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kernel.cfa@ 3c039b0

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Last change on this file since 3c039b0 was 4069faad, checked in by Thierry Delisle <tdelisle@…>, 5 years ago
Fix error in benchmark where the wrong fd was used. Changed behcnmark to use seperate cluster for I/O. Changed some debug prints to use new versions with groups. Fixed halting race condition leading to deadlock.
Property mode set to `100644`
File size: 34.6 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 : Tue Feb 4 13:03:15 2020
13	// Update Count : 58
14	//
15
16	#define __cforall_thread__
17	// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
18
19	//C Includes
20	#include <stddef.h>
21	#include <errno.h>
22	#include <string.h>
23	extern "C" {
24	#include <stdio.h>
25	#include <fenv.h>
26	#include <sys/resource.h>
27	#include <signal.h>
28	#include <unistd.h>
29	#include <limits.h> // PTHREAD_STACK_MIN
30	#include <sys/mman.h> // mprotect
31	}
32
33	//CFA Includes
34	#include "time.hfa"
35	#include "kernel_private.hfa"
36	#include "preemption.hfa"
37	#include "startup.hfa"
38
39	//Private includes
40	#define __CFA_INVOKE_PRIVATE__
41	#include "invoke.h"
42
43
44	//-----------------------------------------------------------------------------
45	// Some assembly required
46	#if defined( __i386 )
47	#define CtxGet( ctx ) \
48	__asm__ volatile ( \
49	"movl %%esp,%0\n"\
50	"movl %%ebp,%1\n"\
51	: "=rm" (ctx.SP),\
52	"=rm" (ctx.FP) \
53	)
54
55	// mxcr : SSE Status and Control bits (control bits are preserved across function calls)
56	// fcw : X87 FPU control word (preserved across function calls)
57	#define __x87_store \
58	uint32_t __mxcr; \
59	uint16_t __fcw; \
60	__asm__ volatile ( \
61	"stmxcsr %0\n" \
62	"fnstcw %1\n" \
63	: "=m" (__mxcr),\
64	"=m" (__fcw) \
65	)
66
67	#define __x87_load \
68	__asm__ volatile ( \
69	"fldcw %1\n" \
70	"ldmxcsr %0\n" \
71	::"m" (__mxcr),\
72	"m" (__fcw) \
73	)
74
75	#elif defined( __x86_64 )
76	#define CtxGet( ctx ) \
77	__asm__ volatile ( \
78	"movq %%rsp,%0\n"\
79	"movq %%rbp,%1\n"\
80	: "=rm" (ctx.SP),\
81	"=rm" (ctx.FP) \
82	)
83
84	#define __x87_store \
85	uint32_t __mxcr; \
86	uint16_t __fcw; \
87	__asm__ volatile ( \
88	"stmxcsr %0\n" \
89	"fnstcw %1\n" \
90	: "=m" (__mxcr),\
91	"=m" (__fcw) \
92	)
93
94	#define __x87_load \
95	__asm__ volatile ( \
96	"fldcw %1\n" \
97	"ldmxcsr %0\n" \
98	:: "m" (__mxcr),\
99	"m" (__fcw) \
100	)
101
102
103	#elif defined( __ARM_ARCH )
104	#define CtxGet( ctx ) __asm__ ( \
105	"mov %0,%%sp\n" \
106	"mov %1,%%r11\n" \
107	: "=rm" (ctx.SP), "=rm" (ctx.FP) )
108	#else
109	#error unknown hardware architecture
110	#endif
111
112	//-----------------------------------------------------------------------------
113	//Start and stop routine for the kernel, declared first to make sure they run first
114	static void __kernel_startup (void) __attribute__(( constructor( STARTUP_PRIORITY_KERNEL ) ));
115	static void __kernel_shutdown(void) __attribute__(( destructor ( STARTUP_PRIORITY_KERNEL ) ));
116
117	//-----------------------------------------------------------------------------
118	// Kernel Scheduling logic
119	static $thread * __next_thread(cluster * this);
120	static void __run_thread(processor * this, $thread * dst);
121	static $thread * __halt(processor * this);
122	static bool __wake_one(cluster * cltr, bool was_empty);
123	static bool __wake_proc(processor *);
124
125	//-----------------------------------------------------------------------------
126	// Kernel storage
127	KERNEL_STORAGE(cluster, mainCluster);
128	KERNEL_STORAGE(processor, mainProcessor);
129	KERNEL_STORAGE($thread, mainThread);
130	KERNEL_STORAGE(__stack_t, mainThreadCtx);
131
132	cluster * mainCluster;
133	processor * mainProcessor;
134	$thread * mainThread;
135
136	extern "C" {
137	struct { __dllist_t(cluster) list; __spinlock_t lock; } __cfa_dbg_global_clusters;
138	}
139
140	size_t __page_size = 0;
141
142	//-----------------------------------------------------------------------------
143	// Global state
144	thread_local struct KernelThreadData kernelTLS __attribute__ ((tls_model ( "initial-exec" ))) = {
145	NULL, // cannot use 0p
146	NULL,
147	{ 1, false, false },
148	6u //this should be seeded better but due to a bug calling rdtsc doesn't work
149	};
150
151	//-----------------------------------------------------------------------------
152	// Struct to steal stack
153	struct current_stack_info_t {
154	__stack_t * storage; // pointer to stack object
155	void * base; // base of stack
156	void * limit; // stack grows towards stack limit
157	void * context; // address of cfa_context_t
158	};
159
160	void ?{}( current_stack_info_t & this ) {
161	__stack_context_t ctx;
162	CtxGet( ctx );
163	this.base = ctx.FP;
164
165	rlimit r;
166	getrlimit( RLIMIT_STACK, &r);
167	size_t size = r.rlim_cur;
168
169	this.limit = (void *)(((intptr_t)this.base) - size);
170	this.context = &storage_mainThreadCtx;
171	}
172
173	//-----------------------------------------------------------------------------
174	// Main thread construction
175
176	void ?{}( $coroutine & this, current_stack_info_t * info) with( this ) {
177	stack.storage = info->storage;
178	with(*stack.storage) {
179	limit = info->limit;
180	base = info->base;
181	}
182	__attribute__((may_alias)) intptr_t * istorage = (intptr_t*) &stack.storage;
183	*istorage \|= 0x1;
184	name = "Main Thread";
185	state = Start;
186	starter = 0p;
187	last = 0p;
188	cancellation = 0p;
189	}
190
191	void ?{}( $thread & this, current_stack_info_t * info) with( this ) {
192	state = Start;
193	self_cor{ info };
194	curr_cor = &self_cor;
195	curr_cluster = mainCluster;
196	self_mon.owner = &this;
197	self_mon.recursion = 1;
198	self_mon_p = &self_mon;
199	next = 0p;
200
201	node.next = 0p;
202	node.prev = 0p;
203	doregister(curr_cluster, this);
204
205	monitors{ &self_mon_p, 1, (fptr_t)0 };
206	}
207
208	//-----------------------------------------------------------------------------
209	// Processor coroutine
210	void ?{}(processorCtx_t & this) {
211
212	}
213
214	// Construct the processor context of non-main processors
215	static void ?{}(processorCtx_t & this, processor * proc, current_stack_info_t * info) {
216	(this.__cor){ info };
217	this.proc = proc;
218	}
219
220	static void * __invoke_processor(void * arg);
221
222	void ?{}(processor & this, const char name[], cluster & cltr) with( this ) {
223	this.name = name;
224	this.cltr = &cltr;
225	terminated{ 0 };
226	destroyer = 0p;
227	do_terminate = false;
228	preemption_alarm = 0p;
229	pending_preemption = false;
230	runner.proc = &this;
231
232	idle{};
233
234	__cfadbg_print_safe(runtime_core, "Kernel : Starting core %p\n", &this);
235
236	this.stack = __create_pthread( &this.kernel_thread, __invoke_processor, (void *)&this );
237
238	__cfadbg_print_safe(runtime_core, "Kernel : core %p created\n", &this);
239	}
240
241	void ^?{}(processor & this) with( this ){
242	if( ! __atomic_load_n(&do_terminate, __ATOMIC_ACQUIRE) ) {
243	__cfadbg_print_safe(runtime_core, "Kernel : core %p signaling termination\n", &this);
244
245	__atomic_store_n(&do_terminate, true, __ATOMIC_RELAXED);
246	__wake_proc( &this );
247
248	P( terminated );
249	verify( kernelTLS.this_processor != &this);
250	}
251
252	pthread_join( kernel_thread, 0p );
253	free( this.stack );
254	}
255
256	void ?{}(cluster & this, const char name[], Duration preemption_rate) with( this ) {
257	this.name = name;
258	this.preemption_rate = preemption_rate;
259	ready_queue{};
260	ready_queue_lock{};
261
262	#if !defined(__CFA_NO_STATISTICS__)
263	print_stats = false;
264	#endif
265
266	procs{ __get };
267	idles{ __get };
268	threads{ __get };
269
270	__kernel_io_startup( this, &this == mainCluster );
271
272	doregister(this);
273	}
274
275	void ^?{}(cluster & this) {
276	__kernel_io_shutdown( this, &this == mainCluster );
277
278	unregister(this);
279	}
280
281	//=============================================================================================
282	// Kernel Scheduling logic
283	//=============================================================================================
284	//Main of the processor contexts
285	void main(processorCtx_t & runner) {
286	// Because of a bug, we couldn't initialized the seed on construction
287	// Do it here
288	kernelTLS.rand_seed ^= rdtscl();
289
290	processor * this = runner.proc;
291	verify(this);
292
293	__cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
294
295	doregister(this->cltr, this);
296
297	{
298	// Setup preemption data
299	preemption_scope scope = { this };
300
301	__cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
302
303	$thread * readyThread = 0p;
304	for( unsigned int spin_count = 0; ! __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST); spin_count++ ) {
305	// Try to get the next thread
306	readyThread = __next_thread( this->cltr );
307
308	// If no ready thread
309	if( readyThread == 0p ) {
310	// Block until a thread is ready
311	readyThread = __halt(this);
312	}
313
314	// Check if we actually found a thread
315	if( readyThread ) {
316	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
317	/* paranoid */ verifyf( readyThread->state == Ready \|\| readyThread->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", readyThread->state, readyThread->preempted);
318	/* paranoid */ verifyf( readyThread->next == 0p, "Expected null got %p", readyThread->next );
319
320	// We found a thread run it
321	__run_thread(this, readyThread);
322
323	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
324	}
325	}
326
327	__cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
328	}
329
330	unregister(this->cltr, this);
331
332	V( this->terminated );
333
334	__cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
335
336	// HACK : the coroutine context switch expects this_thread to be set
337	// and it make sense for it to be set in all other cases except here
338	// fake it
339	if( this == mainProcessor ) kernelTLS.this_thread = mainThread;
340	}
341
342	static int * __volatile_errno() __attribute__((noinline));
343	static int * __volatile_errno() { asm(""); return &errno; }
344
345	// KERNEL ONLY
346	// runThread runs a thread by context switching
347	// from the processor coroutine to the target thread
348	static void __run_thread(processor * this, $thread * thrd_dst) {
349	$coroutine * proc_cor = get_coroutine(this->runner);
350
351	// Update global state
352	kernelTLS.this_thread = thrd_dst;
353
354	// set state of processor coroutine to inactive
355	verify(proc_cor->state == Active);
356	proc_cor->state = Blocked;
357
358	// Actually run the thread
359	RUNNING: while(true) {
360	if(unlikely(thrd_dst->preempted)) {
361	thrd_dst->preempted = __NO_PREEMPTION;
362	verify(thrd_dst->state == Active \|\| thrd_dst->state == Rerun);
363	} else {
364	verify(thrd_dst->state == Blocked \|\| thrd_dst->state == Ready); // Ready means scheduled normally, blocked means rerun
365	thrd_dst->state = Active;
366	}
367
368	__cfaabi_dbg_debug_do(
369	thrd_dst->park_stale = true;
370	thrd_dst->unpark_stale = true;
371	)
372
373	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
374	/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ) \|\| thrd_dst->curr_cor == proc_cor, "ERROR : Destination $thread %p has been corrupted.\n StackPointer too small.\n", thrd_dst ); // add escape condition if we are setting up the processor
375	/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit) \|\| thrd_dst->curr_cor == proc_cor, "ERROR : Destination $thread %p has been corrupted.\n StackPointer too large.\n", thrd_dst ); // add escape condition if we are setting up the processor
376
377	// set context switch to the thread that the processor is executing
378	verify( thrd_dst->context.SP );
379	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
380	// when __cfactx_switch returns we are back in the processor coroutine
381
382	/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit), "ERROR : Destination $thread %p has been corrupted.\n StackPointer too large.\n", thrd_dst );
383	/* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ), "ERROR : Destination $thread %p has been corrupted.\n StackPointer too small.\n", thrd_dst );
384	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
385
386
387	// We just finished running a thread, there are a few things that could have happened.
388	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
389	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
390	// 4 - Preempted
391	// In case 1, we may have won a race so we can't write to the state again.
392	// In case 2, we lost the race so we now own the thread.
393
394	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
395	// The thread was preempted, reschedule it and reset the flag
396	__schedule_thread( thrd_dst );
397	break RUNNING;
398	}
399
400	// set state of processor coroutine to active and the thread to inactive
401	static_assert(sizeof(thrd_dst->state) == sizeof(int));
402	enum coroutine_state old_state = __atomic_exchange_n(&thrd_dst->state, Blocked, __ATOMIC_SEQ_CST);
403	__cfaabi_dbg_debug_do( thrd_dst->park_result = old_state; )
404	switch(old_state) {
405	case Halted:
406	// The thread has halted, it should never be scheduled/run again, leave it back to Halted and move on
407	thrd_dst->state = Halted;
408
409	// We may need to wake someone up here since
410	unpark( this->destroyer __cfaabi_dbg_ctx2 );
411	this->destroyer = 0p;
412	break RUNNING;
413	case Active:
414	// This is case 1, the regular case, nothing more is needed
415	break RUNNING;
416	case Rerun:
417	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
418	// In this case, just run it again.
419	continue RUNNING;
420	default:
421	// This makes no sense, something is wrong abort
422	abort("Finished running a thread that was Blocked/Start/Primed %d\n", old_state);
423	}
424	}
425
426	// Just before returning to the processor, set the processor coroutine to active
427	proc_cor->state = Active;
428	kernelTLS.this_thread = 0p;
429	}
430
431	// KERNEL_ONLY
432	void returnToKernel() {
433	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
434	$coroutine * proc_cor = get_coroutine(kernelTLS.this_processor->runner);
435	$thread * thrd_src = kernelTLS.this_thread;
436
437	// Run the thread on this processor
438	{
439	int local_errno = *__volatile_errno();
440	#if defined( __i386 ) \|\| defined( __x86_64 )
441	__x87_store;
442	#endif
443	verify( proc_cor->context.SP );
444	__cfactx_switch( &thrd_src->context, &proc_cor->context );
445	#if defined( __i386 ) \|\| defined( __x86_64 )
446	__x87_load;
447	#endif
448	*__volatile_errno() = local_errno;
449	}
450
451	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
452	/* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) < ((uintptr_t)__get_stack(thrd_src->curr_cor)->base ), "ERROR : Returning $thread %p has been corrupted.\n StackPointer too small.\n", thrd_src );
453	/* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) > ((uintptr_t)__get_stack(thrd_src->curr_cor)->limit), "ERROR : Returning $thread %p has been corrupted.\n StackPointer too large.\n", thrd_src );
454	}
455
456	// KERNEL_ONLY
457	// Context invoker for processors
458	// This is the entry point for processors (kernel threads)
459	// It effectively constructs a coroutine by stealing the pthread stack
460	static void * __invoke_processor(void * arg) {
461	processor * proc = (processor *) arg;
462	kernelTLS.this_processor = proc;
463	kernelTLS.this_thread = 0p;
464	kernelTLS.preemption_state.[enabled, disable_count] = [false, 1];
465	// SKULLDUGGERY: We want to create a context for the processor coroutine
466	// which is needed for the 2-step context switch. However, there is no reason
467	// to waste the perfectly valid stack create by pthread.
468	current_stack_info_t info;
469	__stack_t ctx;
470	info.storage = &ctx;
471	(proc->runner){ proc, &info };
472
473	__cfaabi_dbg_print_safe("Coroutine : created stack %p\n", get_coroutine(proc->runner)->stack.storage);
474
475	//Set global state
476	kernelTLS.this_thread = 0p;
477
478	//We now have a proper context from which to schedule threads
479	__cfadbg_print_safe(runtime_core, "Kernel : core %p created (%p, %p)\n", proc, &proc->runner, &ctx);
480
481	// SKULLDUGGERY: Since the coroutine doesn't have its own stack, we can't
482	// resume it to start it like it normally would, it will just context switch
483	// back to here. Instead directly call the main since we already are on the
484	// appropriate stack.
485	get_coroutine(proc->runner)->state = Active;
486	main( proc->runner );
487	get_coroutine(proc->runner)->state = Halted;
488
489	// Main routine of the core returned, the core is now fully terminated
490	__cfadbg_print_safe(runtime_core, "Kernel : core %p main ended (%p)\n", proc, &proc->runner);
491
492	return 0p;
493	}
494
495	static void Abort( int ret, const char func[] ) {
496	if ( ret ) { // pthread routines return errno values
497	abort( "%s : internal error, error(%d) %s.", func, ret, strerror( ret ) );
498	} // if
499	} // Abort
500
501	void * __create_pthread( pthread_t * pthread, void * (start)(void ), void * arg ) {
502	pthread_attr_t attr;
503
504	Abort( pthread_attr_init( &attr ), "pthread_attr_init" ); // initialize attribute
505
506	size_t stacksize;
507	// default stack size, normally defined by shell limit
508	Abort( pthread_attr_getstacksize( &attr, &stacksize ), "pthread_attr_getstacksize" );
509	assert( stacksize >= PTHREAD_STACK_MIN );
510
511	void * stack;
512	__cfaabi_dbg_debug_do(
513	stack = memalign( __page_size, stacksize + __page_size );
514	// pthread has no mechanism to create the guard page in user supplied stack.
515	if ( mprotect( stack, __page_size, PROT_NONE ) == -1 ) {
516	abort( "mprotect : internal error, mprotect failure, error(%d) %s.", errno, strerror( errno ) );
517	} // if
518	);
519	__cfaabi_dbg_no_debug_do(
520	stack = malloc( stacksize );
521	);
522
523	Abort( pthread_attr_setstack( &attr, stack, stacksize ), "pthread_attr_setstack" );
524
525	Abort( pthread_create( pthread, &attr, start, arg ), "pthread_create" );
526	return stack;
527	}
528
529	// KERNEL_ONLY
530	static void __kernel_first_resume( processor * this ) {
531	$thread * src = mainThread;
532	$coroutine * dst = get_coroutine(this->runner);
533
534	verify( ! kernelTLS.preemption_state.enabled );
535
536	kernelTLS.this_thread->curr_cor = dst;
537	__stack_prepare( &dst->stack, 65000 );
538	__cfactx_start(main, dst, this->runner, __cfactx_invoke_coroutine);
539
540	verify( ! kernelTLS.preemption_state.enabled );
541
542	dst->last = &src->self_cor;
543	dst->starter = dst->starter ? dst->starter : &src->self_cor;
544
545	// make sure the current state is still correct
546	/* paranoid */ verify(src->state == Ready);
547
548	// context switch to specified coroutine
549	verify( dst->context.SP );
550	__cfactx_switch( &src->context, &dst->context );
551	// when __cfactx_switch returns we are back in the src coroutine
552
553	mainThread->curr_cor = &mainThread->self_cor;
554
555	// make sure the current state has been update
556	/* paranoid */ verify(src->state == Active);
557
558	verify( ! kernelTLS.preemption_state.enabled );
559	}
560
561	// KERNEL_ONLY
562	static void __kernel_last_resume( processor * this ) {
563	$coroutine * src = &mainThread->self_cor;
564	$coroutine * dst = get_coroutine(this->runner);
565
566	verify( ! kernelTLS.preemption_state.enabled );
567	verify( dst->starter == src );
568	verify( dst->context.SP );
569
570	// SKULLDUGGERY in debug the processors check that the
571	// stack is still within the limit of the stack limits after running a thread.
572	// that check doesn't make sense if we context switch to the processor using the
573	// coroutine semantics. Since this is a special case, use the current context
574	// info to populate these fields.
575	__cfaabi_dbg_debug_do(
576	__stack_context_t ctx;
577	CtxGet( ctx );
578	mainThread->context.SP = ctx.SP;
579	mainThread->context.FP = ctx.FP;
580	)
581
582	// context switch to the processor
583	__cfactx_switch( &src->context, &dst->context );
584	}
585
586	//-----------------------------------------------------------------------------
587	// Scheduler routines
588	// KERNEL ONLY
589	void __schedule_thread( $thread * thrd ) with( *thrd->curr_cluster ) {
590	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
591	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
592	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
593	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
594	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active \|\| thrd->state == Rerun,
595	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
596	/* paranoid */ #endif
597	/* paranoid */ verifyf( thrd->next == 0p, "Expected null got %p", thrd->next );
598
599	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
600
601	lock ( ready_queue_lock __cfaabi_dbg_ctx2 );
602	bool was_empty = !(ready_queue != 0);
603	append( ready_queue, thrd );
604	unlock( ready_queue_lock );
605
606	__wake_one(thrd->curr_cluster, was_empty);
607
608	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
609	}
610
611	// KERNEL ONLY
612	static $thread * __next_thread(cluster * this) with( *this ) {
613	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
614
615	lock( ready_queue_lock __cfaabi_dbg_ctx2 );
616	$thread * head = pop_head( ready_queue );
617	unlock( ready_queue_lock );
618
619	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
620	return head;
621	}
622
623	// KERNEL ONLY unpark with out disabling interrupts
624	void __unpark( $thread * thrd __cfaabi_dbg_ctx_param2 ) {
625	static_assert(sizeof(thrd->state) == sizeof(int));
626
627	// record activity
628	__cfaabi_dbg_record_thrd( *thrd, false, caller );
629
630	enum coroutine_state old_state = __atomic_exchange_n(&thrd->state, Rerun, __ATOMIC_SEQ_CST);
631	__cfaabi_dbg_debug_do( thrd->unpark_result = old_state; )
632	switch(old_state) {
633	case Active:
634	// Wake won the race, the thread will reschedule/rerun itself
635	break;
636	case Blocked:
637	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
638
639	// Wake lost the race,
640	thrd->state = Blocked;
641	__schedule_thread( thrd );
642	break;
643	case Rerun:
644	abort("More than one thread attempted to schedule thread %p\n", thrd);
645	break;
646	case Halted:
647	case Start:
648	case Primed:
649	default:
650	// This makes no sense, something is wrong abort
651	abort();
652	}
653	}
654
655	void unpark( $thread * thrd __cfaabi_dbg_ctx_param2 ) {
656	if( !thrd ) return;
657
658	disable_interrupts();
659	__unpark( thrd __cfaabi_dbg_ctx_fwd2 );
660	enable_interrupts( __cfaabi_dbg_ctx );
661	}
662
663	void park( __cfaabi_dbg_ctx_param ) {
664	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
665	disable_interrupts();
666	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
667	/* paranoid */ verify( kernelTLS.this_thread->preempted == __NO_PREEMPTION );
668
669	// record activity
670	__cfaabi_dbg_record_thrd( *kernelTLS.this_thread, true, caller );
671
672	returnToKernel();
673
674	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
675	enable_interrupts( __cfaabi_dbg_ctx );
676	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
677
678	}
679
680	// KERNEL ONLY
681	void __leave_thread() {
682	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
683	returnToKernel();
684	abort();
685	}
686
687	// KERNEL ONLY
688	bool force_yield( __Preemption_Reason reason ) {
689	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
690	disable_interrupts();
691	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
692
693	$thread * thrd = kernelTLS.this_thread;
694	/* paranoid */ verify(thrd->state == Active \|\| thrd->state == Rerun);
695
696	// SKULLDUGGERY: It is possible that we are preempting this thread just before
697	// it was going to park itself. If that is the case and it is already using the
698	// intrusive fields then we can't use them to preempt the thread
699	// If that is the case, abandon the preemption.
700	bool preempted = false;
701	if(thrd->next == 0p) {
702	preempted = true;
703	thrd->preempted = reason;
704	returnToKernel();
705	}
706
707	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
708	enable_interrupts_noPoll();
709	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
710
711	return preempted;
712	}
713
714	//=============================================================================================
715	// Kernel Setup logic
716	//=============================================================================================
717	//-----------------------------------------------------------------------------
718	// Kernel boot procedures
719	static void __kernel_startup(void) {
720	verify( ! kernelTLS.preemption_state.enabled );
721	__cfadbg_print_safe(runtime_core, "Kernel : Starting\n");
722
723	__page_size = sysconf( _SC_PAGESIZE );
724
725	__cfa_dbg_global_clusters.list{ __get };
726	__cfa_dbg_global_clusters.lock{};
727
728	// Initialize the main cluster
729	mainCluster = (cluster *)&storage_mainCluster;
730	(*mainCluster){"Main Cluster"};
731
732	__cfadbg_print_safe(runtime_core, "Kernel : Main cluster ready\n");
733
734	// Start by initializing the main thread
735	// SKULLDUGGERY: the mainThread steals the process main thread
736	// which will then be scheduled by the mainProcessor normally
737	mainThread = ($thread *)&storage_mainThread;
738	current_stack_info_t info;
739	info.storage = (__stack_t*)&storage_mainThreadCtx;
740	(*mainThread){ &info };
741
742	__cfadbg_print_safe(runtime_core, "Kernel : Main thread ready\n");
743
744
745
746	// Construct the processor context of the main processor
747	void ?{}(processorCtx_t & this, processor * proc) {
748	(this.__cor){ "Processor" };
749	this.__cor.starter = 0p;
750	this.proc = proc;
751	}
752
753	void ?{}(processor & this) with( this ) {
754	name = "Main Processor";
755	cltr = mainCluster;
756	terminated{ 0 };
757	do_terminate = false;
758	preemption_alarm = 0p;
759	pending_preemption = false;
760	kernel_thread = pthread_self();
761
762	runner{ &this };
763	__cfadbg_print_safe(runtime_core, "Kernel : constructed main processor context %p\n", &runner);
764	}
765
766	// Initialize the main processor and the main processor ctx
767	// (the coroutine that contains the processing control flow)
768	mainProcessor = (processor *)&storage_mainProcessor;
769	(*mainProcessor){};
770
771	//initialize the global state variables
772	kernelTLS.this_processor = mainProcessor;
773	kernelTLS.this_thread = mainThread;
774
775	// Enable preemption
776	kernel_start_preemption();
777
778	// Add the main thread to the ready queue
779	// once resume is called on mainProcessor->runner the mainThread needs to be scheduled like any normal thread
780	__schedule_thread(mainThread);
781
782	// SKULLDUGGERY: Force a context switch to the main processor to set the main thread's context to the current UNIX
783	// context. Hence, the main thread does not begin through __cfactx_invoke_thread, like all other threads. The trick here is that
784	// mainThread is on the ready queue when this call is made.
785	__kernel_first_resume( kernelTLS.this_processor );
786
787
788	// THE SYSTEM IS NOW COMPLETELY RUNNING
789
790
791	// Now that the system is up, finish creating systems that need threading
792	__kernel_io_finish_start( *mainCluster );
793
794
795	__cfadbg_print_safe(runtime_core, "Kernel : Started\n--------------------------------------------------\n\n");
796
797	verify( ! kernelTLS.preemption_state.enabled );
798	enable_interrupts( __cfaabi_dbg_ctx );
799	verify( TL_GET( preemption_state.enabled ) );
800	}
801
802	static void __kernel_shutdown(void) {
803	//Before we start shutting things down, wait for systems that need threading to shutdown
804	__kernel_io_prepare_stop( *mainCluster );
805
806	/* paranoid */ verify( TL_GET( preemption_state.enabled ) );
807	disable_interrupts();
808	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
809
810	__cfadbg_print_safe(runtime_core, "\n--------------------------------------------------\nKernel : Shutting down\n");
811
812	// SKULLDUGGERY: Notify the mainProcessor it needs to terminates.
813	// When its coroutine terminates, it return control to the mainThread
814	// which is currently here
815	__atomic_store_n(&mainProcessor->do_terminate, true, __ATOMIC_RELEASE);
816	__kernel_last_resume( kernelTLS.this_processor );
817	mainThread->self_cor.state = Halted;
818
819	// THE SYSTEM IS NOW COMPLETELY STOPPED
820
821	// Disable preemption
822	kernel_stop_preemption();
823
824	// Destroy the main processor and its context in reverse order of construction
825	// These were manually constructed so we need manually destroy them
826	^(*mainProcessor){};
827
828	// Final step, destroy the main thread since it is no longer needed
829	// Since we provided a stack to this taxk it will not destroy anything
830	/* paranoid / verify(mainThread->self_cor.stack.storage == (__stack_t)(((uintptr_t)&storage_mainThreadCtx)\| 0x1));
831	^(*mainThread){};
832
833	^(*mainCluster){};
834
835	^(__cfa_dbg_global_clusters.list){};
836	^(__cfa_dbg_global_clusters.lock){};
837
838	__cfadbg_print_safe(runtime_core, "Kernel : Shutdown complete\n");
839	}
840
841	//=============================================================================================
842	// Kernel Idle Sleep
843	//=============================================================================================
844	static $thread * __halt(processor * this) with( *this ) {
845	if( do_terminate ) return 0p;
846
847	// First, lock the cluster idle
848	lock( cltr->idle_lock __cfaabi_dbg_ctx2 );
849
850	// Check if we can find a thread
851	if( $thread * found = __next_thread( cltr ) ) {
852	unlock( cltr->idle_lock );
853	return found;
854	}
855
856	// Move this processor from the active list to the idle list
857	move_to_front(cltr->procs, cltr->idles, *this);
858
859	// Unlock the idle lock so we don't go to sleep with a lock
860	unlock (cltr->idle_lock);
861
862	// We are ready to sleep
863	__cfadbg_print_safe(runtime_core, "Kernel : Processor %p ready to sleep\n", this);
864	wait( idle );
865
866	// We have woken up
867	__cfadbg_print_safe(runtime_core, "Kernel : Processor %p woke up and ready to run\n", this);
868
869	// Get ourself off the idle list
870	with( *cltr ) {
871	lock (idle_lock __cfaabi_dbg_ctx2);
872	move_to_front(idles, procs, *this);
873	unlock(idle_lock);
874	}
875
876	// Don't check the ready queue again, we may not be in a position to run a thread
877	return 0p;
878	}
879
880	// Wake a thread from the front if there are any
881	static bool __wake_one(cluster * this, __attribute__((unused)) bool force) {
882	// if we don't want to force check if we know it's false
883	// if( !this->idles.head && !force ) return false;
884
885	// First, lock the cluster idle
886	lock( this->idle_lock __cfaabi_dbg_ctx2 );
887
888	// Check if there is someone to wake up
889	if( !this->idles.head ) {
890	// Nope unlock and return false
891	unlock( this->idle_lock );
892	return false;
893	}
894
895	// Wake them up
896	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this->idles.head);
897	post( this->idles.head->idle );
898
899	// Unlock and return true
900	unlock( this->idle_lock );
901	return true;
902	}
903
904	// Unconditionnaly wake a thread
905	static bool __wake_proc(processor * this) {
906	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
907	return post( this->idle );
908	}
909
910	//=============================================================================================
911	// Unexpected Terminating logic
912	//=============================================================================================
913	static __spinlock_t kernel_abort_lock;
914	static bool kernel_abort_called = false;
915
916	void * kernel_abort(void) __attribute__ ((__nothrow__)) {
917	// abort cannot be recursively entered by the same or different processors because all signal handlers return when
918	// the globalAbort flag is true.
919	lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
920
921	// first task to abort ?
922	if ( kernel_abort_called ) { // not first task to abort ?
923	unlock( kernel_abort_lock );
924
925	sigset_t mask;
926	sigemptyset( &mask );
927	sigaddset( &mask, SIGALRM ); // block SIGALRM signals
928	sigaddset( &mask, SIGUSR1 ); // block SIGALRM signals
929	sigsuspend( &mask ); // block the processor to prevent further damage during abort
930	_exit( EXIT_FAILURE ); // if processor unblocks before it is killed, terminate it
931	}
932	else {
933	kernel_abort_called = true;
934	unlock( kernel_abort_lock );
935	}
936
937	return kernelTLS.this_thread;
938	}
939
940	void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
941	$thread * thrd = kernel_data;
942
943	if(thrd) {
944	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
945	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
946
947	if ( &thrd->self_cor != thrd->curr_cor ) {
948	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
949	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
950	}
951	else {
952	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
953	}
954	}
955	else {
956	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
957	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
958	}
959	}
960
961	int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
962	return get_coroutine(kernelTLS.this_thread) == get_coroutine(mainThread) ? 4 : 2;
963	}
964
965	static __spinlock_t kernel_debug_lock;
966
967	extern "C" {
968	void __cfaabi_bits_acquire() {
969	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
970	}
971
972	void __cfaabi_bits_release() {
973	unlock( kernel_debug_lock );
974	}
975	}
976
977	//=============================================================================================
978	// Kernel Utilities
979	//=============================================================================================
980	//-----------------------------------------------------------------------------
981	// Locks
982	void ?{}( semaphore & this, int count = 1 ) {
983	(this.lock){};
984	this.count = count;
985	(this.waiting){};
986	}
987	void ^?{}(semaphore & this) {}
988
989	void P(semaphore & this) with( this ){
990	lock( lock __cfaabi_dbg_ctx2 );
991	count -= 1;
992	if ( count < 0 ) {
993	// queue current task
994	append( waiting, kernelTLS.this_thread );
995
996	// atomically release spin lock and block
997	unlock( lock );
998	park( __cfaabi_dbg_ctx );
999	}
1000	else {
1001	unlock( lock );
1002	}
1003	}
1004
1005	bool V(semaphore & this) with( this ) {
1006	$thread * thrd = 0p;
1007	lock( lock __cfaabi_dbg_ctx2 );
1008	count += 1;
1009	if ( count <= 0 ) {
1010	// remove task at head of waiting list
1011	thrd = pop_head( waiting );
1012	}
1013
1014	unlock( lock );
1015
1016	// make new owner
1017	unpark( thrd __cfaabi_dbg_ctx2 );
1018
1019	return thrd != 0p;
1020	}
1021
1022	bool V(semaphore & this, unsigned diff) with( this ) {
1023	$thread * thrd = 0p;
1024	lock( lock __cfaabi_dbg_ctx2 );
1025	int release = max(-count, (int)diff);
1026	count += diff;
1027	for(release) {
1028	unpark( pop_head( waiting ) __cfaabi_dbg_ctx2 );
1029	}
1030
1031	unlock( lock );
1032
1033	return thrd != 0p;
1034	}
1035
1036	//-----------------------------------------------------------------------------
1037	// Global Queues
1038	void doregister( cluster & cltr ) {
1039	lock ( __cfa_dbg_global_clusters.lock __cfaabi_dbg_ctx2);
1040	push_front( __cfa_dbg_global_clusters.list, cltr );
1041	unlock ( __cfa_dbg_global_clusters.lock );
1042	}
1043
1044	void unregister( cluster & cltr ) {
1045	lock ( __cfa_dbg_global_clusters.lock __cfaabi_dbg_ctx2);
1046	remove( __cfa_dbg_global_clusters.list, cltr );
1047	unlock( __cfa_dbg_global_clusters.lock );
1048	}
1049
1050	void doregister( cluster * cltr, $thread & thrd ) {
1051	lock (cltr->thread_list_lock __cfaabi_dbg_ctx2);
1052	cltr->nthreads += 1;
1053	push_front(cltr->threads, thrd);
1054	unlock (cltr->thread_list_lock);
1055	}
1056
1057	void unregister( cluster * cltr, $thread & thrd ) {
1058	lock (cltr->thread_list_lock __cfaabi_dbg_ctx2);
1059	remove(cltr->threads, thrd );
1060	cltr->nthreads -= 1;
1061	unlock(cltr->thread_list_lock);
1062	}
1063
1064	void doregister( cluster * cltr, processor * proc ) {
1065	lock (cltr->idle_lock __cfaabi_dbg_ctx2);
1066	cltr->nprocessors += 1;
1067	push_front(cltr->procs, *proc);
1068	unlock (cltr->idle_lock);
1069	}
1070
1071	void unregister( cluster * cltr, processor * proc ) {
1072	lock (cltr->idle_lock __cfaabi_dbg_ctx2);
1073	remove(cltr->procs, *proc );
1074	cltr->nprocessors -= 1;
1075	unlock(cltr->idle_lock);
1076	}
1077
1078	//-----------------------------------------------------------------------------
1079	// Debug
1080	__cfaabi_dbg_debug_do(
1081	extern "C" {
1082	void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
1083	this.prev_name = prev_name;
1084	this.prev_thrd = kernelTLS.this_thread;
1085	}
1086
1087	void __cfaabi_dbg_record_thrd($thread & this, bool park, const char prev_name[]) {
1088	if(park) {
1089	this.park_caller = prev_name;
1090	this.park_stale = false;
1091	}
1092	else {
1093	this.unpark_caller = prev_name;
1094	this.unpark_stale = false;
1095	}
1096	}
1097	}
1098	)
1099
1100	//-----------------------------------------------------------------------------
1101	// Debug
1102	bool threading_enabled(void) __attribute__((const)) {
1103	return true;
1104	}
1105	// Local Variables: //
1106	// mode: c //
1107	// tab-width: 4 //
1108	// End: //

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