source: libcfa/src/concurrency/kernel.cfa@ 2b23d78

ADT arm-eh ast-experimental enum forall-pointer-decay jacob/cs343-translation new-ast new-ast-unique-expr pthread-emulation qualifiedEnum
Last change on this file since 2b23d78 was efc171d1, checked in by Thierry Delisle <tdelisle@…>, 5 years ago

Fixed several concurrency warnings
  • Property mode set to 100644
File size: 38.2 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 : Thu Jul 9 06:22:54 2020
13// Update Count : 66
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#include <stdio.h>
24#include <fenv.h>
25#include <signal.h>
26#include <unistd.h>
27#include <limits.h> // PTHREAD_STACK_MIN
28#include <sys/mman.h> // mprotect
29extern "C" {
30#include <sys/resource.h>
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
114static void __kernel_startup (void) __attribute__(( constructor( STARTUP_PRIORITY_KERNEL ) ));
115static void __kernel_shutdown(void) __attribute__(( destructor ( STARTUP_PRIORITY_KERNEL ) ));
116
117//-----------------------------------------------------------------------------
118// Kernel Scheduling logic
119static $thread * __next_thread(cluster * this);
120static bool __has_next_thread(cluster * this);
121static void __run_thread(processor * this, $thread * dst);
122static bool __wake_proc(processor *);
123static bool __wake_one(struct __processor_id_t * id, cluster * cltr);
124static void __halt(processor * this);
125
126//-----------------------------------------------------------------------------
127// Kernel storage
128KERNEL_STORAGE(cluster, mainCluster);
129KERNEL_STORAGE(processor, mainProcessor);
130KERNEL_STORAGE($thread, mainThread);
131KERNEL_STORAGE(__stack_t, mainThreadCtx);
132KERNEL_STORAGE(__scheduler_RWLock_t, __scheduler_lock);
133#if !defined(__CFA_NO_STATISTICS__)
134KERNEL_STORAGE(__stats_t, mainProcStats);
135#endif
136
137cluster * mainCluster;
138processor * mainProcessor;
139$thread * mainThread;
140__scheduler_RWLock_t * __scheduler_lock;
141
142extern "C" {
143 struct { __dllist_t(cluster) list; __spinlock_t lock; } __cfa_dbg_global_clusters;
144}
145
146size_t __page_size = 0;
147
148//-----------------------------------------------------------------------------
149// Global state
150thread_local struct KernelThreadData kernelTLS __attribute__ ((tls_model ( "initial-exec" ))) @= {
151 NULL, // cannot use 0p
152 NULL,
153 NULL,
154 { 1, false, false },
155};
156
157//-----------------------------------------------------------------------------
158// Struct to steal stack
159struct current_stack_info_t {
160 __stack_t * storage; // pointer to stack object
161 void * base; // base of stack
162 void * limit; // stack grows towards stack limit
163 void * context; // address of cfa_context_t
164};
165
166void ?{}( current_stack_info_t & this ) {
167 __stack_context_t ctx;
168 CtxGet( ctx );
169 this.base = ctx.FP;
170
171 rlimit r;
172 getrlimit( RLIMIT_STACK, &r);
173 size_t size = r.rlim_cur;
174
175 this.limit = (void *)(((intptr_t)this.base) - size);
176 this.context = &storage_mainThreadCtx;
177}
178
179//-----------------------------------------------------------------------------
180// Main thread construction
181
182void ?{}( $coroutine & this, current_stack_info_t * info) with( this ) {
183 stack.storage = info->storage;
184 with(*stack.storage) {
185 limit = info->limit;
186 base = info->base;
187 }
188 __attribute__((may_alias)) intptr_t * istorage = (intptr_t*) &stack.storage;
189 *istorage |= 0x1;
190 name = "Main Thread";
191 state = Start;
192 starter = 0p;
193 last = 0p;
194 cancellation = 0p;
195}
196
197void ?{}( $thread & this, current_stack_info_t * info) with( this ) {
198 ticket = 1;
199 state = Start;
200 self_cor{ info };
201 curr_cor = &self_cor;
202 curr_cluster = mainCluster;
203 self_mon.owner = &this;
204 self_mon.recursion = 1;
205 self_mon_p = &self_mon;
206 link.next = 0p;
207 link.prev = 0p;
208
209 node.next = 0p;
210 node.prev = 0p;
211 doregister(curr_cluster, this);
212
213 monitors{ &self_mon_p, 1, (fptr_t)0 };
214}
215
216//-----------------------------------------------------------------------------
217// Processor coroutine
218void ?{}(processorCtx_t & this) {
219
220}
221
222// Construct the processor context of non-main processors
223static void ?{}(processorCtx_t & this, processor * proc, current_stack_info_t * info) {
224 (this.__cor){ info };
225 this.proc = proc;
226}
227
228static void * __invoke_processor(void * arg);
229
230void ?{}(processor & this, const char name[], cluster & _cltr) with( this ) {
231 this.name = name;
232 this.cltr = &_cltr;
233 id = -1u;
234 terminated{ 0 };
235 destroyer = 0p;
236 do_terminate = false;
237 preemption_alarm = 0p;
238 pending_preemption = false;
239 runner.proc = &this;
240
241 #if !defined(__CFA_NO_STATISTICS__)
242 print_stats = 0;
243 print_halts = false;
244 #endif
245
246 idle{};
247
248 __cfadbg_print_safe(runtime_core, "Kernel : Starting core %p\n", &this);
249
250 this.stack = __create_pthread( &this.kernel_thread, __invoke_processor, (void *)&this );
251 __atomic_fetch_add( &cltr->nprocessors, 1u, __ATOMIC_SEQ_CST );
252
253 __cfadbg_print_safe(runtime_core, "Kernel : core %p created\n", &this);
254}
255
256void ^?{}(processor & this) with( this ){
257 if( ! __atomic_load_n(&do_terminate, __ATOMIC_ACQUIRE) ) {
258 __cfadbg_print_safe(runtime_core, "Kernel : core %p signaling termination\n", &this);
259
260 __atomic_store_n(&do_terminate, true, __ATOMIC_RELAXED);
261 __wake_proc( &this );
262
263 P( terminated );
264 verify( kernelTLS.this_processor != &this);
265 }
266
267 int err = pthread_join( kernel_thread, 0p );
268 if( err != 0 ) abort("KERNEL ERROR: joining processor %p caused error %s\n", &this, strerror(err));
269
270 free( this.stack );
271
272 __atomic_fetch_sub( &cltr->nprocessors, 1u, __ATOMIC_SEQ_CST );
273}
274
275void ?{}(cluster & this, const char name[], Duration preemption_rate, unsigned io_flags) with( this ) {
276 this.name = name;
277 this.preemption_rate = preemption_rate;
278 this.nprocessors = 0;
279 ready_queue{};
280
281 #if !defined(__CFA_NO_STATISTICS__)
282 print_stats = 0;
283 stats = alloc();
284 __init_stats( stats );
285 #endif
286
287 threads{ __get };
288
289 __kernel_io_startup( this, io_flags, &this == mainCluster );
290
291 doregister(this);
292}
293
294void ^?{}(cluster & this) {
295 __kernel_io_shutdown( this, &this == mainCluster );
296
297 #if !defined(__CFA_NO_STATISTICS__)
298 if( 0 != this.print_stats ) {
299 __print_stats( this.stats, this.print_stats, true, this.name, (void*)&this );
300 }
301 free( this.stats );
302 #endif
303
304 unregister(this);
305}
306
307//=============================================================================================
308// Kernel Scheduling logic
309//=============================================================================================
310//Main of the processor contexts
311void main(processorCtx_t & runner) {
312 // Because of a bug, we couldn't initialized the seed on construction
313 // Do it here
314 kernelTLS.rand_seed ^= rdtscl();
315
316 processor * this = runner.proc;
317 verify(this);
318
319 __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
320
321 // register the processor unless it's the main thread which is handled in the boot sequence
322 if(this != mainProcessor) {
323 this->id = doregister((__processor_id_t*)this);
324 #if !defined(__CFA_NO_STATISTICS__)
325 if( this->print_halts ) {
326 __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->id, this->name, (void*)this);
327 }
328 #endif
329
330 // Lock the RWlock so no-one pushes/pops while we are changing the queue
331 uint_fast32_t last_size = ready_mutate_lock();
332
333 // Adjust the ready queue size
334 ready_queue_grow( this->cltr );
335
336 // Unlock the RWlock
337 ready_mutate_unlock( last_size );
338 }
339
340 {
341 // Setup preemption data
342 preemption_scope scope = { this };
343
344 __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
345
346 $thread * readyThread = 0p;
347 for( unsigned int spin_count = 0;; spin_count++ ) {
348 // Try to get the next thread
349 readyThread = __next_thread( this->cltr );
350
351 // Check if we actually found a thread
352 if( readyThread ) {
353 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
354 /* paranoid */ verifyf( readyThread->state == Ready || readyThread->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", readyThread->state, readyThread->preempted);
355 /* paranoid */ verifyf( readyThread->link.next == 0p, "Expected null got %p", readyThread->link.next );
356 __builtin_prefetch( readyThread->context.SP );
357
358 // We found a thread run it
359 __run_thread(this, readyThread);
360
361 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
362 }
363
364 if(__atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST)) break;
365
366 if( !readyThread ) {
367 // Block until a thread is ready
368 __halt(this);
369 }
370 }
371
372 __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
373 }
374
375 V( this->terminated );
376
377 // unregister the processor unless it's the main thread which is handled in the boot sequence
378 if(this != mainProcessor) {
379 // Lock the RWlock so no-one pushes/pops while we are changing the queue
380 uint_fast32_t last_size = ready_mutate_lock();
381
382 // Adjust the ready queue size
383 ready_queue_shrink( this->cltr );
384
385 // Make sure we aren't on the idle queue
386 #if !defined(__CFA_NO_STATISTICS__)
387 bool removed =
388 #endif
389 unsafe_remove( this->cltr->idles, this );
390
391 #if !defined(__CFA_NO_STATISTICS__)
392 if(removed) __tls_stats()->ready.sleep.exits++;
393 #endif
394
395 // Unlock the RWlock
396 ready_mutate_unlock( last_size );
397
398 // Finally we don't need the read_lock any more
399 unregister((__processor_id_t*)this);
400 }
401 else {
402 // HACK : the coroutine context switch expects this_thread to be set
403 // and it make sense for it to be set in all other cases except here
404 // fake it
405 kernelTLS.this_thread = mainThread;
406 }
407
408 __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
409}
410
411static int * __volatile_errno() __attribute__((noinline));
412static int * __volatile_errno() { asm(""); return &errno; }
413
414// KERNEL ONLY
415// runThread runs a thread by context switching
416// from the processor coroutine to the target thread
417static void __run_thread(processor * this, $thread * thrd_dst) {
418 $coroutine * proc_cor = get_coroutine(this->runner);
419
420 // Update global state
421 kernelTLS.this_thread = thrd_dst;
422
423 // set state of processor coroutine to inactive
424 verify(proc_cor->state == Active);
425 proc_cor->state = Blocked;
426
427 // Actually run the thread
428 RUNNING: while(true) {
429 thrd_dst->preempted = __NO_PREEMPTION;
430 thrd_dst->state = Active;
431
432 __cfaabi_dbg_debug_do(
433 thrd_dst->park_stale = true;
434 thrd_dst->unpark_stale = true;
435 )
436
437 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
438 /* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
439 /* 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
440 /* 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
441
442 // set context switch to the thread that the processor is executing
443 verify( thrd_dst->context.SP );
444 __cfactx_switch( &proc_cor->context, &thrd_dst->context );
445 // when __cfactx_switch returns we are back in the processor coroutine
446
447 /* 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 );
448 /* 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 );
449 /* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
450 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
451
452
453 // We just finished running a thread, there are a few things that could have happened.
454 // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
455 // 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
456 // 4 - Preempted
457 // In case 1, we may have won a race so we can't write to the state again.
458 // In case 2, we lost the race so we now own the thread.
459
460 if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
461 // The thread was preempted, reschedule it and reset the flag
462 __schedule_thread( (__processor_id_t*)this, thrd_dst );
463 break RUNNING;
464 }
465
466 if(unlikely(thrd_dst->state == Halted)) {
467 // The thread has halted, it should never be scheduled/run again
468 // We may need to wake someone up here since
469 unpark( this->destroyer __cfaabi_dbg_ctx2 );
470 this->destroyer = 0p;
471 break RUNNING;
472 }
473
474 /* paranoid */ verify( thrd_dst->state == Active );
475 thrd_dst->state = Blocked;
476
477 // set state of processor coroutine to active and the thread to inactive
478 int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
479 __cfaabi_dbg_debug_do( thrd_dst->park_result = old_ticket; )
480 switch(old_ticket) {
481 case 1:
482 // This is case 1, the regular case, nothing more is needed
483 break RUNNING;
484 case 2:
485 // This is case 2, the racy case, someone tried to run this thread before it finished blocking
486 // In this case, just run it again.
487 continue RUNNING;
488 default:
489 // This makes no sense, something is wrong abort
490 abort();
491 }
492 }
493
494 // Just before returning to the processor, set the processor coroutine to active
495 proc_cor->state = Active;
496 kernelTLS.this_thread = 0p;
497}
498
499// KERNEL_ONLY
500void returnToKernel() {
501 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
502 $coroutine * proc_cor = get_coroutine(kernelTLS.this_processor->runner);
503 $thread * thrd_src = kernelTLS.this_thread;
504
505 #if !defined(__CFA_NO_STATISTICS__)
506 struct processor * last_proc = kernelTLS.this_processor;
507 #endif
508
509 // Run the thread on this processor
510 {
511 int local_errno = *__volatile_errno();
512 #if defined( __i386 ) || defined( __x86_64 )
513 __x87_store;
514 #endif
515 verify( proc_cor->context.SP );
516 __cfactx_switch( &thrd_src->context, &proc_cor->context );
517 #if defined( __i386 ) || defined( __x86_64 )
518 __x87_load;
519 #endif
520 *__volatile_errno() = local_errno;
521 }
522
523 #if !defined(__CFA_NO_STATISTICS__)
524 if(last_proc != kernelTLS.this_processor) {
525 __tls_stats()->ready.threads.migration++;
526 }
527 #endif
528
529 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
530 /* 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 );
531 /* 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 );
532}
533
534// KERNEL_ONLY
535// Context invoker for processors
536// This is the entry point for processors (kernel threads)
537// It effectively constructs a coroutine by stealing the pthread stack
538static void * __invoke_processor(void * arg) {
539 #if !defined( __CFA_NO_STATISTICS__ )
540 __stats_t local_stats;
541 __init_stats( &local_stats );
542 kernelTLS.this_stats = &local_stats;
543 #endif
544
545 processor * proc = (processor *) arg;
546 kernelTLS.this_processor = proc;
547 kernelTLS.this_thread = 0p;
548 kernelTLS.preemption_state.[enabled, disable_count] = [false, 1];
549 // SKULLDUGGERY: We want to create a context for the processor coroutine
550 // which is needed for the 2-step context switch. However, there is no reason
551 // to waste the perfectly valid stack create by pthread.
552 current_stack_info_t info;
553 __stack_t ctx;
554 info.storage = &ctx;
555 (proc->runner){ proc, &info };
556
557 __cfaabi_dbg_print_safe("Coroutine : created stack %p\n", get_coroutine(proc->runner)->stack.storage);
558
559 //Set global state
560 kernelTLS.this_thread = 0p;
561
562 //We now have a proper context from which to schedule threads
563 __cfadbg_print_safe(runtime_core, "Kernel : core %p created (%p, %p)\n", proc, &proc->runner, &ctx);
564
565 // SKULLDUGGERY: Since the coroutine doesn't have its own stack, we can't
566 // resume it to start it like it normally would, it will just context switch
567 // back to here. Instead directly call the main since we already are on the
568 // appropriate stack.
569 get_coroutine(proc->runner)->state = Active;
570 main( proc->runner );
571 get_coroutine(proc->runner)->state = Halted;
572
573 // Main routine of the core returned, the core is now fully terminated
574 __cfadbg_print_safe(runtime_core, "Kernel : core %p main ended (%p)\n", proc, &proc->runner);
575
576 #if !defined(__CFA_NO_STATISTICS__)
577 __tally_stats(proc->cltr->stats, &local_stats);
578 if( 0 != proc->print_stats ) {
579 __print_stats( &local_stats, proc->print_stats, true, proc->name, (void*)proc );
580 }
581 #endif
582
583 return 0p;
584}
585
586static void Abort( int ret, const char func[] ) {
587 if ( ret ) { // pthread routines return errno values
588 abort( "%s : internal error, error(%d) %s.", func, ret, strerror( ret ) );
589 } // if
590} // Abort
591
592void * __create_pthread( pthread_t * pthread, void * (*start)(void *), void * arg ) {
593 pthread_attr_t attr;
594
595 Abort( pthread_attr_init( &attr ), "pthread_attr_init" ); // initialize attribute
596
597 size_t stacksize;
598 // default stack size, normally defined by shell limit
599 Abort( pthread_attr_getstacksize( &attr, &stacksize ), "pthread_attr_getstacksize" );
600 assert( stacksize >= PTHREAD_STACK_MIN );
601
602 void * stack;
603 __cfaabi_dbg_debug_do(
604 stack = memalign( __page_size, stacksize + __page_size );
605 // pthread has no mechanism to create the guard page in user supplied stack.
606 if ( mprotect( stack, __page_size, PROT_NONE ) == -1 ) {
607 abort( "mprotect : internal error, mprotect failure, error(%d) %s.", errno, strerror( errno ) );
608 } // if
609 );
610 __cfaabi_dbg_no_debug_do(
611 stack = malloc( stacksize );
612 );
613
614 Abort( pthread_attr_setstack( &attr, stack, stacksize ), "pthread_attr_setstack" );
615
616 Abort( pthread_create( pthread, &attr, start, arg ), "pthread_create" );
617 return stack;
618}
619
620// KERNEL_ONLY
621static void __kernel_first_resume( processor * this ) {
622 $thread * src = mainThread;
623 $coroutine * dst = get_coroutine(this->runner);
624
625 verify( ! kernelTLS.preemption_state.enabled );
626
627 kernelTLS.this_thread->curr_cor = dst;
628 __stack_prepare( &dst->stack, 65000 );
629 __cfactx_start(main, dst, this->runner, __cfactx_invoke_coroutine);
630
631 verify( ! kernelTLS.preemption_state.enabled );
632
633 dst->last = &src->self_cor;
634 dst->starter = dst->starter ? dst->starter : &src->self_cor;
635
636 // make sure the current state is still correct
637 /* paranoid */ verify(src->state == Ready);
638
639 // context switch to specified coroutine
640 verify( dst->context.SP );
641 __cfactx_switch( &src->context, &dst->context );
642 // when __cfactx_switch returns we are back in the src coroutine
643
644 mainThread->curr_cor = &mainThread->self_cor;
645
646 // make sure the current state has been update
647 /* paranoid */ verify(src->state == Active);
648
649 verify( ! kernelTLS.preemption_state.enabled );
650}
651
652// KERNEL_ONLY
653static void __kernel_last_resume( processor * this ) {
654 $coroutine * src = &mainThread->self_cor;
655 $coroutine * dst = get_coroutine(this->runner);
656
657 verify( ! kernelTLS.preemption_state.enabled );
658 verify( dst->starter == src );
659 verify( dst->context.SP );
660
661 // SKULLDUGGERY in debug the processors check that the
662 // stack is still within the limit of the stack limits after running a thread.
663 // that check doesn't make sense if we context switch to the processor using the
664 // coroutine semantics. Since this is a special case, use the current context
665 // info to populate these fields.
666 __cfaabi_dbg_debug_do(
667 __stack_context_t ctx;
668 CtxGet( ctx );
669 mainThread->context.SP = ctx.SP;
670 mainThread->context.FP = ctx.FP;
671 )
672
673 // context switch to the processor
674 __cfactx_switch( &src->context, &dst->context );
675}
676
677//-----------------------------------------------------------------------------
678// Scheduler routines
679// KERNEL ONLY
680void __schedule_thread( struct __processor_id_t * id, $thread * thrd ) {
681 /* paranoid */ verify( thrd );
682 /* paranoid */ verify( thrd->state != Halted );
683 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
684 /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
685 /* paranoid */ if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
686 "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
687 /* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
688 "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
689 /* paranoid */ #endif
690 /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
691
692 if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
693
694 ready_schedule_lock ( id );
695 push( thrd->curr_cluster, thrd );
696
697 #if !defined(__CFA_NO_STATISTICS__)
698 bool woke =
699 #endif
700 __wake_one(id, thrd->curr_cluster);
701
702 #if !defined(__CFA_NO_STATISTICS__)
703 if(woke) __tls_stats()->ready.sleep.wakes++;
704 #endif
705 ready_schedule_unlock( id );
706
707 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
708}
709
710// KERNEL ONLY
711static $thread * __next_thread(cluster * this) with( *this ) {
712 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
713
714 ready_schedule_lock ( (__processor_id_t*)kernelTLS.this_processor );
715 $thread * head = pop( this );
716 ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
717
718 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
719 return head;
720}
721
722// KERNEL ONLY
723static bool __has_next_thread(cluster * this) with( *this ) {
724 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
725
726 ready_schedule_lock ( (__processor_id_t*)kernelTLS.this_processor );
727 bool not_empty = query( this );
728 ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
729
730 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
731 return not_empty;
732}
733
734// KERNEL ONLY unpark with out disabling interrupts
735void __unpark( struct __processor_id_t * id, $thread * thrd __cfaabi_dbg_ctx_param2 ) {
736 // record activity
737 __cfaabi_dbg_record_thrd( *thrd, false, caller );
738
739 int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
740 __cfaabi_dbg_debug_do( thrd->unpark_result = old_ticket; thrd->unpark_state = thrd->state; )
741 switch(old_ticket) {
742 case 1:
743 // Wake won the race, the thread will reschedule/rerun itself
744 break;
745 case 0:
746 /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
747 /* paranoid */ verify( thrd->state == Blocked );
748
749 // Wake lost the race,
750 __schedule_thread( id, thrd );
751 break;
752 default:
753 // This makes no sense, something is wrong abort
754 abort();
755 }
756}
757
758void unpark( $thread * thrd __cfaabi_dbg_ctx_param2 ) {
759 if( !thrd ) return;
760
761 disable_interrupts();
762 __unpark( (__processor_id_t*)kernelTLS.this_processor, thrd __cfaabi_dbg_ctx_fwd2 );
763 enable_interrupts( __cfaabi_dbg_ctx );
764}
765
766void park( __cfaabi_dbg_ctx_param ) {
767 /* paranoid */ verify( kernelTLS.preemption_state.enabled );
768 disable_interrupts();
769 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
770 /* paranoid */ verify( kernelTLS.this_thread->preempted == __NO_PREEMPTION );
771
772 // record activity
773 __cfaabi_dbg_record_thrd( *kernelTLS.this_thread, true, caller );
774
775 returnToKernel();
776
777 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
778 enable_interrupts( __cfaabi_dbg_ctx );
779 /* paranoid */ verify( kernelTLS.preemption_state.enabled );
780
781}
782
783// KERNEL ONLY
784void __leave_thread() {
785 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
786 returnToKernel();
787 abort();
788}
789
790// KERNEL ONLY
791bool force_yield( __Preemption_Reason reason ) {
792 /* paranoid */ verify( kernelTLS.preemption_state.enabled );
793 disable_interrupts();
794 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
795
796 $thread * thrd = kernelTLS.this_thread;
797 /* paranoid */ verify(thrd->state == Active);
798
799 // SKULLDUGGERY: It is possible that we are preempting this thread just before
800 // it was going to park itself. If that is the case and it is already using the
801 // intrusive fields then we can't use them to preempt the thread
802 // If that is the case, abandon the preemption.
803 bool preempted = false;
804 if(thrd->link.next == 0p) {
805 preempted = true;
806 thrd->preempted = reason;
807 returnToKernel();
808 }
809
810 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
811 enable_interrupts_noPoll();
812 /* paranoid */ verify( kernelTLS.preemption_state.enabled );
813
814 return preempted;
815}
816
817//=============================================================================================
818// Kernel Setup logic
819//=============================================================================================
820//-----------------------------------------------------------------------------
821// Kernel boot procedures
822static void __kernel_startup(void) {
823 verify( ! kernelTLS.preemption_state.enabled );
824 __cfadbg_print_safe(runtime_core, "Kernel : Starting\n");
825
826 __page_size = sysconf( _SC_PAGESIZE );
827
828 __cfa_dbg_global_clusters.list{ __get };
829 __cfa_dbg_global_clusters.lock{};
830
831 // Initialize the global scheduler lock
832 __scheduler_lock = (__scheduler_RWLock_t*)&storage___scheduler_lock;
833 (*__scheduler_lock){};
834
835 // Initialize the main cluster
836 mainCluster = (cluster *)&storage_mainCluster;
837 (*mainCluster){"Main Cluster"};
838
839 __cfadbg_print_safe(runtime_core, "Kernel : Main cluster ready\n");
840
841 // Start by initializing the main thread
842 // SKULLDUGGERY: the mainThread steals the process main thread
843 // which will then be scheduled by the mainProcessor normally
844 mainThread = ($thread *)&storage_mainThread;
845 current_stack_info_t info;
846 info.storage = (__stack_t*)&storage_mainThreadCtx;
847 (*mainThread){ &info };
848
849 __cfadbg_print_safe(runtime_core, "Kernel : Main thread ready\n");
850
851
852
853 // Construct the processor context of the main processor
854 void ?{}(processorCtx_t & this, processor * proc) {
855 (this.__cor){ "Processor" };
856 this.__cor.starter = 0p;
857 this.proc = proc;
858 }
859
860 void ?{}(processor & this) with( this ) {
861 name = "Main Processor";
862 cltr = mainCluster;
863 terminated{ 0 };
864 do_terminate = false;
865 preemption_alarm = 0p;
866 pending_preemption = false;
867 kernel_thread = pthread_self();
868 id = -1u;
869
870 #if !defined(__CFA_NO_STATISTICS__)
871 print_stats = false;
872 print_halts = false;
873 #endif
874
875 runner{ &this };
876 __cfadbg_print_safe(runtime_core, "Kernel : constructed main processor context %p\n", &runner);
877
878 __atomic_fetch_add( &cltr->nprocessors, 1u, __ATOMIC_SEQ_CST );
879 }
880
881 // Initialize the main processor and the main processor ctx
882 // (the coroutine that contains the processing control flow)
883 mainProcessor = (processor *)&storage_mainProcessor;
884 (*mainProcessor){};
885
886 mainProcessor->id = doregister( (__processor_id_t*)mainProcessor);
887
888 //initialize the global state variables
889 kernelTLS.this_processor = mainProcessor;
890 kernelTLS.this_thread = mainThread;
891
892 #if !defined( __CFA_NO_STATISTICS__ )
893 kernelTLS.this_stats = (__stats_t *)& storage_mainProcStats;
894 __init_stats( kernelTLS.this_stats );
895 #endif
896
897 // Enable preemption
898 kernel_start_preemption();
899
900 // Add the main thread to the ready queue
901 // once resume is called on mainProcessor->runner the mainThread needs to be scheduled like any normal thread
902 __schedule_thread((__processor_id_t *)mainProcessor, mainThread);
903
904 // SKULLDUGGERY: Force a context switch to the main processor to set the main thread's context to the current UNIX
905 // context. Hence, the main thread does not begin through __cfactx_invoke_thread, like all other threads. The trick here is that
906 // mainThread is on the ready queue when this call is made.
907 __kernel_first_resume( kernelTLS.this_processor );
908
909
910 // THE SYSTEM IS NOW COMPLETELY RUNNING
911
912
913 // Now that the system is up, finish creating systems that need threading
914 __kernel_io_finish_start( *mainCluster );
915
916
917 __cfadbg_print_safe(runtime_core, "Kernel : Started\n--------------------------------------------------\n\n");
918
919 verify( ! kernelTLS.preemption_state.enabled );
920 enable_interrupts( __cfaabi_dbg_ctx );
921 verify( TL_GET( preemption_state.enabled ) );
922}
923
924static void __kernel_shutdown(void) {
925 //Before we start shutting things down, wait for systems that need threading to shutdown
926 __kernel_io_prepare_stop( *mainCluster );
927
928 /* paranoid */ verify( TL_GET( preemption_state.enabled ) );
929 disable_interrupts();
930 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
931
932 __cfadbg_print_safe(runtime_core, "\n--------------------------------------------------\nKernel : Shutting down\n");
933
934 // SKULLDUGGERY: Notify the mainProcessor it needs to terminates.
935 // When its coroutine terminates, it return control to the mainThread
936 // which is currently here
937 __atomic_store_n(&mainProcessor->do_terminate, true, __ATOMIC_RELEASE);
938 __kernel_last_resume( kernelTLS.this_processor );
939 mainThread->self_cor.state = Halted;
940
941 // THE SYSTEM IS NOW COMPLETELY STOPPED
942
943 // Disable preemption
944 kernel_stop_preemption();
945
946 unregister((__processor_id_t*)mainProcessor);
947
948 // Destroy the main processor and its context in reverse order of construction
949 // These were manually constructed so we need manually destroy them
950 void ^?{}(processor & this) with( this ){
951 /* paranoid */ verify( this.do_terminate == true );
952 __atomic_fetch_sub( &cltr->nprocessors, 1u, __ATOMIC_SEQ_CST );
953 __cfaabi_dbg_print_safe("Kernel : destroyed main processor context %p\n", &runner);
954 }
955
956 ^(*mainProcessor){};
957
958 // Final step, destroy the main thread since it is no longer needed
959
960 // Since we provided a stack to this taxk it will not destroy anything
961 /* paranoid */ verify(mainThread->self_cor.stack.storage == (__stack_t*)(((uintptr_t)&storage_mainThreadCtx)| 0x1));
962 ^(*mainThread){};
963
964 ^(*mainCluster){};
965
966 ^(*__scheduler_lock){};
967
968 ^(__cfa_dbg_global_clusters.list){};
969 ^(__cfa_dbg_global_clusters.lock){};
970
971 __cfadbg_print_safe(runtime_core, "Kernel : Shutdown complete\n");
972}
973
974//=============================================================================================
975// Kernel Idle Sleep
976//=============================================================================================
977// Wake a thread from the front if there are any
978static bool __wake_one(struct __processor_id_t * id, cluster * this) {
979 /* paranoid */ verify( ready_schedule_islocked( id ) );
980
981 // Check if there is a sleeping processor
982 processor * p = pop(this->idles);
983
984 // If no one is sleeping, we are done
985 if( 0p == p ) return false;
986
987 // We found a processor, wake it up
988 post( p->idle );
989
990 return true;
991}
992
993// Unconditionnaly wake a thread
994static bool __wake_proc(processor * this) {
995 __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
996
997 disable_interrupts();
998 /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
999 bool ret = post( this->idle );
1000 enable_interrupts( __cfaabi_dbg_ctx );
1001
1002 return ret;
1003}
1004
1005static void __halt(processor * this) with( *this ) {
1006 if( do_terminate ) return;
1007
1008 #if !defined(__CFA_NO_STATISTICS__)
1009 __tls_stats()->ready.sleep.halts++;
1010 #endif
1011 // Push self to queue
1012 push(cltr->idles, *this);
1013
1014 // Makre sure we don't miss a thread
1015 if( __has_next_thread(cltr) ) {
1016 // A thread was posted, make sure a processor is woken up
1017 struct __processor_id_t *id = (struct __processor_id_t *) this;
1018 ready_schedule_lock ( id );
1019 __wake_one( id, cltr );
1020 ready_schedule_unlock( id );
1021 #if !defined(__CFA_NO_STATISTICS__)
1022 __tls_stats()->ready.sleep.cancels++;
1023 #endif
1024 }
1025
1026 #if !defined(__CFA_NO_STATISTICS__)
1027 if(this->print_halts) {
1028 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->id, rdtscl());
1029 }
1030 #endif
1031
1032 wait( idle );
1033
1034 #if !defined(__CFA_NO_STATISTICS__)
1035 if(this->print_halts) {
1036 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->id, rdtscl());
1037 }
1038 #endif
1039}
1040
1041//=============================================================================================
1042// Unexpected Terminating logic
1043//=============================================================================================
1044static __spinlock_t kernel_abort_lock;
1045static bool kernel_abort_called = false;
1046
1047void * kernel_abort(void) __attribute__ ((__nothrow__)) {
1048 // abort cannot be recursively entered by the same or different processors because all signal handlers return when
1049 // the globalAbort flag is true.
1050 lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
1051
1052 // first task to abort ?
1053 if ( kernel_abort_called ) { // not first task to abort ?
1054 unlock( kernel_abort_lock );
1055
1056 sigset_t mask;
1057 sigemptyset( &mask );
1058 sigaddset( &mask, SIGALRM ); // block SIGALRM signals
1059 sigaddset( &mask, SIGUSR1 ); // block SIGALRM signals
1060 sigsuspend( &mask ); // block the processor to prevent further damage during abort
1061 _exit( EXIT_FAILURE ); // if processor unblocks before it is killed, terminate it
1062 }
1063 else {
1064 kernel_abort_called = true;
1065 unlock( kernel_abort_lock );
1066 }
1067
1068 return kernelTLS.this_thread;
1069}
1070
1071void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
1072 $thread * thrd = kernel_data;
1073
1074 if(thrd) {
1075 int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
1076 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
1077
1078 if ( &thrd->self_cor != thrd->curr_cor ) {
1079 len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
1080 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
1081 }
1082 else {
1083 __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
1084 }
1085 }
1086 else {
1087 int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
1088 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
1089 }
1090}
1091
1092int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
1093 return get_coroutine(kernelTLS.this_thread) == get_coroutine(mainThread) ? 4 : 2;
1094}
1095
1096static __spinlock_t kernel_debug_lock;
1097
1098extern "C" {
1099 void __cfaabi_bits_acquire() {
1100 lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
1101 }
1102
1103 void __cfaabi_bits_release() {
1104 unlock( kernel_debug_lock );
1105 }
1106}
1107
1108//=============================================================================================
1109// Kernel Utilities
1110//=============================================================================================
1111//-----------------------------------------------------------------------------
1112// Locks
1113void ?{}( semaphore & this, int count = 1 ) {
1114 (this.lock){};
1115 this.count = count;
1116 (this.waiting){};
1117}
1118void ^?{}(semaphore & this) {}
1119
1120bool P(semaphore & this) with( this ){
1121 lock( lock __cfaabi_dbg_ctx2 );
1122 count -= 1;
1123 if ( count < 0 ) {
1124 // queue current task
1125 append( waiting, kernelTLS.this_thread );
1126
1127 // atomically release spin lock and block
1128 unlock( lock );
1129 park( __cfaabi_dbg_ctx );
1130 return true;
1131 }
1132 else {
1133 unlock( lock );
1134 return false;
1135 }
1136}
1137
1138bool V(semaphore & this) with( this ) {
1139 $thread * thrd = 0p;
1140 lock( lock __cfaabi_dbg_ctx2 );
1141 count += 1;
1142 if ( count <= 0 ) {
1143 // remove task at head of waiting list
1144 thrd = pop_head( waiting );
1145 }
1146
1147 unlock( lock );
1148
1149 // make new owner
1150 unpark( thrd __cfaabi_dbg_ctx2 );
1151
1152 return thrd != 0p;
1153}
1154
1155bool V(semaphore & this, unsigned diff) with( this ) {
1156 $thread * thrd = 0p;
1157 lock( lock __cfaabi_dbg_ctx2 );
1158 int release = max(-count, (int)diff);
1159 count += diff;
1160 for(release) {
1161 unpark( pop_head( waiting ) __cfaabi_dbg_ctx2 );
1162 }
1163
1164 unlock( lock );
1165
1166 return thrd != 0p;
1167}
1168
1169//-----------------------------------------------------------------------------
1170// Global Queues
1171void doregister( cluster & cltr ) {
1172 lock ( __cfa_dbg_global_clusters.lock __cfaabi_dbg_ctx2);
1173 push_front( __cfa_dbg_global_clusters.list, cltr );
1174 unlock ( __cfa_dbg_global_clusters.lock );
1175}
1176
1177void unregister( cluster & cltr ) {
1178 lock ( __cfa_dbg_global_clusters.lock __cfaabi_dbg_ctx2);
1179 remove( __cfa_dbg_global_clusters.list, cltr );
1180 unlock( __cfa_dbg_global_clusters.lock );
1181}
1182
1183void doregister( cluster * cltr, $thread & thrd ) {
1184 lock (cltr->thread_list_lock __cfaabi_dbg_ctx2);
1185 cltr->nthreads += 1;
1186 push_front(cltr->threads, thrd);
1187 unlock (cltr->thread_list_lock);
1188}
1189
1190void unregister( cluster * cltr, $thread & thrd ) {
1191 lock (cltr->thread_list_lock __cfaabi_dbg_ctx2);
1192 remove(cltr->threads, thrd );
1193 cltr->nthreads -= 1;
1194 unlock(cltr->thread_list_lock);
1195}
1196
1197//-----------------------------------------------------------------------------
1198// Debug
1199__cfaabi_dbg_debug_do(
1200 extern "C" {
1201 void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
1202 this.prev_name = prev_name;
1203 this.prev_thrd = kernelTLS.this_thread;
1204 }
1205
1206 void __cfaabi_dbg_record_thrd($thread & this, bool park, const char prev_name[]) {
1207 if(park) {
1208 this.park_caller = prev_name;
1209 this.park_stale = false;
1210 }
1211 else {
1212 this.unpark_caller = prev_name;
1213 this.unpark_stale = false;
1214 }
1215 }
1216 }
1217)
1218
1219//-----------------------------------------------------------------------------
1220// Debug
1221bool threading_enabled(void) __attribute__((const)) {
1222 return true;
1223}
1224
1225//-----------------------------------------------------------------------------
1226// Statistics
1227#if !defined(__CFA_NO_STATISTICS__)
1228 void print_halts( processor & this ) {
1229 this.print_halts = true;
1230 }
1231#endif
1232// Local Variables: //
1233// mode: c //
1234// tab-width: 4 //
1235// End: //
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