source: libcfa/src/concurrency/kernel.cfa @ e67a82d

arm-ehjacob/cs343-translationnew-ast-unique-expr
Last change on this file since e67a82d was e67a82d, checked in by Peter A. Buhr <pabuhr@…>, 15 months ago

fix conflicts

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1//
2// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// kernel.c --
8//
9// Author           : Thierry Delisle
10// Created On       : Tue Jan 17 12:27:26 2017
11// Last Modified By : Peter A. Buhr
12// Last Modified On : Fri Aug 14 15:23:00 2020
13// Update Count     : 69
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_ARCH )
77        #define __x87_store              \
78                uint32_t __fpcntl[2];    \
79                __asm__ volatile (    \
80                        "mrs x9, FPCR\n" \
81                        "mrs x10, FPSR\n"  \
82                        "stp x9, x10, %0\n"  \
83                        : "=m" (__fpcntl) : : "x9", "x10" \
84                )
85
86        #define __x87_load         \
87                __asm__ volatile (    \
88                        "ldp x9, x10, %0\n"  \
89                        "msr FPSR, x10\n"  \
90                        "msr FPCR, x9\n" \
91                : "=m" (__fpcntl) : : "x9", "x10" \
92                )
93
94#else
95        #error unknown hardware architecture
96#endif
97
98extern $thread * mainThread;
99extern processor * mainProcessor;
100
101//-----------------------------------------------------------------------------
102// Kernel Scheduling logic
103static $thread * __next_thread(cluster * this);
104static $thread * __next_thread_slow(cluster * this);
105static void __run_thread(processor * this, $thread * dst);
106static void __wake_one(struct __processor_id_t * id, cluster * cltr);
107
108static void push  (__cluster_idles & idles, processor & proc);
109static void remove(__cluster_idles & idles, processor & proc);
110static [unsigned idle, unsigned total, * processor] query( & __cluster_idles idles );
111
112
113//=============================================================================================
114// Kernel Scheduling logic
115//=============================================================================================
116//Main of the processor contexts
117void main(processorCtx_t & runner) {
118        // Because of a bug, we couldn't initialized the seed on construction
119        // Do it here
120        kernelTLS.rand_seed ^= rdtscl();
121        kernelTLS.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
122        __tls_rand_advance_bck();
123
124        processor * this = runner.proc;
125        verify(this);
126
127        __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
128        #if !defined(__CFA_NO_STATISTICS__)
129                if( this->print_halts ) {
130                        __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->id, this->name, (void*)this);
131                }
132        #endif
133
134        {
135                // Setup preemption data
136                preemption_scope scope = { this };
137
138                __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
139
140                $thread * readyThread = 0p;
141                MAIN_LOOP:
142                for() {
143                        // Try to get the next thread
144                        readyThread = __next_thread( this->cltr );
145
146                        if( !readyThread ) {
147                                readyThread = __next_thread_slow( this->cltr );
148                        }
149
150                        HALT:
151                        if( !readyThread ) {
152                                // Don't block if we are done
153                                if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
154
155                                #if !defined(__CFA_NO_STATISTICS__)
156                                        __tls_stats()->ready.sleep.halts++;
157                                #endif
158
159                                // Push self to idle stack
160                                push(this->cltr->idles, * this);
161
162                                // Confirm the ready-queue is empty
163                                readyThread = __next_thread_slow( this->cltr );
164                                if( readyThread ) {
165                                        // A thread was found, cancel the halt
166                                        remove(this->cltr->idles, * this);
167
168                                        #if !defined(__CFA_NO_STATISTICS__)
169                                                __tls_stats()->ready.sleep.cancels++;
170                                        #endif
171
172                                        // continue the mai loop
173                                        break HALT;
174                                }
175
176                                #if !defined(__CFA_NO_STATISTICS__)
177                                        if(this->print_halts) {
178                                                __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->id, rdtscl());
179                                        }
180                                #endif
181
182                                wait( this->idle );
183
184                                #if !defined(__CFA_NO_STATISTICS__)
185                                        if(this->print_halts) {
186                                                __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->id, rdtscl());
187                                        }
188                                #endif
189
190                                // We were woken up, remove self from idle
191                                remove(this->cltr->idles, * this);
192
193                                // DON'T just proceed, start looking again
194                                continue MAIN_LOOP;
195                        }
196
197                        /* paranoid */ verify( readyThread );
198
199                        // We found a thread run it
200                        __run_thread(this, readyThread);
201
202                        // Are we done?
203                        if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
204                }
205
206                __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
207        }
208
209        V( this->terminated );
210
211        if(this == mainProcessor) {
212                // HACK : the coroutine context switch expects this_thread to be set
213                // and it make sense for it to be set in all other cases except here
214                // fake it
215                kernelTLS.this_thread = mainThread;
216        }
217
218        __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
219}
220
221static int * __volatile_errno() __attribute__((noinline));
222static int * __volatile_errno() { asm(""); return &errno; }
223
224// KERNEL ONLY
225// runThread runs a thread by context switching
226// from the processor coroutine to the target thread
227static void __run_thread(processor * this, $thread * thrd_dst) {
228        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
229        /* paranoid */ verifyf( thrd_dst->state == Ready || thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
230        /* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
231        __builtin_prefetch( thrd_dst->context.SP );
232
233        $coroutine * proc_cor = get_coroutine(this->runner);
234
235        // Update global state
236        kernelTLS.this_thread = thrd_dst;
237
238        // set state of processor coroutine to inactive
239        verify(proc_cor->state == Active);
240        proc_cor->state = Blocked;
241
242        // Actually run the thread
243        RUNNING:  while(true) {
244                thrd_dst->preempted = __NO_PREEMPTION;
245                thrd_dst->state = Active;
246
247                __cfaabi_dbg_debug_do(
248                        thrd_dst->park_stale   = true;
249                        thrd_dst->unpark_stale = true;
250                )
251
252                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
253                /* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
254                /* 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
255                /* 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
256
257                // set context switch to the thread that the processor is executing
258                verify( thrd_dst->context.SP );
259                __cfactx_switch( &proc_cor->context, &thrd_dst->context );
260                // when __cfactx_switch returns we are back in the processor coroutine
261
262                /* 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 );
263                /* 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 );
264                /* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
265                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
266
267
268                // We just finished running a thread, there are a few things that could have happened.
269                // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
270                // 2 - Racy case    : the thread has blocked but someone has already tried to schedule it.
271                // 4 - Preempted
272                // In case 1, we may have won a race so we can't write to the state again.
273                // In case 2, we lost the race so we now own the thread.
274
275                if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
276                        // The thread was preempted, reschedule it and reset the flag
277                        __schedule_thread( (__processor_id_t*)this, thrd_dst );
278                        break RUNNING;
279                }
280
281                if(unlikely(thrd_dst->state == Halted)) {
282                        // The thread has halted, it should never be scheduled/run again
283                        // We may need to wake someone up here since
284                        unpark( this->destroyer __cfaabi_dbg_ctx2 );
285                        this->destroyer = 0p;
286                        break RUNNING;
287                }
288
289                /* paranoid */ verify( thrd_dst->state == Active );
290                thrd_dst->state = Blocked;
291
292                // set state of processor coroutine to active and the thread to inactive
293                int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
294                __cfaabi_dbg_debug_do( thrd_dst->park_result = old_ticket; )
295                switch(old_ticket) {
296                        case 1:
297                                // This is case 1, the regular case, nothing more is needed
298                                break RUNNING;
299                        case 2:
300                                // This is case 2, the racy case, someone tried to run this thread before it finished blocking
301                                // In this case, just run it again.
302                                continue RUNNING;
303                        default:
304                                // This makes no sense, something is wrong abort
305                                abort();
306                }
307        }
308
309        // Just before returning to the processor, set the processor coroutine to active
310        proc_cor->state = Active;
311        kernelTLS.this_thread = 0p;
312
313        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
314}
315
316// KERNEL_ONLY
317void returnToKernel() {
318        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
319        $coroutine * proc_cor = get_coroutine(kernelTLS.this_processor->runner);
320        $thread * thrd_src = kernelTLS.this_thread;
321
322        #if !defined(__CFA_NO_STATISTICS__)
323                struct processor * last_proc = kernelTLS.this_processor;
324        #endif
325
326        // Run the thread on this processor
327        {
328                int local_errno = *__volatile_errno();
329                #if defined( __i386 ) || defined( __x86_64 )
330                        __x87_store;
331                #endif
332                verify( proc_cor->context.SP );
333                __cfactx_switch( &thrd_src->context, &proc_cor->context );
334                #if defined( __i386 ) || defined( __x86_64 )
335                        __x87_load;
336                #endif
337                *__volatile_errno() = local_errno;
338        }
339
340        #if !defined(__CFA_NO_STATISTICS__)
341                if(last_proc != kernelTLS.this_processor) {
342                        __tls_stats()->ready.threads.migration++;
343                }
344        #endif
345
346        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
347        /* 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 );
348        /* 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 );
349}
350
351//-----------------------------------------------------------------------------
352// Scheduler routines
353// KERNEL ONLY
354void __schedule_thread( struct __processor_id_t * id, $thread * thrd ) {
355        /* paranoid */ verify( thrd );
356        /* paranoid */ verify( thrd->state != Halted );
357        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
358        /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
359        /* paranoid */  if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
360                                        "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
361        /* paranoid */  if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
362                                        "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
363        /* paranoid */ #endif
364        /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
365
366        if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
367
368        ready_schedule_lock  ( id );
369                push( thrd->curr_cluster, thrd );
370                __wake_one(id, thrd->curr_cluster);
371        ready_schedule_unlock( id );
372
373        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
374}
375
376// KERNEL ONLY
377static inline $thread * __next_thread(cluster * this) with( *this ) {
378        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
379
380        ready_schedule_lock  ( (__processor_id_t*)kernelTLS.this_processor );
381                $thread * thrd = pop( this );
382        ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
383
384        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
385        return thrd;
386}
387
388// KERNEL ONLY
389static inline $thread * __next_thread_slow(cluster * this) with( *this ) {
390        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
391
392        ready_schedule_lock  ( (__processor_id_t*)kernelTLS.this_processor );
393                $thread * thrd = pop_slow( this );
394        ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
395
396        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
397        return thrd;
398}
399
400// KERNEL ONLY unpark with out disabling interrupts
401void __unpark(  struct __processor_id_t * id, $thread * thrd __cfaabi_dbg_ctx_param2 ) {
402        // record activity
403        __cfaabi_dbg_record_thrd( *thrd, false, caller );
404
405        int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
406        __cfaabi_dbg_debug_do( thrd->unpark_result = old_ticket; thrd->unpark_state = thrd->state; )
407        switch(old_ticket) {
408                case 1:
409                        // Wake won the race, the thread will reschedule/rerun itself
410                        break;
411                case 0:
412                        /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
413                        /* paranoid */ verify( thrd->state == Blocked );
414
415                        // Wake lost the race,
416                        __schedule_thread( id, thrd );
417                        break;
418                default:
419                        // This makes no sense, something is wrong abort
420                        abort();
421        }
422}
423
424void unpark( $thread * thrd __cfaabi_dbg_ctx_param2 ) {
425        if( !thrd ) return;
426
427        disable_interrupts();
428        __unpark( (__processor_id_t*)kernelTLS.this_processor, thrd __cfaabi_dbg_ctx_fwd2 );
429        enable_interrupts( __cfaabi_dbg_ctx );
430}
431
432void park( __cfaabi_dbg_ctx_param ) {
433        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
434        disable_interrupts();
435        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
436        /* paranoid */ verify( kernelTLS.this_thread->preempted == __NO_PREEMPTION );
437
438        // record activity
439        __cfaabi_dbg_record_thrd( *kernelTLS.this_thread, true, caller );
440
441        returnToKernel();
442
443        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
444        enable_interrupts( __cfaabi_dbg_ctx );
445        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
446
447}
448
449// KERNEL ONLY
450void __leave_thread() {
451        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
452        returnToKernel();
453        abort();
454}
455
456// KERNEL ONLY
457bool force_yield( __Preemption_Reason reason ) {
458        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
459        disable_interrupts();
460        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
461
462        $thread * thrd = kernelTLS.this_thread;
463        /* paranoid */ verify(thrd->state == Active);
464
465        // SKULLDUGGERY: It is possible that we are preempting this thread just before
466        // it was going to park itself. If that is the case and it is already using the
467        // intrusive fields then we can't use them to preempt the thread
468        // If that is the case, abandon the preemption.
469        bool preempted = false;
470        if(thrd->link.next == 0p) {
471                preempted = true;
472                thrd->preempted = reason;
473                returnToKernel();
474        }
475
476        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
477        enable_interrupts_noPoll();
478        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
479
480        return preempted;
481}
482
483//=============================================================================================
484// Kernel Idle Sleep
485//=============================================================================================
486// Wake a thread from the front if there are any
487static void __wake_one(struct __processor_id_t * id, cluster * this) {
488        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
489        /* paranoid */ verify( ready_schedule_islocked( id ) );
490
491        // Check if there is a sleeping processor
492        processor * p;
493        unsigned idle;
494        unsigned total;
495        [idle, total, p] = query(this->idles);
496
497        // If no one is sleeping, we are done
498        if( idle == 0 ) return;
499
500        // We found a processor, wake it up
501        post( p->idle );
502
503        #if !defined(__CFA_NO_STATISTICS__)
504                __tls_stats()->ready.sleep.wakes++;
505        #endif
506
507        /* paranoid */ verify( ready_schedule_islocked( id ) );
508        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
509
510        return;
511}
512
513// Unconditionnaly wake a thread
514void __wake_proc(processor * this) {
515        __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
516
517        disable_interrupts();
518                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
519                bool ret = post( this->idle );
520        enable_interrupts( __cfaabi_dbg_ctx );
521}
522
523static void push  (__cluster_idles & this, processor & proc) {
524        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
525        lock( this );
526                this.idle++;
527                /* paranoid */ verify( this.idle <= this.total );
528
529                insert_first(this.list, proc);
530        unlock( this );
531        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
532}
533
534static void remove(__cluster_idles & this, processor & proc) {
535        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
536        lock( this );
537                this.idle--;
538                /* paranoid */ verify( this.idle >= 0 );
539
540                remove(proc);
541        unlock( this );
542        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
543}
544
545static [unsigned idle, unsigned total, * processor] query( & __cluster_idles this ) {
546        for() {
547                uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
548                if( 1 == (l % 2) ) { Pause(); continue; }
549                unsigned idle    = this.idle;
550                unsigned total   = this.total;
551                processor * proc = &this.list`first;
552                // Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
553                asm volatile("": : :"memory");
554                if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
555                return [idle, total, proc];
556        }
557}
558
559//=============================================================================================
560// Unexpected Terminating logic
561//=============================================================================================
562static __spinlock_t kernel_abort_lock;
563static bool kernel_abort_called = false;
564
565void * kernel_abort(void) __attribute__ ((__nothrow__)) {
566        // abort cannot be recursively entered by the same or different processors because all signal handlers return when
567        // the globalAbort flag is true.
568        lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
569
570        // first task to abort ?
571        if ( kernel_abort_called ) {                    // not first task to abort ?
572                unlock( kernel_abort_lock );
573
574                sigset_t mask;
575                sigemptyset( &mask );
576                sigaddset( &mask, SIGALRM );            // block SIGALRM signals
577                sigaddset( &mask, SIGUSR1 );            // block SIGALRM signals
578                sigsuspend( &mask );                            // block the processor to prevent further damage during abort
579                _exit( EXIT_FAILURE );                          // if processor unblocks before it is killed, terminate it
580        }
581        else {
582                kernel_abort_called = true;
583                unlock( kernel_abort_lock );
584        }
585
586        return kernelTLS.this_thread;
587}
588
589void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
590        $thread * thrd = ( $thread * ) kernel_data;
591
592        if(thrd) {
593                int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
594                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
595
596                if ( &thrd->self_cor != thrd->curr_cor ) {
597                        len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
598                        __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
599                }
600                else {
601                        __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
602                }
603        }
604        else {
605                int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
606                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
607        }
608}
609
610int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
611        return get_coroutine(kernelTLS.this_thread) == get_coroutine(mainThread) ? 4 : 2;
612}
613
614static __spinlock_t kernel_debug_lock;
615
616extern "C" {
617        void __cfaabi_bits_acquire() {
618                lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
619        }
620
621        void __cfaabi_bits_release() {
622                unlock( kernel_debug_lock );
623        }
624}
625
626//=============================================================================================
627// Kernel Utilities
628//=============================================================================================
629//-----------------------------------------------------------------------------
630// Locks
631void  ?{}( semaphore & this, int count = 1 ) {
632        (this.lock){};
633        this.count = count;
634        (this.waiting){};
635}
636void ^?{}(semaphore & this) {}
637
638bool P(semaphore & this) with( this ){
639        lock( lock __cfaabi_dbg_ctx2 );
640        count -= 1;
641        if ( count < 0 ) {
642                // queue current task
643                append( waiting, kernelTLS.this_thread );
644
645                // atomically release spin lock and block
646                unlock( lock );
647                park( __cfaabi_dbg_ctx );
648                return true;
649        }
650        else {
651            unlock( lock );
652            return false;
653        }
654}
655
656bool V(semaphore & this) with( this ) {
657        $thread * thrd = 0p;
658        lock( lock __cfaabi_dbg_ctx2 );
659        count += 1;
660        if ( count <= 0 ) {
661                // remove task at head of waiting list
662                thrd = pop_head( waiting );
663        }
664
665        unlock( lock );
666
667        // make new owner
668        unpark( thrd __cfaabi_dbg_ctx2 );
669
670        return thrd != 0p;
671}
672
673bool V(semaphore & this, unsigned diff) with( this ) {
674        $thread * thrd = 0p;
675        lock( lock __cfaabi_dbg_ctx2 );
676        int release = max(-count, (int)diff);
677        count += diff;
678        for(release) {
679                unpark( pop_head( waiting ) __cfaabi_dbg_ctx2 );
680        }
681
682        unlock( lock );
683
684        return thrd != 0p;
685}
686
687//-----------------------------------------------------------------------------
688// Debug
689__cfaabi_dbg_debug_do(
690        extern "C" {
691                void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
692                        this.prev_name = prev_name;
693                        this.prev_thrd = kernelTLS.this_thread;
694                }
695
696                void __cfaabi_dbg_record_thrd($thread & this, bool park, const char prev_name[]) {
697                        if(park) {
698                                this.park_caller   = prev_name;
699                                this.park_stale    = false;
700                        }
701                        else {
702                                this.unpark_caller = prev_name;
703                                this.unpark_stale  = false;
704                        }
705                }
706        }
707)
708
709//-----------------------------------------------------------------------------
710// Debug
711bool threading_enabled(void) __attribute__((const)) {
712        return true;
713}
714
715//-----------------------------------------------------------------------------
716// Statistics
717#if !defined(__CFA_NO_STATISTICS__)
718        void print_halts( processor & this ) {
719                this.print_halts = true;
720        }
721#endif
722// Local Variables: //
723// mode: c //
724// tab-width: 4 //
725// End: //
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