source: libcfa/src/concurrency/kernel.cfa @ 6011658

arm-ehjacob/cs343-translationnew-ast-unique-expr
Last change on this file since 6011658 was 6011658, checked in by Thierry Delisle <tdelisle@…>, 11 months ago

Fixed abort to no longer deadlock when calling itself recursively.
abort now disable interrupts indefinitely.

  • Property mode set to 100644
File size: 24.1 KB
Line 
1//
2// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// kernel.c --
8//
9// Author           : Thierry Delisle
10// Created On       : Tue Jan 17 12:27:26 2017
11// Last Modified By : Peter A. Buhr
12// Last Modified On : Mon Aug 31 07:08:20 2020
13// Update Count     : 71
14//
15
16#define __cforall_thread__
17// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
18
19//C Includes
20#include <errno.h>
21#include <stdio.h>
22#include <signal.h>
23#include <unistd.h>
24
25//CFA Includes
26#include "kernel_private.hfa"
27#include "preemption.hfa"
28
29//Private includes
30#define __CFA_INVOKE_PRIVATE__
31#include "invoke.h"
32
33
34//-----------------------------------------------------------------------------
35// Some assembly required
36#if defined( __i386 )
37        // mxcr : SSE Status and Control bits (control bits are preserved across function calls)
38        // fcw  : X87 FPU control word (preserved across function calls)
39        #define __x87_store         \
40                uint32_t __mxcr;      \
41                uint16_t __fcw;       \
42                __asm__ volatile (    \
43                        "stmxcsr %0\n"  \
44                        "fnstcw  %1\n"  \
45                        : "=m" (__mxcr),\
46                                "=m" (__fcw)  \
47                )
48
49        #define __x87_load         \
50                __asm__ volatile (   \
51                        "fldcw  %1\n"  \
52                        "ldmxcsr %0\n" \
53                        ::"m" (__mxcr),\
54                                "m" (__fcw)  \
55                )
56
57#elif defined( __x86_64 )
58        #define __x87_store         \
59                uint32_t __mxcr;      \
60                uint16_t __fcw;       \
61                __asm__ volatile (    \
62                        "stmxcsr %0\n"  \
63                        "fnstcw  %1\n"  \
64                        : "=m" (__mxcr),\
65                                "=m" (__fcw)  \
66                )
67
68        #define __x87_load          \
69                __asm__ volatile (    \
70                        "fldcw  %1\n"   \
71                        "ldmxcsr %0\n"  \
72                        :: "m" (__mxcr),\
73                                "m" (__fcw)  \
74                )
75
76#elif defined( __arm__ )
77        #define __x87_store
78        #define __x87_load
79
80#elif defined( __aarch64__ )
81        #define __x87_store              \
82                uint32_t __fpcntl[2];    \
83                __asm__ volatile (    \
84                        "mrs x9, FPCR\n" \
85                        "mrs x10, FPSR\n"  \
86                        "stp x9, x10, %0\n"  \
87                        : "=m" (__fpcntl) : : "x9", "x10" \
88                )
89
90        #define __x87_load         \
91                __asm__ volatile (    \
92                        "ldp x9, x10, %0\n"  \
93                        "msr FPSR, x10\n"  \
94                        "msr FPCR, x9\n" \
95                : "=m" (__fpcntl) : : "x9", "x10" \
96                )
97
98#else
99        #error unsupported hardware architecture
100#endif
101
102extern $thread * mainThread;
103extern processor * mainProcessor;
104
105//-----------------------------------------------------------------------------
106// Kernel Scheduling logic
107static $thread * __next_thread(cluster * this);
108static $thread * __next_thread_slow(cluster * this);
109static void __run_thread(processor * this, $thread * dst);
110static void __wake_one(cluster * cltr);
111
112static void push  (__cluster_idles & idles, processor & proc);
113static void remove(__cluster_idles & idles, processor & proc);
114static [unsigned idle, unsigned total, * processor] query( & __cluster_idles idles );
115
116
117//=============================================================================================
118// Kernel Scheduling logic
119//=============================================================================================
120//Main of the processor contexts
121void main(processorCtx_t & runner) {
122        // Because of a bug, we couldn't initialized the seed on construction
123        // Do it here
124        __cfaabi_tls.rand_seed ^= rdtscl();
125        __cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
126        __tls_rand_advance_bck();
127
128        processor * this = runner.proc;
129        verify(this);
130
131        __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
132        #if !defined(__CFA_NO_STATISTICS__)
133                if( this->print_halts ) {
134                        __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->id, this->name, (void*)this);
135                }
136        #endif
137
138        {
139                // Setup preemption data
140                preemption_scope scope = { this };
141
142                __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
143
144                $thread * readyThread = 0p;
145                MAIN_LOOP:
146                for() {
147                        // Try to get the next thread
148                        readyThread = __next_thread( this->cltr );
149
150                        if( !readyThread ) {
151                                readyThread = __next_thread_slow( this->cltr );
152                        }
153
154                        HALT:
155                        if( !readyThread ) {
156                                // Don't block if we are done
157                                if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
158
159                                #if !defined(__CFA_NO_STATISTICS__)
160                                        __tls_stats()->ready.sleep.halts++;
161                                #endif
162
163                                // Push self to idle stack
164                                push(this->cltr->idles, * this);
165
166                                // Confirm the ready-queue is empty
167                                readyThread = __next_thread_slow( this->cltr );
168                                if( readyThread ) {
169                                        // A thread was found, cancel the halt
170                                        remove(this->cltr->idles, * this);
171
172                                        #if !defined(__CFA_NO_STATISTICS__)
173                                                __tls_stats()->ready.sleep.cancels++;
174                                        #endif
175
176                                        // continue the mai loop
177                                        break HALT;
178                                }
179
180                                #if !defined(__CFA_NO_STATISTICS__)
181                                        if(this->print_halts) {
182                                                __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->id, rdtscl());
183                                        }
184                                #endif
185
186                                wait( this->idle );
187
188                                #if !defined(__CFA_NO_STATISTICS__)
189                                        if(this->print_halts) {
190                                                __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->id, rdtscl());
191                                        }
192                                #endif
193
194                                // We were woken up, remove self from idle
195                                remove(this->cltr->idles, * this);
196
197                                // DON'T just proceed, start looking again
198                                continue MAIN_LOOP;
199                        }
200
201                        /* paranoid */ verify( readyThread );
202
203                        // We found a thread run it
204                        __run_thread(this, readyThread);
205
206                        // Are we done?
207                        if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
208                }
209
210                __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
211        }
212
213        V( this->terminated );
214
215        if(this == mainProcessor) {
216                // HACK : the coroutine context switch expects this_thread to be set
217                // and it make sense for it to be set in all other cases except here
218                // fake it
219                __cfaabi_tls.this_thread = mainThread;
220        }
221
222        __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
223}
224
225static int * __volatile_errno() __attribute__((noinline));
226static int * __volatile_errno() { asm(""); return &errno; }
227
228// KERNEL ONLY
229// runThread runs a thread by context switching
230// from the processor coroutine to the target thread
231static void __run_thread(processor * this, $thread * thrd_dst) {
232        /* paranoid */ verify( ! __preemption_enabled() );
233        /* paranoid */ verifyf( thrd_dst->state == Ready || thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
234        /* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
235        __builtin_prefetch( thrd_dst->context.SP );
236
237        $coroutine * proc_cor = get_coroutine(this->runner);
238
239        // set state of processor coroutine to inactive
240        verify(proc_cor->state == Active);
241        proc_cor->state = Blocked;
242
243        // Actually run the thread
244        RUNNING:  while(true) {
245                thrd_dst->preempted = __NO_PREEMPTION;
246                thrd_dst->state = Active;
247
248                // Update global state
249                kernelTLS().this_thread = thrd_dst;
250
251                /* paranoid */ verify( ! __preemption_enabled() );
252                /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
253                /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
254                /* paranoid */ verify( thrd_dst->context.SP );
255                /* paranoid */ verify( thrd_dst->state != Halted );
256                /* 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
257                /* 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
258                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
259
260
261
262                // set context switch to the thread that the processor is executing
263                __cfactx_switch( &proc_cor->context, &thrd_dst->context );
264                // when __cfactx_switch returns we are back in the processor coroutine
265
266                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
267                /* 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 );
268                /* 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 );
269                /* paranoid */ verify( thrd_dst->context.SP );
270                /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
271                /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
272                /* paranoid */ verify( ! __preemption_enabled() );
273
274                // Reset global state
275                kernelTLS().this_thread = 0p;
276
277                // We just finished running a thread, there are a few things that could have happened.
278                // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
279                // 2 - Racy case    : the thread has blocked but someone has already tried to schedule it.
280                // 4 - Preempted
281                // In case 1, we may have won a race so we can't write to the state again.
282                // In case 2, we lost the race so we now own the thread.
283
284                if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
285                        // The thread was preempted, reschedule it and reset the flag
286                        __schedule_thread( thrd_dst );
287                        break RUNNING;
288                }
289
290                if(unlikely(thrd_dst->state == Halting)) {
291                        // The thread has halted, it should never be scheduled/run again
292                        // finish the thread
293                        __thread_finish( thrd_dst );
294                        break RUNNING;
295                }
296
297                /* paranoid */ verify( thrd_dst->state == Active );
298                thrd_dst->state = Blocked;
299
300                // set state of processor coroutine to active and the thread to inactive
301                int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
302                switch(old_ticket) {
303                        case TICKET_RUNNING:
304                                // This is case 1, the regular case, nothing more is needed
305                                break RUNNING;
306                        case TICKET_UNBLOCK:
307                                // This is case 2, the racy case, someone tried to run this thread before it finished blocking
308                                // In this case, just run it again.
309                                continue RUNNING;
310                        default:
311                                // This makes no sense, something is wrong abort
312                                abort();
313                }
314        }
315
316        // Just before returning to the processor, set the processor coroutine to active
317        proc_cor->state = Active;
318
319        /* paranoid */ verify( ! __preemption_enabled() );
320}
321
322// KERNEL_ONLY
323void returnToKernel() {
324        /* paranoid */ verify( ! __preemption_enabled() );
325        $coroutine * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
326        $thread * thrd_src = kernelTLS().this_thread;
327
328        #if !defined(__CFA_NO_STATISTICS__)
329                struct processor * last_proc = kernelTLS().this_processor;
330        #endif
331
332        // Run the thread on this processor
333        {
334                int local_errno = *__volatile_errno();
335                #if defined( __i386 ) || defined( __x86_64 )
336                        __x87_store;
337                #endif
338                /* paranoid */ verify( proc_cor->context.SP );
339                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
340                __cfactx_switch( &thrd_src->context, &proc_cor->context );
341                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
342                #if defined( __i386 ) || defined( __x86_64 )
343                        __x87_load;
344                #endif
345                *__volatile_errno() = local_errno;
346        }
347
348        #if !defined(__CFA_NO_STATISTICS__)
349                if(last_proc != kernelTLS().this_processor) {
350                        __tls_stats()->ready.threads.migration++;
351                }
352        #endif
353
354        /* paranoid */ verify( ! __preemption_enabled() );
355        /* 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 );
356        /* 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 );
357}
358
359//-----------------------------------------------------------------------------
360// Scheduler routines
361// KERNEL ONLY
362void __schedule_thread( $thread * thrd ) {
363        /* paranoid */ verify( ! __preemption_enabled() );
364        /* paranoid */ verify( kernelTLS().this_proc_id );
365        /* paranoid */ verify( thrd );
366        /* paranoid */ verify( thrd->state != Halted );
367        /* paranoid */ verify( thrd->curr_cluster );
368        /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
369        /* paranoid */  if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
370                                        "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
371        /* paranoid */  if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
372                                        "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
373        /* paranoid */ #endif
374        /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
375        /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
376
377
378        if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
379
380        ready_schedule_lock();
381                // Dereference the thread now because once we push it, there is not guaranteed it's still valid.
382                struct cluster * cl = thrd->curr_cluster;
383
384                // push the thread to the cluster ready-queue
385                push( cl, thrd );
386
387                // variable thrd is no longer safe to use
388
389                // wake the cluster using the save variable.
390                __wake_one( cl );
391        ready_schedule_unlock();
392
393        /* paranoid */ verify( ! __preemption_enabled() );
394}
395
396// KERNEL ONLY
397static inline $thread * __next_thread(cluster * this) with( *this ) {
398        /* paranoid */ verify( ! __preemption_enabled() );
399        /* paranoid */ verify( kernelTLS().this_proc_id );
400
401        ready_schedule_lock();
402                $thread * thrd = pop( this );
403        ready_schedule_unlock();
404
405        /* paranoid */ verify( kernelTLS().this_proc_id );
406        /* paranoid */ verify( ! __preemption_enabled() );
407        return thrd;
408}
409
410// KERNEL ONLY
411static inline $thread * __next_thread_slow(cluster * this) with( *this ) {
412        /* paranoid */ verify( ! __preemption_enabled() );
413        /* paranoid */ verify( kernelTLS().this_proc_id );
414
415        ready_schedule_lock();
416                $thread * thrd = pop_slow( this );
417        ready_schedule_unlock();
418
419        /* paranoid */ verify( kernelTLS().this_proc_id );
420        /* paranoid */ verify( ! __preemption_enabled() );
421        return thrd;
422}
423
424void unpark( $thread * thrd ) {
425        if( !thrd ) return;
426
427        int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
428        switch(old_ticket) {
429                case TICKET_RUNNING:
430                        // Wake won the race, the thread will reschedule/rerun itself
431                        break;
432                case TICKET_BLOCKED:
433                        /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
434                        /* paranoid */ verify( thrd->state == Blocked );
435
436                        {
437                                /* paranoid */ verify( publicTLS_get(this_proc_id) );
438                                bool full = publicTLS_get(this_proc_id)->full_proc;
439                                if(full) disable_interrupts();
440
441                                /* paranoid */ verify( ! __preemption_enabled() );
442
443                                // Wake lost the race,
444                                __schedule_thread( thrd );
445
446                                /* paranoid */ verify( ! __preemption_enabled() );
447
448                                if(full) enable_interrupts( __cfaabi_dbg_ctx );
449                                /* paranoid */ verify( publicTLS_get(this_proc_id) );
450                        }
451
452                        break;
453                default:
454                        // This makes no sense, something is wrong abort
455                        abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
456        }
457}
458
459void park( void ) {
460        /* paranoid */ verify( __preemption_enabled() );
461        disable_interrupts();
462        /* paranoid */ verify( ! __preemption_enabled() );
463        /* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
464
465        returnToKernel();
466
467        /* paranoid */ verify( ! __preemption_enabled() );
468        enable_interrupts( __cfaabi_dbg_ctx );
469        /* paranoid */ verify( __preemption_enabled() );
470
471}
472
473extern "C" {
474        // Leave the thread monitor
475        // last routine called by a thread.
476        // Should never return
477        void __cfactx_thrd_leave() {
478                $thread * thrd = active_thread();
479                $monitor * this = &thrd->self_mon;
480
481                // Lock the monitor now
482                lock( this->lock __cfaabi_dbg_ctx2 );
483
484                disable_interrupts();
485
486                /* paranoid */ verify( ! __preemption_enabled() );
487                /* paranoid */ verify( thrd->state == Active );
488                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
489                /* paranoid */ verify( kernelTLS().this_thread == thrd );
490                /* paranoid */ verify( thrd->context.SP );
491                /* paranoid */ verifyf( ((uintptr_t)thrd->context.SP) > ((uintptr_t)__get_stack(thrd->curr_cor)->limit), "ERROR : $thread %p has been corrupted.\n StackPointer too large.\n", thrd );
492                /* paranoid */ verifyf( ((uintptr_t)thrd->context.SP) < ((uintptr_t)__get_stack(thrd->curr_cor)->base ), "ERROR : $thread %p has been corrupted.\n StackPointer too small.\n", thrd );
493
494                thrd->state = Halting;
495                if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
496                if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
497                if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
498
499                // Leave the thread
500                returnToKernel();
501
502                // Control flow should never reach here!
503                abort();
504        }
505}
506
507// KERNEL ONLY
508bool force_yield( __Preemption_Reason reason ) {
509        /* paranoid */ verify( __preemption_enabled() );
510        disable_interrupts();
511        /* paranoid */ verify( ! __preemption_enabled() );
512
513        $thread * thrd = kernelTLS().this_thread;
514        /* paranoid */ verify(thrd->state == Active);
515
516        // SKULLDUGGERY: It is possible that we are preempting this thread just before
517        // it was going to park itself. If that is the case and it is already using the
518        // intrusive fields then we can't use them to preempt the thread
519        // If that is the case, abandon the preemption.
520        bool preempted = false;
521        if(thrd->link.next == 0p) {
522                preempted = true;
523                thrd->preempted = reason;
524                returnToKernel();
525        }
526
527        /* paranoid */ verify( ! __preemption_enabled() );
528        enable_interrupts_noPoll();
529        /* paranoid */ verify( __preemption_enabled() );
530
531        return preempted;
532}
533
534//=============================================================================================
535// Kernel Idle Sleep
536//=============================================================================================
537// Wake a thread from the front if there are any
538static void __wake_one(cluster * this) {
539        /* paranoid */ verify( ! __preemption_enabled() );
540        /* paranoid */ verify( ready_schedule_islocked() );
541
542        // Check if there is a sleeping processor
543        processor * p;
544        unsigned idle;
545        unsigned total;
546        [idle, total, p] = query(this->idles);
547
548        // If no one is sleeping, we are done
549        if( idle == 0 ) return;
550
551        // We found a processor, wake it up
552        post( p->idle );
553
554        #if !defined(__CFA_NO_STATISTICS__)
555                __tls_stats()->ready.sleep.wakes++;
556        #endif
557
558        /* paranoid */ verify( ready_schedule_islocked() );
559        /* paranoid */ verify( ! __preemption_enabled() );
560
561        return;
562}
563
564// Unconditionnaly wake a thread
565void __wake_proc(processor * this) {
566        __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
567
568        disable_interrupts();
569                /* paranoid */ verify( ! __preemption_enabled() );
570                post( this->idle );
571        enable_interrupts( __cfaabi_dbg_ctx );
572}
573
574static void push  (__cluster_idles & this, processor & proc) {
575        /* paranoid */ verify( ! __preemption_enabled() );
576        lock( this );
577                this.idle++;
578                /* paranoid */ verify( this.idle <= this.total );
579
580                insert_first(this.list, proc);
581        unlock( this );
582        /* paranoid */ verify( ! __preemption_enabled() );
583}
584
585static void remove(__cluster_idles & this, processor & proc) {
586        /* paranoid */ verify( ! __preemption_enabled() );
587        lock( this );
588                this.idle--;
589                /* paranoid */ verify( this.idle >= 0 );
590
591                remove(proc);
592        unlock( this );
593        /* paranoid */ verify( ! __preemption_enabled() );
594}
595
596static [unsigned idle, unsigned total, * processor] query( & __cluster_idles this ) {
597        for() {
598                uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
599                if( 1 == (l % 2) ) { Pause(); continue; }
600                unsigned idle    = this.idle;
601                unsigned total   = this.total;
602                processor * proc = &this.list`first;
603                // Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
604                asm volatile("": : :"memory");
605                if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
606                return [idle, total, proc];
607        }
608}
609
610//=============================================================================================
611// Unexpected Terminating logic
612//=============================================================================================
613static __spinlock_t kernel_abort_lock;
614static bool kernel_abort_called = false;
615
616void * kernel_abort(void) __attribute__ ((__nothrow__)) {
617        // abort cannot be recursively entered by the same or different processors because all signal handlers return when
618        // the globalAbort flag is true.
619        lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
620
621        // disable interrupts, it no longer makes sense to try to interrupt this processor
622        disable_interrupts();
623
624        // first task to abort ?
625        if ( kernel_abort_called ) {                    // not first task to abort ?
626                unlock( kernel_abort_lock );
627
628                sigset_t mask;
629                sigemptyset( &mask );
630                sigaddset( &mask, SIGALRM );            // block SIGALRM signals
631                sigaddset( &mask, SIGUSR1 );            // block SIGALRM signals
632                sigsuspend( &mask );                            // block the processor to prevent further damage during abort
633                _exit( EXIT_FAILURE );                          // if processor unblocks before it is killed, terminate it
634        }
635        else {
636                kernel_abort_called = true;
637                unlock( kernel_abort_lock );
638        }
639
640        return __cfaabi_tls.this_thread;
641}
642
643void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
644        $thread * thrd = ( $thread * ) kernel_data;
645
646        if(thrd) {
647                int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
648                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
649
650                if ( &thrd->self_cor != thrd->curr_cor ) {
651                        len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
652                        __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
653                }
654                else {
655                        __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
656                }
657        }
658        else {
659                int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
660                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
661        }
662}
663
664int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
665        return get_coroutine(kernelTLS().this_thread) == get_coroutine(mainThread) ? 4 : 2;
666}
667
668static __spinlock_t kernel_debug_lock;
669
670extern "C" {
671        void __cfaabi_bits_acquire() {
672                lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
673        }
674
675        void __cfaabi_bits_release() {
676                unlock( kernel_debug_lock );
677        }
678}
679
680//=============================================================================================
681// Kernel Utilities
682//=============================================================================================
683//-----------------------------------------------------------------------------
684// Locks
685void  ?{}( semaphore & this, int count = 1 ) {
686        (this.lock){};
687        this.count = count;
688        (this.waiting){};
689}
690void ^?{}(semaphore & this) {}
691
692bool P(semaphore & this) with( this ){
693        lock( lock __cfaabi_dbg_ctx2 );
694        count -= 1;
695        if ( count < 0 ) {
696                // queue current task
697                append( waiting, active_thread() );
698
699                // atomically release spin lock and block
700                unlock( lock );
701                park();
702                return true;
703        }
704        else {
705            unlock( lock );
706            return false;
707        }
708}
709
710bool V(semaphore & this) with( this ) {
711        $thread * thrd = 0p;
712        lock( lock __cfaabi_dbg_ctx2 );
713        count += 1;
714        if ( count <= 0 ) {
715                // remove task at head of waiting list
716                thrd = pop_head( waiting );
717        }
718
719        unlock( lock );
720
721        // make new owner
722        unpark( thrd );
723
724        return thrd != 0p;
725}
726
727bool V(semaphore & this, unsigned diff) with( this ) {
728        $thread * thrd = 0p;
729        lock( lock __cfaabi_dbg_ctx2 );
730        int release = max(-count, (int)diff);
731        count += diff;
732        for(release) {
733                unpark( pop_head( waiting ) );
734        }
735
736        unlock( lock );
737
738        return thrd != 0p;
739}
740
741//-----------------------------------------------------------------------------
742// Debug
743__cfaabi_dbg_debug_do(
744        extern "C" {
745                void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
746                        this.prev_name = prev_name;
747                        this.prev_thrd = kernelTLS().this_thread;
748                }
749        }
750)
751
752//-----------------------------------------------------------------------------
753// Debug
754bool threading_enabled(void) __attribute__((const)) {
755        return true;
756}
757
758//-----------------------------------------------------------------------------
759// Statistics
760#if !defined(__CFA_NO_STATISTICS__)
761        void print_halts( processor & this ) {
762                this.print_halts = true;
763        }
764
765        void print_stats_now( cluster & this, int flags ) {
766                __print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
767        }
768
769        extern int __print_alarm_stats;
770        void print_alarm_stats() {
771                __print_alarm_stats = -1;
772        }
773#endif
774// Local Variables: //
775// mode: c //
776// tab-width: 4 //
777// End: //
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