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kernel.cfa @ 8477fc4

ADTast-experimentalenumforall-pointer-decayjacob/cs343-translationnew-ast-unique-exprpthread-emulationqualifiedEnum

Last change on this file since 8477fc4 was e84ab3d, checked in by Thierry Delisle <tdelisle@…>, 3 years ago
Step 1 of changing $thread to thread$
Property mode set to `100644`
File size: 29.7 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 _GNU_SOURCE
18
19	// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
20
21	//C Includes
22	#include <errno.h>
23	#include <stdio.h>
24	#include <signal.h>
25	#include <unistd.h>
26	extern "C" {
27	#include <sys/eventfd.h>
28	}
29
30	//CFA Includes
31	#include "kernel_private.hfa"
32	#include "preemption.hfa"
33
34	//Private includes
35	#define __CFA_INVOKE_PRIVATE__
36	#include "invoke.h"
37
38	#if !defined(__CFA_NO_STATISTICS__)
39	#define __STATS( ...) __VA_ARGS__
40	#else
41	#define __STATS( ...)
42	#endif
43
44	//-----------------------------------------------------------------------------
45	// Some assembly required
46	#if defined( __i386 )
47	// mxcr : SSE Status and Control bits (control bits are preserved across function calls)
48	// fcw : X87 FPU control word (preserved across function calls)
49	#define __x87_store \
50	uint32_t __mxcr; \
51	uint16_t __fcw; \
52	__asm__ volatile ( \
53	"stmxcsr %0\n" \
54	"fnstcw %1\n" \
55	: "=m" (__mxcr),\
56	"=m" (__fcw) \
57	)
58
59	#define __x87_load \
60	__asm__ volatile ( \
61	"fldcw %1\n" \
62	"ldmxcsr %0\n" \
63	::"m" (__mxcr),\
64	"m" (__fcw) \
65	)
66
67	#elif defined( __x86_64 )
68	#define __x87_store \
69	uint32_t __mxcr; \
70	uint16_t __fcw; \
71	__asm__ volatile ( \
72	"stmxcsr %0\n" \
73	"fnstcw %1\n" \
74	: "=m" (__mxcr),\
75	"=m" (__fcw) \
76	)
77
78	#define __x87_load \
79	__asm__ volatile ( \
80	"fldcw %1\n" \
81	"ldmxcsr %0\n" \
82	:: "m" (__mxcr),\
83	"m" (__fcw) \
84	)
85
86	#elif defined( __arm__ )
87	#define __x87_store
88	#define __x87_load
89
90	#elif defined( __aarch64__ )
91	#define __x87_store \
92	uint32_t __fpcntl[2]; \
93	__asm__ volatile ( \
94	"mrs x9, FPCR\n" \
95	"mrs x10, FPSR\n" \
96	"stp x9, x10, %0\n" \
97	: "=m" (__fpcntl) : : "x9", "x10" \
98	)
99
100	#define __x87_load \
101	__asm__ volatile ( \
102	"ldp x9, x10, %0\n" \
103	"msr FPSR, x10\n" \
104	"msr FPCR, x9\n" \
105	: "=m" (__fpcntl) : : "x9", "x10" \
106	)
107
108	#else
109	#error unsupported hardware architecture
110	#endif
111
112	extern thread$ * mainThread;
113	extern processor * mainProcessor;
114
115	//-----------------------------------------------------------------------------
116	// Kernel Scheduling logic
117	static thread$ * __next_thread(cluster * this);
118	static thread$ * __next_thread_slow(cluster * this);
119	static inline bool __must_unpark( thread$ * thrd ) __attribute((nonnull(1)));
120	static void __run_thread(processor * this, thread$ * dst);
121	static void __wake_one(cluster * cltr);
122
123	static void mark_idle (__cluster_proc_list & idles, processor & proc);
124	static void mark_awake(__cluster_proc_list & idles, processor & proc);
125	static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list idles );
126
127	extern void __cfa_io_start( processor * );
128	extern bool __cfa_io_drain( processor * );
129	extern void __cfa_io_flush( processor * );
130	extern void __cfa_io_stop ( processor * );
131	static inline bool __maybe_io_drain( processor * );
132
133	extern void __disable_interrupts_hard();
134	extern void __enable_interrupts_hard();
135
136	static inline void __disable_interrupts_checked() {
137	/* paranoid */ verify( __preemption_enabled() );
138	disable_interrupts();
139	/* paranoid */ verify( ! __preemption_enabled() );
140	}
141
142	static inline void __enable_interrupts_checked( bool poll = true ) {
143	/* paranoid */ verify( ! __preemption_enabled() );
144	enable_interrupts( poll );
145	/* paranoid */ verify( __preemption_enabled() );
146	}
147
148	//=============================================================================================
149	// Kernel Scheduling logic
150	//=============================================================================================
151	//Main of the processor contexts
152	void main(processorCtx_t & runner) {
153	// Because of a bug, we couldn't initialized the seed on construction
154	// Do it here
155	__cfaabi_tls.rand_seed ^= rdtscl();
156	__cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
157	__tls_rand_advance_bck();
158
159	processor * this = runner.proc;
160	verify(this);
161
162	__cfa_io_start( this );
163
164	__cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
165	#if !defined(__CFA_NO_STATISTICS__)
166	if( this->print_halts ) {
167	__cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
168	}
169	#endif
170
171	{
172	// Setup preemption data
173	preemption_scope scope = { this };
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	#define OLD_MAIN 1
187	#if OLD_MAIN
188	// Check if there is pending io
189	__maybe_io_drain( this );
190
191	// Try to get the next thread
192	readyThread = __next_thread( this->cltr );
193
194	if( !readyThread ) {
195	__cfa_io_flush( this );
196	readyThread = __next_thread_slow( this->cltr );
197	}
198
199	HALT:
200	if( !readyThread ) {
201	// Don't block if we are done
202	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
203
204	#if !defined(__CFA_NO_STATISTICS__)
205	__tls_stats()->ready.sleep.halts++;
206	#endif
207
208	// Push self to idle stack
209	mark_idle(this->cltr->procs, * this);
210
211	// Confirm the ready-queue is empty
212	readyThread = __next_thread_slow( this->cltr );
213	if( readyThread ) {
214	// A thread was found, cancel the halt
215	mark_awake(this->cltr->procs, * this);
216
217	#if !defined(__CFA_NO_STATISTICS__)
218	__tls_stats()->ready.sleep.cancels++;
219	#endif
220
221	// continue the mai loop
222	break HALT;
223	}
224
225	#if !defined(__CFA_NO_STATISTICS__)
226	if(this->print_halts) {
227	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
228	}
229	#endif
230
231	__cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
232
233	__disable_interrupts_hard();
234	eventfd_t val;
235	eventfd_read( this->idle, &val );
236	__enable_interrupts_hard();
237
238	#if !defined(__CFA_NO_STATISTICS__)
239	if(this->print_halts) {
240	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
241	}
242	#endif
243
244	// We were woken up, remove self from idle
245	mark_awake(this->cltr->procs, * this);
246
247	// DON'T just proceed, start looking again
248	continue MAIN_LOOP;
249	}
250
251	/* paranoid */ verify( readyThread );
252
253	// Reset io dirty bit
254	this->io.dirty = false;
255
256	// We found a thread run it
257	__run_thread(this, readyThread);
258
259	// Are we done?
260	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
261
262	if(this->io.pending && !this->io.dirty) {
263	__cfa_io_flush( this );
264	}
265
266	#else
267	#warning new kernel loop
268	SEARCH: {
269	/* paranoid */ verify( ! __preemption_enabled() );
270
271	// First, lock the scheduler since we are searching for a thread
272	ready_schedule_lock();
273
274	// Try to get the next thread
275	readyThread = pop_fast( this->cltr );
276	if(readyThread) { ready_schedule_unlock(); break SEARCH; }
277
278	// If we can't find a thread, might as well flush any outstanding I/O
279	if(this->io.pending) { __cfa_io_flush( this ); }
280
281	// Spin a little on I/O, just in case
282	for(5) {
283	__maybe_io_drain( this );
284	readyThread = pop_fast( this->cltr );
285	if(readyThread) { ready_schedule_unlock(); break SEARCH; }
286	}
287
288	// no luck, try stealing a few times
289	for(5) {
290	if( __maybe_io_drain( this ) ) {
291	readyThread = pop_fast( this->cltr );
292	} else {
293	readyThread = pop_slow( this->cltr );
294	}
295	if(readyThread) { ready_schedule_unlock(); break SEARCH; }
296	}
297
298	// still no luck, search for a thread
299	readyThread = pop_search( this->cltr );
300	if(readyThread) { ready_schedule_unlock(); break SEARCH; }
301
302	// Don't block if we are done
303	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
304
305	__STATS( __tls_stats()->ready.sleep.halts++; )
306
307	// Push self to idle stack
308	ready_schedule_unlock();
309	mark_idle(this->cltr->procs, * this);
310	ready_schedule_lock();
311
312	// Confirm the ready-queue is empty
313	__maybe_io_drain( this );
314	readyThread = pop_search( this->cltr );
315	ready_schedule_unlock();
316
317	if( readyThread ) {
318	// A thread was found, cancel the halt
319	mark_awake(this->cltr->procs, * this);
320
321	__STATS( __tls_stats()->ready.sleep.cancels++; )
322
323	// continue the main loop
324	break SEARCH;
325	}
326
327	__STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl()); )
328	__cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
329
330	// __disable_interrupts_hard();
331	eventfd_t val;
332	eventfd_read( this->idle, &val );
333	// __enable_interrupts_hard();
334
335	__STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl()); )
336
337	// We were woken up, remove self from idle
338	mark_awake(this->cltr->procs, * this);
339
340	// DON'T just proceed, start looking again
341	continue MAIN_LOOP;
342	}
343
344	RUN_THREAD:
345	/* paranoid */ verify( ! __preemption_enabled() );
346	/* paranoid */ verify( readyThread );
347
348	// Reset io dirty bit
349	this->io.dirty = false;
350
351	// We found a thread run it
352	__run_thread(this, readyThread);
353
354	// Are we done?
355	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
356
357	if(this->io.pending && !this->io.dirty) {
358	__cfa_io_flush( this );
359	}
360
361	ready_schedule_lock();
362	__maybe_io_drain( this );
363	ready_schedule_unlock();
364	#endif
365	}
366
367	__cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
368	}
369
370	__cfa_io_stop( this );
371
372	post( this->terminated );
373
374	if(this == mainProcessor) {
375	// HACK : the coroutine context switch expects this_thread to be set
376	// and it make sense for it to be set in all other cases except here
377	// fake it
378	__cfaabi_tls.this_thread = mainThread;
379	}
380
381	__cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
382	}
383
384	static int * __volatile_errno() __attribute__((noinline));
385	static int * __volatile_errno() { asm(""); return &errno; }
386
387	// KERNEL ONLY
388	// runThread runs a thread by context switching
389	// from the processor coroutine to the target thread
390	static void __run_thread(processor * this, thread$ * thrd_dst) {
391	/* paranoid */ verify( ! __preemption_enabled() );
392	/* paranoid */ verifyf( thrd_dst->state == Ready \|\| thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
393	/* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
394	__builtin_prefetch( thrd_dst->context.SP );
395
396	__cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
397
398	coroutine$ * proc_cor = get_coroutine(this->runner);
399
400	// set state of processor coroutine to inactive
401	verify(proc_cor->state == Active);
402	proc_cor->state = Blocked;
403
404	// Actually run the thread
405	RUNNING: while(true) {
406	thrd_dst->preempted = __NO_PREEMPTION;
407	thrd_dst->state = Active;
408
409	// Update global state
410	kernelTLS().this_thread = thrd_dst;
411
412	/* paranoid */ verify( ! __preemption_enabled() );
413	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
414	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
415	/* paranoid */ verify( thrd_dst->context.SP );
416	/* paranoid */ verify( thrd_dst->state != Halted );
417	/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ) \|\| thrd_dst->curr_cor == proc_cor \|\| thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too small.\n", thrd_dst ); // add escape condition if we are setting up the processor
418	/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit) \|\| thrd_dst->curr_cor == proc_cor \|\| thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too large.\n", thrd_dst ); // add escape condition if we are setting up the processor
419	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
420
421
422
423	// set context switch to the thread that the processor is executing
424	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
425	// when __cfactx_switch returns we are back in the processor coroutine
426
427
428
429	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
430	/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit) \|\| thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too large.\n", thrd_dst );
431	/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ) \|\| thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too small.\n", thrd_dst );
432	/* paranoid */ verify( thrd_dst->context.SP );
433	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
434	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
435	/* paranoid */ verify( ! __preemption_enabled() );
436
437	// Reset global state
438	kernelTLS().this_thread = 0p;
439
440	// We just finished running a thread, there are a few things that could have happened.
441	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
442	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
443	// 4 - Preempted
444	// In case 1, we may have won a race so we can't write to the state again.
445	// In case 2, we lost the race so we now own the thread.
446
447	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
448	// The thread was preempted, reschedule it and reset the flag
449	schedule_thread$( thrd_dst );
450	break RUNNING;
451	}
452
453	if(unlikely(thrd_dst->state == Halting)) {
454	// The thread has halted, it should never be scheduled/run again
455	// finish the thread
456	__thread_finish( thrd_dst );
457	break RUNNING;
458	}
459
460	/* paranoid */ verify( thrd_dst->state == Active );
461	thrd_dst->state = Blocked;
462
463	// set state of processor coroutine to active and the thread to inactive
464	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
465	switch(old_ticket) {
466	case TICKET_RUNNING:
467	// This is case 1, the regular case, nothing more is needed
468	break RUNNING;
469	case TICKET_UNBLOCK:
470	#if !defined(__CFA_NO_STATISTICS__)
471	__tls_stats()->ready.threads.threads++;
472	__push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", this );
473	#endif
474	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
475	// In this case, just run it again.
476	continue RUNNING;
477	default:
478	// This makes no sense, something is wrong abort
479	abort();
480	}
481	}
482
483	// Just before returning to the processor, set the processor coroutine to active
484	proc_cor->state = Active;
485
486	__cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
487
488	#if !defined(__CFA_NO_STATISTICS__)
489	__tls_stats()->ready.threads.threads--;
490	__push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", this );
491	#endif
492
493	/* paranoid */ verify( ! __preemption_enabled() );
494	}
495
496	// KERNEL_ONLY
497	void returnToKernel() {
498	/* paranoid */ verify( ! __preemption_enabled() );
499	coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
500	thread$ * thrd_src = kernelTLS().this_thread;
501
502	__STATS( thrd_src->last_proc = kernelTLS().this_processor; )
503
504	// Run the thread on this processor
505	{
506	int local_errno = *__volatile_errno();
507	#if defined( __i386 ) \|\| defined( __x86_64 )
508	__x87_store;
509	#endif
510	/* paranoid */ verify( proc_cor->context.SP );
511	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
512	__cfactx_switch( &thrd_src->context, &proc_cor->context );
513	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
514	#if defined( __i386 ) \|\| defined( __x86_64 )
515	__x87_load;
516	#endif
517	*__volatile_errno() = local_errno;
518	}
519
520	#if !defined(__CFA_NO_STATISTICS__)
521	/* paranoid */ verify( thrd_src->last_proc != 0p );
522	if(thrd_src->last_proc != kernelTLS().this_processor) {
523	__tls_stats()->ready.threads.migration++;
524	}
525	#endif
526
527	/* paranoid */ verify( ! __preemption_enabled() );
528	/* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) < ((uintptr_t)__get_stack(thrd_src->curr_cor)->base ) \|\| thrd_src->corctx_flag, "ERROR : Returning thread$ %p has been corrupted.\n StackPointer too small.\n", thrd_src );
529	/* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) > ((uintptr_t)__get_stack(thrd_src->curr_cor)->limit) \|\| thrd_src->corctx_flag, "ERROR : Returning thread$ %p has been corrupted.\n StackPointer too large.\n", thrd_src );
530	}
531
532	//-----------------------------------------------------------------------------
533	// Scheduler routines
534	// KERNEL ONLY
535	static void __schedule_thread( thread$ * thrd ) {
536	/* paranoid */ verify( ! __preemption_enabled() );
537	/* paranoid */ verify( ready_schedule_islocked());
538	/* paranoid */ verify( thrd );
539	/* paranoid */ verify( thrd->state != Halted );
540	/* paranoid */ verify( thrd->curr_cluster );
541	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
542	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
543	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
544	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
545	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
546	/* paranoid */ #endif
547	/* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
548	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
549
550	const bool local = thrd->state != Start;
551	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
552
553	// Dereference the thread now because once we push it, there is not guaranteed it's still valid.
554	struct cluster * cl = thrd->curr_cluster;
555	__STATS(bool outside = thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
556
557	// push the thread to the cluster ready-queue
558	push( cl, thrd, local );
559
560	// variable thrd is no longer safe to use
561	thrd = 0xdeaddeaddeaddeadp;
562
563	// wake the cluster using the save variable.
564	__wake_one( cl );
565
566	#if !defined(__CFA_NO_STATISTICS__)
567	if( kernelTLS().this_stats ) {
568	__tls_stats()->ready.threads.threads++;
569	if(outside) {
570	__tls_stats()->ready.threads.extunpark++;
571	}
572	__push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", kernelTLS().this_processor );
573	}
574	else {
575	__atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
576	__atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
577	__push_stat( cl->stats, cl->stats->ready.threads.threads, true, "Cluster", cl );
578	}
579	#endif
580
581	/* paranoid */ verify( ready_schedule_islocked());
582	/* paranoid */ verify( ! __preemption_enabled() );
583	}
584
585	void schedule_thread$( thread$ * thrd ) {
586	ready_schedule_lock();
587	__schedule_thread( thrd );
588	ready_schedule_unlock();
589	}
590
591	// KERNEL ONLY
592	static inline thread$ * __next_thread(cluster * this) with( *this ) {
593	/* paranoid */ verify( ! __preemption_enabled() );
594
595	ready_schedule_lock();
596	thread$ * thrd = pop_fast( this );
597	ready_schedule_unlock();
598
599	/* paranoid */ verify( ! __preemption_enabled() );
600	return thrd;
601	}
602
603	// KERNEL ONLY
604	static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
605	/* paranoid */ verify( ! __preemption_enabled() );
606
607	ready_schedule_lock();
608	thread$ * thrd;
609	for(25) {
610	thrd = pop_slow( this );
611	if(thrd) goto RET;
612	}
613	thrd = pop_search( this );
614
615	RET:
616	ready_schedule_unlock();
617
618	/* paranoid */ verify( ! __preemption_enabled() );
619	return thrd;
620	}
621
622	static inline bool __must_unpark( thread$ * thrd ) {
623	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
624	switch(old_ticket) {
625	case TICKET_RUNNING:
626	// Wake won the race, the thread will reschedule/rerun itself
627	return false;
628	case TICKET_BLOCKED:
629	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
630	/* paranoid */ verify( thrd->state == Blocked );
631	return true;
632	default:
633	// This makes no sense, something is wrong abort
634	abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
635	}
636	}
637
638	void __kernel_unpark( thread$ * thrd ) {
639	/* paranoid */ verify( ! __preemption_enabled() );
640	/* paranoid */ verify( ready_schedule_islocked());
641
642	if( !thrd ) return;
643
644	if(__must_unpark(thrd)) {
645	// Wake lost the race,
646	__schedule_thread( thrd );
647	}
648
649	/* paranoid */ verify( ready_schedule_islocked());
650	/* paranoid */ verify( ! __preemption_enabled() );
651	}
652
653	void unpark( thread$ * thrd ) {
654	if( !thrd ) return;
655
656	if(__must_unpark(thrd)) {
657	disable_interrupts();
658	// Wake lost the race,
659	schedule_thread$( thrd );
660	enable_interrupts(false);
661	}
662	}
663
664	void park( void ) {
665	__disable_interrupts_checked();
666	/* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
667	returnToKernel();
668	__enable_interrupts_checked();
669
670	}
671
672	extern "C" {
673	// Leave the thread monitor
674	// last routine called by a thread.
675	// Should never return
676	void __cfactx_thrd_leave() {
677	thread$ * thrd = active_thread();
678	monitor$ * this = &thrd->self_mon;
679
680	// Lock the monitor now
681	lock( this->lock __cfaabi_dbg_ctx2 );
682
683	disable_interrupts();
684
685	/* paranoid */ verify( ! __preemption_enabled() );
686	/* paranoid */ verify( thrd->state == Active );
687	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
688	/* paranoid */ verify( kernelTLS().this_thread == thrd );
689	/* paranoid */ verify( thrd->context.SP );
690	/* 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 );
691	/* 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 );
692
693	thrd->state = Halting;
694	if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
695	if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
696	if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
697
698	// Leave the thread
699	returnToKernel();
700
701	// Control flow should never reach here!
702	abort();
703	}
704	}
705
706	// KERNEL ONLY
707	bool force_yield( __Preemption_Reason reason ) {
708	__disable_interrupts_checked();
709	thread$ * thrd = kernelTLS().this_thread;
710	/* paranoid */ verify(thrd->state == Active);
711
712	// SKULLDUGGERY: It is possible that we are preempting this thread just before
713	// it was going to park itself. If that is the case and it is already using the
714	// intrusive fields then we can't use them to preempt the thread
715	// If that is the case, abandon the preemption.
716	bool preempted = false;
717	if(thrd->link.next == 0p) {
718	preempted = true;
719	thrd->preempted = reason;
720	returnToKernel();
721	}
722	__enable_interrupts_checked( false );
723	return preempted;
724	}
725
726	//=============================================================================================
727	// Kernel Idle Sleep
728	//=============================================================================================
729	// Wake a thread from the front if there are any
730	static void __wake_one(cluster * this) {
731	/* paranoid */ verify( ! __preemption_enabled() );
732	/* paranoid */ verify( ready_schedule_islocked() );
733
734	// Check if there is a sleeping processor
735	processor * p;
736	unsigned idle;
737	unsigned total;
738	[idle, total, p] = query_idles(this->procs);
739
740	// If no one is sleeping, we are done
741	if( idle == 0 ) return;
742
743	// We found a processor, wake it up
744	eventfd_t val;
745	val = 1;
746	eventfd_write( p->idle, val );
747
748	#if !defined(__CFA_NO_STATISTICS__)
749	if( kernelTLS().this_stats ) {
750	__tls_stats()->ready.sleep.wakes++;
751	}
752	else {
753	__atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED);
754	}
755	#endif
756
757	/* paranoid */ verify( ready_schedule_islocked() );
758	/* paranoid */ verify( ! __preemption_enabled() );
759
760	return;
761	}
762
763	// Unconditionnaly wake a thread
764	void __wake_proc(processor * this) {
765	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
766
767	__disable_interrupts_checked();
768	/* paranoid */ verify( ! __preemption_enabled() );
769	eventfd_t val;
770	val = 1;
771	eventfd_write( this->idle, val );
772	__enable_interrupts_checked();
773	}
774
775	static void mark_idle(__cluster_proc_list & this, processor & proc) {
776	/* paranoid */ verify( ! __preemption_enabled() );
777	lock( this );
778	this.idle++;
779	/* paranoid */ verify( this.idle <= this.total );
780	remove(proc);
781	insert_first(this.idles, proc);
782	unlock( this );
783	/* paranoid */ verify( ! __preemption_enabled() );
784	}
785
786	static void mark_awake(__cluster_proc_list & this, processor & proc) {
787	/* paranoid */ verify( ! __preemption_enabled() );
788	lock( this );
789	this.idle--;
790	/* paranoid */ verify( this.idle >= 0 );
791	remove(proc);
792	insert_last(this.actives, proc);
793	unlock( this );
794	/* paranoid */ verify( ! __preemption_enabled() );
795	}
796
797	static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list this ) {
798	/* paranoid */ verify( ! __preemption_enabled() );
799	/* paranoid */ verify( ready_schedule_islocked() );
800
801	for() {
802	uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
803	if( 1 == (l % 2) ) { Pause(); continue; }
804	unsigned idle = this.idle;
805	unsigned total = this.total;
806	processor * proc = &this.idles`first;
807	// Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
808	asm volatile("": : :"memory");
809	if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
810	return [idle, total, proc];
811	}
812
813	/* paranoid */ verify( ready_schedule_islocked() );
814	/* paranoid */ verify( ! __preemption_enabled() );
815	}
816
817	//=============================================================================================
818	// Unexpected Terminating logic
819	//=============================================================================================
820	void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
821	thread$ * thrd = __cfaabi_tls.this_thread;
822
823	if(thrd) {
824	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
825	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
826
827	if ( &thrd->self_cor != thrd->curr_cor ) {
828	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
829	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
830	}
831	else {
832	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
833	}
834	}
835	else {
836	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
837	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
838	}
839	}
840
841	int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
842	return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
843	}
844
845	static __spinlock_t kernel_debug_lock;
846
847	extern "C" {
848	void __cfaabi_bits_acquire() {
849	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
850	}
851
852	void __cfaabi_bits_release() {
853	unlock( kernel_debug_lock );
854	}
855	}
856
857	//=============================================================================================
858	// Kernel Utilities
859	//=============================================================================================
860	#if defined(CFA_HAVE_LINUX_IO_URING_H)
861	#include "io/types.hfa"
862	#endif
863
864	static inline bool __maybe_io_drain( processor * proc ) {
865	bool ret = false;
866	#if defined(CFA_HAVE_LINUX_IO_URING_H)
867	__cfadbg_print_safe(runtime_core, "Kernel : core %p checking io for ring %d\n", proc, proc->io.ctx->fd);
868
869	// Check if we should drain the queue
870	$io_context * ctx = proc->io.ctx;
871	unsigned head = *ctx->cq.head;
872	unsigned tail = *ctx->cq.tail;
873	if(head == tail) return false;
874	#if OLD_MAIN
875	ready_schedule_lock();
876	ret = __cfa_io_drain( proc );
877	ready_schedule_unlock();
878	#else
879	ret = __cfa_io_drain( proc );
880	#endif
881	#endif
882	return ret;
883	}
884
885	//-----------------------------------------------------------------------------
886	// Debug
887	__cfaabi_dbg_debug_do(
888	extern "C" {
889	void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
890	this.prev_name = prev_name;
891	this.prev_thrd = kernelTLS().this_thread;
892	}
893	}
894	)
895
896	//-----------------------------------------------------------------------------
897	// Debug
898	bool threading_enabled(void) __attribute__((const)) {
899	return true;
900	}
901
902	//-----------------------------------------------------------------------------
903	// Statistics
904	#if !defined(__CFA_NO_STATISTICS__)
905	void print_halts( processor & this ) {
906	this.print_halts = true;
907	}
908
909	static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
910	/* paranoid */ verify( cltr->stats );
911
912	processor * it = &list`first;
913	for(unsigned i = 0; i < count; i++) {
914	/* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
915	/* paranoid */ verify( it->local_data->this_stats );
916	__tally_stats( cltr->stats, it->local_data->this_stats );
917	it = &(*it)`next;
918	}
919	}
920
921	void crawl_cluster_stats( cluster & this ) {
922	// Stop the world, otherwise stats could get really messed-up
923	// this doesn't solve all problems but does solve many
924	// so it's probably good enough
925	uint_fast32_t last_size = ready_mutate_lock();
926
927	crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
928	crawl_list(&this, this.procs.idles , this.procs.idle );
929
930	// Unlock the RWlock
931	ready_mutate_unlock( last_size );
932	}
933
934
935	void print_stats_now( cluster & this, int flags ) {
936	crawl_cluster_stats( this );
937	__print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
938	}
939	#endif
940	// Local Variables: //
941	// mode: c //
942	// tab-width: 4 //
943	// End: //

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