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kernel.cfa@ 210b8b3

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Last change on this file since 210b8b3 was 210b8b3, checked in by Thierry Delisle <tdelisle@…>, 6 years ago
Added checks that the stack pointer is consistent when running and returning from a thread
Property mode set to `100644`
File size: 30.9 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
18	//C Includes
19	#include <stddef.h>
20	#include <errno.h>
21	#include <string.h>
22	extern "C" {
23	#include <stdio.h>
24	#include <fenv.h>
25	#include <sys/resource.h>
26	#include <signal.h>
27	#include <unistd.h>
28	#include <limits.h> // PTHREAD_STACK_MIN
29	#include <sys/mman.h> // mprotect
30	}
31
32	//CFA Includes
33	#include "time.hfa"
34	#include "kernel_private.hfa"
35	#include "preemption.hfa"
36	#include "startup.hfa"
37
38	//Private includes
39	#define __CFA_INVOKE_PRIVATE__
40	#include "invoke.h"
41
42	//-----------------------------------------------------------------------------
43	// Some assembly required
44	#if defined( __i386 )
45	#define CtxGet( ctx ) \
46	__asm__ volatile ( \
47	"movl %%esp,%0\n"\
48	"movl %%ebp,%1\n"\
49	: "=rm" (ctx.SP),\
50	"=rm" (ctx.FP) \
51	)
52
53	// mxcr : SSE Status and Control bits (control bits are preserved across function calls)
54	// fcw : X87 FPU control word (preserved across function calls)
55	#define __x87_store \
56	uint32_t __mxcr; \
57	uint16_t __fcw; \
58	__asm__ volatile ( \
59	"stmxcsr %0\n" \
60	"fnstcw %1\n" \
61	: "=m" (__mxcr),\
62	"=m" (__fcw) \
63	)
64
65	#define __x87_load \
66	__asm__ volatile ( \
67	"fldcw %1\n" \
68	"ldmxcsr %0\n" \
69	::"m" (__mxcr),\
70	"m" (__fcw) \
71	)
72
73	#elif defined( __x86_64 )
74	#define CtxGet( ctx ) \
75	__asm__ volatile ( \
76	"movq %%rsp,%0\n"\
77	"movq %%rbp,%1\n"\
78	: "=rm" (ctx.SP),\
79	"=rm" (ctx.FP) \
80	)
81
82	#define __x87_store \
83	uint32_t __mxcr; \
84	uint16_t __fcw; \
85	__asm__ volatile ( \
86	"stmxcsr %0\n" \
87	"fnstcw %1\n" \
88	: "=m" (__mxcr),\
89	"=m" (__fcw) \
90	)
91
92	#define __x87_load \
93	__asm__ volatile ( \
94	"fldcw %1\n" \
95	"ldmxcsr %0\n" \
96	:: "m" (__mxcr),\
97	"m" (__fcw) \
98	)
99
100
101	#elif defined( __ARM_ARCH )
102	#define CtxGet( ctx ) __asm__ ( \
103	"mov %0,%%sp\n" \
104	"mov %1,%%r11\n" \
105	: "=rm" (ctx.SP), "=rm" (ctx.FP) )
106	#else
107	#error unknown hardware architecture
108	#endif
109
110	//-----------------------------------------------------------------------------
111	//Start and stop routine for the kernel, declared first to make sure they run first
112	static void __kernel_startup (void) __attribute__(( constructor( STARTUP_PRIORITY_KERNEL ) ));
113	static void __kernel_shutdown(void) __attribute__(( destructor ( STARTUP_PRIORITY_KERNEL ) ));
114
115	//-----------------------------------------------------------------------------
116	// Kernel storage
117	KERNEL_STORAGE(cluster, mainCluster);
118	KERNEL_STORAGE(processor, mainProcessor);
119	KERNEL_STORAGE($thread, mainThread);
120	KERNEL_STORAGE(__stack_t, mainThreadCtx);
121
122	cluster * mainCluster;
123	processor * mainProcessor;
124	$thread * mainThread;
125
126	extern "C" {
127	struct { __dllist_t(cluster) list; __spinlock_t lock; } __cfa_dbg_global_clusters;
128	}
129
130	size_t __page_size = 0;
131
132	//-----------------------------------------------------------------------------
133	// Global state
134	thread_local struct KernelThreadData kernelTLS __attribute__ ((tls_model ( "initial-exec" ))) = {
135	NULL, // cannot use 0p
136	NULL,
137	{ 1, false, false },
138	6u //this should be seeded better but due to a bug calling rdtsc doesn't work
139	};
140
141	//-----------------------------------------------------------------------------
142	// Struct to steal stack
143	struct current_stack_info_t {
144	__stack_t * storage; // pointer to stack object
145	void * base; // base of stack
146	void * limit; // stack grows towards stack limit
147	void * context; // address of cfa_context_t
148	};
149
150	void ?{}( current_stack_info_t & this ) {
151	__stack_context_t ctx;
152	CtxGet( ctx );
153	this.base = ctx.FP;
154
155	rlimit r;
156	getrlimit( RLIMIT_STACK, &r);
157	size_t size = r.rlim_cur;
158
159	this.limit = (void *)(((intptr_t)this.base) - size);
160	this.context = &storage_mainThreadCtx;
161	}
162
163	//-----------------------------------------------------------------------------
164	// Main thread construction
165
166	void ?{}( $coroutine & this, current_stack_info_t * info) with( this ) {
167	stack.storage = info->storage;
168	with(*stack.storage) {
169	limit = info->limit;
170	base = info->base;
171	}
172	__attribute__((may_alias)) intptr_t * istorage = (intptr_t*) &stack.storage;
173	*istorage \|= 0x1;
174	name = "Main Thread";
175	state = Start;
176	starter = 0p;
177	last = 0p;
178	cancellation = 0p;
179	}
180
181	void ?{}( $thread & this, current_stack_info_t * info) with( this ) {
182	state = Start;
183	self_cor{ info };
184	curr_cor = &self_cor;
185	curr_cluster = mainCluster;
186	self_mon.owner = &this;
187	self_mon.recursion = 1;
188	self_mon_p = &self_mon;
189	next = 0p;
190
191	node.next = 0p;
192	node.prev = 0p;
193	doregister(curr_cluster, this);
194
195	monitors{ &self_mon_p, 1, (fptr_t)0 };
196	}
197
198	//-----------------------------------------------------------------------------
199	// Processor coroutine
200	void ?{}(processorCtx_t & this) {
201
202	}
203
204	// Construct the processor context of non-main processors
205	static void ?{}(processorCtx_t & this, processor * proc, current_stack_info_t * info) {
206	(this.__cor){ info };
207	this.proc = proc;
208	}
209
210	static void * __invoke_processor(void * arg);
211
212	void ?{}(processor & this, const char name[], cluster & cltr) with( this ) {
213	this.name = name;
214	this.cltr = &cltr;
215	terminated{ 0 };
216	destroyer = 0p;
217	do_terminate = false;
218	preemption_alarm = 0p;
219	pending_preemption = false;
220	runner.proc = &this;
221
222	idleLock{};
223
224	__cfaabi_dbg_print_safe("Kernel : Starting core %p\n", &this);
225
226	this.stack = __create_pthread( &this.kernel_thread, __invoke_processor, (void *)&this );
227
228	__cfaabi_dbg_print_safe("Kernel : core %p started\n", &this);
229	}
230
231	void ^?{}(processor & this) with( this ){
232	if( ! __atomic_load_n(&do_terminate, __ATOMIC_ACQUIRE) ) {
233	__cfaabi_dbg_print_safe("Kernel : core %p signaling termination\n", &this);
234
235	__atomic_store_n(&do_terminate, true, __ATOMIC_RELAXED);
236	wake( &this );
237
238	P( terminated );
239	verify( kernelTLS.this_processor != &this);
240	}
241
242	pthread_join( kernel_thread, 0p );
243	free( this.stack );
244	}
245
246	void ?{}(cluster & this, const char name[], Duration preemption_rate) with( this ) {
247	this.name = name;
248	this.preemption_rate = preemption_rate;
249	ready_queue{};
250	ready_queue_lock{};
251
252	procs{ __get };
253	idles{ __get };
254	threads{ __get };
255
256	doregister(this);
257	}
258
259	void ^?{}(cluster & this) {
260	unregister(this);
261	}
262
263	//=============================================================================================
264	// Kernel Scheduling logic
265	//=============================================================================================
266	static $thread * __next_thread(cluster * this);
267	static void __run_thread(processor * this, $thread * dst);
268	static void __halt(processor * this);
269
270	//Main of the processor contexts
271	void main(processorCtx_t & runner) {
272	// Because of a bug, we couldn't initialized the seed on construction
273	// Do it here
274	kernelTLS.rand_seed ^= rdtscl();
275
276	processor * this = runner.proc;
277	verify(this);
278
279	__cfaabi_dbg_print_safe("Kernel : core %p starting\n", this);
280
281	doregister(this->cltr, this);
282
283	{
284	// Setup preemption data
285	preemption_scope scope = { this };
286
287	__cfaabi_dbg_print_safe("Kernel : core %p started\n", this);
288
289	$thread * readyThread = 0p;
290	for( unsigned int spin_count = 0; ! __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST); spin_count++ ) {
291	readyThread = __next_thread( this->cltr );
292
293	if(readyThread) {
294	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
295	/* paranoid */ verifyf( readyThread->state == Inactive \|\| readyThread->state == Start \|\| readyThread->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", readyThread->state, readyThread->preempted);
296	/* paranoid */ verifyf( readyThread->next == 0p, "Expected null got %p", readyThread->next );
297
298	__run_thread(this, readyThread);
299
300	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
301
302	spin_count = 0;
303	} else {
304	// spin(this, &spin_count);
305	__halt(this);
306	}
307	}
308
309	__cfaabi_dbg_print_safe("Kernel : core %p stopping\n", this);
310	}
311
312	unregister(this->cltr, this);
313
314	V( this->terminated );
315
316	__cfaabi_dbg_print_safe("Kernel : core %p terminated\n", this);
317	}
318
319	static int * __volatile_errno() __attribute__((noinline));
320	static int * __volatile_errno() { asm(""); return &errno; }
321
322	// KERNEL ONLY
323	// runThread runs a thread by context switching
324	// from the processor coroutine to the target thread
325	static void __run_thread(processor * this, $thread * thrd_dst) {
326	$coroutine * proc_cor = get_coroutine(this->runner);
327
328	// Update global state
329	kernelTLS.this_thread = thrd_dst;
330
331	// set state of processor coroutine to inactive
332	verify(proc_cor->state == Active);
333	proc_cor->state = Inactive;
334
335	// Actually run the thread
336	RUNNING: while(true) {
337	if(unlikely(thrd_dst->preempted)) {
338	thrd_dst->preempted = __NO_PREEMPTION;
339	verify(thrd_dst->state == Active \|\| thrd_dst->state == Rerun);
340	} else {
341	verify(thrd_dst->state == Start \|\| thrd_dst->state == Primed \|\| thrd_dst->state == Inactive);
342	thrd_dst->state = Active;
343	}
344
345	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
346	/* 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
347	/* 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
348
349	// set context switch to the thread that the processor is executing
350	verify( thrd_dst->context.SP );
351	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
352	// when __cfactx_switch returns we are back in the processor coroutine
353
354	/* 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 );
355	/* 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 );
356	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
357
358
359	// We just finished running a thread, there are a few things that could have happened.
360	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
361	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
362	// 3 - Polite Racy case : the thread has blocked, someone has already tried to schedule it, but the thread is nice and wants to go through the ready-queue any way
363	// 4 - Preempted
364	// In case 1, we may have won a race so we can't write to the state again.
365	// In case 2, we lost the race so we now own the thread.
366	// In case 3, we lost the race but can just reschedule the thread.
367
368	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
369	// The thread was preempted, reschedule it and reset the flag
370	__schedule_thread( thrd_dst );
371	break RUNNING;
372	}
373
374	// set state of processor coroutine to active and the thread to inactive
375	static_assert(sizeof(thrd_dst->state) == sizeof(int));
376	enum coroutine_state old_state = __atomic_exchange_n(&thrd_dst->state, Inactive, __ATOMIC_SEQ_CST);
377	switch(old_state) {
378	case Halted:
379	// The thread has halted, it should never be scheduled/run again, leave it back to Halted and move on
380	thrd_dst->state = Halted;
381
382	// We may need to wake someone up here since
383	unpark( this->destroyer );
384	this->destroyer = 0p;
385	break RUNNING;
386	case Active:
387	// This is case 1, the regular case, nothing more is needed
388	break RUNNING;
389	case Rerun:
390	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
391	// In this case, just run it again.
392	continue RUNNING;
393	default:
394	// This makes no sense, something is wrong abort
395	abort("Finished running a thread that was Inactive/Start/Primed %d\n", old_state);
396	}
397	}
398
399	// Just before returning to the processor, set the processor coroutine to active
400	proc_cor->state = Active;
401	}
402
403	// KERNEL_ONLY
404	void returnToKernel() {
405	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
406	$coroutine * proc_cor = get_coroutine(kernelTLS.this_processor->runner);
407	$thread * thrd_src = kernelTLS.this_thread;
408
409	// Run the thread on this processor
410	{
411	int local_errno = *__volatile_errno();
412	#if defined( __i386 ) \|\| defined( __x86_64 )
413	__x87_store;
414	#endif
415	verify( proc_cor->context.SP );
416	__cfactx_switch( &thrd_src->context, &proc_cor->context );
417	#if defined( __i386 ) \|\| defined( __x86_64 )
418	__x87_load;
419	#endif
420	*__volatile_errno() = local_errno;
421	}
422
423	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
424	/* 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 );
425	/* 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 );
426	}
427
428	// KERNEL_ONLY
429	// Context invoker for processors
430	// This is the entry point for processors (kernel threads)
431	// It effectively constructs a coroutine by stealing the pthread stack
432	static void * __invoke_processor(void * arg) {
433	processor * proc = (processor *) arg;
434	kernelTLS.this_processor = proc;
435	kernelTLS.this_thread = 0p;
436	kernelTLS.preemption_state.[enabled, disable_count] = [false, 1];
437	// SKULLDUGGERY: We want to create a context for the processor coroutine
438	// which is needed for the 2-step context switch. However, there is no reason
439	// to waste the perfectly valid stack create by pthread.
440	current_stack_info_t info;
441	__stack_t ctx;
442	info.storage = &ctx;
443	(proc->runner){ proc, &info };
444
445	__cfaabi_dbg_print_safe("Coroutine : created stack %p\n", get_coroutine(proc->runner)->stack.storage);
446
447	//Set global state
448	kernelTLS.this_thread = 0p;
449
450	//We now have a proper context from which to schedule threads
451	__cfaabi_dbg_print_safe("Kernel : core %p created (%p, %p)\n", proc, &proc->runner, &ctx);
452
453	// SKULLDUGGERY: Since the coroutine doesn't have its own stack, we can't
454	// resume it to start it like it normally would, it will just context switch
455	// back to here. Instead directly call the main since we already are on the
456	// appropriate stack.
457	get_coroutine(proc->runner)->state = Active;
458	main( proc->runner );
459	get_coroutine(proc->runner)->state = Halted;
460
461	// Main routine of the core returned, the core is now fully terminated
462	__cfaabi_dbg_print_safe("Kernel : core %p main ended (%p)\n", proc, &proc->runner);
463
464	return 0p;
465	}
466
467	static void Abort( int ret, const char func[] ) {
468	if ( ret ) { // pthread routines return errno values
469	abort( "%s : internal error, error(%d) %s.", func, ret, strerror( ret ) );
470	} // if
471	} // Abort
472
473	void * __create_pthread( pthread_t * pthread, void * (start)(void ), void * arg ) {
474	pthread_attr_t attr;
475
476	Abort( pthread_attr_init( &attr ), "pthread_attr_init" ); // initialize attribute
477
478	size_t stacksize;
479	// default stack size, normally defined by shell limit
480	Abort( pthread_attr_getstacksize( &attr, &stacksize ), "pthread_attr_getstacksize" );
481	assert( stacksize >= PTHREAD_STACK_MIN );
482
483	void * stack;
484	__cfaabi_dbg_debug_do(
485	stack = memalign( __page_size, stacksize + __page_size );
486	// pthread has no mechanism to create the guard page in user supplied stack.
487	if ( mprotect( stack, __page_size, PROT_NONE ) == -1 ) {
488	abort( "mprotect : internal error, mprotect failure, error(%d) %s.", errno, strerror( errno ) );
489	} // if
490	);
491	__cfaabi_dbg_no_debug_do(
492	stack = malloc( stacksize );
493	);
494
495	Abort( pthread_attr_setstack( &attr, stack, stacksize ), "pthread_attr_setstack" );
496
497	Abort( pthread_create( pthread, &attr, start, arg ), "pthread_create" );
498	return stack;
499	}
500
501	// KERNEL_ONLY
502	static void __kernel_first_resume( processor * this ) {
503	$thread * src = mainThread;
504	$coroutine * dst = get_coroutine(this->runner);
505
506	verify( ! kernelTLS.preemption_state.enabled );
507
508	kernelTLS.this_thread->curr_cor = dst;
509	__stack_prepare( &dst->stack, 65000 );
510	__cfactx_start(main, dst, this->runner, __cfactx_invoke_coroutine);
511
512	verify( ! kernelTLS.preemption_state.enabled );
513
514	dst->last = &src->self_cor;
515	dst->starter = dst->starter ? dst->starter : &src->self_cor;
516
517	// set state of current coroutine to inactive
518	src->state = src->state == Halted ? Halted : Inactive;
519
520	// context switch to specified coroutine
521	verify( dst->context.SP );
522	__cfactx_switch( &src->context, &dst->context );
523	// when __cfactx_switch returns we are back in the src coroutine
524
525	mainThread->curr_cor = &mainThread->self_cor;
526
527	// set state of new coroutine to active
528	src->state = Active;
529
530	verify( ! kernelTLS.preemption_state.enabled );
531	}
532
533	// KERNEL_ONLY
534	static void __kernel_last_resume( processor * this ) {
535	$coroutine * src = &mainThread->self_cor;
536	$coroutine * dst = get_coroutine(this->runner);
537
538	verify( ! kernelTLS.preemption_state.enabled );
539	verify( dst->starter == src );
540	verify( dst->context.SP );
541
542	// context switch to the processor
543	__cfactx_switch( &src->context, &dst->context );
544	}
545
546	//-----------------------------------------------------------------------------
547	// Scheduler routines
548	// KERNEL ONLY
549	void __schedule_thread( $thread * thrd ) with( *thrd->curr_cluster ) {
550	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
551	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
552	/* paranoid */ if( thrd->state == Inactive \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
553	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
554	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active \|\| thrd->state == Rerun,
555	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
556	/* paranoid */ #endif
557	/* paranoid */ verifyf( thrd->next == 0p, "Expected null got %p", thrd->next );
558
559	lock ( ready_queue_lock __cfaabi_dbg_ctx2 );
560	bool was_empty = !(ready_queue != 0);
561	append( ready_queue, thrd );
562	unlock( ready_queue_lock );
563
564	if(was_empty) {
565	lock (proc_list_lock __cfaabi_dbg_ctx2);
566	if(idles) {
567	wake_fast(idles.head);
568	}
569	unlock (proc_list_lock);
570	}
571	else if( struct processor * idle = idles.head ) {
572	wake_fast(idle);
573	}
574
575	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
576	}
577
578	// KERNEL ONLY
579	static $thread * __next_thread(cluster * this) with( *this ) {
580	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
581
582	lock( ready_queue_lock __cfaabi_dbg_ctx2 );
583	$thread * head = pop_head( ready_queue );
584	unlock( ready_queue_lock );
585
586	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
587	return head;
588	}
589
590	void unpark( $thread * thrd ) {
591	if( !thrd ) return;
592
593	disable_interrupts();
594	static_assert(sizeof(thrd->state) == sizeof(int));
595	enum coroutine_state old_state = __atomic_exchange_n(&thrd->state, Rerun, __ATOMIC_SEQ_CST);
596	switch(old_state) {
597	case Active:
598	// Wake won the race, the thread will reschedule/rerun itself
599	break;
600	case Inactive:
601	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
602
603	// Wake lost the race,
604	thrd->state = Inactive;
605	__schedule_thread( thrd );
606	break;
607	case Rerun:
608	abort("More than one thread attempted to schedule thread %p\n", thrd);
609	break;
610	case Halted:
611	case Start:
612	case Primed:
613	default:
614	// This makes no sense, something is wrong abort
615	abort();
616	}
617	enable_interrupts( __cfaabi_dbg_ctx );
618	}
619
620	void park( void ) {
621	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
622	disable_interrupts();
623	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
624	/* paranoid */ verify( kernelTLS.this_thread->preempted == __NO_PREEMPTION );
625
626	returnToKernel();
627
628	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
629	enable_interrupts( __cfaabi_dbg_ctx );
630	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
631
632	}
633
634	// KERNEL ONLY
635	void __leave_thread() {
636	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
637	returnToKernel();
638	abort();
639	}
640
641	// KERNEL ONLY
642	bool force_yield( __Preemption_Reason reason ) {
643	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
644	disable_interrupts();
645	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
646
647	$thread * thrd = kernelTLS.this_thread;
648	/* paranoid */ verify(thrd->state == Active \|\| thrd->state == Rerun);
649
650	// SKULLDUGGERY: It is possible that we are preempting this thread just before
651	// it was going to park itself. If that is the case and it is already using the
652	// intrusive fields then we can't use them to preempt the thread
653	// If that is the case, abandon the preemption.
654	bool preempted = false;
655	if(thrd->next == 0p) {
656	preempted = true;
657	thrd->preempted = reason;
658	returnToKernel();
659	}
660
661	/* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
662	enable_interrupts_noPoll();
663	/* paranoid */ verify( kernelTLS.preemption_state.enabled );
664
665	return preempted;
666	}
667
668	//=============================================================================================
669	// Kernel Setup logic
670	//=============================================================================================
671	//-----------------------------------------------------------------------------
672	// Kernel boot procedures
673	static void __kernel_startup(void) {
674	verify( ! kernelTLS.preemption_state.enabled );
675	__cfaabi_dbg_print_safe("Kernel : Starting\n");
676
677	__page_size = sysconf( _SC_PAGESIZE );
678
679	__cfa_dbg_global_clusters.list{ __get };
680	__cfa_dbg_global_clusters.lock{};
681
682	// Initialize the main cluster
683	mainCluster = (cluster *)&storage_mainCluster;
684	(*mainCluster){"Main Cluster"};
685
686	__cfaabi_dbg_print_safe("Kernel : Main cluster ready\n");
687
688	// Start by initializing the main thread
689	// SKULLDUGGERY: the mainThread steals the process main thread
690	// which will then be scheduled by the mainProcessor normally
691	mainThread = ($thread *)&storage_mainThread;
692	current_stack_info_t info;
693	info.storage = (__stack_t*)&storage_mainThreadCtx;
694	(*mainThread){ &info };
695
696	__cfaabi_dbg_print_safe("Kernel : Main thread ready\n");
697
698
699
700	// Construct the processor context of the main processor
701	void ?{}(processorCtx_t & this, processor * proc) {
702	(this.__cor){ "Processor" };
703	this.__cor.starter = 0p;
704	this.proc = proc;
705	}
706
707	void ?{}(processor & this) with( this ) {
708	name = "Main Processor";
709	cltr = mainCluster;
710	terminated{ 0 };
711	do_terminate = false;
712	preemption_alarm = 0p;
713	pending_preemption = false;
714	kernel_thread = pthread_self();
715
716	runner{ &this };
717	__cfaabi_dbg_print_safe("Kernel : constructed main processor context %p\n", &runner);
718	}
719
720	// Initialize the main processor and the main processor ctx
721	// (the coroutine that contains the processing control flow)
722	mainProcessor = (processor *)&storage_mainProcessor;
723	(*mainProcessor){};
724
725	//initialize the global state variables
726	kernelTLS.this_processor = mainProcessor;
727	kernelTLS.this_thread = mainThread;
728
729	// Enable preemption
730	kernel_start_preemption();
731
732	// Add the main thread to the ready queue
733	// once resume is called on mainProcessor->runner the mainThread needs to be scheduled like any normal thread
734	__schedule_thread(mainThread);
735
736	// SKULLDUGGERY: Force a context switch to the main processor to set the main thread's context to the current UNIX
737	// context. Hence, the main thread does not begin through __cfactx_invoke_thread, like all other threads. The trick here is that
738	// mainThread is on the ready queue when this call is made.
739	__kernel_first_resume( kernelTLS.this_processor );
740
741
742
743	// THE SYSTEM IS NOW COMPLETELY RUNNING
744	__cfaabi_dbg_print_safe("Kernel : Started\n--------------------------------------------------\n\n");
745
746	verify( ! kernelTLS.preemption_state.enabled );
747	enable_interrupts( __cfaabi_dbg_ctx );
748	verify( TL_GET( preemption_state.enabled ) );
749	}
750
751	static void __kernel_shutdown(void) {
752	__cfaabi_dbg_print_safe("\n--------------------------------------------------\nKernel : Shutting down\n");
753
754	verify( TL_GET( preemption_state.enabled ) );
755	disable_interrupts();
756	verify( ! kernelTLS.preemption_state.enabled );
757
758	// SKULLDUGGERY: Notify the mainProcessor it needs to terminates.
759	// When its coroutine terminates, it return control to the mainThread
760	// which is currently here
761	__atomic_store_n(&mainProcessor->do_terminate, true, __ATOMIC_RELEASE);
762	__kernel_last_resume( kernelTLS.this_processor );
763	mainThread->self_cor.state = Halted;
764
765	// THE SYSTEM IS NOW COMPLETELY STOPPED
766
767	// Disable preemption
768	kernel_stop_preemption();
769
770	// Destroy the main processor and its context in reverse order of construction
771	// These were manually constructed so we need manually destroy them
772	^(*mainProcessor){};
773
774	// Final step, destroy the main thread since it is no longer needed
775	// Since we provided a stack to this taxk it will not destroy anything
776	/* paranoid / verify(mainThread->self_cor.stack.storage == (__stack_t)(((uintptr_t)&storage_mainThreadCtx)\| 0x1));
777	^(*mainThread){};
778
779	^(__cfa_dbg_global_clusters.list){};
780	^(__cfa_dbg_global_clusters.lock){};
781
782	__cfaabi_dbg_print_safe("Kernel : Shutdown complete\n");
783	}
784
785	//=============================================================================================
786	// Kernel Quiescing
787	//=============================================================================================
788	static void __halt(processor * this) with( *this ) {
789	// verify( ! __atomic_load_n(&do_terminate, __ATOMIC_SEQ_CST) );
790
791	with( *cltr ) {
792	lock (proc_list_lock __cfaabi_dbg_ctx2);
793	remove (procs, *this);
794	push_front(idles, *this);
795	unlock (proc_list_lock);
796	}
797
798	__cfaabi_dbg_print_safe("Kernel : Processor %p ready to sleep\n", this);
799
800	wait( idleLock );
801
802	__cfaabi_dbg_print_safe("Kernel : Processor %p woke up and ready to run\n", this);
803
804	with( *cltr ) {
805	lock (proc_list_lock __cfaabi_dbg_ctx2);
806	remove (idles, *this);
807	push_front(procs, *this);
808	unlock (proc_list_lock);
809	}
810	}
811
812	//=============================================================================================
813	// Unexpected Terminating logic
814	//=============================================================================================
815	static __spinlock_t kernel_abort_lock;
816	static bool kernel_abort_called = false;
817
818	void * kernel_abort(void) __attribute__ ((__nothrow__)) {
819	// abort cannot be recursively entered by the same or different processors because all signal handlers return when
820	// the globalAbort flag is true.
821	lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
822
823	// first task to abort ?
824	if ( kernel_abort_called ) { // not first task to abort ?
825	unlock( kernel_abort_lock );
826
827	sigset_t mask;
828	sigemptyset( &mask );
829	sigaddset( &mask, SIGALRM ); // block SIGALRM signals
830	sigaddset( &mask, SIGUSR1 ); // block SIGALRM signals
831	sigsuspend( &mask ); // block the processor to prevent further damage during abort
832	_exit( EXIT_FAILURE ); // if processor unblocks before it is killed, terminate it
833	}
834	else {
835	kernel_abort_called = true;
836	unlock( kernel_abort_lock );
837	}
838
839	return kernelTLS.this_thread;
840	}
841
842	void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
843	$thread * thrd = kernel_data;
844
845	if(thrd) {
846	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
847	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
848
849	if ( &thrd->self_cor != thrd->curr_cor ) {
850	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
851	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
852	}
853	else {
854	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
855	}
856	}
857	else {
858	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
859	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
860	}
861	}
862
863	int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
864	return get_coroutine(kernelTLS.this_thread) == get_coroutine(mainThread) ? 4 : 2;
865	}
866
867	static __spinlock_t kernel_debug_lock;
868
869	extern "C" {
870	void __cfaabi_bits_acquire() {
871	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
872	}
873
874	void __cfaabi_bits_release() {
875	unlock( kernel_debug_lock );
876	}
877	}
878
879	//=============================================================================================
880	// Kernel Utilities
881	//=============================================================================================
882	//-----------------------------------------------------------------------------
883	// Locks
884	void ?{}( semaphore & this, int count = 1 ) {
885	(this.lock){};
886	this.count = count;
887	(this.waiting){};
888	}
889	void ^?{}(semaphore & this) {}
890
891	void P(semaphore & this) with( this ){
892	lock( lock __cfaabi_dbg_ctx2 );
893	count -= 1;
894	if ( count < 0 ) {
895	// queue current task
896	append( waiting, kernelTLS.this_thread );
897
898	// atomically release spin lock and block
899	unlock( lock );
900	park();
901	}
902	else {
903	unlock( lock );
904	}
905	}
906
907	void V(semaphore & this) with( this ) {
908	$thread * thrd = 0p;
909	lock( lock __cfaabi_dbg_ctx2 );
910	count += 1;
911	if ( count <= 0 ) {
912	// remove task at head of waiting list
913	thrd = pop_head( waiting );
914	}
915
916	unlock( lock );
917
918	// make new owner
919	unpark( thrd );
920	}
921
922	//-----------------------------------------------------------------------------
923	// Global Queues
924	void doregister( cluster & cltr ) {
925	lock ( __cfa_dbg_global_clusters.lock __cfaabi_dbg_ctx2);
926	push_front( __cfa_dbg_global_clusters.list, cltr );
927	unlock ( __cfa_dbg_global_clusters.lock );
928	}
929
930	void unregister( cluster & cltr ) {
931	lock ( __cfa_dbg_global_clusters.lock __cfaabi_dbg_ctx2);
932	remove( __cfa_dbg_global_clusters.list, cltr );
933	unlock( __cfa_dbg_global_clusters.lock );
934	}
935
936	void doregister( cluster * cltr, $thread & thrd ) {
937	lock (cltr->thread_list_lock __cfaabi_dbg_ctx2);
938	cltr->nthreads += 1;
939	push_front(cltr->threads, thrd);
940	unlock (cltr->thread_list_lock);
941	}
942
943	void unregister( cluster * cltr, $thread & thrd ) {
944	lock (cltr->thread_list_lock __cfaabi_dbg_ctx2);
945	remove(cltr->threads, thrd );
946	cltr->nthreads -= 1;
947	unlock(cltr->thread_list_lock);
948	}
949
950	void doregister( cluster * cltr, processor * proc ) {
951	lock (cltr->proc_list_lock __cfaabi_dbg_ctx2);
952	cltr->nprocessors += 1;
953	push_front(cltr->procs, *proc);
954	unlock (cltr->proc_list_lock);
955	}
956
957	void unregister( cluster * cltr, processor * proc ) {
958	lock (cltr->proc_list_lock __cfaabi_dbg_ctx2);
959	remove(cltr->procs, *proc );
960	cltr->nprocessors -= 1;
961	unlock(cltr->proc_list_lock);
962	}
963
964	//-----------------------------------------------------------------------------
965	// Debug
966	__cfaabi_dbg_debug_do(
967	extern "C" {
968	void __cfaabi_dbg_record(__spinlock_t & this, const char prev_name[]) {
969	this.prev_name = prev_name;
970	this.prev_thrd = kernelTLS.this_thread;
971	}
972	}
973	)
974
975	//-----------------------------------------------------------------------------
976	// Debug
977	bool threading_enabled(void) __attribute__((const)) {
978	return true;
979	}
980	// Local Variables: //
981	// mode: c //
982	// tab-width: 4 //
983	// End: //

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