source: libcfa/src/concurrency/kernel.cfa @ 6a77224

arm-ehenumforall-pointer-decayjacob/cs343-translationnew-ast-unique-exprpthread-emulationqualifiedEnum
Last change on this file since 6a77224 was 6a77224, checked in by Thierry Delisle <tdelisle@…>, 2 years ago

Changed park/unpark ticket to be -1,0,1 instead of 0,1,2 because it's more natural.
Also added defines in kernel_private.h to avoid these magic numbers

  • Property mode set to 100644
File size: 22.8 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(struct __processor_id_t * id, 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        kernelTLS.rand_seed ^= rdtscl();
125        kernelTLS.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                kernelTLS.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( ! kernelTLS.preemption_state.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( ! kernelTLS.preemption_state.enabled );
252                /* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
253                /* paranoid */ verify( thrd_dst->context.SP );
254                /* paranoid */ verify( thrd_dst->state != Halted );
255                /* 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
256                /* 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
257                /* paranoid */ verify( 0x0D15EA5E0D15EA5E == thrd_dst->canary );
258
259
260
261                // set context switch to the thread that the processor is executing
262                __cfactx_switch( &proc_cor->context, &thrd_dst->context );
263                // when __cfactx_switch returns we are back in the processor coroutine
264
265                /* paranoid */ verify( 0x0D15EA5E0D15EA5E == thrd_dst->canary );
266                /* 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 );
267                /* 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 );
268                /* paranoid */ verify( thrd_dst->context.SP );
269                /* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
270                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
271
272                // Reset global state
273                kernelTLS.this_thread = 0p;
274
275                // We just finished running a thread, there are a few things that could have happened.
276                // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
277                // 2 - Racy case    : the thread has blocked but someone has already tried to schedule it.
278                // 4 - Preempted
279                // In case 1, we may have won a race so we can't write to the state again.
280                // In case 2, we lost the race so we now own the thread.
281
282                if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
283                        // The thread was preempted, reschedule it and reset the flag
284                        __schedule_thread( (__processor_id_t*)this, thrd_dst );
285                        break RUNNING;
286                }
287
288                if(unlikely(thrd_dst->state == Halted)) {
289                        // The thread has halted, it should never be scheduled/run again
290                        // finish the thread
291                        __thread_finish( thrd_dst );
292                        break RUNNING;
293                }
294
295                /* paranoid */ verify( thrd_dst->state == Active );
296                thrd_dst->state = Blocked;
297
298                // set state of processor coroutine to active and the thread to inactive
299                int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
300                switch(old_ticket) {
301                        case TICKET_RUNNING:
302                                // This is case 1, the regular case, nothing more is needed
303                                break RUNNING;
304                        case TICKET_UNBLOCK:
305                                // This is case 2, the racy case, someone tried to run this thread before it finished blocking
306                                // In this case, just run it again.
307                                continue RUNNING;
308                        default:
309                                // This makes no sense, something is wrong abort
310                                abort();
311                }
312        }
313
314        // Just before returning to the processor, set the processor coroutine to active
315        proc_cor->state = Active;
316
317        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
318}
319
320// KERNEL_ONLY
321void returnToKernel() {
322        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
323        $coroutine * proc_cor = get_coroutine(kernelTLS.this_processor->runner);
324        $thread * thrd_src = kernelTLS.this_thread;
325
326        #if !defined(__CFA_NO_STATISTICS__)
327                struct processor * last_proc = kernelTLS.this_processor;
328        #endif
329
330        // Run the thread on this processor
331        {
332                int local_errno = *__volatile_errno();
333                #if defined( __i386 ) || defined( __x86_64 )
334                        __x87_store;
335                #endif
336                /* paranoid */ verify( proc_cor->context.SP );
337                /* paranoid */ verify( 0x0D15EA5E0D15EA5E == thrd_src->canary );
338                __cfactx_switch( &thrd_src->context, &proc_cor->context );
339                /* paranoid */ verify( 0x0D15EA5E0D15EA5E == thrd_src->canary );
340                #if defined( __i386 ) || defined( __x86_64 )
341                        __x87_load;
342                #endif
343                *__volatile_errno() = local_errno;
344        }
345
346        #if !defined(__CFA_NO_STATISTICS__)
347                if(last_proc != kernelTLS.this_processor) {
348                        __tls_stats()->ready.threads.migration++;
349                }
350        #endif
351
352        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
353        /* 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 );
354        /* 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 );
355}
356
357//-----------------------------------------------------------------------------
358// Scheduler routines
359// KERNEL ONLY
360void __schedule_thread( struct __processor_id_t * id, $thread * thrd ) {
361        /* paranoid */ verify( thrd );
362        /* paranoid */ verify( thrd->state != Halted );
363        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
364        /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
365        /* paranoid */  if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
366                                        "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
367        /* paranoid */  if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
368                                        "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
369        /* paranoid */ #endif
370        /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
371        /* paranoid */ verify( 0x0D15EA5E0D15EA5E == thrd->canary );
372
373
374        if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
375
376        ready_schedule_lock  ( id );
377                push( thrd->curr_cluster, thrd );
378                __wake_one(id, thrd->curr_cluster);
379        ready_schedule_unlock( id );
380
381        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
382}
383
384// KERNEL ONLY
385static inline $thread * __next_thread(cluster * this) with( *this ) {
386        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
387
388        ready_schedule_lock  ( (__processor_id_t*)kernelTLS.this_processor );
389                $thread * thrd = pop( this );
390        ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
391
392        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
393        return thrd;
394}
395
396// KERNEL ONLY
397static inline $thread * __next_thread_slow(cluster * this) with( *this ) {
398        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
399
400        ready_schedule_lock  ( (__processor_id_t*)kernelTLS.this_processor );
401                $thread * thrd = pop_slow( this );
402        ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
403
404        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
405        return thrd;
406}
407
408// KERNEL ONLY unpark with out disabling interrupts
409void __unpark(  struct __processor_id_t * id, $thread * thrd ) {
410        int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
411        switch(old_ticket) {
412                case TICKET_RUNNING:
413                        // Wake won the race, the thread will reschedule/rerun itself
414                        break;
415                case TICKET_BLOCKED:
416                        /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
417                        /* paranoid */ verify( thrd->state == Blocked );
418
419                        // Wake lost the race,
420                        __schedule_thread( id, thrd );
421                        break;
422                default:
423                        // This makes no sense, something is wrong abort
424                        abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
425        }
426}
427
428void unpark( $thread * thrd ) {
429        if( !thrd ) return;
430
431        disable_interrupts();
432        __unpark( (__processor_id_t*)kernelTLS.this_processor, thrd );
433        enable_interrupts( __cfaabi_dbg_ctx );
434}
435
436void park( void ) {
437        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
438        disable_interrupts();
439        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
440        /* paranoid */ verify( kernelTLS.this_thread->preempted == __NO_PREEMPTION );
441
442        returnToKernel();
443
444        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
445        enable_interrupts( __cfaabi_dbg_ctx );
446        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
447
448}
449
450extern "C" {
451        // Leave the thread monitor
452        // last routine called by a thread.
453        // Should never return
454        void __cfactx_thrd_leave() {
455                $thread * thrd = TL_GET( this_thread );
456                $monitor * this = &thrd->self_mon;
457
458                // Lock the monitor now
459                lock( this->lock __cfaabi_dbg_ctx2 );
460
461                disable_interrupts();
462
463                thrd->state = Halted;
464
465                if( thrd != this->owner || this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
466
467                // Leave the thread
468                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
469                returnToKernel();
470                abort();
471
472                // Control flow should never reach here!
473        }
474}
475
476// KERNEL ONLY
477bool force_yield( __Preemption_Reason reason ) {
478        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
479        disable_interrupts();
480        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
481
482        $thread * thrd = kernelTLS.this_thread;
483        /* paranoid */ verify(thrd->state == Active);
484
485        // SKULLDUGGERY: It is possible that we are preempting this thread just before
486        // it was going to park itself. If that is the case and it is already using the
487        // intrusive fields then we can't use them to preempt the thread
488        // If that is the case, abandon the preemption.
489        bool preempted = false;
490        if(thrd->link.next == 0p) {
491                preempted = true;
492                thrd->preempted = reason;
493                returnToKernel();
494        }
495
496        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
497        enable_interrupts_noPoll();
498        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
499
500        return preempted;
501}
502
503//=============================================================================================
504// Kernel Idle Sleep
505//=============================================================================================
506// Wake a thread from the front if there are any
507static void __wake_one(struct __processor_id_t * id, cluster * this) {
508        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
509        /* paranoid */ verify( ready_schedule_islocked( id ) );
510
511        // Check if there is a sleeping processor
512        processor * p;
513        unsigned idle;
514        unsigned total;
515        [idle, total, p] = query(this->idles);
516
517        // If no one is sleeping, we are done
518        if( idle == 0 ) return;
519
520        // We found a processor, wake it up
521        post( p->idle );
522
523        #if !defined(__CFA_NO_STATISTICS__)
524                __tls_stats()->ready.sleep.wakes++;
525        #endif
526
527        /* paranoid */ verify( ready_schedule_islocked( id ) );
528        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
529
530        return;
531}
532
533// Unconditionnaly wake a thread
534void __wake_proc(processor * this) {
535        __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
536
537        disable_interrupts();
538                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
539                post( this->idle );
540        enable_interrupts( __cfaabi_dbg_ctx );
541}
542
543static void push  (__cluster_idles & this, processor & proc) {
544        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
545        lock( this );
546                this.idle++;
547                /* paranoid */ verify( this.idle <= this.total );
548
549                insert_first(this.list, proc);
550        unlock( this );
551        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
552}
553
554static void remove(__cluster_idles & this, processor & proc) {
555        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
556        lock( this );
557                this.idle--;
558                /* paranoid */ verify( this.idle >= 0 );
559
560                remove(proc);
561        unlock( this );
562        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
563}
564
565static [unsigned idle, unsigned total, * processor] query( & __cluster_idles this ) {
566        for() {
567                uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
568                if( 1 == (l % 2) ) { Pause(); continue; }
569                unsigned idle    = this.idle;
570                unsigned total   = this.total;
571                processor * proc = &this.list`first;
572                // Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
573                asm volatile("": : :"memory");
574                if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
575                return [idle, total, proc];
576        }
577}
578
579//=============================================================================================
580// Unexpected Terminating logic
581//=============================================================================================
582static __spinlock_t kernel_abort_lock;
583static bool kernel_abort_called = false;
584
585void * kernel_abort(void) __attribute__ ((__nothrow__)) {
586        // abort cannot be recursively entered by the same or different processors because all signal handlers return when
587        // the globalAbort flag is true.
588        lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
589
590        // first task to abort ?
591        if ( kernel_abort_called ) {                    // not first task to abort ?
592                unlock( kernel_abort_lock );
593
594                sigset_t mask;
595                sigemptyset( &mask );
596                sigaddset( &mask, SIGALRM );            // block SIGALRM signals
597                sigaddset( &mask, SIGUSR1 );            // block SIGALRM signals
598                sigsuspend( &mask );                            // block the processor to prevent further damage during abort
599                _exit( EXIT_FAILURE );                          // if processor unblocks before it is killed, terminate it
600        }
601        else {
602                kernel_abort_called = true;
603                unlock( kernel_abort_lock );
604        }
605
606        return kernelTLS.this_thread;
607}
608
609void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
610        $thread * thrd = ( $thread * ) kernel_data;
611
612        if(thrd) {
613                int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
614                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
615
616                if ( &thrd->self_cor != thrd->curr_cor ) {
617                        len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
618                        __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
619                }
620                else {
621                        __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
622                }
623        }
624        else {
625                int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
626                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
627        }
628}
629
630int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
631        return get_coroutine(kernelTLS.this_thread) == get_coroutine(mainThread) ? 4 : 2;
632}
633
634static __spinlock_t kernel_debug_lock;
635
636extern "C" {
637        void __cfaabi_bits_acquire() {
638                lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
639        }
640
641        void __cfaabi_bits_release() {
642                unlock( kernel_debug_lock );
643        }
644}
645
646//=============================================================================================
647// Kernel Utilities
648//=============================================================================================
649//-----------------------------------------------------------------------------
650// Locks
651void  ?{}( semaphore & this, int count = 1 ) {
652        (this.lock){};
653        this.count = count;
654        (this.waiting){};
655}
656void ^?{}(semaphore & this) {}
657
658bool P(semaphore & this) with( this ){
659        lock( lock __cfaabi_dbg_ctx2 );
660        count -= 1;
661        if ( count < 0 ) {
662                // queue current task
663                append( waiting, kernelTLS.this_thread );
664
665                // atomically release spin lock and block
666                unlock( lock );
667                park();
668                return true;
669        }
670        else {
671            unlock( lock );
672            return false;
673        }
674}
675
676bool V(semaphore & this) with( this ) {
677        $thread * thrd = 0p;
678        lock( lock __cfaabi_dbg_ctx2 );
679        count += 1;
680        if ( count <= 0 ) {
681                // remove task at head of waiting list
682                thrd = pop_head( waiting );
683        }
684
685        unlock( lock );
686
687        // make new owner
688        unpark( thrd );
689
690        return thrd != 0p;
691}
692
693bool V(semaphore & this, unsigned diff) with( this ) {
694        $thread * thrd = 0p;
695        lock( lock __cfaabi_dbg_ctx2 );
696        int release = max(-count, (int)diff);
697        count += diff;
698        for(release) {
699                unpark( pop_head( waiting ) );
700        }
701
702        unlock( lock );
703
704        return thrd != 0p;
705}
706
707//-----------------------------------------------------------------------------
708// Debug
709__cfaabi_dbg_debug_do(
710        extern "C" {
711                void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
712                        this.prev_name = prev_name;
713                        this.prev_thrd = kernelTLS.this_thread;
714                }
715        }
716)
717
718//-----------------------------------------------------------------------------
719// Debug
720bool threading_enabled(void) __attribute__((const)) {
721        return true;
722}
723
724//-----------------------------------------------------------------------------
725// Statistics
726#if !defined(__CFA_NO_STATISTICS__)
727        void print_halts( processor & this ) {
728                this.print_halts = true;
729        }
730#endif
731// Local Variables: //
732// mode: c //
733// tab-width: 4 //
734// End: //
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