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kernel.cfa @ b797d978

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Last change on this file since b797d978 was 26544f9, checked in by Thierry Delisle <tdelisle@…>, 2 years ago
added helping and lock to allow remote processors to flush unresponsive procs
Property mode set to `100644`
File size: 28.6 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 : Wed Nov 30 18:14:08 2022
13	// Update Count : 76
14	//
15
16	#define __cforall_thread__
17	#define _GNU_SOURCE
18
19	// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
20
21	#pragma GCC diagnostic push
22	#pragma GCC diagnostic ignored "-Waddress-of-packed-member"
23
24	//C Includes
25	#include <errno.h>
26	#include <stdio.h>
27	#include <string.h>
28	#include <signal.h>
29	#include <unistd.h>
30
31	extern "C" {
32	#include <sys/eventfd.h>
33	#include <sys/uio.h>
34	}
35
36	//CFA Includes
37	#include "kernel/private.hfa"
38	#include "preemption.hfa"
39	#include "strstream.hfa"
40	#include "device/cpu.hfa"
41	#include "io/types.hfa"
42
43	//Private includes
44	#define __CFA_INVOKE_PRIVATE__
45	#include "invoke.h"
46	#pragma GCC diagnostic pop
47
48	#if !defined(__CFA_NO_STATISTICS__)
49	#define __STATS_DEF( ...) __VA_ARGS__
50	#else
51	#define __STATS_DEF( ...)
52	#endif
53
54	//-----------------------------------------------------------------------------
55	// Some assembly required
56	#if defined( __i386 )
57	// mxcr : SSE Status and Control bits (control bits are preserved across function calls)
58	// fcw : X87 FPU control word (preserved across function calls)
59	#define __x87_store \
60	uint32_t __mxcr; \
61	uint16_t __fcw; \
62	__asm__ volatile ( \
63	"stmxcsr %0\n" \
64	"fnstcw %1\n" \
65	: "=m" (__mxcr),\
66	"=m" (__fcw) \
67	)
68
69	#define __x87_load \
70	__asm__ volatile ( \
71	"fldcw %1\n" \
72	"ldmxcsr %0\n" \
73	::"m" (__mxcr),\
74	"m" (__fcw) \
75	)
76
77	#elif defined( __x86_64 )
78	#define __x87_store \
79	uint32_t __mxcr; \
80	uint16_t __fcw; \
81	__asm__ volatile ( \
82	"stmxcsr %0\n" \
83	"fnstcw %1\n" \
84	: "=m" (__mxcr),\
85	"=m" (__fcw) \
86	)
87
88	#define __x87_load \
89	__asm__ volatile ( \
90	"fldcw %1\n" \
91	"ldmxcsr %0\n" \
92	:: "m" (__mxcr),\
93	"m" (__fcw) \
94	)
95
96	#elif defined( __arm__ )
97	#define __x87_store
98	#define __x87_load
99
100	#elif defined( __aarch64__ )
101	#define __x87_store \
102	uint32_t __fpcntl[2]; \
103	__asm__ volatile ( \
104	"mrs x9, FPCR\n" \
105	"mrs x10, FPSR\n" \
106	"stp x9, x10, %0\n" \
107	: "=m" (__fpcntl) : : "x9", "x10" \
108	)
109
110	#define __x87_load \
111	__asm__ volatile ( \
112	"ldp x9, x10, %0\n" \
113	"msr FPSR, x10\n" \
114	"msr FPCR, x9\n" \
115	: "=m" (__fpcntl) : : "x9", "x10" \
116	)
117
118	#else
119	#error unsupported hardware architecture
120	#endif
121
122	extern thread$ * mainThread;
123	extern processor * mainProcessor;
124
125	//-----------------------------------------------------------------------------
126	// Kernel Scheduling logic
127	static thread$ * __next_thread(cluster * this);
128	static thread$ * __next_thread_slow(cluster * this);
129	static thread$ * __next_thread_search(cluster * this);
130	static inline bool __must_unpark( thread$ * thrd ) __attribute((nonnull(1)));
131	static void __run_thread(processor * this, thread$ * dst);
132	static void __wake_one(cluster * cltr);
133
134	static void idle_sleep(processor * proc);
135	static bool mark_idle (__cluster_proc_list & idles, processor & proc);
136	static void mark_awake(__cluster_proc_list & idles, processor & proc);
137
138	extern bool __cfa_io_drain( processor * proc ) __attribute__((nonnull (1)));
139	extern bool __cfa_io_flush( processor * ) __attribute__((nonnull (1)));
140
141
142	extern void __disable_interrupts_hard();
143	extern void __enable_interrupts_hard();
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	PRNG_SET_SEED( __cfaabi_tls.random_state, 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	__cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
161	#if !defined(__CFA_NO_STATISTICS__)
162	if( this->print_halts ) {
163	__cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
164	}
165	#endif
166
167	{
168	// Setup preemption data
169	preemption_scope scope = { this };
170
171	// if we need to run some special setup, now is the time to do it.
172	if(this->init.thrd) {
173	this->init.thrd->curr_cluster = this->cltr;
174	__run_thread(this, this->init.thrd);
175	}
176
177	__cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
178
179	thread$ * readyThread = 0p;
180	MAIN_LOOP:
181	for() {
182	// Check if there is pending io
183	__cfa_io_drain( this );
184
185	// Try to get the next thread
186	readyThread = __next_thread( this->cltr );
187
188	if( !readyThread ) {
189	// there is no point in holding submissions if we are idle
190	__IO_STATS__(true, io.flush.idle++; )
191	__cfa_io_flush( this );
192
193	// drain again in case something showed up
194	__cfa_io_drain( this );
195
196	readyThread = __next_thread( this->cltr );
197	}
198
199	if( !readyThread ) for(5) {
200	readyThread = __next_thread_slow( this->cltr );
201
202	if( readyThread ) break;
203
204	// It's unlikely we still I/O to submit, but the arbiter could
205	__IO_STATS__(true, io.flush.idle++; )
206	__cfa_io_flush( this );
207
208	// drain again in case something showed up
209	__cfa_io_drain( this );
210	}
211
212	HALT:
213	if( !readyThread ) {
214	// Don't block if we are done
215	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
216
217	// Push self to idle stack
218	if(!mark_idle(this->cltr->procs, * this)) continue MAIN_LOOP;
219
220	// Confirm the ready-queue is empty
221	readyThread = __next_thread_search( this->cltr );
222	if( readyThread ) {
223	// A thread was found, cancel the halt
224	mark_awake(this->cltr->procs, * this);
225
226	__STATS__(true, ready.sleep.cancels++; )
227
228	// continue the mai loop
229	break HALT;
230	}
231
232	idle_sleep( this );
233
234	// We were woken up, remove self from idle
235	mark_awake(this->cltr->procs, * this);
236
237	// DON'T just proceed, start looking again
238	continue MAIN_LOOP;
239	}
240
241	/* paranoid */ verify( readyThread );
242
243	// Reset io dirty bit
244	this->io.dirty = false;
245
246	// We found a thread run it
247	__run_thread(this, readyThread);
248
249	// Are we done?
250	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
251
252	if(__atomic_load_n(&this->io.pending, __ATOMIC_RELAXED) && !__atomic_load_n(&this->io.dirty, __ATOMIC_RELAXED)) {
253	__IO_STATS__(true, io.flush.dirty++; )
254	__cfa_io_flush( this );
255	}
256	}
257
258	__cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
259	}
260
261	__cfa_io_flush( this );
262	__cfa_io_drain( this );
263
264	post( this->terminated );
265
266	if(this == mainProcessor) {
267	// HACK : the coroutine context switch expects this_thread to be set
268	// and it make sense for it to be set in all other cases except here
269	// fake it
270	__cfaabi_tls.this_thread = mainThread;
271	}
272
273	__cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
274	}
275
276	static int * __volatile_errno() __attribute__((noinline));
277	static int * __volatile_errno() { asm(""); return &errno; }
278
279	// KERNEL ONLY
280	// runThread runs a thread by context switching
281	// from the processor coroutine to the target thread
282	static void __run_thread(processor * this, thread$ * thrd_dst) {
283	/* paranoid */ verify( ! __preemption_enabled() );
284	/* paranoid */ verifyf( thrd_dst->state == Ready \|\| thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
285	/* paranoid */ verifyf( thrd_dst->rdy_link.next == 0p, "Expected null got %p", thrd_dst->rdy_link.next );
286	__builtin_prefetch( thrd_dst->context.SP );
287
288	__cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
289
290	coroutine$ * proc_cor = get_coroutine(this->runner);
291
292	// set state of processor coroutine to inactive
293	verify(proc_cor->state == Active);
294	proc_cor->state = Blocked;
295
296	// Actually run the thread
297	RUNNING: while(true) {
298	thrd_dst->preempted = __NO_PREEMPTION;
299
300	// Update global state
301	kernelTLS().this_thread = thrd_dst;
302
303	// Update the state after setting this_thread
304	// so that the debugger can find all active threads
305	// in tls storage
306	thrd_dst->state = Active;
307
308	/* paranoid */ verify( ! __preemption_enabled() );
309	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
310	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
311	/* paranoid */ verify( thrd_dst->context.SP );
312	/* paranoid */ verify( thrd_dst->state != Halted );
313	/* 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
314	/* 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
315	/* paranoid */ verify( __atomic_exchange_n( &thrd_dst->executing, this, __ATOMIC_SEQ_CST) == 0p );
316	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
317
318
319
320	// set context switch to the thread that the processor is executing
321	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
322	// when __cfactx_switch returns we are back in the processor coroutine
323
324
325
326	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
327	/* paranoid */ verify( __atomic_exchange_n( &thrd_dst->executing, 0p, __ATOMIC_SEQ_CST) == this );
328	/* 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 );
329	/* 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 );
330	/* paranoid */ verify( thrd_dst->state != Halted );
331	/* paranoid */ verify( thrd_dst->context.SP );
332	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
333	/* paranoid */ verify( ! __preemption_enabled() );
334
335	// We just finished running a thread, there are a few things that could have happened.
336	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
337	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
338	// 4 - Preempted
339	// In case 1, we may have won a race so we can't write to the state again.
340	// In case 2, we lost the race so we now own the thread.
341
342	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
343	// Reset the this_thread now that we know
344	// the state isn't active anymore
345	kernelTLS().this_thread = 0p;
346
347	// The thread was preempted, reschedule it and reset the flag
348	schedule_thread$( thrd_dst, UNPARK_LOCAL );
349	break RUNNING;
350	}
351
352	if(unlikely(thrd_dst->state == Halting)) {
353	// Reset the this_thread now that we know
354	// the state isn't active anymore
355	kernelTLS().this_thread = 0p;
356
357	// The thread has halted, it should never be scheduled/run again
358	// finish the thread
359	__thread_finish( thrd_dst );
360	break RUNNING;
361	}
362
363	/* paranoid */ verify( thrd_dst->state == Active );
364	thrd_dst->state = Blocked;
365
366	// Reset the this_thread now that we know
367	// the state isn't active anymore
368	kernelTLS().this_thread = 0p;
369
370	// set state of processor coroutine to active and the thread to inactive
371	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
372	switch(old_ticket) {
373	case TICKET_RUNNING:
374	// This is case 1, the regular case, nothing more is needed
375	break RUNNING;
376	case TICKET_UNBLOCK:
377	__STATS__(true, ready.threads.threads++; )
378	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
379	// In this case, just run it again.
380	continue RUNNING;
381	default:
382	// This makes no sense, something is wrong abort
383	abort();
384	}
385	}
386
387	// Just before returning to the processor, set the processor coroutine to active
388	proc_cor->state = Active;
389
390	__cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
391
392	__STATS__(true, ready.threads.threads--; )
393
394	/* paranoid */ verify( ! __preemption_enabled() );
395	}
396
397	// KERNEL_ONLY
398	static void returnToKernel() {
399	/* paranoid */ verify( ! __preemption_enabled() );
400	coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
401	thread$ * thrd_src = kernelTLS().this_thread;
402
403	__STATS_DEF( thrd_src->last_proc = kernelTLS().this_processor; )
404
405	// Run the thread on this processor
406	{
407	int local_errno = *__volatile_errno();
408	#if defined( __i386 ) \|\| defined( __x86_64 )
409	__x87_store;
410	#endif
411	/* paranoid */ verify( proc_cor->context.SP );
412	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
413	__cfactx_switch( &thrd_src->context, &proc_cor->context );
414	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
415	#if defined( __i386 ) \|\| defined( __x86_64 )
416	__x87_load;
417	#endif
418	*__volatile_errno() = local_errno;
419	}
420
421	#if !defined(__CFA_NO_STATISTICS__)
422	/* paranoid */ verify( thrd_src->last_proc != 0p );
423	if(thrd_src->last_proc != kernelTLS().this_processor) {
424	__tls_stats()->ready.threads.migration++;
425	}
426	#endif
427
428	/* paranoid */ verify( ! __preemption_enabled() );
429	/* 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 );
430	/* 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 );
431	}
432
433	//-----------------------------------------------------------------------------
434	// Scheduler routines
435	// KERNEL ONLY
436	static void __schedule_thread( thread$ * thrd, unpark_hint hint ) {
437	/* paranoid */ verify( ! __preemption_enabled() );
438	/* paranoid */ verify( ready_schedule_islocked());
439	/* paranoid */ verify( thrd );
440	/* paranoid */ verify( thrd->state != Halted );
441	/* paranoid */ verify( thrd->curr_cluster );
442	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
443	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
444	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
445	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
446	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
447	/* paranoid */ #endif
448	/* paranoid */ verifyf( thrd->rdy_link.next == 0p, "Expected null got %p", thrd->rdy_link.next );
449	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
450
451	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
452
453	// Dereference the thread now because once we push it, there is not guaranteed it's still valid.
454	struct cluster * cl = thrd->curr_cluster;
455	__STATS_DEF(bool outside = hint == UNPARK_LOCAL && thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
456
457	// push the thread to the cluster ready-queue
458	push( cl, thrd, hint );
459
460	// variable thrd is no longer safe to use
461	thrd = 0xdeaddeaddeaddeadp;
462
463	// wake the cluster using the save variable.
464	__wake_one( cl );
465
466	#if !defined(__CFA_NO_STATISTICS__)
467	if( kernelTLS().this_stats ) {
468	__tls_stats()->ready.threads.threads++;
469	if(outside) {
470	__tls_stats()->ready.threads.extunpark++;
471	}
472	}
473	else {
474	__atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
475	__atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
476	}
477	#endif
478
479	/* paranoid */ verify( ready_schedule_islocked());
480	/* paranoid */ verify( ! __preemption_enabled() );
481	}
482
483	void schedule_thread$( thread$ * thrd, unpark_hint hint ) {
484	ready_schedule_lock();
485	__schedule_thread( thrd, hint );
486	ready_schedule_unlock();
487	}
488
489	// KERNEL ONLY
490	static inline thread$ * __next_thread(cluster * this) with( *this ) {
491	/* paranoid */ verify( ! __preemption_enabled() );
492
493	ready_schedule_lock();
494	thread$ * thrd = pop_fast( this );
495	ready_schedule_unlock();
496
497	/* paranoid */ verify( ! __preemption_enabled() );
498	return thrd;
499	}
500
501	// KERNEL ONLY
502	static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
503	/* paranoid */ verify( ! __preemption_enabled() );
504
505	ready_schedule_lock();
506	thread$ * thrd = pop_slow( this );
507	ready_schedule_unlock();
508
509	/* paranoid */ verify( ! __preemption_enabled() );
510	return thrd;
511	}
512
513	// KERNEL ONLY
514	static inline thread$ * __next_thread_search(cluster * this) with( *this ) {
515	/* paranoid */ verify( ! __preemption_enabled() );
516
517	ready_schedule_lock();
518	thread$ * thrd = pop_search( this );
519	ready_schedule_unlock();
520
521	/* paranoid */ verify( ! __preemption_enabled() );
522	return thrd;
523	}
524
525	static inline bool __must_unpark( thread$ * thrd ) {
526	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
527	switch(old_ticket) {
528	case TICKET_RUNNING:
529	// Wake won the race, the thread will reschedule/rerun itself
530	return false;
531	case TICKET_BLOCKED:
532	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
533	/* paranoid */ verify( thrd->state == Blocked );
534	return true;
535	default:
536	// This makes no sense, something is wrong abort
537	abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
538	}
539	}
540
541	void __kernel_unpark( thread$ * thrd, unpark_hint hint ) {
542	/* paranoid */ verify( ! __preemption_enabled() );
543	/* paranoid */ verify( ready_schedule_islocked());
544
545	if( !thrd ) return;
546
547	if(__must_unpark(thrd)) {
548	// Wake lost the race,
549	__schedule_thread( thrd, hint );
550	}
551
552	/* paranoid */ verify( ready_schedule_islocked());
553	/* paranoid */ verify( ! __preemption_enabled() );
554	}
555
556	void unpark( thread$ * thrd, unpark_hint hint ) libcfa_public {
557	if( !thrd ) return;
558
559	if(__must_unpark(thrd)) {
560	disable_interrupts();
561	// Wake lost the race,
562	schedule_thread$( thrd, hint );
563	enable_interrupts(false);
564	}
565	}
566
567	void park( void ) libcfa_public {
568	__disable_interrupts_checked();
569	/* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
570	returnToKernel();
571	__enable_interrupts_checked();
572
573	}
574
575	extern "C" {
576	// Leave the thread monitor
577	// last routine called by a thread.
578	// Should never return
579	void __cfactx_thrd_leave() {
580	thread$ * thrd = active_thread();
581	monitor$ * this = &thrd->self_mon;
582
583	// Lock the monitor now
584	lock( this->lock __cfaabi_dbg_ctx2 );
585
586	disable_interrupts();
587
588	/* paranoid */ verify( ! __preemption_enabled() );
589	/* paranoid */ verify( thrd->state == Active );
590	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
591	/* paranoid */ verify( kernelTLS().this_thread == thrd );
592	/* paranoid */ verify( thrd->context.SP );
593	/* 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 );
594	/* 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 );
595
596	if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
597	if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
598	if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
599
600	thrd->state = Halting;
601	thrd->ticket = TICKET_DEAD;
602
603	// Leave the thread
604	returnToKernel();
605
606	// Control flow should never reach here!
607	abort();
608	}
609	}
610
611	// KERNEL ONLY
612	bool force_yield( __Preemption_Reason reason ) libcfa_public {
613	__disable_interrupts_checked();
614	thread$ * thrd = kernelTLS().this_thread;
615	/* paranoid */ verify(thrd->state == Active);
616
617	// SKULLDUGGERY: It is possible that we are preempting this thread just before
618	// it was going to park itself. If that is the case and it is already using the
619	// intrusive fields then we can't use them to preempt the thread
620	// If that is the case, abandon the preemption.
621	bool preempted = false;
622	if(thrd->rdy_link.next == 0p) {
623	preempted = true;
624	thrd->preempted = reason;
625	returnToKernel();
626	}
627	__enable_interrupts_checked( false );
628	return preempted;
629	}
630
631	//=============================================================================================
632	// Kernel Idle Sleep
633	//=============================================================================================
634	// Wake a thread from the front if there are any
635	static void __wake_one(cluster * this) {
636	eventfd_t val;
637
638	/* paranoid */ verify( ! __preemption_enabled() );
639	/* paranoid */ verify( ready_schedule_islocked() );
640
641	// Check if there is a sleeping processor
642	struct __fd_waitctx * fdp = __atomic_load_n(&this->procs.fdw, __ATOMIC_SEQ_CST);
643
644	// If no one is sleeping: we are done
645	if( fdp == 0p ) return;
646
647	int fd = 1;
648	if( __atomic_load_n(&fdp->sem, __ATOMIC_SEQ_CST) != 1 ) {
649	fd = __atomic_exchange_n(&fdp->sem, 1, __ATOMIC_RELAXED);
650	}
651
652	switch(fd) {
653	__attribute__((unused)) int ret;
654	case 0:
655	// If the processor isn't ready to sleep then the exchange will already wake it up
656	#if !defined(__CFA_NO_STATISTICS__)
657	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.early++;
658	} else { __atomic_fetch_add(&this->stats->ready.sleep.early, 1, __ATOMIC_RELAXED); }
659	#endif
660	break;
661	case 1:
662	// If someone else already said they will wake them: we are done
663	#if !defined(__CFA_NO_STATISTICS__)
664	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.seen++;
665	} else { __atomic_fetch_add(&this->stats->ready.sleep.seen, 1, __ATOMIC_RELAXED); }
666	#endif
667	break;
668	default:
669	// If the processor was ready to sleep, we need to wake it up with an actual write
670	val = 1;
671	ret = eventfd_write( fd, val );
672	/* paranoid */ verifyf( ret == 0, "Expected return to be 0, was %d\n", ret );
673
674	#if !defined(__CFA_NO_STATISTICS__)
675	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.wakes++;
676	} else { __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED); }
677	#endif
678	break;
679	}
680
681	/* paranoid */ verify( ready_schedule_islocked() );
682	/* paranoid */ verify( ! __preemption_enabled() );
683
684	return;
685	}
686
687	// Unconditionnaly wake a thread
688	void __wake_proc(processor * this) {
689	/* paranoid */ verify( ! __preemption_enabled() );
690
691	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
692
693	this->idle_wctx.sem = 1;
694
695	this->idle_wctx.wake__time = rdtscl();
696
697	eventfd_t val;
698	val = 1;
699	__attribute__((unused)) int ret = eventfd_write( this->idle_wctx.evfd, val );
700
701	/* paranoid */ verifyf( ret == 0, "Expected return to be 0, was %d\n", ret );
702	/* paranoid */ verify( ! __preemption_enabled() );
703	}
704
705	static void idle_sleep(processor * this) {
706	/* paranoid */ verify( this->idle_wctx.evfd != 1 );
707	/* paranoid */ verify( this->idle_wctx.evfd != 2 );
708
709	// Tell everyone we are ready to go do sleep
710	for() {
711	int expected = this->idle_wctx.sem;
712
713	// Someone already told us to wake-up! No time for a nap.
714	if(expected == 1) { return; }
715
716	// Try to mark that we are going to sleep
717	if(__atomic_compare_exchange_n(&this->idle_wctx.sem, &expected, this->idle_wctx.evfd, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ) {
718	// Every one agreed, taking a nap
719	break;
720	}
721	}
722
723
724	#if !defined(__CFA_NO_STATISTICS__)
725	if(this->print_halts) {
726	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
727	}
728	#endif
729
730	__cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle_fd);
731
732	{
733	eventfd_t val;
734	ssize_t ret = read( this->idle_wctx.evfd, &val, sizeof(val) );
735	if(ret < 0) {
736	switch((int)errno) {
737	case EAGAIN:
738	#if EAGAIN != EWOULDBLOCK
739	case EWOULDBLOCK:
740	#endif
741	case EINTR:
742	// No need to do anything special here, just assume it's a legitimate wake-up
743	break;
744	default:
745	abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
746	}
747	}
748	}
749
750	#if !defined(__CFA_NO_STATISTICS__)
751	if(this->print_halts) {
752	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
753	}
754	#endif
755	}
756
757	static bool mark_idle(__cluster_proc_list & this, processor & proc) {
758	__STATS__(true, ready.sleep.halts++; )
759
760	proc.idle_wctx.sem = 0;
761
762	/* paranoid */ verify( ! __preemption_enabled() );
763	if(!try_lock( this )) return false;
764	this.idle++;
765	/* paranoid */ verify( this.idle <= this.total );
766	remove(proc);
767	insert_first(this.idles, proc);
768
769	// update the pointer to the head wait context, which should now point to this proc.
770	__atomic_store_n(&this.fdw, &proc.idle_wctx, __ATOMIC_SEQ_CST);
771	unlock( this );
772	/* paranoid */ verify( ! __preemption_enabled() );
773
774	return true;
775	}
776
777	static void mark_awake(__cluster_proc_list & this, processor & proc) {
778	/* paranoid */ verify( ! __preemption_enabled() );
779	lock( this );
780	this.idle--;
781	/* paranoid */ verify( this.idle >= 0 );
782	remove(proc);
783	insert_last(this.actives, proc);
784
785	{
786	// update the pointer to the head wait context
787	struct __fd_waitctx * wctx = 0;
788	if(!this.idles`isEmpty) wctx = &this.idles`first.idle_wctx;
789	__atomic_store_n(&this.fdw, wctx, __ATOMIC_SEQ_CST);
790	}
791
792	unlock( this );
793	/* paranoid */ verify( ! __preemption_enabled() );
794	}
795
796	//=============================================================================================
797	// Unexpected Terminating logic
798	//=============================================================================================
799	void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
800	thread$ * thrd = __cfaabi_tls.this_thread;
801
802	if(thrd) {
803	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
804	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
805
806	if ( &thrd->self_cor != thrd->curr_cor ) {
807	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
808	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
809	}
810	else {
811	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
812	}
813	}
814	else {
815	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
816	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
817	}
818	}
819
820	int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
821	return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
822	}
823
824	static __spinlock_t kernel_debug_lock;
825
826	extern "C" {
827	void __cfaabi_bits_acquire() {
828	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
829	}
830
831	void __cfaabi_bits_release() {
832	unlock( kernel_debug_lock );
833	}
834	}
835
836	//=============================================================================================
837	// Kernel Utilities
838	//=============================================================================================
839	#if defined(CFA_HAVE_LINUX_IO_URING_H)
840	#include "io/types.hfa"
841	#endif
842
843	//-----------------------------------------------------------------------------
844	// Debug
845	bool threading_enabled(void) __attribute__((const)) libcfa_public {
846	return true;
847	}
848
849	//-----------------------------------------------------------------------------
850	// Statistics
851	#if !defined(__CFA_NO_STATISTICS__)
852	void print_halts( processor & this ) libcfa_public {
853	this.print_halts = true;
854	}
855
856	static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
857	/* paranoid */ verify( cltr->stats );
858
859	processor * it = &list`first;
860	for(unsigned i = 0; i < count; i++) {
861	/* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
862	/* paranoid */ verify( it->local_data->this_stats );
863	// __print_stats( it->local_data->this_stats, cltr->print_stats, "Processor", it->name, (void*)it );
864	__tally_stats( cltr->stats, it->local_data->this_stats );
865	it = &(*it)`next;
866	}
867	}
868
869	static void crawl_cluster_stats( cluster & this ) {
870	// Stop the world, otherwise stats could get really messed-up
871	// this doesn't solve all problems but does solve many
872	// so it's probably good enough
873	disable_interrupts();
874	uint_fast32_t last_size = ready_mutate_lock();
875
876	crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
877	crawl_list(&this, this.procs.idles , this.procs.idle );
878
879	// Unlock the RWlock
880	ready_mutate_unlock( last_size );
881	enable_interrupts();
882	}
883
884
885	void print_stats_now( cluster & this, int flags ) libcfa_public {
886	crawl_cluster_stats( this );
887	__print_stats( this.stats, flags, "Cluster", this.name, (void*)&this );
888	}
889	#endif
890	// Local Variables: //
891	// mode: c //
892	// tab-width: 4 //
893	// End: //

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