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kernel.cfa @ ad89296

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

Last change on this file since ad89296 was 34b2796, checked in by Thierry Delisle <tdelisle@…>, 3 years ago
Changed comments to ifdef
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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	#if !defined(__CFA_NO_STATISTICS__)
37	#define __STATS( ...) __VA_ARGS__
38	#else
39	#define __STATS( ...)
40	#endif
41
42	//-----------------------------------------------------------------------------
43	// Some assembly required
44	#if defined( __i386 )
45	// mxcr : SSE Status and Control bits (control bits are preserved across function calls)
46	// fcw : X87 FPU control word (preserved across function calls)
47	#define __x87_store \
48	uint32_t __mxcr; \
49	uint16_t __fcw; \
50	__asm__ volatile ( \
51	"stmxcsr %0\n" \
52	"fnstcw %1\n" \
53	: "=m" (__mxcr),\
54	"=m" (__fcw) \
55	)
56
57	#define __x87_load \
58	__asm__ volatile ( \
59	"fldcw %1\n" \
60	"ldmxcsr %0\n" \
61	::"m" (__mxcr),\
62	"m" (__fcw) \
63	)
64
65	#elif defined( __x86_64 )
66	#define __x87_store \
67	uint32_t __mxcr; \
68	uint16_t __fcw; \
69	__asm__ volatile ( \
70	"stmxcsr %0\n" \
71	"fnstcw %1\n" \
72	: "=m" (__mxcr),\
73	"=m" (__fcw) \
74	)
75
76	#define __x87_load \
77	__asm__ volatile ( \
78	"fldcw %1\n" \
79	"ldmxcsr %0\n" \
80	:: "m" (__mxcr),\
81	"m" (__fcw) \
82	)
83
84	#elif defined( __arm__ )
85	#define __x87_store
86	#define __x87_load
87
88	#elif defined( __aarch64__ )
89	#define __x87_store \
90	uint32_t __fpcntl[2]; \
91	__asm__ volatile ( \
92	"mrs x9, FPCR\n" \
93	"mrs x10, FPSR\n" \
94	"stp x9, x10, %0\n" \
95	: "=m" (__fpcntl) : : "x9", "x10" \
96	)
97
98	#define __x87_load \
99	__asm__ volatile ( \
100	"ldp x9, x10, %0\n" \
101	"msr FPSR, x10\n" \
102	"msr FPCR, x9\n" \
103	: "=m" (__fpcntl) : : "x9", "x10" \
104	)
105
106	#else
107	#error unsupported hardware architecture
108	#endif
109
110	extern $thread * mainThread;
111	extern processor * mainProcessor;
112
113	//-----------------------------------------------------------------------------
114	// Kernel Scheduling logic
115	static $thread * __next_thread(cluster * this);
116	static $thread * __next_thread_slow(cluster * this);
117	static inline bool __must_unpark( $thread * thrd ) __attribute((nonnull(1)));
118	static void __run_thread(processor * this, $thread * dst);
119	static void __wake_one(cluster * cltr);
120
121	static void mark_idle (__cluster_proc_list & idles, processor & proc);
122	static void mark_awake(__cluster_proc_list & idles, processor & proc);
123	static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list idles );
124
125	extern void __cfa_io_start( processor * );
126	extern bool __cfa_io_drain( processor * );
127	extern void __cfa_io_flush( processor * );
128	extern void __cfa_io_stop ( processor * );
129	static inline bool __maybe_io_drain( processor * );
130
131	extern void __disable_interrupts_hard();
132	extern void __enable_interrupts_hard();
133
134	static inline void __disable_interrupts_checked() {
135	/* paranoid */ verify( __preemption_enabled() );
136	disable_interrupts();
137	/* paranoid */ verify( ! __preemption_enabled() );
138	}
139
140	static inline void __enable_interrupts_checked( bool poll = true ) {
141	/* paranoid */ verify( ! __preemption_enabled() );
142	enable_interrupts( poll );
143	/* paranoid */ verify( __preemption_enabled() );
144	}
145
146	//=============================================================================================
147	// Kernel Scheduling logic
148	//=============================================================================================
149	//Main of the processor contexts
150	void main(processorCtx_t & runner) {
151	// Because of a bug, we couldn't initialized the seed on construction
152	// Do it here
153	__cfaabi_tls.rand_seed ^= rdtscl();
154	__cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
155	__tls_rand_advance_bck();
156
157	processor * this = runner.proc;
158	verify(this);
159
160	__cfa_io_start( this );
161
162	__cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
163	#if !defined(__CFA_NO_STATISTICS__)
164	if( this->print_halts ) {
165	__cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
166	}
167	#endif
168
169	{
170	// Setup preemption data
171	preemption_scope scope = { this };
172
173	__STATS( unsigned long long last_tally = rdtscl(); )
174
175	// if we need to run some special setup, now is the time to do it.
176	if(this->init.thrd) {
177	this->init.thrd->curr_cluster = this->cltr;
178	__run_thread(this, this->init.thrd);
179	}
180
181	__cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
182
183	$thread * readyThread = 0p;
184	MAIN_LOOP:
185	for() {
186	#if 1
187	// Check if there is pending io
188	__maybe_io_drain( this );
189
190	// Try to get the next thread
191	readyThread = __next_thread( this->cltr );
192
193	if( !readyThread ) {
194	__cfa_io_flush( this );
195	readyThread = __next_thread_slow( this->cltr );
196	}
197
198	HALT:
199	if( !readyThread ) {
200	// Don't block if we are done
201	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
202
203	#if !defined(__CFA_NO_STATISTICS__)
204	__tls_stats()->ready.sleep.halts++;
205	#endif
206
207	// Push self to idle stack
208	mark_idle(this->cltr->procs, * this);
209
210	// Confirm the ready-queue is empty
211	readyThread = __next_thread_slow( this->cltr );
212	if( readyThread ) {
213	// A thread was found, cancel the halt
214	mark_awake(this->cltr->procs, * this);
215
216	#if !defined(__CFA_NO_STATISTICS__)
217	__tls_stats()->ready.sleep.cancels++;
218	#endif
219
220	// continue the mai loop
221	break HALT;
222	}
223
224	#if !defined(__CFA_NO_STATISTICS__)
225	if(this->print_halts) {
226	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
227	}
228	#endif
229
230	__cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
231
232	__disable_interrupts_hard();
233	eventfd_t val;
234	eventfd_read( this->idle, &val );
235	__enable_interrupts_hard();
236
237	#if !defined(__CFA_NO_STATISTICS__)
238	if(this->print_halts) {
239	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
240	}
241	#endif
242
243	// We were woken up, remove self from idle
244	mark_awake(this->cltr->procs, * this);
245
246	// DON'T just proceed, start looking again
247	continue MAIN_LOOP;
248	}
249
250	/* paranoid */ verify( readyThread );
251
252	// Reset io dirty bit
253	this->io.dirty = false;
254
255	// We found a thread run it
256	__run_thread(this, readyThread);
257
258	// Are we done?
259	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
260
261	#if !defined(__CFA_NO_STATISTICS__)
262	unsigned long long curr = rdtscl();
263	if(curr > (last_tally + 500000000)) {
264	__tally_stats(this->cltr->stats, __cfaabi_tls.this_stats);
265	last_tally = curr;
266	}
267	#endif
268
269	if(this->io.pending && !this->io.dirty) {
270	__cfa_io_flush( this );
271	}
272
273	#else
274
275	SEARCH: {
276	/* paranoid */ verify( ! __preemption_enabled() );
277	/* paranoid */ verify( kernelTLS().this_proc_id );
278
279	// First, lock the scheduler since we are searching for a thread
280	ready_schedule_lock();
281
282	// Try to get the next thread
283	readyThread = pop_fast( this->cltr );
284	if(readyThread) { ready_schedule_unlock(); break SEARCH; }
285
286	// If we can't find a thread, might as well flush any outstanding I/O
287	if(this->io.pending) { __cfa_io_flush( this ); }
288
289	// Spin a little on I/O, just in case
290	for(25) {
291	__maybe_io_drain( this );
292	readyThread = pop_fast( this->cltr );
293	if(readyThread) { ready_schedule_unlock(); break SEARCH; }
294	}
295
296	// no luck, try stealing a few times
297	for(25) {
298	if( __maybe_io_drain( this ) ) {
299	readyThread = pop_fast( this->cltr );
300	} else {
301	readyThread = pop_slow( this->cltr );
302	}
303	if(readyThread) { ready_schedule_unlock(); break SEARCH; }
304	}
305
306	// still no luck, search for a thread
307	readyThread = pop_search( this->cltr );
308	if(readyThread) { ready_schedule_unlock(); break SEARCH; }
309
310	// Don't block if we are done
311	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
312
313	__STATS( __tls_stats()->ready.sleep.halts++; )
314
315	// Push self to idle stack
316	ready_schedule_unlock();
317	mark_idle(this->cltr->procs, * this);
318	ready_schedule_lock();
319
320	// Confirm the ready-queue is empty
321	__maybe_io_drain( this );
322	readyThread = pop_search( this->cltr );
323	ready_schedule_unlock();
324
325	if( readyThread ) {
326	// A thread was found, cancel the halt
327	mark_awake(this->cltr->procs, * this);
328
329	__STATS( __tls_stats()->ready.sleep.cancels++; )
330
331	// continue the main loop
332	break SEARCH;
333	}
334
335	__STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->id, rdtscl()); )
336	__cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
337
338	// __disable_interrupts_hard();
339	eventfd_t val;
340	eventfd_read( this->idle, &val );
341	// __enable_interrupts_hard();
342
343	__STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->id, rdtscl()); )
344
345	// We were woken up, remove self from idle
346	mark_awake(this->cltr->procs, * this);
347
348	// DON'T just proceed, start looking again
349	continue MAIN_LOOP;
350	}
351
352	RUN_THREAD:
353	/* paranoid */ verify( kernelTLS().this_proc_id );
354	/* paranoid */ verify( ! __preemption_enabled() );
355	/* paranoid */ verify( readyThread );
356
357	// Reset io dirty bit
358	this->io.dirty = false;
359
360	// We found a thread run it
361	__run_thread(this, readyThread);
362
363	// Are we done?
364	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
365
366	#if !defined(__CFA_NO_STATISTICS__)
367	unsigned long long curr = rdtscl();
368	if(curr > (last_tally + 500000000)) {
369	__tally_stats(this->cltr->stats, __cfaabi_tls.this_stats);
370	last_tally = curr;
371	}
372	#endif
373
374	if(this->io.pending && !this->io.dirty) {
375	__cfa_io_flush( this );
376	}
377
378	ready_schedule_lock();
379	__maybe_io_drain( this );
380	ready_schedule_unlock();
381	#endif
382	}
383
384	__cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
385	}
386
387	__cfa_io_stop( this );
388
389	post( this->terminated );
390
391	if(this == mainProcessor) {
392	// HACK : the coroutine context switch expects this_thread to be set
393	// and it make sense for it to be set in all other cases except here
394	// fake it
395	__cfaabi_tls.this_thread = mainThread;
396	}
397
398	__cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
399	}
400
401	static int * __volatile_errno() __attribute__((noinline));
402	static int * __volatile_errno() { asm(""); return &errno; }
403
404	// KERNEL ONLY
405	// runThread runs a thread by context switching
406	// from the processor coroutine to the target thread
407	static void __run_thread(processor * this, $thread * thrd_dst) {
408	/* paranoid */ verify( ! __preemption_enabled() );
409	/* paranoid */ verifyf( thrd_dst->state == Ready \|\| thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
410	/* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
411	__builtin_prefetch( thrd_dst->context.SP );
412
413	__cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
414
415	$coroutine * proc_cor = get_coroutine(this->runner);
416
417	// set state of processor coroutine to inactive
418	verify(proc_cor->state == Active);
419	proc_cor->state = Blocked;
420
421	// Actually run the thread
422	RUNNING: while(true) {
423	thrd_dst->preempted = __NO_PREEMPTION;
424	thrd_dst->state = Active;
425
426	// Update global state
427	kernelTLS().this_thread = thrd_dst;
428
429	/* paranoid */ verify( ! __preemption_enabled() );
430	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
431	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
432	/* paranoid */ verify( thrd_dst->context.SP );
433	/* paranoid */ verify( thrd_dst->state != Halted );
434	/* 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
435	/* 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
436	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
437
438
439
440	// set context switch to the thread that the processor is executing
441	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
442	// when __cfactx_switch returns we are back in the processor coroutine
443
444	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
445	/* 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 );
446	/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ), "ERROR : Destination $thread %p has been corrupted.\n StackPointer too small.\n", thrd_dst );
447	/* paranoid */ verify( thrd_dst->context.SP );
448	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
449	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
450	/* paranoid */ verify( ! __preemption_enabled() );
451
452	// Reset global state
453	kernelTLS().this_thread = 0p;
454
455	// We just finished running a thread, there are a few things that could have happened.
456	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
457	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
458	// 4 - Preempted
459	// In case 1, we may have won a race so we can't write to the state again.
460	// In case 2, we lost the race so we now own the thread.
461
462	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
463	// The thread was preempted, reschedule it and reset the flag
464	schedule_thread$( thrd_dst );
465	break RUNNING;
466	}
467
468	if(unlikely(thrd_dst->state == Halting)) {
469	// The thread has halted, it should never be scheduled/run again
470	// finish the thread
471	__thread_finish( thrd_dst );
472	break RUNNING;
473	}
474
475	/* paranoid */ verify( thrd_dst->state == Active );
476	thrd_dst->state = Blocked;
477
478	// set state of processor coroutine to active and the thread to inactive
479	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
480	switch(old_ticket) {
481	case TICKET_RUNNING:
482	// This is case 1, the regular case, nothing more is needed
483	break RUNNING;
484	case TICKET_UNBLOCK:
485	#if !defined(__CFA_NO_STATISTICS__)
486	__tls_stats()->ready.threads.threads++;
487	__push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", this );
488	#endif
489	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
490	// In this case, just run it again.
491	continue RUNNING;
492	default:
493	// This makes no sense, something is wrong abort
494	abort();
495	}
496	}
497
498	// Just before returning to the processor, set the processor coroutine to active
499	proc_cor->state = Active;
500
501	__cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
502
503	#if !defined(__CFA_NO_STATISTICS__)
504	__tls_stats()->ready.threads.threads--;
505	__push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", this );
506	#endif
507
508	/* paranoid */ verify( ! __preemption_enabled() );
509	}
510
511	// KERNEL_ONLY
512	void returnToKernel() {
513	/* paranoid */ verify( ! __preemption_enabled() );
514	$coroutine * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
515	$thread * thrd_src = kernelTLS().this_thread;
516
517	__STATS( thrd_src->last_proc = kernelTLS().this_processor; )
518
519	// Run the thread on this processor
520	{
521	int local_errno = *__volatile_errno();
522	#if defined( __i386 ) \|\| defined( __x86_64 )
523	__x87_store;
524	#endif
525	/* paranoid */ verify( proc_cor->context.SP );
526	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
527	__cfactx_switch( &thrd_src->context, &proc_cor->context );
528	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
529	#if defined( __i386 ) \|\| defined( __x86_64 )
530	__x87_load;
531	#endif
532	*__volatile_errno() = local_errno;
533	}
534
535	#if !defined(__CFA_NO_STATISTICS__)
536	/* paranoid */ verify( thrd_src->last_proc != 0p );
537	if(thrd_src->last_proc != kernelTLS().this_processor) {
538	__tls_stats()->ready.threads.migration++;
539	}
540	#endif
541
542	/* paranoid */ verify( ! __preemption_enabled() );
543	/* 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 );
544	/* 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 );
545	}
546
547	//-----------------------------------------------------------------------------
548	// Scheduler routines
549	// KERNEL ONLY
550	static void __schedule_thread( $thread * thrd ) {
551	/* paranoid */ verify( ! __preemption_enabled() );
552	/* paranoid */ verify( ready_schedule_islocked());
553	/* paranoid */ verify( thrd );
554	/* paranoid */ verify( thrd->state != Halted );
555	/* paranoid */ verify( thrd->curr_cluster );
556	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
557	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
558	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
559	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
560	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
561	/* paranoid */ #endif
562	/* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
563	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
564
565
566	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
567
568	// Dereference the thread now because once we push it, there is not guaranteed it's still valid.
569	struct cluster * cl = thrd->curr_cluster;
570	__STATS(bool outside = thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
571
572	// push the thread to the cluster ready-queue
573	push( cl, thrd );
574
575	// variable thrd is no longer safe to use
576	thrd = 0xdeaddeaddeaddeadp;
577
578	// wake the cluster using the save variable.
579	__wake_one( cl );
580
581	#if !defined(__CFA_NO_STATISTICS__)
582	if( kernelTLS().this_stats ) {
583	__tls_stats()->ready.threads.threads++;
584	if(outside) {
585	__tls_stats()->ready.threads.extunpark++;
586	}
587	__push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", kernelTLS().this_processor );
588	}
589	else {
590	__atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
591	__atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
592	__push_stat( cl->stats, cl->stats->ready.threads.threads, true, "Cluster", cl );
593	}
594	#endif
595
596	/* paranoid */ verify( ready_schedule_islocked());
597	/* paranoid */ verify( ! __preemption_enabled() );
598	}
599
600	void schedule_thread$( $thread * thrd ) {
601	ready_schedule_lock();
602	__schedule_thread( thrd );
603	ready_schedule_unlock();
604	}
605
606	// KERNEL ONLY
607	static inline $thread * __next_thread(cluster * this) with( *this ) {
608	/* paranoid */ verify( ! __preemption_enabled() );
609
610	ready_schedule_lock();
611	$thread * thrd = pop_fast( this );
612	ready_schedule_unlock();
613
614	/* paranoid */ verify( ! __preemption_enabled() );
615	return thrd;
616	}
617
618	// KERNEL ONLY
619	static inline $thread * __next_thread_slow(cluster * this) with( *this ) {
620	/* paranoid */ verify( ! __preemption_enabled() );
621
622	ready_schedule_lock();
623	$thread * thrd;
624	for(25) {
625	thrd = pop_slow( this );
626	if(thrd) goto RET;
627	}
628	thrd = pop_search( this );
629
630	RET:
631	ready_schedule_unlock();
632
633	/* paranoid */ verify( ! __preemption_enabled() );
634	return thrd;
635	}
636
637	static inline bool __must_unpark( $thread * thrd ) {
638	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
639	switch(old_ticket) {
640	case TICKET_RUNNING:
641	// Wake won the race, the thread will reschedule/rerun itself
642	return false;
643	case TICKET_BLOCKED:
644	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
645	/* paranoid */ verify( thrd->state == Blocked );
646	return true;
647	default:
648	// This makes no sense, something is wrong abort
649	abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
650	}
651	}
652
653	void __kernel_unpark( $thread * thrd ) {
654	/* paranoid */ verify( ! __preemption_enabled() );
655	/* paranoid */ verify( ready_schedule_islocked());
656
657	if( !thrd ) return;
658
659	if(__must_unpark(thrd)) {
660	// Wake lost the race,
661	__schedule_thread( thrd );
662	}
663
664	/* paranoid */ verify( ready_schedule_islocked());
665	/* paranoid */ verify( ! __preemption_enabled() );
666	}
667
668	void unpark( $thread * thrd ) {
669	if( !thrd ) return;
670
671	if(__must_unpark(thrd)) {
672	disable_interrupts();
673	// Wake lost the race,
674	schedule_thread$( thrd );
675	enable_interrupts(false);
676	}
677	}
678
679	void park( void ) {
680	__disable_interrupts_checked();
681	/* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
682	returnToKernel();
683	__enable_interrupts_checked();
684
685	}
686
687	extern "C" {
688	// Leave the thread monitor
689	// last routine called by a thread.
690	// Should never return
691	void __cfactx_thrd_leave() {
692	$thread * thrd = active_thread();
693	$monitor * this = &thrd->self_mon;
694
695	// Lock the monitor now
696	lock( this->lock __cfaabi_dbg_ctx2 );
697
698	disable_interrupts();
699
700	/* paranoid */ verify( ! __preemption_enabled() );
701	/* paranoid */ verify( thrd->state == Active );
702	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
703	/* paranoid */ verify( kernelTLS().this_thread == thrd );
704	/* paranoid */ verify( thrd->context.SP );
705	/* 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 );
706	/* 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 );
707
708	thrd->state = Halting;
709	if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
710	if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
711	if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
712
713	// Leave the thread
714	returnToKernel();
715
716	// Control flow should never reach here!
717	abort();
718	}
719	}
720
721	// KERNEL ONLY
722	bool force_yield( __Preemption_Reason reason ) {
723	__disable_interrupts_checked();
724	$thread * thrd = kernelTLS().this_thread;
725	/* paranoid */ verify(thrd->state == Active);
726
727	// SKULLDUGGERY: It is possible that we are preempting this thread just before
728	// it was going to park itself. If that is the case and it is already using the
729	// intrusive fields then we can't use them to preempt the thread
730	// If that is the case, abandon the preemption.
731	bool preempted = false;
732	if(thrd->link.next == 0p) {
733	preempted = true;
734	thrd->preempted = reason;
735	returnToKernel();
736	}
737	__enable_interrupts_checked( false );
738	return preempted;
739	}
740
741	//=============================================================================================
742	// Kernel Idle Sleep
743	//=============================================================================================
744	// Wake a thread from the front if there are any
745	static void __wake_one(cluster * this) {
746	/* paranoid */ verify( ! __preemption_enabled() );
747	/* paranoid */ verify( ready_schedule_islocked() );
748
749	// Check if there is a sleeping processor
750	processor * p;
751	unsigned idle;
752	unsigned total;
753	[idle, total, p] = query_idles(this->procs);
754
755	// If no one is sleeping, we are done
756	if( idle == 0 ) return;
757
758	// We found a processor, wake it up
759	eventfd_t val;
760	val = 1;
761	eventfd_write( p->idle, val );
762
763	#if !defined(__CFA_NO_STATISTICS__)
764	if( kernelTLS().this_stats ) {
765	__tls_stats()->ready.sleep.wakes++;
766	}
767	else {
768	__atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED);
769	}
770	#endif
771
772	/* paranoid */ verify( ready_schedule_islocked() );
773	/* paranoid */ verify( ! __preemption_enabled() );
774
775	return;
776	}
777
778	// Unconditionnaly wake a thread
779	void __wake_proc(processor * this) {
780	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
781
782	__disable_interrupts_checked();
783	/* paranoid */ verify( ! __preemption_enabled() );
784	eventfd_t val;
785	val = 1;
786	eventfd_write( this->idle, val );
787	__enable_interrupts_checked();
788	}
789
790	static void mark_idle(__cluster_proc_list & this, processor & proc) {
791	/* paranoid */ verify( ! __preemption_enabled() );
792	lock( this );
793	this.idle++;
794	/* paranoid */ verify( this.idle <= this.total );
795	remove(proc);
796	insert_first(this.idles, proc);
797	unlock( this );
798	/* paranoid */ verify( ! __preemption_enabled() );
799	}
800
801	static void mark_awake(__cluster_proc_list & this, processor & proc) {
802	/* paranoid */ verify( ! __preemption_enabled() );
803	lock( this );
804	this.idle--;
805	/* paranoid */ verify( this.idle >= 0 );
806	remove(proc);
807	insert_last(this.actives, proc);
808	unlock( this );
809	/* paranoid */ verify( ! __preemption_enabled() );
810	}
811
812	static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list this ) {
813	/* paranoid */ verify( ! __preemption_enabled() );
814	/* paranoid */ verify( ready_schedule_islocked() );
815
816	for() {
817	uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
818	if( 1 == (l % 2) ) { Pause(); continue; }
819	unsigned idle = this.idle;
820	unsigned total = this.total;
821	processor * proc = &this.idles`first;
822	// Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
823	asm volatile("": : :"memory");
824	if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
825	return [idle, total, proc];
826	}
827
828	/* paranoid */ verify( ready_schedule_islocked() );
829	/* paranoid */ verify( ! __preemption_enabled() );
830	}
831
832	//=============================================================================================
833	// Unexpected Terminating logic
834	//=============================================================================================
835	void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
836	$thread * thrd = __cfaabi_tls.this_thread;
837
838	if(thrd) {
839	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
840	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
841
842	if ( &thrd->self_cor != thrd->curr_cor ) {
843	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
844	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
845	}
846	else {
847	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
848	}
849	}
850	else {
851	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
852	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
853	}
854	}
855
856	int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
857	return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
858	}
859
860	static __spinlock_t kernel_debug_lock;
861
862	extern "C" {
863	void __cfaabi_bits_acquire() {
864	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
865	}
866
867	void __cfaabi_bits_release() {
868	unlock( kernel_debug_lock );
869	}
870	}
871
872	//=============================================================================================
873	// Kernel Utilities
874	//=============================================================================================
875	#if defined(CFA_HAVE_LINUX_IO_URING_H)
876	#include "io/types.hfa"
877	#endif
878
879	static inline bool __maybe_io_drain( processor * proc ) {
880	bool ret = false;
881	#if defined(CFA_HAVE_LINUX_IO_URING_H)
882	__cfadbg_print_safe(runtime_core, "Kernel : core %p checking io for ring %d\n", proc, proc->io.ctx->fd);
883
884	// Check if we should drain the queue
885	$io_context * ctx = proc->io.ctx;
886	unsigned head = *ctx->cq.head;
887	unsigned tail = *ctx->cq.tail;
888	if(head == tail) return false;
889	ready_schedule_lock();
890	ret = __cfa_io_drain( proc );
891	ready_schedule_unlock();
892	#endif
893	return ret;
894	}
895
896	//-----------------------------------------------------------------------------
897	// Debug
898	__cfaabi_dbg_debug_do(
899	extern "C" {
900	void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
901	this.prev_name = prev_name;
902	this.prev_thrd = kernelTLS().this_thread;
903	}
904	}
905	)
906
907	//-----------------------------------------------------------------------------
908	// Debug
909	bool threading_enabled(void) __attribute__((const)) {
910	return true;
911	}
912
913	//-----------------------------------------------------------------------------
914	// Statistics
915	#if !defined(__CFA_NO_STATISTICS__)
916	void print_halts( processor & this ) {
917	this.print_halts = true;
918	}
919
920	void print_stats_now( cluster & this, int flags ) {
921	__print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
922	}
923	#endif
924	// Local Variables: //
925	// mode: c //
926	// tab-width: 4 //
927	// End: //

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