source: libcfa/src/concurrency/kernel.cfa @ 69d1748

ADTarm-ehast-experimentalenumforall-pointer-decayjacob/cs343-translationnew-ast-unique-exprpthread-emulationqualifiedEnum
Last change on this file since 69d1748 was 3ea8ad1, checked in by Thierry Delisle <tdelisle@…>, 4 years ago

Added more checks for thread termination synchronization

  • Property mode set to 100644
File size: 23.7 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                push( thrd->curr_cluster, thrd );
382                __wake_one(thrd->curr_cluster);
383        ready_schedule_unlock();
384
385        /* paranoid */ verify( ! __preemption_enabled() );
386}
387
388// KERNEL ONLY
389static inline $thread * __next_thread(cluster * this) with( *this ) {
390        /* paranoid */ verify( ! __preemption_enabled() );
391        /* paranoid */ verify( kernelTLS().this_proc_id );
392
393        ready_schedule_lock();
394                $thread * thrd = pop( this );
395        ready_schedule_unlock();
396
397        /* paranoid */ verify( kernelTLS().this_proc_id );
398        /* paranoid */ verify( ! __preemption_enabled() );
399        return thrd;
400}
401
402// KERNEL ONLY
403static inline $thread * __next_thread_slow(cluster * this) with( *this ) {
404        /* paranoid */ verify( ! __preemption_enabled() );
405        /* paranoid */ verify( kernelTLS().this_proc_id );
406
407        ready_schedule_lock();
408                $thread * thrd = pop_slow( this );
409        ready_schedule_unlock();
410
411        /* paranoid */ verify( kernelTLS().this_proc_id );
412        /* paranoid */ verify( ! __preemption_enabled() );
413        return thrd;
414}
415
416void unpark( $thread * thrd ) {
417        if( !thrd ) return;
418
419        int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
420        switch(old_ticket) {
421                case TICKET_RUNNING:
422                        // Wake won the race, the thread will reschedule/rerun itself
423                        break;
424                case TICKET_BLOCKED:
425                        /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
426                        /* paranoid */ verify( thrd->state == Blocked );
427
428                        {
429                                /* paranoid */ verify( publicTLS_get(this_proc_id) );
430                                bool full = publicTLS_get(this_proc_id)->full_proc;
431                                if(full) disable_interrupts();
432
433                                /* paranoid */ verify( ! __preemption_enabled() );
434
435                                // Wake lost the race,
436                                __schedule_thread( thrd );
437
438                                /* paranoid */ verify( ! __preemption_enabled() );
439
440                                if(full) enable_interrupts( __cfaabi_dbg_ctx );
441                                /* paranoid */ verify( publicTLS_get(this_proc_id) );
442                        }
443
444                        break;
445                default:
446                        // This makes no sense, something is wrong abort
447                        abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
448        }
449}
450
451void park( void ) {
452        /* paranoid */ verify( __preemption_enabled() );
453        disable_interrupts();
454        /* paranoid */ verify( ! __preemption_enabled() );
455        /* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
456
457        returnToKernel();
458
459        /* paranoid */ verify( ! __preemption_enabled() );
460        enable_interrupts( __cfaabi_dbg_ctx );
461        /* paranoid */ verify( __preemption_enabled() );
462
463}
464
465extern "C" {
466        // Leave the thread monitor
467        // last routine called by a thread.
468        // Should never return
469        void __cfactx_thrd_leave() {
470                $thread * thrd = active_thread();
471                $monitor * this = &thrd->self_mon;
472
473                // Lock the monitor now
474                lock( this->lock __cfaabi_dbg_ctx2 );
475
476                disable_interrupts();
477
478                /* paranoid */ verify( ! __preemption_enabled() );
479                /* paranoid */ verify( thrd->state == Active );
480                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
481                /* paranoid */ verify( kernelTLS().this_thread == thrd );
482                /* paranoid */ verify( thrd->context.SP );
483                /* 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 );
484                /* 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 );
485
486                thrd->state = Halting;
487                if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
488                if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
489                if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
490
491                // Leave the thread
492                returnToKernel();
493
494                // Control flow should never reach here!
495                abort();
496        }
497}
498
499// KERNEL ONLY
500bool force_yield( __Preemption_Reason reason ) {
501        /* paranoid */ verify( __preemption_enabled() );
502        disable_interrupts();
503        /* paranoid */ verify( ! __preemption_enabled() );
504
505        $thread * thrd = kernelTLS().this_thread;
506        /* paranoid */ verify(thrd->state == Active);
507
508        // SKULLDUGGERY: It is possible that we are preempting this thread just before
509        // it was going to park itself. If that is the case and it is already using the
510        // intrusive fields then we can't use them to preempt the thread
511        // If that is the case, abandon the preemption.
512        bool preempted = false;
513        if(thrd->link.next == 0p) {
514                preempted = true;
515                thrd->preempted = reason;
516                returnToKernel();
517        }
518
519        /* paranoid */ verify( ! __preemption_enabled() );
520        enable_interrupts_noPoll();
521        /* paranoid */ verify( __preemption_enabled() );
522
523        return preempted;
524}
525
526//=============================================================================================
527// Kernel Idle Sleep
528//=============================================================================================
529// Wake a thread from the front if there are any
530static void __wake_one(cluster * this) {
531        /* paranoid */ verify( ! __preemption_enabled() );
532        /* paranoid */ verify( ready_schedule_islocked() );
533
534        // Check if there is a sleeping processor
535        processor * p;
536        unsigned idle;
537        unsigned total;
538        [idle, total, p] = query(this->idles);
539
540        // If no one is sleeping, we are done
541        if( idle == 0 ) return;
542
543        // We found a processor, wake it up
544        post( p->idle );
545
546        #if !defined(__CFA_NO_STATISTICS__)
547                __tls_stats()->ready.sleep.wakes++;
548        #endif
549
550        /* paranoid */ verify( ready_schedule_islocked() );
551        /* paranoid */ verify( ! __preemption_enabled() );
552
553        return;
554}
555
556// Unconditionnaly wake a thread
557void __wake_proc(processor * this) {
558        __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
559
560        disable_interrupts();
561                /* paranoid */ verify( ! __preemption_enabled() );
562                post( this->idle );
563        enable_interrupts( __cfaabi_dbg_ctx );
564}
565
566static void push  (__cluster_idles & this, processor & proc) {
567        /* paranoid */ verify( ! __preemption_enabled() );
568        lock( this );
569                this.idle++;
570                /* paranoid */ verify( this.idle <= this.total );
571
572                insert_first(this.list, proc);
573        unlock( this );
574        /* paranoid */ verify( ! __preemption_enabled() );
575}
576
577static void remove(__cluster_idles & this, processor & proc) {
578        /* paranoid */ verify( ! __preemption_enabled() );
579        lock( this );
580                this.idle--;
581                /* paranoid */ verify( this.idle >= 0 );
582
583                remove(proc);
584        unlock( this );
585        /* paranoid */ verify( ! __preemption_enabled() );
586}
587
588static [unsigned idle, unsigned total, * processor] query( & __cluster_idles this ) {
589        for() {
590                uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
591                if( 1 == (l % 2) ) { Pause(); continue; }
592                unsigned idle    = this.idle;
593                unsigned total   = this.total;
594                processor * proc = &this.list`first;
595                // Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
596                asm volatile("": : :"memory");
597                if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
598                return [idle, total, proc];
599        }
600}
601
602//=============================================================================================
603// Unexpected Terminating logic
604//=============================================================================================
605static __spinlock_t kernel_abort_lock;
606static bool kernel_abort_called = false;
607
608void * kernel_abort(void) __attribute__ ((__nothrow__)) {
609        // abort cannot be recursively entered by the same or different processors because all signal handlers return when
610        // the globalAbort flag is true.
611        lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
612
613        // first task to abort ?
614        if ( kernel_abort_called ) {                    // not first task to abort ?
615                unlock( kernel_abort_lock );
616
617                sigset_t mask;
618                sigemptyset( &mask );
619                sigaddset( &mask, SIGALRM );            // block SIGALRM signals
620                sigaddset( &mask, SIGUSR1 );            // block SIGALRM signals
621                sigsuspend( &mask );                            // block the processor to prevent further damage during abort
622                _exit( EXIT_FAILURE );                          // if processor unblocks before it is killed, terminate it
623        }
624        else {
625                kernel_abort_called = true;
626                unlock( kernel_abort_lock );
627        }
628
629        return __cfaabi_tls.this_thread;
630}
631
632void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
633        $thread * thrd = ( $thread * ) kernel_data;
634
635        if(thrd) {
636                int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
637                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
638
639                if ( &thrd->self_cor != thrd->curr_cor ) {
640                        len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
641                        __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
642                }
643                else {
644                        __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
645                }
646        }
647        else {
648                int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
649                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
650        }
651}
652
653int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
654        return get_coroutine(kernelTLS().this_thread) == get_coroutine(mainThread) ? 4 : 2;
655}
656
657static __spinlock_t kernel_debug_lock;
658
659extern "C" {
660        void __cfaabi_bits_acquire() {
661                lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
662        }
663
664        void __cfaabi_bits_release() {
665                unlock( kernel_debug_lock );
666        }
667}
668
669//=============================================================================================
670// Kernel Utilities
671//=============================================================================================
672//-----------------------------------------------------------------------------
673// Locks
674void  ?{}( semaphore & this, int count = 1 ) {
675        (this.lock){};
676        this.count = count;
677        (this.waiting){};
678}
679void ^?{}(semaphore & this) {}
680
681bool P(semaphore & this) with( this ){
682        lock( lock __cfaabi_dbg_ctx2 );
683        count -= 1;
684        if ( count < 0 ) {
685                // queue current task
686                append( waiting, active_thread() );
687
688                // atomically release spin lock and block
689                unlock( lock );
690                park();
691                return true;
692        }
693        else {
694            unlock( lock );
695            return false;
696        }
697}
698
699bool V(semaphore & this) with( this ) {
700        $thread * thrd = 0p;
701        lock( lock __cfaabi_dbg_ctx2 );
702        count += 1;
703        if ( count <= 0 ) {
704                // remove task at head of waiting list
705                thrd = pop_head( waiting );
706        }
707
708        unlock( lock );
709
710        // make new owner
711        unpark( thrd );
712
713        return thrd != 0p;
714}
715
716bool V(semaphore & this, unsigned diff) with( this ) {
717        $thread * thrd = 0p;
718        lock( lock __cfaabi_dbg_ctx2 );
719        int release = max(-count, (int)diff);
720        count += diff;
721        for(release) {
722                unpark( pop_head( waiting ) );
723        }
724
725        unlock( lock );
726
727        return thrd != 0p;
728}
729
730//-----------------------------------------------------------------------------
731// Debug
732__cfaabi_dbg_debug_do(
733        extern "C" {
734                void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
735                        this.prev_name = prev_name;
736                        this.prev_thrd = kernelTLS().this_thread;
737                }
738        }
739)
740
741//-----------------------------------------------------------------------------
742// Debug
743bool threading_enabled(void) __attribute__((const)) {
744        return true;
745}
746
747//-----------------------------------------------------------------------------
748// Statistics
749#if !defined(__CFA_NO_STATISTICS__)
750        void print_halts( processor & this ) {
751                this.print_halts = true;
752        }
753
754        void print_stats_now( cluster & this, int flags ) {
755                __print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
756        }
757
758        extern int __print_alarm_stats;
759        void print_alarm_stats() {
760                __print_alarm_stats = -1;
761        }
762#endif
763// Local Variables: //
764// mode: c //
765// tab-width: 4 //
766// End: //
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