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kernel.cfa @ 08e0d65

Last change on this file since 08e0d65 was b93bf85, checked in by caparsons <caparson@…>, 17 months ago
fixed spurious channel close waituntil error case. Was caused by a race condition causing an exception to be thrown while another was in flight
Property mode set to `100644`
File size: 28.6 KB

Line
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 Jan 9 08:42:05 2023
13	// Update Count : 77
14	//
15
16	#define __cforall_thread__
17
18	// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
19
20	#pragma GCC diagnostic push
21	#pragma GCC diagnostic ignored "-Waddress-of-packed-member"
22
23	//C Includes
24	#include <errno.h>
25	#include <stdio.h>
26	#include <string.h>
27	#include <signal.h>
28	#include <unistd.h>
29
30	extern "C" {
31	#include <sys/eventfd.h>
32	#include <sys/uio.h>
33	}
34
35	//CFA Includes
36	#include "kernel/private.hfa"
37	#include "preemption.hfa"
38	#include "strstream.hfa"
39	#include "device/cpu.hfa"
40	#include "io/types.hfa"
41
42	//Private includes
43	#define __CFA_INVOKE_PRIVATE__
44	#include "invoke.h"
45	#pragma GCC diagnostic pop
46
47	#if !defined(__CFA_NO_STATISTICS__)
48	#define __STATS_DEF( ...) __VA_ARGS__
49	#else
50	#define __STATS_DEF( ...)
51	#endif
52
53	//-----------------------------------------------------------------------------
54	// Some assembly required
55	#if defined( __i386 )
56	// mxcr : SSE Status and Control bits (control bits are preserved across function calls)
57	// fcw : X87 FPU control word (preserved across function calls)
58	#define __x87_store \
59	uint32_t __mxcr; \
60	uint16_t __fcw; \
61	__asm__ volatile ( \
62	"stmxcsr %0\n" \
63	"fnstcw %1\n" \
64	: "=m" (__mxcr),\
65	"=m" (__fcw) \
66	)
67
68	#define __x87_load \
69	__asm__ volatile ( \
70	"fldcw %1\n" \
71	"ldmxcsr %0\n" \
72	::"m" (__mxcr),\
73	"m" (__fcw) \
74	)
75
76	#elif defined( __x86_64 )
77	#define __x87_store \
78	uint32_t __mxcr; \
79	uint16_t __fcw; \
80	__asm__ volatile ( \
81	"stmxcsr %0\n" \
82	"fnstcw %1\n" \
83	: "=m" (__mxcr),\
84	"=m" (__fcw) \
85	)
86
87	#define __x87_load \
88	__asm__ volatile ( \
89	"fldcw %1\n" \
90	"ldmxcsr %0\n" \
91	:: "m" (__mxcr),\
92	"m" (__fcw) \
93	)
94
95	#elif defined( __arm__ )
96	#define __x87_store
97	#define __x87_load
98
99	#elif defined( __aarch64__ )
100	#define __x87_store \
101	uint32_t __fpcntl[2]; \
102	__asm__ volatile ( \
103	"mrs x9, FPCR\n" \
104	"mrs x10, FPSR\n" \
105	"stp x9, x10, %0\n" \
106	: "=m" (__fpcntl) : : "x9", "x10" \
107	)
108
109	#define __x87_load \
110	__asm__ volatile ( \
111	"ldp x9, x10, %0\n" \
112	"msr FPSR, x10\n" \
113	"msr FPCR, x9\n" \
114	: "=m" (__fpcntl) : : "x9", "x10" \
115	)
116
117	#else
118	#error unsupported hardware architecture
119	#endif
120
121	extern thread$ * mainThread;
122	extern processor * mainProcessor;
123
124	//-----------------------------------------------------------------------------
125	// Kernel Scheduling logic
126	static thread$ * __next_thread(cluster * this);
127	static thread$ * __next_thread_slow(cluster * this);
128	static thread$ * __next_thread_search(cluster * this);
129	static inline bool __must_unpark( thread$ * thrd ) __attribute((nonnull(1)));
130	static void __run_thread(processor * this, thread$ * dst);
131	static void __wake_one(cluster * cltr);
132
133	static void idle_sleep(processor * proc);
134	static bool mark_idle (__cluster_proc_list & idles, processor & proc);
135	static void mark_awake(__cluster_proc_list & idles, processor & proc);
136
137	extern bool __cfa_io_drain( processor * proc ) __attribute__((nonnull (1)));
138	extern bool __cfa_io_flush( processor * ) __attribute__((nonnull (1)));
139
140
141	extern void __disable_interrupts_hard();
142	extern void __enable_interrupts_hard();
143
144
145	//=============================================================================================
146	// Kernel Scheduling logic
147	//=============================================================================================
148	//Main of the processor contexts
149	void main(processorCtx_t & runner) {
150	// Because of a bug, we couldn't initialized the seed on construction
151	// Do it here
152	PRNG_SET_SEED( __cfaabi_tls.random_state, rdtscl() );
153	__cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
154	__tls_rand_advance_bck();
155
156	processor * this = runner.proc;
157	verify(this);
158
159	__cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
160	#if !defined(__CFA_NO_STATISTICS__)
161	if( this->print_halts ) {
162	__cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
163	}
164	#endif
165
166	{
167	// Setup preemption data
168	preemption_scope scope = { this };
169
170	// if we need to run some special setup, now is the time to do it.
171	if(this->init.thrd) {
172	this->init.thrd->curr_cluster = this->cltr;
173	__run_thread(this, this->init.thrd);
174	}
175
176	__cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
177
178	thread$ * readyThread = 0p;
179	MAIN_LOOP:
180	for() {
181	// Check if there is pending io
182	__cfa_io_drain( this );
183
184	// Try to get the next thread
185	readyThread = __next_thread( this->cltr );
186
187	if( !readyThread ) {
188	// there is no point in holding submissions if we are idle
189	__IO_STATS__(true, io.flush.idle++; )
190	__cfa_io_flush( this );
191
192	// drain again in case something showed up
193	__cfa_io_drain( this );
194
195	readyThread = __next_thread( this->cltr );
196	}
197
198	if( !readyThread ) for(5) {
199	readyThread = __next_thread_slow( this->cltr );
200
201	if( readyThread ) break;
202
203	// It's unlikely we still I/O to submit, but the arbiter could
204	__IO_STATS__(true, io.flush.idle++; )
205	__cfa_io_flush( this );
206
207	// drain again in case something showed up
208	__cfa_io_drain( this );
209	}
210
211	HALT:
212	if( !readyThread ) {
213	// Don't block if we are done
214	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
215
216	// Push self to idle stack
217	if(!mark_idle(this->cltr->procs, * this)) continue MAIN_LOOP;
218
219	// Confirm the ready-queue is empty
220	readyThread = __next_thread_search( this->cltr );
221	if( readyThread ) {
222	// A thread was found, cancel the halt
223	mark_awake(this->cltr->procs, * this);
224
225	__STATS__(true, ready.sleep.cancels++; )
226
227	// continue the mai loop
228	break HALT;
229	}
230
231	idle_sleep( this );
232
233	// We were woken up, remove self from idle
234	mark_awake(this->cltr->procs, * this);
235
236	// DON'T just proceed, start looking again
237	continue MAIN_LOOP;
238	}
239
240	/* paranoid */ verify( readyThread );
241
242	// Reset io dirty bit
243	this->io.dirty = false;
244
245	// We found a thread run it
246	__run_thread(this, readyThread);
247
248	// Are we done?
249	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
250
251	if(__atomic_load_n(&this->io.pending, __ATOMIC_RELAXED) && !__atomic_load_n(&this->io.dirty, __ATOMIC_RELAXED)) {
252	__IO_STATS__(true, io.flush.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_flush( this );
261	__cfa_io_drain( this );
262
263	post( this->terminated );
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->rdy_link.next == 0p, "Expected null got %p", thrd_dst->rdy_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
299	// Update global state
300	kernelTLS().this_thread = thrd_dst;
301
302	// Update the state after setting this_thread
303	// so that the debugger can find all active threads
304	// in tls storage
305	thrd_dst->state = Active;
306
307	/* paranoid */ verify( ! __preemption_enabled() );
308	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
309	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
310	/* paranoid */ verify( thrd_dst->context.SP );
311	/* paranoid */ verify( thrd_dst->state != Halted );
312	/* 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
313	/* 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
314	/* paranoid */ verify( __atomic_exchange_n( &thrd_dst->executing, this, __ATOMIC_SEQ_CST) == 0p );
315	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
316
317
318
319	// set context switch to the thread that the processor is executing
320	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
321	// when __cfactx_switch returns we are back in the processor coroutine
322
323
324
325	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
326	/* paranoid */ verify( __atomic_exchange_n( &thrd_dst->executing, 0p, __ATOMIC_SEQ_CST) == this );
327	/* 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 );
328	/* 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 );
329	/* paranoid */ verify( thrd_dst->state != Halted );
330	/* paranoid */ verify( thrd_dst->context.SP );
331	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
332	/* paranoid */ verify( ! __preemption_enabled() );
333
334	// We just finished running a thread, there are a few things that could have happened.
335	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
336	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
337	// 4 - Preempted
338	// In case 1, we may have won a race so we can't write to the state again.
339	// In case 2, we lost the race so we now own the thread.
340
341	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
342	// Reset the this_thread now that we know
343	// the state isn't active anymore
344	kernelTLS().this_thread = 0p;
345
346	// The thread was preempted, reschedule it and reset the flag
347	schedule_thread$( thrd_dst, UNPARK_LOCAL );
348	break RUNNING;
349	}
350
351	if(unlikely(thrd_dst->state == Halting)) {
352	// Reset the this_thread now that we know
353	// the state isn't active anymore
354	kernelTLS().this_thread = 0p;
355
356	// The thread has halted, it should never be scheduled/run again
357	// finish the thread
358	__thread_finish( thrd_dst );
359	break RUNNING;
360	}
361
362	/* paranoid */ verify( thrd_dst->state == Active );
363	thrd_dst->state = Blocked;
364
365	// Reset the this_thread now that we know
366	// the state isn't active anymore
367	kernelTLS().this_thread = 0p;
368
369	// set state of processor coroutine to active and the thread to inactive
370	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
371	switch(old_ticket) {
372	case TICKET_RUNNING:
373	// This is case 1, the regular case, nothing more is needed
374	break RUNNING;
375	case TICKET_UNBLOCK:
376	__STATS__(true, ready.threads.threads++; )
377	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
378	// In this case, just run it again.
379	continue RUNNING;
380	default:
381	// This makes no sense, something is wrong abort
382	abort();
383	}
384	}
385
386	// Just before returning to the processor, set the processor coroutine to active
387	proc_cor->state = Active;
388
389	__cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
390
391	__STATS__(true, ready.threads.threads--; )
392
393	/* paranoid */ verify( ! __preemption_enabled() );
394	}
395
396	// KERNEL_ONLY
397	static void returnToKernel() {
398	/* paranoid */ verify( ! __preemption_enabled() );
399	coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
400	thread$ * thrd_src = kernelTLS().this_thread;
401
402	__STATS_DEF( thrd_src->last_proc = kernelTLS().this_processor; )
403
404	// Run the thread on this processor
405	{
406	int local_errno = *__volatile_errno();
407	#if defined( __i386 ) \|\| defined( __x86_64 )
408	__x87_store;
409	#endif
410	/* paranoid */ verify( proc_cor->context.SP );
411	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
412	__cfactx_switch( &thrd_src->context, &proc_cor->context );
413	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
414	#if defined( __i386 ) \|\| defined( __x86_64 )
415	__x87_load;
416	#endif
417	*__volatile_errno() = local_errno;
418	}
419
420	#if !defined(__CFA_NO_STATISTICS__)
421	/* paranoid */ verify( thrd_src->last_proc != 0p );
422	if(thrd_src->last_proc != kernelTLS().this_processor) {
423	__tls_stats()->ready.threads.migration++;
424	}
425	#endif
426
427	/* paranoid */ verify( ! __preemption_enabled() );
428	/* 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 );
429	/* 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 );
430	}
431
432	//-----------------------------------------------------------------------------
433	// Scheduler routines
434	// KERNEL ONLY
435	static void __schedule_thread( thread$ * thrd, unpark_hint hint ) {
436	/* paranoid */ verify( ! __preemption_enabled() );
437	/* paranoid */ verify( ready_schedule_islocked());
438	/* paranoid */ verify( thrd );
439	/* paranoid */ verify( thrd->state != Halted );
440	/* paranoid */ verify( thrd->curr_cluster );
441	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
442	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
443	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
444	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
445	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
446	/* paranoid */ #endif
447	/* paranoid */ verifyf( thrd->rdy_link.next == 0p, "Expected null got %p", thrd->rdy_link.next );
448	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
449
450	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
451
452	// Dereference the thread now because once we push it, there is not guaranteed it's still valid.
453	struct cluster * cl = thrd->curr_cluster;
454	__STATS_DEF(bool outside = hint == UNPARK_LOCAL && thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
455
456	// push the thread to the cluster ready-queue
457	push( cl, thrd, hint );
458
459	// variable thrd is no longer safe to use
460	thrd = 0xdeaddeaddeaddeadp;
461
462	// wake the cluster using the save variable.
463	__wake_one( cl );
464
465	#if !defined(__CFA_NO_STATISTICS__)
466	if( kernelTLS().this_stats ) {
467	__tls_stats()->ready.threads.threads++;
468	if(outside) {
469	__tls_stats()->ready.threads.extunpark++;
470	}
471	}
472	else {
473	__atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
474	__atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
475	}
476	#endif
477
478	/* paranoid */ verify( ready_schedule_islocked());
479	/* paranoid */ verify( ! __preemption_enabled() );
480	}
481
482	void schedule_thread$( thread$ * thrd, unpark_hint hint ) {
483	ready_schedule_lock();
484	__schedule_thread( thrd, hint );
485	ready_schedule_unlock();
486	}
487
488	// KERNEL ONLY
489	static inline thread$ * __next_thread(cluster * this) with( *this ) {
490	/* paranoid */ verify( ! __preemption_enabled() );
491
492	ready_schedule_lock();
493	thread$ * thrd = pop_fast( this );
494	ready_schedule_unlock();
495
496	/* paranoid */ verify( ! __preemption_enabled() );
497	return thrd;
498	}
499
500	// KERNEL ONLY
501	static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
502	/* paranoid */ verify( ! __preemption_enabled() );
503
504	ready_schedule_lock();
505	thread$ * thrd = pop_slow( this );
506	ready_schedule_unlock();
507
508	/* paranoid */ verify( ! __preemption_enabled() );
509	return thrd;
510	}
511
512	// KERNEL ONLY
513	static inline thread$ * __next_thread_search(cluster * this) with( *this ) {
514	/* paranoid */ verify( ! __preemption_enabled() );
515
516	ready_schedule_lock();
517	thread$ * thrd = pop_search( this );
518	ready_schedule_unlock();
519
520	/* paranoid */ verify( ! __preemption_enabled() );
521	return thrd;
522	}
523
524	static inline bool __must_unpark( thread$ * thrd ) {
525	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
526	switch(old_ticket) {
527	case TICKET_RUNNING:
528	// Wake won the race, the thread will reschedule/rerun itself
529	return false;
530	case TICKET_BLOCKED:
531	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
532	/* paranoid */ verify( thrd->state == Blocked );
533	return true;
534	default:
535	// This makes no sense, something is wrong abort
536	abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
537	}
538	}
539
540	void __kernel_unpark( thread$ * thrd, unpark_hint hint ) {
541	/* paranoid */ verify( ! __preemption_enabled() );
542	/* paranoid */ verify( ready_schedule_islocked());
543
544	if( !thrd ) return;
545
546	if(__must_unpark(thrd)) {
547	// Wake lost the race,
548	__schedule_thread( thrd, hint );
549	}
550
551	/* paranoid */ verify( ready_schedule_islocked());
552	/* paranoid */ verify( ! __preemption_enabled() );
553	}
554
555	void unpark( thread$ * thrd, unpark_hint hint ) libcfa_public {
556	if( !thrd ) return;
557
558	if(__must_unpark(thrd)) {
559	disable_interrupts();
560	// Wake lost the race,
561	schedule_thread$( thrd, hint );
562	enable_interrupts(false);
563	}
564	}
565
566	void park( void ) libcfa_public {
567	__disable_interrupts_checked();
568	/* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
569	returnToKernel();
570	__enable_interrupts_checked();
571	}
572
573	extern "C" {
574	// Leave the thread monitor
575	// last routine called by a thread.
576	// Should never return
577	void __cfactx_thrd_leave() {
578	thread$ * thrd = active_thread();
579	monitor$ * this = &thrd->self_mon;
580
581	// Lock the monitor now
582	lock( this->lock __cfaabi_dbg_ctx2 );
583
584	disable_interrupts();
585
586	/* paranoid */ verify( ! __preemption_enabled() );
587	/* paranoid */ verify( thrd->state == Active );
588	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
589	/* paranoid */ verify( kernelTLS().this_thread == thrd );
590	/* paranoid */ verify( thrd->context.SP );
591	/* 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 );
592	/* 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 );
593
594	if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
595	if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
596	if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
597
598	thrd->state = Halting;
599	thrd->ticket = TICKET_DEAD;
600
601	// Leave the thread
602	returnToKernel();
603
604	// Control flow should never reach here!
605	abort();
606	}
607	}
608
609	// KERNEL ONLY
610	bool force_yield( __Preemption_Reason reason ) libcfa_public {
611	__disable_interrupts_checked();
612	thread$ * thrd = kernelTLS().this_thread;
613	/* paranoid */ verify(thrd->state == Active);
614
615	// SKULLDUGGERY: It is possible that we are preempting this thread just before
616	// it was going to park itself. If that is the case and it is already using the
617	// intrusive fields then we can't use them to preempt the thread
618	// If that is the case, abandon the preemption.
619	bool preempted = false;
620	if(thrd->rdy_link.next == 0p) {
621	preempted = true;
622	thrd->preempted = reason;
623	returnToKernel();
624	}
625	__enable_interrupts_checked( false );
626	return preempted;
627	}
628
629	//=============================================================================================
630	// Kernel Idle Sleep
631	//=============================================================================================
632	// Wake a thread from the front if there are any
633	static void __wake_one(cluster * this) {
634	eventfd_t val;
635
636	/* paranoid */ verify( ! __preemption_enabled() );
637	/* paranoid */ verify( ready_schedule_islocked() );
638
639	// Check if there is a sleeping processor
640	struct __fd_waitctx * fdp = __atomic_load_n(&this->procs.fdw, __ATOMIC_SEQ_CST);
641
642	// If no one is sleeping: we are done
643	if( fdp == 0p ) return;
644
645	int fd = 1;
646	if( __atomic_load_n(&fdp->sem, __ATOMIC_SEQ_CST) != 1 ) {
647	fd = __atomic_exchange_n(&fdp->sem, 1, __ATOMIC_RELAXED);
648	}
649
650	switch(fd) {
651	__attribute__((unused)) int ret;
652	case 0:
653	// If the processor isn't ready to sleep then the exchange will already wake it up
654	#if !defined(__CFA_NO_STATISTICS__)
655	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.early++;
656	} else { __atomic_fetch_add(&this->stats->ready.sleep.early, 1, __ATOMIC_RELAXED); }
657	#endif
658	break;
659	case 1:
660	// If someone else already said they will wake them: we are done
661	#if !defined(__CFA_NO_STATISTICS__)
662	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.seen++;
663	} else { __atomic_fetch_add(&this->stats->ready.sleep.seen, 1, __ATOMIC_RELAXED); }
664	#endif
665	break;
666	default:
667	// If the processor was ready to sleep, we need to wake it up with an actual write
668	val = 1;
669	ret = eventfd_write( fd, val );
670	/* paranoid */ verifyf( ret == 0, "Expected return to be 0, was %d\n", ret );
671
672	#if !defined(__CFA_NO_STATISTICS__)
673	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.wakes++;
674	} else { __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED); }
675	#endif
676	break;
677	}
678
679	/* paranoid */ verify( ready_schedule_islocked() );
680	/* paranoid */ verify( ! __preemption_enabled() );
681
682	return;
683	}
684
685	// Unconditionnaly wake a thread
686	void __wake_proc(processor * this) {
687	/* paranoid */ verify( ! __preemption_enabled() );
688
689	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
690
691	this->idle_wctx.sem = 1;
692
693	this->idle_wctx.wake__time = rdtscl();
694
695	eventfd_t val;
696	val = 1;
697	__attribute__((unused)) int ret = eventfd_write( this->idle_wctx.evfd, val );
698
699	/* paranoid */ verifyf( ret == 0, "Expected return to be 0, was %d\n", ret );
700	/* paranoid */ verify( ! __preemption_enabled() );
701	}
702
703	static void idle_sleep(processor * this) {
704	/* paranoid */ verify( this->idle_wctx.evfd != 1 );
705	/* paranoid */ verify( this->idle_wctx.evfd != 2 );
706
707	// Tell everyone we are ready to go do sleep
708	for() {
709	int expected = this->idle_wctx.sem;
710
711	// Someone already told us to wake-up! No time for a nap.
712	if(expected == 1) { return; }
713
714	// Try to mark that we are going to sleep
715	if(__atomic_compare_exchange_n(&this->idle_wctx.sem, &expected, this->idle_wctx.evfd, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ) {
716	// Every one agreed, taking a nap
717	break;
718	}
719	}
720
721
722	#if !defined(__CFA_NO_STATISTICS__)
723	if(this->print_halts) {
724	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
725	}
726	#endif
727
728	__cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle_fd);
729
730	{
731	eventfd_t val;
732	ssize_t ret = read( this->idle_wctx.evfd, &val, sizeof(val) );
733	if(ret < 0) {
734	switch((int)errno) {
735	case EAGAIN:
736	#if EAGAIN != EWOULDBLOCK
737	case EWOULDBLOCK:
738	#endif
739	case EINTR:
740	// No need to do anything special here, just assume it's a legitimate wake-up
741	break;
742	default:
743	abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
744	}
745	}
746	}
747
748	#if !defined(__CFA_NO_STATISTICS__)
749	if(this->print_halts) {
750	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
751	}
752	#endif
753	}
754
755	static bool mark_idle(__cluster_proc_list & this, processor & proc) {
756	__STATS__(true, ready.sleep.halts++; )
757
758	proc.idle_wctx.sem = 0;
759
760	/* paranoid */ verify( ! __preemption_enabled() );
761	if(!try_lock( this )) return false;
762	this.idle++;
763	/* paranoid */ verify( this.idle <= this.total );
764	remove(proc);
765	insert_first(this.idles, proc);
766
767	// update the pointer to the head wait context, which should now point to this proc.
768	__atomic_store_n(&this.fdw, &proc.idle_wctx, __ATOMIC_SEQ_CST);
769	unlock( this );
770	/* paranoid */ verify( ! __preemption_enabled() );
771
772	return true;
773	}
774
775	static void mark_awake(__cluster_proc_list & this, processor & proc) {
776	/* paranoid */ verify( ! __preemption_enabled() );
777	lock( this );
778	this.idle--;
779	/* paranoid */ verify( this.idle >= 0 );
780	remove(proc);
781	insert_last(this.actives, proc);
782
783	{
784	// update the pointer to the head wait context
785	struct __fd_waitctx * wctx = 0;
786	if(!this.idles`isEmpty) wctx = &this.idles`first.idle_wctx;
787	__atomic_store_n(&this.fdw, wctx, __ATOMIC_SEQ_CST);
788	}
789
790	unlock( this );
791	/* paranoid */ verify( ! __preemption_enabled() );
792	}
793
794	//=============================================================================================
795	// Unexpected Terminating logic
796	//=============================================================================================
797	void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
798	thread$ * thrd = __cfaabi_tls.this_thread;
799
800	if(thrd) {
801	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
802	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
803
804	if ( &thrd->self_cor != thrd->curr_cor ) {
805	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
806	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
807	}
808	else {
809	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
810	}
811	}
812	else {
813	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
814	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
815	}
816	}
817
818	int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
819	return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
820	}
821
822	static __spinlock_t kernel_debug_lock;
823
824	extern "C" {
825	void __cfaabi_bits_acquire() {
826	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
827	}
828
829	void __cfaabi_bits_release() {
830	unlock( kernel_debug_lock );
831	}
832	}
833
834	//=============================================================================================
835	// Kernel Utilities
836	//=============================================================================================
837	#if defined(CFA_HAVE_LINUX_IO_URING_H)
838	#include "io/types.hfa"
839	#endif
840
841	//-----------------------------------------------------------------------------
842	// Debug
843	bool threading_enabled(void) __attribute__((const)) libcfa_public {
844	return true;
845	}
846
847	//-----------------------------------------------------------------------------
848	// Statistics
849	#if !defined(__CFA_NO_STATISTICS__)
850	void print_halts( processor & this ) libcfa_public {
851	this.print_halts = true;
852	}
853
854	static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
855	/* paranoid */ verify( cltr->stats );
856
857	processor * it = &list`first;
858	for(unsigned i = 0; i < count; i++) {
859	/* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
860	/* paranoid */ verify( it->local_data->this_stats );
861	// __print_stats( it->local_data->this_stats, cltr->print_stats, "Processor", it->name, (void*)it );
862	__tally_stats( cltr->stats, it->local_data->this_stats );
863	it = &(*it)`next;
864	}
865	}
866
867	static void crawl_cluster_stats( cluster & this ) {
868	// Stop the world, otherwise stats could get really messed-up
869	// this doesn't solve all problems but does solve many
870	// so it's probably good enough
871	disable_interrupts();
872	uint_fast32_t last_size = ready_mutate_lock();
873
874	crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
875	crawl_list(&this, this.procs.idles , this.procs.idle );
876
877	// Unlock the RWlock
878	ready_mutate_unlock( last_size );
879	enable_interrupts();
880	}
881
882
883	void print_stats_now( cluster & this, int flags ) libcfa_public {
884	crawl_cluster_stats( this );
885	__print_stats( this.stats, flags, "Cluster", this.name, (void*)&this );
886	}
887	#endif
888	// Local Variables: //
889	// mode: c //
890	// tab-width: 4 //
891	// End: //

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