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kernel.cfa @ d080549

ADTast-experimentalenumpthread-emulationqualifiedEnum

Last change on this file since d080549 was d080549, checked in by Thierry Delisle <tdelisle@…>, 2 years ago
Added a verify for the result of wake_proc
Property mode set to `100644`
File size: 28.4 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 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	#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	extern void __cfa_io_idle( processor * ) __attribute__((nonnull (1)));
141
142	#if defined(CFA_WITH_IO_URING_IDLE)
143	extern bool __kernel_read(processor * proc, io_future_t & future, iovec &, int fd);
144	#endif
145
146	extern void __disable_interrupts_hard();
147	extern void __enable_interrupts_hard();
148
149
150	//=============================================================================================
151	// Kernel Scheduling logic
152	//=============================================================================================
153	//Main of the processor contexts
154	void main(processorCtx_t & runner) {
155	// Because of a bug, we couldn't initialized the seed on construction
156	// Do it here
157	__cfaabi_tls.rand_seed ^= rdtscl();
158	__cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
159	__tls_rand_advance_bck();
160
161	processor * this = runner.proc;
162	verify(this);
163
164	/* paranoid */ verify( this->idle_wctx.ftr != 0p );
165	/* paranoid */ verify( this->idle_wctx.rdbuf != 0p );
166
167	// used for idle sleep when io_uring is present
168	// mark it as already fulfilled so we know if there is a pending request or not
169	this->idle_wctx.ftr->self.ptr = 1p;
170
171	__cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
172	#if !defined(__CFA_NO_STATISTICS__)
173	if( this->print_halts ) {
174	__cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
175	}
176	#endif
177
178	{
179	// Setup preemption data
180	preemption_scope scope = { this };
181
182	// if we need to run some special setup, now is the time to do it.
183	if(this->init.thrd) {
184	this->init.thrd->curr_cluster = this->cltr;
185	__run_thread(this, this->init.thrd);
186	}
187
188	__cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
189
190	thread$ * readyThread = 0p;
191	MAIN_LOOP:
192	for() {
193	// Check if there is pending io
194	__cfa_io_drain( this );
195
196	// Try to get the next thread
197	readyThread = __next_thread( this->cltr );
198
199	if( !readyThread ) {
200	// there is no point in holding submissions if we are idle
201	__IO_STATS__(true, io.flush.idle++; )
202	__cfa_io_flush( this );
203
204	// drain again in case something showed up
205	__cfa_io_drain( this );
206
207	readyThread = __next_thread( this->cltr );
208	}
209
210	if( !readyThread ) for(5) {
211	readyThread = __next_thread_slow( this->cltr );
212
213	if( readyThread ) break;
214
215	// It's unlikely we still I/O to submit, but the arbiter could
216	__IO_STATS__(true, io.flush.idle++; )
217	__cfa_io_flush( this );
218
219	// drain again in case something showed up
220	__cfa_io_drain( this );
221	}
222
223	HALT:
224	if( !readyThread ) {
225	// Don't block if we are done
226	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
227
228	// Push self to idle stack
229	if(!mark_idle(this->cltr->procs, * this)) continue MAIN_LOOP;
230
231	// Confirm the ready-queue is empty
232	readyThread = __next_thread_search( this->cltr );
233	if( readyThread ) {
234	// A thread was found, cancel the halt
235	mark_awake(this->cltr->procs, * this);
236
237	__STATS__(true, ready.sleep.cancels++; )
238
239	// continue the mai loop
240	break HALT;
241	}
242
243	idle_sleep( this );
244
245	// We were woken up, remove self from idle
246	mark_awake(this->cltr->procs, * this);
247
248	// DON'T just proceed, start looking again
249	continue MAIN_LOOP;
250	}
251
252	/* paranoid */ verify( readyThread );
253
254	// Reset io dirty bit
255	this->io.dirty = false;
256
257	// We found a thread run it
258	__run_thread(this, readyThread);
259
260	// Are we done?
261	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
262
263	if(__atomic_load_n(&this->io.pending, __ATOMIC_RELAXED) && !__atomic_load_n(&this->io.dirty, __ATOMIC_RELAXED)) {
264	__IO_STATS__(true, io.flush.dirty++; )
265	__cfa_io_flush( this );
266	}
267	}
268
269	__cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
270	}
271
272	post( this->terminated );
273
274	if(this == mainProcessor) {
275	// HACK : the coroutine context switch expects this_thread to be set
276	// and it make sense for it to be set in all other cases except here
277	// fake it
278	__cfaabi_tls.this_thread = mainThread;
279	}
280
281	__cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
282	}
283
284	static int * __volatile_errno() __attribute__((noinline));
285	static int * __volatile_errno() { asm(""); return &errno; }
286
287	// KERNEL ONLY
288	// runThread runs a thread by context switching
289	// from the processor coroutine to the target thread
290	static void __run_thread(processor * this, thread$ * thrd_dst) {
291	/* paranoid */ verify( ! __preemption_enabled() );
292	/* paranoid */ verifyf( thrd_dst->state == Ready \|\| thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
293	/* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
294	__builtin_prefetch( thrd_dst->context.SP );
295
296	__cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
297
298	coroutine$ * proc_cor = get_coroutine(this->runner);
299
300	// set state of processor coroutine to inactive
301	verify(proc_cor->state == Active);
302	proc_cor->state = Blocked;
303
304	// Actually run the thread
305	RUNNING: while(true) {
306	thrd_dst->preempted = __NO_PREEMPTION;
307	thrd_dst->state = Active;
308
309	// Update global state
310	kernelTLS().this_thread = thrd_dst;
311
312	/* paranoid */ verify( ! __preemption_enabled() );
313	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
314	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
315	/* paranoid */ verify( thrd_dst->context.SP );
316	/* paranoid */ verify( thrd_dst->state != Halted );
317	/* 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
318	/* 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
319	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
320
321
322
323	// set context switch to the thread that the processor is executing
324	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
325	// when __cfactx_switch returns we are back in the processor coroutine
326
327
328
329	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
330	/* 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 );
331	/* 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 );
332	/* paranoid */ verify( thrd_dst->context.SP );
333	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
334	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
335	/* paranoid */ verify( ! __preemption_enabled() );
336
337	// Reset global state
338	kernelTLS().this_thread = 0p;
339
340	// We just finished running a thread, there are a few things that could have happened.
341	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
342	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
343	// 4 - Preempted
344	// In case 1, we may have won a race so we can't write to the state again.
345	// In case 2, we lost the race so we now own the thread.
346
347	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
348	// The thread was preempted, reschedule it and reset the flag
349	schedule_thread$( thrd_dst, UNPARK_LOCAL );
350	break RUNNING;
351	}
352
353	if(unlikely(thrd_dst->state == Halting)) {
354	// The thread has halted, it should never be scheduled/run again
355	// finish the thread
356	__thread_finish( thrd_dst );
357	break RUNNING;
358	}
359
360	/* paranoid */ verify( thrd_dst->state == Active );
361	thrd_dst->state = Blocked;
362
363	// set state of processor coroutine to active and the thread to inactive
364	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
365	switch(old_ticket) {
366	case TICKET_RUNNING:
367	// This is case 1, the regular case, nothing more is needed
368	break RUNNING;
369	case TICKET_UNBLOCK:
370	__STATS__(true, ready.threads.threads++; )
371	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
372	// In this case, just run it again.
373	continue RUNNING;
374	default:
375	// This makes no sense, something is wrong abort
376	abort();
377	}
378	}
379
380	// Just before returning to the processor, set the processor coroutine to active
381	proc_cor->state = Active;
382
383	__cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
384
385	__STATS__(true, ready.threads.threads--; )
386
387	/* paranoid */ verify( ! __preemption_enabled() );
388	}
389
390	// KERNEL_ONLY
391	void returnToKernel() {
392	/* paranoid */ verify( ! __preemption_enabled() );
393	coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
394	thread$ * thrd_src = kernelTLS().this_thread;
395
396	__STATS_DEF( thrd_src->last_proc = kernelTLS().this_processor; )
397
398	// Run the thread on this processor
399	{
400	int local_errno = *__volatile_errno();
401	#if defined( __i386 ) \|\| defined( __x86_64 )
402	__x87_store;
403	#endif
404	/* paranoid */ verify( proc_cor->context.SP );
405	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
406	__cfactx_switch( &thrd_src->context, &proc_cor->context );
407	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
408	#if defined( __i386 ) \|\| defined( __x86_64 )
409	__x87_load;
410	#endif
411	*__volatile_errno() = local_errno;
412	}
413
414	#if !defined(__CFA_NO_STATISTICS__)
415	/* paranoid */ verify( thrd_src->last_proc != 0p );
416	if(thrd_src->last_proc != kernelTLS().this_processor) {
417	__tls_stats()->ready.threads.migration++;
418	}
419	#endif
420
421	/* paranoid */ verify( ! __preemption_enabled() );
422	/* 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 );
423	/* 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 );
424	}
425
426	//-----------------------------------------------------------------------------
427	// Scheduler routines
428	// KERNEL ONLY
429	static void __schedule_thread( thread$ * thrd, unpark_hint hint ) {
430	/* paranoid */ verify( ! __preemption_enabled() );
431	/* paranoid */ verify( ready_schedule_islocked());
432	/* paranoid */ verify( thrd );
433	/* paranoid */ verify( thrd->state != Halted );
434	/* paranoid */ verify( thrd->curr_cluster );
435	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
436	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
437	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
438	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
439	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
440	/* paranoid */ #endif
441	/* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
442	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
443
444	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
445
446	// Dereference the thread now because once we push it, there is not guaranteed it's still valid.
447	struct cluster * cl = thrd->curr_cluster;
448	__STATS_DEF(bool outside = hint == UNPARK_LOCAL && thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
449
450	// push the thread to the cluster ready-queue
451	push( cl, thrd, hint );
452
453	// variable thrd is no longer safe to use
454	thrd = 0xdeaddeaddeaddeadp;
455
456	// wake the cluster using the save variable.
457	__wake_one( cl );
458
459	#if !defined(__CFA_NO_STATISTICS__)
460	if( kernelTLS().this_stats ) {
461	__tls_stats()->ready.threads.threads++;
462	if(outside) {
463	__tls_stats()->ready.threads.extunpark++;
464	}
465	}
466	else {
467	__atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
468	__atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
469	}
470	#endif
471
472	/* paranoid */ verify( ready_schedule_islocked());
473	/* paranoid */ verify( ! __preemption_enabled() );
474	}
475
476	void schedule_thread$( thread$ * thrd, unpark_hint hint ) {
477	ready_schedule_lock();
478	__schedule_thread( thrd, hint );
479	ready_schedule_unlock();
480	}
481
482	// KERNEL ONLY
483	static inline thread$ * __next_thread(cluster * this) with( *this ) {
484	/* paranoid */ verify( ! __preemption_enabled() );
485
486	ready_schedule_lock();
487	thread$ * thrd = pop_fast( this );
488	ready_schedule_unlock();
489
490	/* paranoid */ verify( ! __preemption_enabled() );
491	return thrd;
492	}
493
494	// KERNEL ONLY
495	static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
496	/* paranoid */ verify( ! __preemption_enabled() );
497
498	ready_schedule_lock();
499	thread$ * thrd = pop_slow( this );
500	ready_schedule_unlock();
501
502	/* paranoid */ verify( ! __preemption_enabled() );
503	return thrd;
504	}
505
506	// KERNEL ONLY
507	static inline thread$ * __next_thread_search(cluster * this) with( *this ) {
508	/* paranoid */ verify( ! __preemption_enabled() );
509
510	ready_schedule_lock();
511	thread$ * thrd = pop_search( this );
512	ready_schedule_unlock();
513
514	/* paranoid */ verify( ! __preemption_enabled() );
515	return thrd;
516	}
517
518	static inline bool __must_unpark( thread$ * thrd ) {
519	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
520	switch(old_ticket) {
521	case TICKET_RUNNING:
522	// Wake won the race, the thread will reschedule/rerun itself
523	return false;
524	case TICKET_BLOCKED:
525	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
526	/* paranoid */ verify( thrd->state == Blocked );
527	return true;
528	default:
529	// This makes no sense, something is wrong abort
530	abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
531	}
532	}
533
534	void __kernel_unpark( thread$ * thrd, unpark_hint hint ) {
535	/* paranoid */ verify( ! __preemption_enabled() );
536	/* paranoid */ verify( ready_schedule_islocked());
537
538	if( !thrd ) return;
539
540	if(__must_unpark(thrd)) {
541	// Wake lost the race,
542	__schedule_thread( thrd, hint );
543	}
544
545	/* paranoid */ verify( ready_schedule_islocked());
546	/* paranoid */ verify( ! __preemption_enabled() );
547	}
548
549	void unpark( thread$ * thrd, unpark_hint hint ) {
550	if( !thrd ) return;
551
552	if(__must_unpark(thrd)) {
553	disable_interrupts();
554	// Wake lost the race,
555	schedule_thread$( thrd, hint );
556	enable_interrupts(false);
557	}
558	}
559
560	void park( void ) {
561	__disable_interrupts_checked();
562	/* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
563	returnToKernel();
564	__enable_interrupts_checked();
565
566	}
567
568	extern "C" {
569	// Leave the thread monitor
570	// last routine called by a thread.
571	// Should never return
572	void __cfactx_thrd_leave() {
573	thread$ * thrd = active_thread();
574	monitor$ * this = &thrd->self_mon;
575
576	// Lock the monitor now
577	lock( this->lock __cfaabi_dbg_ctx2 );
578
579	disable_interrupts();
580
581	/* paranoid */ verify( ! __preemption_enabled() );
582	/* paranoid */ verify( thrd->state == Active );
583	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
584	/* paranoid */ verify( kernelTLS().this_thread == thrd );
585	/* paranoid */ verify( thrd->context.SP );
586	/* 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 );
587	/* 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 );
588
589	thrd->state = Halting;
590	if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
591	if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
592	if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
593
594	// Leave the thread
595	returnToKernel();
596
597	// Control flow should never reach here!
598	abort();
599	}
600	}
601
602	// KERNEL ONLY
603	bool force_yield( __Preemption_Reason reason ) {
604	__disable_interrupts_checked();
605	thread$ * thrd = kernelTLS().this_thread;
606	/* paranoid */ verify(thrd->state == Active);
607
608	// SKULLDUGGERY: It is possible that we are preempting this thread just before
609	// it was going to park itself. If that is the case and it is already using the
610	// intrusive fields then we can't use them to preempt the thread
611	// If that is the case, abandon the preemption.
612	bool preempted = false;
613	if(thrd->link.next == 0p) {
614	preempted = true;
615	thrd->preempted = reason;
616	returnToKernel();
617	}
618	__enable_interrupts_checked( false );
619	return preempted;
620	}
621
622	//=============================================================================================
623	// Kernel Idle Sleep
624	//=============================================================================================
625	// Wake a thread from the front if there are any
626	static void __wake_one(cluster * this) {
627	eventfd_t val;
628
629	/* paranoid */ verify( ! __preemption_enabled() );
630	/* paranoid */ verify( ready_schedule_islocked() );
631
632	// Check if there is a sleeping processor
633	struct __fd_waitctx * fdp = __atomic_load_n(&this->procs.fdw, __ATOMIC_SEQ_CST);
634
635	// If no one is sleeping: we are done
636	if( fdp == 0p ) return;
637
638	int fd = 1;
639	if( __atomic_load_n(&fdp->sem, __ATOMIC_SEQ_CST) != 1 ) {
640	fd = __atomic_exchange_n(&fdp->sem, 1, __ATOMIC_RELAXED);
641	}
642
643	switch(fd) {
644	case 0:
645	// If the processor isn't ready to sleep then the exchange will already wake it up
646	#if !defined(__CFA_NO_STATISTICS__)
647	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.early++;
648	} else { __atomic_fetch_add(&this->stats->ready.sleep.early, 1, __ATOMIC_RELAXED); }
649	#endif
650	break;
651	case 1:
652	// If someone else already said they will wake them: we are done
653	#if !defined(__CFA_NO_STATISTICS__)
654	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.seen++;
655	} else { __atomic_fetch_add(&this->stats->ready.sleep.seen, 1, __ATOMIC_RELAXED); }
656	#endif
657	break;
658	default:
659	// If the processor was ready to sleep, we need to wake it up with an actual write
660	val = 1;
661	eventfd_write( fd, val );
662
663	#if !defined(__CFA_NO_STATISTICS__)
664	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.wakes++;
665	} else { __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED); }
666	#endif
667	break;
668	}
669
670	/* paranoid */ verify( ready_schedule_islocked() );
671	/* paranoid */ verify( ! __preemption_enabled() );
672
673	return;
674	}
675
676	// Unconditionnaly wake a thread
677	void __wake_proc(processor * this) {
678	/* paranoid */ verify( ! __preemption_enabled() );
679
680	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
681
682	this->idle_wctx.sem = 1;
683
684	this->idle_wctx.wake_time = rdtscl();
685
686	eventfd_t val;
687	val = 1;
688	__attribute__((unused)) int ret = eventfd_write( this->idle_wctx.evfd, val );
689
690	/* paranoid */ verifyf( ret == 0, "Expected return to be 0, was %d\n", ret );
691	/* paranoid */ verify( ! __preemption_enabled() );
692	}
693
694	static void idle_sleep(processor * this) {
695	/* paranoid */ verify( this->idle_wctx.evfd != 1 );
696	/* paranoid */ verify( this->idle_wctx.evfd != 2 );
697
698	// Tell everyone we are ready to go do sleep
699	for() {
700	int expected = this->idle_wctx.sem;
701
702	// Someone already told us to wake-up! No time for a nap.
703	if(expected == 1) { return; }
704
705	// Try to mark that we are going to sleep
706	if(__atomic_compare_exchange_n(&this->idle_wctx.sem, &expected, this->idle_wctx.evfd, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ) {
707	// Every one agreed, taking a nap
708	break;
709	}
710	}
711
712
713	#if !defined(CFA_WITH_IO_URING_IDLE)
714	#if !defined(__CFA_NO_STATISTICS__)
715	if(this->print_halts) {
716	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
717	}
718	#endif
719
720	__cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle_fd);
721
722	{
723	eventfd_t val;
724	ssize_t ret = read( this->idle_wctx.evfd, &val, sizeof(val) );
725	if(ret < 0) {
726	switch((int)errno) {
727	case EAGAIN:
728	#if EAGAIN != EWOULDBLOCK
729	case EWOULDBLOCK:
730	#endif
731	case EINTR:
732	// No need to do anything special here, just assume it's a legitimate wake-up
733	break;
734	default:
735	abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
736	}
737	}
738	}
739
740	#if !defined(__CFA_NO_STATISTICS__)
741	if(this->print_halts) {
742	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
743	}
744	#endif
745	#else
746	__cfa_io_idle( this );
747	#endif
748	}
749
750	static bool mark_idle(__cluster_proc_list & this, processor & proc) {
751	__STATS__(true, ready.sleep.halts++; )
752
753	proc.idle_wctx.sem = 0;
754
755	/* paranoid */ verify( ! __preemption_enabled() );
756	if(!try_lock( this )) return false;
757	this.idle++;
758	/* paranoid */ verify( this.idle <= this.total );
759	remove(proc);
760	insert_first(this.idles, proc);
761
762	__atomic_store_n(&this.fdw, &proc.idle_wctx, __ATOMIC_SEQ_CST);
763	unlock( this );
764	/* paranoid */ verify( ! __preemption_enabled() );
765
766	return true;
767	}
768
769	static void mark_awake(__cluster_proc_list & this, processor & proc) {
770	/* paranoid */ verify( ! __preemption_enabled() );
771	lock( this );
772	this.idle--;
773	/* paranoid */ verify( this.idle >= 0 );
774	remove(proc);
775	insert_last(this.actives, proc);
776
777	{
778	struct __fd_waitctx * wctx = 0;
779	if(!this.idles`isEmpty) wctx = &this.idles`first.idle_wctx;
780	__atomic_store_n(&this.fdw, wctx, __ATOMIC_SEQ_CST);
781	}
782
783	unlock( this );
784	/* paranoid */ verify( ! __preemption_enabled() );
785	}
786
787	//=============================================================================================
788	// Unexpected Terminating logic
789	//=============================================================================================
790	void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
791	thread$ * thrd = __cfaabi_tls.this_thread;
792
793	if(thrd) {
794	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
795	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
796
797	if ( &thrd->self_cor != thrd->curr_cor ) {
798	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
799	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
800	}
801	else {
802	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
803	}
804	}
805	else {
806	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
807	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
808	}
809	}
810
811	int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
812	return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
813	}
814
815	static __spinlock_t kernel_debug_lock;
816
817	extern "C" {
818	void __cfaabi_bits_acquire() {
819	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
820	}
821
822	void __cfaabi_bits_release() {
823	unlock( kernel_debug_lock );
824	}
825	}
826
827	//=============================================================================================
828	// Kernel Utilities
829	//=============================================================================================
830	#if defined(CFA_HAVE_LINUX_IO_URING_H)
831	#include "io/types.hfa"
832	#endif
833
834
835
836	//-----------------------------------------------------------------------------
837	// Debug
838	__cfaabi_dbg_debug_do(
839	extern "C" {
840	void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
841	this.prev_name = prev_name;
842	this.prev_thrd = kernelTLS().this_thread;
843	}
844	}
845	)
846
847	//-----------------------------------------------------------------------------
848	// Debug
849	bool threading_enabled(void) __attribute__((const)) {
850	return true;
851	}
852
853	//-----------------------------------------------------------------------------
854	// Statistics
855	#if !defined(__CFA_NO_STATISTICS__)
856	void print_halts( processor & this ) {
857	this.print_halts = true;
858	}
859
860	static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
861	/* paranoid */ verify( cltr->stats );
862
863	processor * it = &list`first;
864	for(unsigned i = 0; i < count; i++) {
865	/* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
866	/* paranoid */ verify( it->local_data->this_stats );
867	// __print_stats( it->local_data->this_stats, cltr->print_stats, "Processor", it->name, (void*)it );
868	__tally_stats( cltr->stats, it->local_data->this_stats );
869	it = &(*it)`next;
870	}
871	}
872
873	void crawl_cluster_stats( cluster & this ) {
874	// Stop the world, otherwise stats could get really messed-up
875	// this doesn't solve all problems but does solve many
876	// so it's probably good enough
877	disable_interrupts();
878	uint_fast32_t last_size = ready_mutate_lock();
879
880	crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
881	crawl_list(&this, this.procs.idles , this.procs.idle );
882
883	// Unlock the RWlock
884	ready_mutate_unlock( last_size );
885	enable_interrupts();
886	}
887
888
889	void print_stats_now( cluster & this, int flags ) {
890	crawl_cluster_stats( this );
891	__print_stats( this.stats, flags, "Cluster", this.name, (void*)&this );
892	}
893	#endif
894	// Local Variables: //
895	// mode: c //
896	// tab-width: 4 //
897	// End: //

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