatile_errno();
398	#if defined( __i386 ) \|\| defined( __x86_64 )
399	__x87_store;
400	#endif
401	/* paranoid */ verify( proc_cor->context.SP );
402	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
403	__cfactx_switch( &thrd_src->context, &proc_cor->context );
404	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
405	#if defined( __i386 ) \|\| defined( __x86_64 )
406	__x87_load;
407	#endif
408	*__volatile_errno() = local_errno;
409	}
410
411	#if !defined(__CFA_NO_STATISTICS__)
412	if(last_proc != kernelTLS().this_processor) {
413	__tls_stats()->ready.threads.migration++;
414	}
415	#endif
416
417	/* paranoid */ verify( ! __preemption_enabled() );
418	/* 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 );
419	/* 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 );
420	}
421
422	//-----------------------------------------------------------------------------
423	// Scheduler routines
424	// KERNEL ONLY
425	void __schedule_thread( $thread * thrd ) {
426	/* paranoid */ verify( ! __preemption_enabled() );
427	/* paranoid */ verify( kernelTLS().this_proc_id );
428	/* paranoid */ verify( thrd );
429	/* paranoid */ verify( thrd->state != Halted );
430	/* paranoid */ verify( thrd->curr_cluster );
431	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
432	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
433	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
434	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
435	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
436	/* paranoid */ #endif
437	/* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
438	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
439
440
441	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
442
443	// Dereference the thread now because once we push it, there is not guaranteed it's still valid.
444	struct cluster * cl = thrd->curr_cluster;
445
446	ready_schedule_lock();
447	// push the thread to the cluster ready-queue
448	push( cl, thrd );
449
450	// variable thrd is no longer safe to use
451
452	// wake the cluster using the save variable.
453	__wake_one( cl );
454	ready_schedule_unlock();
455
456	#if !defined(__CFA_NO_STATISTICS__)
457	if( kernelTLS().this_stats ) {
458	__tls_stats()->ready.threads.threads++;
459	__push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", kernelTLS().this_processor );
460	}
461	else {
462	__atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
463	__push_stat( cl->stats, cl->stats->ready.threads.threads, true, "Cluster", cl );
464	}
465	#endif
466
467	/* paranoid */ verify( ! __preemption_enabled() );
468	}
469
470	// KERNEL ONLY
471	static inline $thread * __next_thread(cluster * this) with( *this ) {
472	/* paranoid */ verify( ! __preemption_enabled() );
473	/* paranoid */ verify( kernelTLS().this_proc_id );
474
475	ready_schedule_lock();
476	$thread * thrd = pop( this );
477	ready_schedule_unlock();
478
479	/* paranoid */ verify( kernelTLS().this_proc_id );
480	/* paranoid */ verify( ! __preemption_enabled() );
481	return thrd;
482	}
483
484	// KERNEL ONLY
485	static inline $thread * __next_thread_slow(cluster * this) with( *this ) {
486	/* paranoid */ verify( ! __preemption_enabled() );
487	/* paranoid */ verify( kernelTLS().this_proc_id );
488
489	ready_schedule_lock();
490	$thread * thrd = pop_slow( this );
491	ready_schedule_unlock();
492
493	/* paranoid */ verify( kernelTLS().this_proc_id );
494	/* paranoid */ verify( ! __preemption_enabled() );
495	return thrd;
496	}
497
498	void unpark( $thread * thrd ) {
499	if( !thrd ) return;
500
501	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
502	switch(old_ticket) {
503	case TICKET_RUNNING:
504	// Wake won the race, the thread will reschedule/rerun itself
505	break;
506	case TICKET_BLOCKED:
507	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
508	/* paranoid */ verify( thrd->state == Blocked );
509
510	{
511	/* paranoid */ verify( publicTLS_get(this_proc_id) );
512	disable_interrupts();
513
514	/* paranoid */ verify( ! __preemption_enabled() );
515
516	// Wake lost the race,
517	__schedule_thread( thrd );
518
519	/* paranoid */ verify( ! __preemption_enabled() );
520
521	enable_interrupts_noPoll();
522	/* paranoid */ verify( publicTLS_get(this_proc_id) );
523	}
524
525	break;
526	default:
527	// This makes no sense, something is wrong abort
528	abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
529	}
530	}
531
532	void park( void ) {
533	/* paranoid */ verify( __preemption_enabled() );
534	disable_interrupts();
535	/* paranoid */ verify( ! __preemption_enabled() );
536	/* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
537
538	returnToKernel();
539
540	/* paranoid */ verify( ! __preemption_enabled() );
541	enable_interrupts( __cfaabi_dbg_ctx );
542	/* paranoid */ verify( __preemption_enabled() );
543
544	}
545
546	extern "C" {
547	// Leave the thread monitor
548	// last routine called by a thread.
549	// Should never return
550	void __cfactx_thrd_leave() {
551	$thread * thrd = active_thread();
552	$monitor * this = &thrd->self_mon;
553
554	// Lock the monitor now
555	lock( this->lock __cfaabi_dbg_ctx2 );
556
557	disable_interrupts();
558
559	/* paranoid */ verify( ! __preemption_enabled() );
560	/* paranoid */ verify( thrd->state == Active );
561	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
562	/* paranoid */ verify( kernelTLS().this_thread == thrd );
563	/* paranoid */ verify( thrd->context.SP );
564	/* 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 );
565	/* 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 );
566
567	thrd->state = Halting;
568	if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
569	if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
570	if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
571
572	// Leave the thread
573	returnToKernel();
574
575	// Control flow should never reach here!
576	abort();
577	}
578	}
579
580	// KERNEL ONLY
581	bool force_yield( __Preemption_Reason reason ) {
582	/* paranoid */ verify( __preemption_enabled() );
583	disable_interrupts();
584	/* paranoid */ verify( ! __preemption_enabled() );
585
586	$thread * thrd = kernelTLS().this_thread;
587	/* paranoid */ verify(thrd->state == Active);
588
589	// SKULLDUGGERY: It is possible that we are preempting this thread just before
590	// it was going to park itself. If that is the case and it is already using the
591	// intrusive fields then we can't use them to preempt the thread
592	// If that is the case, abandon the preemption.
593	bool preempted = false;
594	if(thrd->link.next == 0p) {
595	preempted = true;
596	thrd->preempted = reason;
597	returnToKernel();
598	}
599
600	/* paranoid */ verify( ! __preemption_enabled() );
601	enable_interrupts_noPoll();
602	/* paranoid */ verify( __preemption_enabled() );
603
604	return preempted;
605	}
606
607	//=============================================================================================
608	// Kernel Idle Sleep
609	//=============================================================================================
610	// Wake a thread from the front if there are any
611	static void __wake_one(cluster * this) {
612	/* paranoid */ verify( ! __preemption_enabled() );
613	/* paranoid */ verify( ready_schedule_islocked() );
614
615	// Check if there is a sleeping processor
616	processor * p;
617	unsigned idle;
618	unsigned total;
619	[idle, total, p] = query(this->idles);
620
621	// If no one is sleeping, we are done
622	if( idle == 0 ) return;
623
624	// We found a processor, wake it up
625	eventfd_t val;
626	val = 1;
627	eventfd_write( p->idle, val );
628
629	#if !defined(__CFA_NO_STATISTICS__)
630	if( kernelTLS().this_stats ) {
631	__tls_stats()->ready.sleep.wakes++;
632	}
633	else {
634	__atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED);
635	}
636	#endif
637
638	/* paranoid */ verify( ready_schedule_islocked() );
639	/* paranoid */ verify( ! __preemption_enabled() );
640
641	return;
642	}
643
644	// Unconditionnaly wake a thread
645	void __wake_proc(processor * this) {
646	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
647
648	disable_interrupts();
649	/* paranoid */ verify( ! __preemption_enabled() );
650	eventfd_t val;
651	val = 1;
652	eventfd_write( this->idle, val );
653	enable_interrupts( __cfaabi_dbg_ctx );
654	}
655
656	static void push (__cluster_idles & this, processor & proc) {
657	/* paranoid */ verify( ! __preemption_enabled() );
658	lock( this );
659	this.idle++;
660	/* paranoid */ verify( this.idle <= this.total );
661
662	insert_first(this.list, proc);
663	unlock( this );
664	/* paranoid */ verify( ! __preemption_enabled() );
665	}
666
667	static void remove(__cluster_idles & this, processor & proc) {
668	/* paranoid */ verify( ! __preemption_enabled() );
669	lock( this );
670	this.idle--;
671	/* paranoid */ verify( this.idle >= 0 );
672
673	remove(proc);
674	unlock( this );
675	/* paranoid */ verify( ! __preemption_enabled() );
676	}
677
678	static [unsigned idle, unsigned total, * processor] query( & __cluster_idles this ) {
679	for() {
680	uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
681	if( 1 == (l % 2) ) { Pause(); continue; }
682	unsigned idle = this.idle;
683	unsigned total = this.total;
684	processor * proc = &this.list`first;
685	// Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
686	asm volatile("": : :"memory");
687	if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
688	return [idle, total, proc];
689	}
690	}
691
692	//=============================================================================================
693	// Unexpected Terminating logic
694	//=============================================================================================
695	void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
696	$thread * thrd = __cfaabi_tls.this_thread;
697
698	if(thrd) {
699	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
700	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
701
702	if ( &thrd->self_cor != thrd->curr_cor ) {
703	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
704	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
705	}
706	else {
707	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
708	}
709	}
710	else {
711	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
712	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
713	}
714	}
715
716	int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
717	return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
718	}
719
720	static __spinlock_t kernel_debug_lock;
721
722	extern "C" {
723	void __cfaabi_bits_acquire() {
724	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
725	}
726
727	void __cfaabi_bits_release() {
728	unlock( kernel_debug_lock );
729	}
730	}
731
732	//=============================================================================================
733	// Kernel Utilities
734	//=============================================================================================
735	#if defined(CFA_HAVE_LINUX_IO_URING_H)
736	#include "io/types.hfa"
737	#endif
738
739	static inline void __maybe_io_drain( processor * proc ) {
740	#if defined(CFA_HAVE_LINUX_IO_URING_H)
741	__cfadbg_print_safe(runtime_core, "Kernel : core %p checking io for ring %d\n", proc, proc->io.ctx->fd);
742
743	// Check if we should drain the queue
744	$io_context * ctx = proc->io.ctx;
745	unsigned head = *ctx->cq.head;
746	unsigned tail = *ctx->cq.tail;
747	if(head != tail) __cfa_io_drain( proc );
748	#endif
749	}
750
751	//-----------------------------------------------------------------------------
752	// Debug
753	__cfaabi_dbg_debug_do(
754	extern "C" {
755	void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
756	this.prev_name = prev_name;
757	this.prev_thrd = kernelTLS().this_thread;
758	}
759	}
760	)
761
762	//-----------------------------------------------------------------------------
763	// Debug
764	bool threading_enabled(void) __attribute__((const)) {
765	return true;
766	}
767
768	//-----------------------------------------------------------------------------
769	// Statistics
770	#if !defined(__CFA_NO_STATISTICS__)
771	void print_halts( processor & this ) {
772	this.print_halts = true;
773	}
774
775	void print_stats_now( cluster & this, int flags ) {
776	__print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
777	}
778	#endif
779	// Local Variables: //
780	// mode: c //
781	// tab-width: 4 //
782	// End: //

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