source: libcfa/src/concurrency/kernel.cfa @ 74f5c83

arm-ehjacob/cs343-translationnew-ast-unique-expr
Last change on this file since 74f5c83 was 74f5c83, checked in by Peter A. Buhr <pabuhr@…>, 16 months ago

assembler for save/restore registers FPSR/FPCR for ARM

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File size: 20.8 KB
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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 bool __has_next_thread(cluster * this);
105static void __run_thread(processor * this, $thread * dst);
106static bool __wake_one(struct __processor_id_t * id, cluster * cltr);
107static void __halt(processor * this);
108bool __wake_proc(processor *);
109
110//=============================================================================================
111// Kernel Scheduling logic
112//=============================================================================================
113//Main of the processor contexts
114void main(processorCtx_t & runner) {
115        // Because of a bug, we couldn't initialized the seed on construction
116        // Do it here
117        kernelTLS.rand_seed ^= rdtscl();
118
119        processor * this = runner.proc;
120        verify(this);
121
122        __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
123        #if !defined(__CFA_NO_STATISTICS__)
124                if( this->print_halts ) {
125                        __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->id, this->name, (void*)this);
126                }
127        #endif
128
129        {
130                // Setup preemption data
131                preemption_scope scope = { this };
132
133                __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
134
135                $thread * readyThread = 0p;
136                for( unsigned int spin_count = 0;; spin_count++ ) {
137                        // Try to get the next thread
138                        readyThread = __next_thread( this->cltr );
139
140                        // Check if we actually found a thread
141                        if( readyThread ) {
142                                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
143                                /* paranoid */ verifyf( readyThread->state == Ready || readyThread->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", readyThread->state, readyThread->preempted);
144                                /* paranoid */ verifyf( readyThread->link.next == 0p, "Expected null got %p", readyThread->link.next );
145                                __builtin_prefetch( readyThread->context.SP );
146
147                                // We found a thread run it
148                                __run_thread(this, readyThread);
149
150                                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
151                        }
152
153                        if(__atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST)) break;
154
155                        if( !readyThread ) {
156                                // Block until a thread is ready
157                                __halt(this);
158                        }
159                }
160
161                __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
162        }
163
164        V( this->terminated );
165
166        if(this == mainProcessor) {
167                // HACK : the coroutine context switch expects this_thread to be set
168                // and it make sense for it to be set in all other cases except here
169                // fake it
170                kernelTLS.this_thread = mainThread;
171        }
172
173        __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
174}
175
176static int * __volatile_errno() __attribute__((noinline));
177static int * __volatile_errno() { asm(""); return &errno; }
178
179// KERNEL ONLY
180// runThread runs a thread by context switching
181// from the processor coroutine to the target thread
182static void __run_thread(processor * this, $thread * thrd_dst) {
183        $coroutine * proc_cor = get_coroutine(this->runner);
184
185        // Update global state
186        kernelTLS.this_thread = thrd_dst;
187
188        // set state of processor coroutine to inactive
189        verify(proc_cor->state == Active);
190        proc_cor->state = Blocked;
191
192        // Actually run the thread
193        RUNNING:  while(true) {
194                thrd_dst->preempted = __NO_PREEMPTION;
195                thrd_dst->state = Active;
196
197                __cfaabi_dbg_debug_do(
198                        thrd_dst->park_stale   = true;
199                        thrd_dst->unpark_stale = true;
200                )
201
202                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
203                /* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
204                /* 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
205                /* 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
206
207                // set context switch to the thread that the processor is executing
208                verify( thrd_dst->context.SP );
209                __cfactx_switch( &proc_cor->context, &thrd_dst->context );
210                // when __cfactx_switch returns we are back in the processor coroutine
211
212                /* 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 );
213                /* 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 );
214                /* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
215                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
216
217
218                // We just finished running a thread, there are a few things that could have happened.
219                // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
220                // 2 - Racy case    : the thread has blocked but someone has already tried to schedule it.
221                // 4 - Preempted
222                // In case 1, we may have won a race so we can't write to the state again.
223                // In case 2, we lost the race so we now own the thread.
224
225                if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
226                        // The thread was preempted, reschedule it and reset the flag
227                        __schedule_thread( (__processor_id_t*)this, thrd_dst );
228                        break RUNNING;
229                }
230
231                if(unlikely(thrd_dst->state == Halted)) {
232                        // The thread has halted, it should never be scheduled/run again
233                        // We may need to wake someone up here since
234                        unpark( this->destroyer __cfaabi_dbg_ctx2 );
235                        this->destroyer = 0p;
236                        break RUNNING;
237                }
238
239                /* paranoid */ verify( thrd_dst->state == Active );
240                thrd_dst->state = Blocked;
241
242                // set state of processor coroutine to active and the thread to inactive
243                int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
244                __cfaabi_dbg_debug_do( thrd_dst->park_result = old_ticket; )
245                switch(old_ticket) {
246                        case 1:
247                                // This is case 1, the regular case, nothing more is needed
248                                break RUNNING;
249                        case 2:
250                                // This is case 2, the racy case, someone tried to run this thread before it finished blocking
251                                // In this case, just run it again.
252                                continue RUNNING;
253                        default:
254                                // This makes no sense, something is wrong abort
255                                abort();
256                }
257        }
258
259        // Just before returning to the processor, set the processor coroutine to active
260        proc_cor->state = Active;
261        kernelTLS.this_thread = 0p;
262}
263
264// KERNEL_ONLY
265void returnToKernel() {
266        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
267        $coroutine * proc_cor = get_coroutine(kernelTLS.this_processor->runner);
268        $thread * thrd_src = kernelTLS.this_thread;
269
270        #if !defined(__CFA_NO_STATISTICS__)
271                struct processor * last_proc = kernelTLS.this_processor;
272        #endif
273
274        // Run the thread on this processor
275        {
276                int local_errno = *__volatile_errno();
277                #if defined( __i386 ) || defined( __x86_64 )
278                        __x87_store;
279                #endif
280                verify( proc_cor->context.SP );
281                __cfactx_switch( &thrd_src->context, &proc_cor->context );
282                #if defined( __i386 ) || defined( __x86_64 )
283                        __x87_load;
284                #endif
285                *__volatile_errno() = local_errno;
286        }
287
288        #if !defined(__CFA_NO_STATISTICS__)
289                if(last_proc != kernelTLS.this_processor) {
290                        __tls_stats()->ready.threads.migration++;
291                }
292        #endif
293
294        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
295        /* 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 );
296        /* 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 );
297}
298
299//-----------------------------------------------------------------------------
300// Scheduler routines
301// KERNEL ONLY
302void __schedule_thread( struct __processor_id_t * id, $thread * thrd ) {
303        /* paranoid */ verify( thrd );
304        /* paranoid */ verify( thrd->state != Halted );
305        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
306        /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
307        /* paranoid */  if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
308                                        "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
309        /* paranoid */  if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
310                                        "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
311        /* paranoid */ #endif
312        /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
313
314        if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
315
316        ready_schedule_lock  ( id );
317                push( thrd->curr_cluster, thrd );
318
319                #if !defined(__CFA_NO_STATISTICS__)
320                        bool woke =
321                #endif
322                        __wake_one(id, thrd->curr_cluster);
323
324                #if !defined(__CFA_NO_STATISTICS__)
325                        if(woke) __tls_stats()->ready.sleep.wakes++;
326                #endif
327        ready_schedule_unlock( id );
328
329        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
330}
331
332// KERNEL ONLY
333static $thread * __next_thread(cluster * this) with( *this ) {
334        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
335
336        ready_schedule_lock  ( (__processor_id_t*)kernelTLS.this_processor );
337                $thread * head = pop( this );
338        ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
339
340        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
341        return head;
342}
343
344// KERNEL ONLY
345static bool __has_next_thread(cluster * this) with( *this ) {
346        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
347
348        ready_schedule_lock  ( (__processor_id_t*)kernelTLS.this_processor );
349                bool not_empty = query( this );
350        ready_schedule_unlock( (__processor_id_t*)kernelTLS.this_processor );
351
352        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
353        return not_empty;
354}
355
356// KERNEL ONLY unpark with out disabling interrupts
357void __unpark(  struct __processor_id_t * id, $thread * thrd __cfaabi_dbg_ctx_param2 ) {
358        // record activity
359        __cfaabi_dbg_record_thrd( *thrd, false, caller );
360
361        int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
362        __cfaabi_dbg_debug_do( thrd->unpark_result = old_ticket; thrd->unpark_state = thrd->state; )
363        switch(old_ticket) {
364                case 1:
365                        // Wake won the race, the thread will reschedule/rerun itself
366                        break;
367                case 0:
368                        /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
369                        /* paranoid */ verify( thrd->state == Blocked );
370
371                        // Wake lost the race,
372                        __schedule_thread( id, thrd );
373                        break;
374                default:
375                        // This makes no sense, something is wrong abort
376                        abort();
377        }
378}
379
380void unpark( $thread * thrd __cfaabi_dbg_ctx_param2 ) {
381        if( !thrd ) return;
382
383        disable_interrupts();
384        __unpark( (__processor_id_t*)kernelTLS.this_processor, thrd __cfaabi_dbg_ctx_fwd2 );
385        enable_interrupts( __cfaabi_dbg_ctx );
386}
387
388void park( __cfaabi_dbg_ctx_param ) {
389        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
390        disable_interrupts();
391        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
392        /* paranoid */ verify( kernelTLS.this_thread->preempted == __NO_PREEMPTION );
393
394        // record activity
395        __cfaabi_dbg_record_thrd( *kernelTLS.this_thread, true, caller );
396
397        returnToKernel();
398
399        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
400        enable_interrupts( __cfaabi_dbg_ctx );
401        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
402
403}
404
405// KERNEL ONLY
406void __leave_thread() {
407        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
408        returnToKernel();
409        abort();
410}
411
412// KERNEL ONLY
413bool force_yield( __Preemption_Reason reason ) {
414        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
415        disable_interrupts();
416        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
417
418        $thread * thrd = kernelTLS.this_thread;
419        /* paranoid */ verify(thrd->state == Active);
420
421        // SKULLDUGGERY: It is possible that we are preempting this thread just before
422        // it was going to park itself. If that is the case and it is already using the
423        // intrusive fields then we can't use them to preempt the thread
424        // If that is the case, abandon the preemption.
425        bool preempted = false;
426        if(thrd->link.next == 0p) {
427                preempted = true;
428                thrd->preempted = reason;
429                returnToKernel();
430        }
431
432        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
433        enable_interrupts_noPoll();
434        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
435
436        return preempted;
437}
438
439//=============================================================================================
440// Kernel Idle Sleep
441//=============================================================================================
442// Wake a thread from the front if there are any
443static bool __wake_one(struct __processor_id_t * id, cluster * this) {
444        /* paranoid */ verify( ready_schedule_islocked( id ) );
445
446        // Check if there is a sleeping processor
447        processor * p = pop(this->idles);
448
449        // If no one is sleeping, we are done
450        if( 0p == p ) return false;
451
452        // We found a processor, wake it up
453        post( p->idle );
454
455        return true;
456}
457
458// Unconditionnaly wake a thread
459bool __wake_proc(processor * this) {
460        __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
461
462        disable_interrupts();
463                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
464                bool ret = post( this->idle );
465        enable_interrupts( __cfaabi_dbg_ctx );
466
467        return ret;
468}
469
470static void __halt(processor * this) with( *this ) {
471        if( do_terminate ) return;
472
473        #if !defined(__CFA_NO_STATISTICS__)
474                __tls_stats()->ready.sleep.halts++;
475        #endif
476        // Push self to queue
477        push(cltr->idles, *this);
478
479        // Makre sure we don't miss a thread
480        if( __has_next_thread(cltr) ) {
481                // A thread was posted, make sure a processor is woken up
482                struct __processor_id_t *id = (struct __processor_id_t *) this;
483                ready_schedule_lock  ( id );
484                        __wake_one( id, cltr );
485                ready_schedule_unlock( id );
486                #if !defined(__CFA_NO_STATISTICS__)
487                        __tls_stats()->ready.sleep.cancels++;
488                #endif
489        }
490
491        #if !defined(__CFA_NO_STATISTICS__)
492                if(this->print_halts) {
493                        __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->id, rdtscl());
494                }
495        #endif
496
497        wait( idle );
498
499        #if !defined(__CFA_NO_STATISTICS__)
500                if(this->print_halts) {
501                        __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->id, rdtscl());
502                }
503        #endif
504}
505
506//=============================================================================================
507// Unexpected Terminating logic
508//=============================================================================================
509static __spinlock_t kernel_abort_lock;
510static bool kernel_abort_called = false;
511
512void * kernel_abort(void) __attribute__ ((__nothrow__)) {
513        // abort cannot be recursively entered by the same or different processors because all signal handlers return when
514        // the globalAbort flag is true.
515        lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
516
517        // first task to abort ?
518        if ( kernel_abort_called ) {                    // not first task to abort ?
519                unlock( kernel_abort_lock );
520
521                sigset_t mask;
522                sigemptyset( &mask );
523                sigaddset( &mask, SIGALRM );            // block SIGALRM signals
524                sigaddset( &mask, SIGUSR1 );            // block SIGALRM signals
525                sigsuspend( &mask );                            // block the processor to prevent further damage during abort
526                _exit( EXIT_FAILURE );                          // if processor unblocks before it is killed, terminate it
527        }
528        else {
529                kernel_abort_called = true;
530                unlock( kernel_abort_lock );
531        }
532
533        return kernelTLS.this_thread;
534}
535
536void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
537        $thread * thrd = ( $thread * ) kernel_data;
538
539        if(thrd) {
540                int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
541                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
542
543                if ( &thrd->self_cor != thrd->curr_cor ) {
544                        len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
545                        __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
546                }
547                else {
548                        __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
549                }
550        }
551        else {
552                int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
553                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
554        }
555}
556
557int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
558        return get_coroutine(kernelTLS.this_thread) == get_coroutine(mainThread) ? 4 : 2;
559}
560
561static __spinlock_t kernel_debug_lock;
562
563extern "C" {
564        void __cfaabi_bits_acquire() {
565                lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
566        }
567
568        void __cfaabi_bits_release() {
569                unlock( kernel_debug_lock );
570        }
571}
572
573//=============================================================================================
574// Kernel Utilities
575//=============================================================================================
576//-----------------------------------------------------------------------------
577// Locks
578void  ?{}( semaphore & this, int count = 1 ) {
579        (this.lock){};
580        this.count = count;
581        (this.waiting){};
582}
583void ^?{}(semaphore & this) {}
584
585bool P(semaphore & this) with( this ){
586        lock( lock __cfaabi_dbg_ctx2 );
587        count -= 1;
588        if ( count < 0 ) {
589                // queue current task
590                append( waiting, kernelTLS.this_thread );
591
592                // atomically release spin lock and block
593                unlock( lock );
594                park( __cfaabi_dbg_ctx );
595                return true;
596        }
597        else {
598            unlock( lock );
599            return false;
600        }
601}
602
603bool V(semaphore & this) with( this ) {
604        $thread * thrd = 0p;
605        lock( lock __cfaabi_dbg_ctx2 );
606        count += 1;
607        if ( count <= 0 ) {
608                // remove task at head of waiting list
609                thrd = pop_head( waiting );
610        }
611
612        unlock( lock );
613
614        // make new owner
615        unpark( thrd __cfaabi_dbg_ctx2 );
616
617        return thrd != 0p;
618}
619
620bool V(semaphore & this, unsigned diff) with( this ) {
621        $thread * thrd = 0p;
622        lock( lock __cfaabi_dbg_ctx2 );
623        int release = max(-count, (int)diff);
624        count += diff;
625        for(release) {
626                unpark( pop_head( waiting ) __cfaabi_dbg_ctx2 );
627        }
628
629        unlock( lock );
630
631        return thrd != 0p;
632}
633
634//-----------------------------------------------------------------------------
635// Debug
636__cfaabi_dbg_debug_do(
637        extern "C" {
638                void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
639                        this.prev_name = prev_name;
640                        this.prev_thrd = kernelTLS.this_thread;
641                }
642
643                void __cfaabi_dbg_record_thrd($thread & this, bool park, const char prev_name[]) {
644                        if(park) {
645                                this.park_caller   = prev_name;
646                                this.park_stale    = false;
647                        }
648                        else {
649                                this.unpark_caller = prev_name;
650                                this.unpark_stale  = false;
651                        }
652                }
653        }
654)
655
656//-----------------------------------------------------------------------------
657// Debug
658bool threading_enabled(void) __attribute__((const)) {
659        return true;
660}
661
662//-----------------------------------------------------------------------------
663// Statistics
664#if !defined(__CFA_NO_STATISTICS__)
665        void print_halts( processor & this ) {
666                this.print_halts = true;
667        }
668#endif
669// Local Variables: //
670// mode: c //
671// tab-width: 4 //
672// End: //
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