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kernel.cfa @ 5a4b403

ADTast-experimental

Last change on this file since 5a4b403 was a757ba1, checked in by Thierry Delisle <tdelisle@…>, 2 years ago
Removed wait-with-io_uring feature which was slow, broken and ifdefed out.
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 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
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	__cfaabi_tls.rand_seed ^= rdtscl();
154	__cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
155	__tls_rand_advance_bck();
156
157	processor * this = runner.proc;
158	verify(this);
159
160	__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	post( this->terminated );
262
263	if(this == mainProcessor) {
264	// HACK : the coroutine context switch expects this_thread to be set
265	// and it make sense for it to be set in all other cases except here
266	// fake it
267	__cfaabi_tls.this_thread = mainThread;
268	}
269
270	__cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
271	}
272
273	static int * __volatile_errno() __attribute__((noinline));
274	static int * __volatile_errno() { asm(""); return &errno; }
275
276	// KERNEL ONLY
277	// runThread runs a thread by context switching
278	// from the processor coroutine to the target thread
279	static void __run_thread(processor * this, thread$ * thrd_dst) {
280	/* paranoid */ verify( ! __preemption_enabled() );
281	/* paranoid */ verifyf( thrd_dst->state == Ready \|\| thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
282	/* paranoid */ verifyf( thrd_dst->rdy_link.next == 0p, "Expected null got %p", thrd_dst->rdy_link.next );
283	__builtin_prefetch( thrd_dst->context.SP );
284
285	__cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
286
287	coroutine$ * proc_cor = get_coroutine(this->runner);
288
289	// set state of processor coroutine to inactive
290	verify(proc_cor->state == Active);
291	proc_cor->state = Blocked;
292
293	// Actually run the thread
294	RUNNING: while(true) {
295	thrd_dst->preempted = __NO_PREEMPTION;
296
297	// Update global state
298	kernelTLS().this_thread = thrd_dst;
299
300	// Update the state after setting this_thread
301	// so that the debugger can find all active threads
302	// in tls storage
303	thrd_dst->state = Active;
304
305	/* paranoid */ verify( ! __preemption_enabled() );
306	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
307	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
308	/* paranoid */ verify( thrd_dst->context.SP );
309	/* paranoid */ verify( thrd_dst->state != Halted );
310	/* 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
311	/* 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
312	/* paranoid */ verify( __atomic_exchange_n( &thrd_dst->executing, this, __ATOMIC_SEQ_CST) == 0p );
313	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
314
315
316
317	// set context switch to the thread that the processor is executing
318	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
319	// when __cfactx_switch returns we are back in the processor coroutine
320
321
322
323	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
324	/* paranoid */ verify( __atomic_exchange_n( &thrd_dst->executing, 0p, __ATOMIC_SEQ_CST) == this );
325	/* 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 );
326	/* 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 );
327	/* paranoid */ verify( thrd_dst->state != Halted );
328	/* paranoid */ verify( thrd_dst->context.SP );
329	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
330	/* paranoid */ verify( ! __preemption_enabled() );
331
332	// We just finished running a thread, there are a few things that could have happened.
333	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
334	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
335	// 4 - Preempted
336	// In case 1, we may have won a race so we can't write to the state again.
337	// In case 2, we lost the race so we now own the thread.
338
339	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
340	// Reset the this_thread now that we know
341	// the state isn't active anymore
342	kernelTLS().this_thread = 0p;
343
344	// The thread was preempted, reschedule it and reset the flag
345	schedule_thread$( thrd_dst, UNPARK_LOCAL );
346	break RUNNING;
347	}
348
349	if(unlikely(thrd_dst->state == Halting)) {
350	// Reset the this_thread now that we know
351	// the state isn't active anymore
352	kernelTLS().this_thread = 0p;
353
354	// The thread has halted, it should never be scheduled/run again
355	// finish the thread
356	__thread_finish( thrd_dst );
357	break RUNNING;
358	}
359
360	/* paranoid */ verify( thrd_dst->state == Active );
361	thrd_dst->state = Blocked;
362
363	// Reset the this_thread now that we know
364	// the state isn't active anymore
365	kernelTLS().this_thread = 0p;
366
367	// set state of processor coroutine to active and the thread to inactive
368	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
369	switch(old_ticket) {
370	case TICKET_RUNNING:
371	// This is case 1, the regular case, nothing more is needed
372	break RUNNING;
373	case TICKET_UNBLOCK:
374	__STATS__(true, ready.threads.threads++; )
375	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
376	// In this case, just run it again.
377	continue RUNNING;
378	default:
379	// This makes no sense, something is wrong abort
380	abort();
381	}
382	}
383
384	// Just before returning to the processor, set the processor coroutine to active
385	proc_cor->state = Active;
386
387	__cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
388
389	__STATS__(true, ready.threads.threads--; )
390
391	/* paranoid */ verify( ! __preemption_enabled() );
392	}
393
394	// KERNEL_ONLY
395	static void returnToKernel() {
396	/* paranoid */ verify( ! __preemption_enabled() );
397	coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
398	thread$ * thrd_src = kernelTLS().this_thread;
399
400	__STATS_DEF( thrd_src->last_proc = kernelTLS().this_processor; )
401
402	// Run the thread on this processor
403	{
404	int local_errno = *__volatile_errno();
405	#if defined( __i386 ) \|\| defined( __x86_64 )
406	__x87_store;
407	#endif
408	/* paranoid */ verify( proc_cor->context.SP );
409	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
410	__cfactx_switch( &thrd_src->context, &proc_cor->context );
411	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
412	#if defined( __i386 ) \|\| defined( __x86_64 )
413	__x87_load;
414	#endif
415	*__volatile_errno() = local_errno;
416	}
417
418	#if !defined(__CFA_NO_STATISTICS__)
419	/* paranoid */ verify( thrd_src->last_proc != 0p );
420	if(thrd_src->last_proc != kernelTLS().this_processor) {
421	__tls_stats()->ready.threads.migration++;
422	}
423	#endif
424
425	/* paranoid */ verify( ! __preemption_enabled() );
426	/* 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 );
427	/* 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 );
428	}
429
430	//-----------------------------------------------------------------------------
431	// Scheduler routines
432	// KERNEL ONLY
433	static void __schedule_thread( thread$ * thrd, unpark_hint hint ) {
434	/* paranoid */ verify( ! __preemption_enabled() );
435	/* paranoid */ verify( ready_schedule_islocked());
436	/* paranoid */ verify( thrd );
437	/* paranoid */ verify( thrd->state != Halted );
438	/* paranoid */ verify( thrd->curr_cluster );
439	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
440	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
441	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
442	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
443	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
444	/* paranoid */ #endif
445	/* paranoid */ verifyf( thrd->rdy_link.next == 0p, "Expected null got %p", thrd->rdy_link.next );
446	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
447
448	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
449
450	// Dereference the thread now because once we push it, there is not guaranteed it's still valid.
451	struct cluster * cl = thrd->curr_cluster;
452	__STATS_DEF(bool outside = hint == UNPARK_LOCAL && thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
453
454	// push the thread to the cluster ready-queue
455	push( cl, thrd, hint );
456
457	// variable thrd is no longer safe to use
458	thrd = 0xdeaddeaddeaddeadp;
459
460	// wake the cluster using the save variable.
461	__wake_one( cl );
462
463	#if !defined(__CFA_NO_STATISTICS__)
464	if( kernelTLS().this_stats ) {
465	__tls_stats()->ready.threads.threads++;
466	if(outside) {
467	__tls_stats()->ready.threads.extunpark++;
468	}
469	}
470	else {
471	__atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
472	__atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
473	}
474	#endif
475
476	/* paranoid */ verify( ready_schedule_islocked());
477	/* paranoid */ verify( ! __preemption_enabled() );
478	}
479
480	void schedule_thread$( thread$ * thrd, unpark_hint hint ) {
481	ready_schedule_lock();
482	__schedule_thread( thrd, hint );
483	ready_schedule_unlock();
484	}
485
486	// KERNEL ONLY
487	static inline thread$ * __next_thread(cluster * this) with( *this ) {
488	/* paranoid */ verify( ! __preemption_enabled() );
489
490	ready_schedule_lock();
491	thread$ * thrd = pop_fast( this );
492	ready_schedule_unlock();
493
494	/* paranoid */ verify( ! __preemption_enabled() );
495	return thrd;
496	}
497
498	// KERNEL ONLY
499	static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
500	/* paranoid */ verify( ! __preemption_enabled() );
501
502	ready_schedule_lock();
503	thread$ * thrd = pop_slow( this );
504	ready_schedule_unlock();
505
506	/* paranoid */ verify( ! __preemption_enabled() );
507	return thrd;
508	}
509
510	// KERNEL ONLY
511	static inline thread$ * __next_thread_search(cluster * this) with( *this ) {
512	/* paranoid */ verify( ! __preemption_enabled() );
513
514	ready_schedule_lock();
515	thread$ * thrd = pop_search( this );
516	ready_schedule_unlock();
517
518	/* paranoid */ verify( ! __preemption_enabled() );
519	return thrd;
520	}
521
522	static inline bool __must_unpark( thread$ * thrd ) {
523	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
524	switch(old_ticket) {
525	case TICKET_RUNNING:
526	// Wake won the race, the thread will reschedule/rerun itself
527	return false;
528	case TICKET_BLOCKED:
529	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
530	/* paranoid */ verify( thrd->state == Blocked );
531	return true;
532	default:
533	// This makes no sense, something is wrong abort
534	abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
535	}
536	}
537
538	void __kernel_unpark( thread$ * thrd, unpark_hint hint ) {
539	/* paranoid */ verify( ! __preemption_enabled() );
540	/* paranoid */ verify( ready_schedule_islocked());
541
542	if( !thrd ) return;
543
544	if(__must_unpark(thrd)) {
545	// Wake lost the race,
546	__schedule_thread( thrd, hint );
547	}
548
549	/* paranoid */ verify( ready_schedule_islocked());
550	/* paranoid */ verify( ! __preemption_enabled() );
551	}
552
553	void unpark( thread$ * thrd, unpark_hint hint ) libcfa_public {
554	if( !thrd ) return;
555
556	if(__must_unpark(thrd)) {
557	disable_interrupts();
558	// Wake lost the race,
559	schedule_thread$( thrd, hint );
560	enable_interrupts(false);
561	}
562	}
563
564	void park( void ) libcfa_public {
565	__disable_interrupts_checked();
566	/* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
567	returnToKernel();
568	__enable_interrupts_checked();
569
570	}
571
572	extern "C" {
573	// Leave the thread monitor
574	// last routine called by a thread.
575	// Should never return
576	void __cfactx_thrd_leave() {
577	thread$ * thrd = active_thread();
578	monitor$ * this = &thrd->self_mon;
579
580	// Lock the monitor now
581	lock( this->lock __cfaabi_dbg_ctx2 );
582
583	disable_interrupts();
584
585	/* paranoid */ verify( ! __preemption_enabled() );
586	/* paranoid */ verify( thrd->state == Active );
587	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
588	/* paranoid */ verify( kernelTLS().this_thread == thrd );
589	/* paranoid */ verify( thrd->context.SP );
590	/* 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 );
591	/* 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 );
592
593	if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
594	if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
595	if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
596
597	thrd->state = Halting;
598	thrd->ticket = TICKET_DEAD;
599
600	// Leave the thread
601	returnToKernel();
602
603	// Control flow should never reach here!
604	abort();
605	}
606	}
607
608	// KERNEL ONLY
609	bool force_yield( __Preemption_Reason reason ) libcfa_public {
610	__disable_interrupts_checked();
611	thread$ * thrd = kernelTLS().this_thread;
612	/* paranoid */ verify(thrd->state == Active);
613
614	// SKULLDUGGERY: It is possible that we are preempting this thread just before
615	// it was going to park itself. If that is the case and it is already using the
616	// intrusive fields then we can't use them to preempt the thread
617	// If that is the case, abandon the preemption.
618	bool preempted = false;
619	if(thrd->rdy_link.next == 0p) {
620	preempted = true;
621	thrd->preempted = reason;
622	returnToKernel();
623	}
624	__enable_interrupts_checked( false );
625	return preempted;
626	}
627
628	//=============================================================================================
629	// Kernel Idle Sleep
630	//=============================================================================================
631	// Wake a thread from the front if there are any
632	static void __wake_one(cluster * this) {
633	eventfd_t val;
634
635	/* paranoid */ verify( ! __preemption_enabled() );
636	/* paranoid */ verify( ready_schedule_islocked() );
637
638	// Check if there is a sleeping processor
639	struct __fd_waitctx * fdp = __atomic_load_n(&this->procs.fdw, __ATOMIC_SEQ_CST);
640
641	// If no one is sleeping: we are done
642	if( fdp == 0p ) return;
643
644	int fd = 1;
645	if( __atomic_load_n(&fdp->sem, __ATOMIC_SEQ_CST) != 1 ) {
646	fd = __atomic_exchange_n(&fdp->sem, 1, __ATOMIC_RELAXED);
647	}
648
649	switch(fd) {
650	__attribute__((unused)) int ret;
651	case 0:
652	// If the processor isn't ready to sleep then the exchange will already wake it up
653	#if !defined(__CFA_NO_STATISTICS__)
654	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.early++;
655	} else { __atomic_fetch_add(&this->stats->ready.sleep.early, 1, __ATOMIC_RELAXED); }
656	#endif
657	break;
658	case 1:
659	// If someone else already said they will wake them: we are done
660	#if !defined(__CFA_NO_STATISTICS__)
661	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.seen++;
662	} else { __atomic_fetch_add(&this->stats->ready.sleep.seen, 1, __ATOMIC_RELAXED); }
663	#endif
664	break;
665	default:
666	// If the processor was ready to sleep, we need to wake it up with an actual write
667	val = 1;
668	ret = eventfd_write( fd, val );
669	/* paranoid */ verifyf( ret == 0, "Expected return to be 0, was %d\n", ret );
670
671	#if !defined(__CFA_NO_STATISTICS__)
672	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.wakes++;
673	} else { __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED); }
674	#endif
675	break;
676	}
677
678	/* paranoid */ verify( ready_schedule_islocked() );
679	/* paranoid */ verify( ! __preemption_enabled() );
680
681	return;
682	}
683
684	// Unconditionnaly wake a thread
685	void __wake_proc(processor * this) {
686	/* paranoid */ verify( ! __preemption_enabled() );
687
688	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
689
690	this->idle_wctx.sem = 1;
691
692	this->idle_wctx.wake__time = rdtscl();
693
694	eventfd_t val;
695	val = 1;
696	__attribute__((unused)) int ret = eventfd_write( this->idle_wctx.evfd, val );
697
698	/* paranoid */ verifyf( ret == 0, "Expected return to be 0, was %d\n", ret );
699	/* paranoid */ verify( ! __preemption_enabled() );
700	}
701
702	static void idle_sleep(processor * this) {
703	/* paranoid */ verify( this->idle_wctx.evfd != 1 );
704	/* paranoid */ verify( this->idle_wctx.evfd != 2 );
705
706	// Tell everyone we are ready to go do sleep
707	for() {
708	int expected = this->idle_wctx.sem;
709
710	// Someone already told us to wake-up! No time for a nap.
711	if(expected == 1) { return; }
712
713	// Try to mark that we are going to sleep
714	if(__atomic_compare_exchange_n(&this->idle_wctx.sem, &expected, this->idle_wctx.evfd, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ) {
715	// Every one agreed, taking a nap
716	break;
717	}
718	}
719
720
721	#if !defined(__CFA_NO_STATISTICS__)
722	if(this->print_halts) {
723	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
724	}
725	#endif
726
727	__cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle_fd);
728
729	{
730	eventfd_t val;
731	ssize_t ret = read( this->idle_wctx.evfd, &val, sizeof(val) );
732	if(ret < 0) {
733	switch((int)errno) {
734	case EAGAIN:
735	#if EAGAIN != EWOULDBLOCK
736	case EWOULDBLOCK:
737	#endif
738	case EINTR:
739	// No need to do anything special here, just assume it's a legitimate wake-up
740	break;
741	default:
742	abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
743	}
744	}
745	}
746
747	#if !defined(__CFA_NO_STATISTICS__)
748	if(this->print_halts) {
749	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
750	}
751	#endif
752	}
753
754	static bool mark_idle(__cluster_proc_list & this, processor & proc) {
755	__STATS__(true, ready.sleep.halts++; )
756
757	proc.idle_wctx.sem = 0;
758
759	/* paranoid */ verify( ! __preemption_enabled() );
760	if(!try_lock( this )) return false;
761	this.idle++;
762	/* paranoid */ verify( this.idle <= this.total );
763	remove(proc);
764	insert_first(this.idles, proc);
765
766	// update the pointer to the head wait context, which should now point to this proc.
767	__atomic_store_n(&this.fdw, &proc.idle_wctx, __ATOMIC_SEQ_CST);
768	unlock( this );
769	/* paranoid */ verify( ! __preemption_enabled() );
770
771	return true;
772	}
773
774	static void mark_awake(__cluster_proc_list & this, processor & proc) {
775	/* paranoid */ verify( ! __preemption_enabled() );
776	lock( this );
777	this.idle--;
778	/* paranoid */ verify( this.idle >= 0 );
779	remove(proc);
780	insert_last(this.actives, proc);
781
782	{
783	// update the pointer to the head wait context
784	struct __fd_waitctx * wctx = 0;
785	if(!this.idles`isEmpty) wctx = &this.idles`first.idle_wctx;
786	__atomic_store_n(&this.fdw, wctx, __ATOMIC_SEQ_CST);
787	}
788
789	unlock( this );
790	/* paranoid */ verify( ! __preemption_enabled() );
791	}
792
793	//=============================================================================================
794	// Unexpected Terminating logic
795	//=============================================================================================
796	void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
797	thread$ * thrd = __cfaabi_tls.this_thread;
798
799	if(thrd) {
800	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
801	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
802
803	if ( &thrd->self_cor != thrd->curr_cor ) {
804	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
805	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
806	}
807	else {
808	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
809	}
810	}
811	else {
812	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
813	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
814	}
815	}
816
817	int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
818	return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
819	}
820
821	static __spinlock_t kernel_debug_lock;
822
823	extern "C" {
824	void __cfaabi_bits_acquire() {
825	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
826	}
827
828	void __cfaabi_bits_release() {
829	unlock( kernel_debug_lock );
830	}
831	}
832
833	//=============================================================================================
834	// Kernel Utilities
835	//=============================================================================================
836	#if defined(CFA_HAVE_LINUX_IO_URING_H)
837	#include "io/types.hfa"
838	#endif
839
840	//-----------------------------------------------------------------------------
841	// Debug
842	bool threading_enabled(void) __attribute__((const)) libcfa_public {
843	return true;
844	}
845
846	//-----------------------------------------------------------------------------
847	// Statistics
848	#if !defined(__CFA_NO_STATISTICS__)
849	void print_halts( processor & this ) libcfa_public {
850	this.print_halts = true;
851	}
852
853	static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
854	/* paranoid */ verify( cltr->stats );
855
856	processor * it = &list`first;
857	for(unsigned i = 0; i < count; i++) {
858	/* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
859	/* paranoid */ verify( it->local_data->this_stats );
860	// __print_stats( it->local_data->this_stats, cltr->print_stats, "Processor", it->name, (void*)it );
861	__tally_stats( cltr->stats, it->local_data->this_stats );
862	it = &(*it)`next;
863	}
864	}
865
866	static void crawl_cluster_stats( cluster & this ) {
867	// Stop the world, otherwise stats could get really messed-up
868	// this doesn't solve all problems but does solve many
869	// so it's probably good enough
870	disable_interrupts();
871	uint_fast32_t last_size = ready_mutate_lock();
872
873	crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
874	crawl_list(&this, this.procs.idles , this.procs.idle );
875
876	// Unlock the RWlock
877	ready_mutate_unlock( last_size );
878	enable_interrupts();
879	}
880
881
882	void print_stats_now( cluster & this, int flags ) libcfa_public {
883	crawl_cluster_stats( this );
884	__print_stats( this.stats, flags, "Cluster", this.name, (void*)&this );
885	}
886	#endif
887	// Local Variables: //
888	// mode: c //
889	// tab-width: 4 //
890	// End: //

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