source: libcfa/src/concurrency/kernel.cfa

Last change on this file was b93bf85, checked in by caparsons <caparson@…>, 8 months ago

fixed spurious channel close waituntil error case. Was caused by a race condition causing an exception to be thrown while another was in flight

  • Property mode set to 100644
File size: 28.6 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 Jan  9 08:42:05 2023
13// Update Count     : 77
14//
15
16#define __cforall_thread__
17
18// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
19
20#pragma GCC diagnostic push
21#pragma GCC diagnostic ignored "-Waddress-of-packed-member"
22
23//C Includes
24#include <errno.h>
25#include <stdio.h>
26#include <string.h>
27#include <signal.h>
28#include <unistd.h>
29
30extern "C" {
31        #include <sys/eventfd.h>
32        #include <sys/uio.h>
33}
34
35//CFA Includes
36#include "kernel/private.hfa"
37#include "preemption.hfa"
38#include "strstream.hfa"
39#include "device/cpu.hfa"
40#include "io/types.hfa"
41
42//Private includes
43#define __CFA_INVOKE_PRIVATE__
44#include "invoke.h"
45#pragma GCC diagnostic pop
46
47#if !defined(__CFA_NO_STATISTICS__)
48        #define __STATS_DEF( ...) __VA_ARGS__
49#else
50        #define __STATS_DEF( ...)
51#endif
52
53//-----------------------------------------------------------------------------
54// Some assembly required
55#if defined( __i386 )
56        // mxcr : SSE Status and Control bits (control bits are preserved across function calls)
57        // fcw  : X87 FPU control word (preserved across function calls)
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( __x86_64 )
77        #define __x87_store         \
78                uint32_t __mxcr;      \
79                uint16_t __fcw;       \
80                __asm__ volatile (    \
81                        "stmxcsr %0\n"  \
82                        "fnstcw  %1\n"  \
83                        : "=m" (__mxcr),\
84                                "=m" (__fcw)  \
85                )
86
87        #define __x87_load          \
88                __asm__ volatile (    \
89                        "fldcw  %1\n"   \
90                        "ldmxcsr %0\n"  \
91                        :: "m" (__mxcr),\
92                                "m" (__fcw)  \
93                )
94
95#elif defined( __arm__ )
96        #define __x87_store
97        #define __x87_load
98
99#elif defined( __aarch64__ )
100        #define __x87_store              \
101                uint32_t __fpcntl[2];    \
102                __asm__ volatile (    \
103                        "mrs x9, FPCR\n" \
104                        "mrs x10, FPSR\n"  \
105                        "stp x9, x10, %0\n"  \
106                        : "=m" (__fpcntl) : : "x9", "x10" \
107                )
108
109        #define __x87_load         \
110                __asm__ volatile (    \
111                        "ldp x9, x10, %0\n"  \
112                        "msr FPSR, x10\n"  \
113                        "msr FPCR, x9\n" \
114                : "=m" (__fpcntl) : : "x9", "x10" \
115                )
116
117#else
118        #error unsupported hardware architecture
119#endif
120
121extern thread$ * mainThread;
122extern processor * mainProcessor;
123
124//-----------------------------------------------------------------------------
125// Kernel Scheduling logic
126static thread$ * __next_thread(cluster * this);
127static thread$ * __next_thread_slow(cluster * this);
128static thread$ * __next_thread_search(cluster * this);
129static inline bool __must_unpark( thread$ * thrd ) __attribute((nonnull(1)));
130static void __run_thread(processor * this, thread$ * dst);
131static void __wake_one(cluster * cltr);
132
133static void idle_sleep(processor * proc);
134static bool mark_idle (__cluster_proc_list & idles, processor & proc);
135static void mark_awake(__cluster_proc_list & idles, processor & proc);
136
137extern bool __cfa_io_drain( processor * proc ) __attribute__((nonnull (1)));
138extern bool __cfa_io_flush( processor * ) __attribute__((nonnull (1)));
139
140
141extern void __disable_interrupts_hard();
142extern void __enable_interrupts_hard();
143
144
145//=============================================================================================
146// Kernel Scheduling logic
147//=============================================================================================
148//Main of the processor contexts
149void main(processorCtx_t & runner) {
150        // Because of a bug, we couldn't initialized the seed on construction
151        // Do it here
152        PRNG_SET_SEED( __cfaabi_tls.random_state, rdtscl() );
153        __cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
154        __tls_rand_advance_bck();
155
156        processor * this = runner.proc;
157        verify(this);
158
159        __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
160        #if !defined(__CFA_NO_STATISTICS__)
161                if( this->print_halts ) {
162                        __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
163                }
164        #endif
165
166        {
167                // Setup preemption data
168                preemption_scope scope = { this };
169
170                // if we need to run some special setup, now is the time to do it.
171                if(this->init.thrd) {
172                        this->init.thrd->curr_cluster = this->cltr;
173                        __run_thread(this, this->init.thrd);
174                }
175
176                __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
177
178                thread$ * readyThread = 0p;
179                MAIN_LOOP:
180                for() {
181                        // Check if there is pending io
182                        __cfa_io_drain( this );
183
184                        // Try to get the next thread
185                        readyThread = __next_thread( this->cltr );
186
187                        if( !readyThread ) {
188                                // there is no point in holding submissions if we are idle
189                                __IO_STATS__(true, io.flush.idle++; )
190                                __cfa_io_flush( this );
191
192                                // drain again in case something showed up
193                                __cfa_io_drain( this );
194
195                                readyThread = __next_thread( this->cltr );
196                        }
197
198                        if( !readyThread ) for(5) {
199                                readyThread = __next_thread_slow( this->cltr );
200
201                                if( readyThread ) break;
202
203                                // It's unlikely we still I/O to submit, but the arbiter could
204                                __IO_STATS__(true, io.flush.idle++; )
205                                __cfa_io_flush( this );
206
207                                // drain again in case something showed up
208                                __cfa_io_drain( this );
209                        }
210
211                        HALT:
212                        if( !readyThread ) {
213                                // Don't block if we are done
214                                if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
215
216                                // Push self to idle stack
217                                if(!mark_idle(this->cltr->procs, * this)) continue MAIN_LOOP;
218
219                                // Confirm the ready-queue is empty
220                                readyThread = __next_thread_search( this->cltr );
221                                if( readyThread ) {
222                                        // A thread was found, cancel the halt
223                                        mark_awake(this->cltr->procs, * this);
224
225                                        __STATS__(true, ready.sleep.cancels++; )
226
227                                        // continue the mai loop
228                                        break HALT;
229                                }
230
231                                idle_sleep( this );
232
233                                // We were woken up, remove self from idle
234                                mark_awake(this->cltr->procs, * this);
235
236                                // DON'T just proceed, start looking again
237                                continue MAIN_LOOP;
238                        }
239
240                        /* paranoid */ verify( readyThread );
241
242                        // Reset io dirty bit
243                        this->io.dirty = false;
244
245                        // We found a thread run it
246                        __run_thread(this, readyThread);
247
248                        // Are we done?
249                        if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
250
251                        if(__atomic_load_n(&this->io.pending, __ATOMIC_RELAXED) && !__atomic_load_n(&this->io.dirty, __ATOMIC_RELAXED)) {
252                                __IO_STATS__(true, io.flush.dirty++; )
253                                __cfa_io_flush( this );
254                        }
255                }
256
257                __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
258        }
259
260        __cfa_io_flush( this );
261        __cfa_io_drain( this );
262
263        post( this->terminated );
264
265        if(this == mainProcessor) {
266                // HACK : the coroutine context switch expects this_thread to be set
267                // and it make sense for it to be set in all other cases except here
268                // fake it
269                __cfaabi_tls.this_thread = mainThread;
270        }
271
272        __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
273}
274
275static int * __volatile_errno() __attribute__((noinline));
276static int * __volatile_errno() { asm(""); return &errno; }
277
278// KERNEL ONLY
279// runThread runs a thread by context switching
280// from the processor coroutine to the target thread
281static void __run_thread(processor * this, thread$ * thrd_dst) {
282        /* paranoid */ verify( ! __preemption_enabled() );
283        /* paranoid */ verifyf( thrd_dst->state == Ready || thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
284        /* paranoid */ verifyf( thrd_dst->rdy_link.next == 0p, "Expected null got %p", thrd_dst->rdy_link.next );
285        __builtin_prefetch( thrd_dst->context.SP );
286
287        __cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
288
289        coroutine$ * proc_cor = get_coroutine(this->runner);
290
291        // set state of processor coroutine to inactive
292        verify(proc_cor->state == Active);
293        proc_cor->state = Blocked;
294
295        // Actually run the thread
296        RUNNING:  while(true) {
297                thrd_dst->preempted = __NO_PREEMPTION;
298
299                // Update global state
300                kernelTLS().this_thread = thrd_dst;
301
302                // Update the state after setting this_thread
303                // so that the debugger can find all active threads
304                // in tls storage
305                thrd_dst->state = Active;
306
307                /* paranoid */ verify( ! __preemption_enabled() );
308                /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
309                /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
310                /* paranoid */ verify( thrd_dst->context.SP );
311                /* paranoid */ verify( thrd_dst->state != Halted );
312                /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ) || thrd_dst->curr_cor == proc_cor || thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too small.\n", thrd_dst ); // add escape condition if we are setting up the processor
313                /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit) || thrd_dst->curr_cor == proc_cor || thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too large.\n", thrd_dst ); // add escape condition if we are setting up the processor
314                /* paranoid */ verify( __atomic_exchange_n( &thrd_dst->executing, this, __ATOMIC_SEQ_CST) == 0p );
315                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
316
317
318
319                // set context switch to the thread that the processor is executing
320                __cfactx_switch( &proc_cor->context, &thrd_dst->context );
321                // when __cfactx_switch returns we are back in the processor coroutine
322
323
324
325                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
326                /* paranoid */ verify( __atomic_exchange_n( &thrd_dst->executing, 0p, __ATOMIC_SEQ_CST) == this );
327                /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit) || thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too large.\n", thrd_dst );
328                /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ) || thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too small.\n", thrd_dst );
329                /* paranoid */ verify( thrd_dst->state != Halted );
330                /* paranoid */ verify( thrd_dst->context.SP );
331                /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
332                /* paranoid */ verify( ! __preemption_enabled() );
333
334                // We just finished running a thread, there are a few things that could have happened.
335                // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
336                // 2 - Racy case    : the thread has blocked but someone has already tried to schedule it.
337                // 4 - Preempted
338                // In case 1, we may have won a race so we can't write to the state again.
339                // In case 2, we lost the race so we now own the thread.
340
341                if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
342                        // Reset the this_thread now that we know
343                        // the state isn't active anymore
344                        kernelTLS().this_thread = 0p;
345
346                        // The thread was preempted, reschedule it and reset the flag
347                        schedule_thread$( thrd_dst, UNPARK_LOCAL );
348                        break RUNNING;
349                }
350
351                if(unlikely(thrd_dst->state == Halting)) {
352                        // Reset the this_thread now that we know
353                        // the state isn't active anymore
354                        kernelTLS().this_thread = 0p;
355
356                        // The thread has halted, it should never be scheduled/run again
357                        // finish the thread
358                        __thread_finish( thrd_dst );
359                        break RUNNING;
360                }
361
362                /* paranoid */ verify( thrd_dst->state == Active );
363                thrd_dst->state = Blocked;
364
365                // Reset the this_thread now that we know
366                // the state isn't active anymore
367                kernelTLS().this_thread = 0p;
368
369                // set state of processor coroutine to active and the thread to inactive
370                int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
371                switch(old_ticket) {
372                        case TICKET_RUNNING:
373                                // This is case 1, the regular case, nothing more is needed
374                                break RUNNING;
375                        case TICKET_UNBLOCK:
376                                __STATS__(true, ready.threads.threads++; )
377                                // This is case 2, the racy case, someone tried to run this thread before it finished blocking
378                                // In this case, just run it again.
379                                continue RUNNING;
380                        default:
381                                // This makes no sense, something is wrong abort
382                                abort();
383                }
384        }
385
386        // Just before returning to the processor, set the processor coroutine to active
387        proc_cor->state = Active;
388
389        __cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
390
391        __STATS__(true, ready.threads.threads--; )
392
393        /* paranoid */ verify( ! __preemption_enabled() );
394}
395
396// KERNEL_ONLY
397static void returnToKernel() {
398        /* paranoid */ verify( ! __preemption_enabled() );
399        coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
400        thread$ * thrd_src = kernelTLS().this_thread;
401
402        __STATS_DEF( thrd_src->last_proc = kernelTLS().this_processor; )
403
404        // Run the thread on this processor
405        {
406                int local_errno = *__volatile_errno();
407                #if defined( __i386 ) || defined( __x86_64 )
408                        __x87_store;
409                #endif
410                /* paranoid */ verify( proc_cor->context.SP );
411                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
412                __cfactx_switch( &thrd_src->context, &proc_cor->context );
413                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
414                #if defined( __i386 ) || defined( __x86_64 )
415                        __x87_load;
416                #endif
417                *__volatile_errno() = local_errno;
418        }
419
420        #if !defined(__CFA_NO_STATISTICS__)
421                /* paranoid */ verify( thrd_src->last_proc != 0p );
422                if(thrd_src->last_proc != kernelTLS().this_processor) {
423                        __tls_stats()->ready.threads.migration++;
424                }
425        #endif
426
427        /* paranoid */ verify( ! __preemption_enabled() );
428        /* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) < ((uintptr_t)__get_stack(thrd_src->curr_cor)->base ) || thrd_src->corctx_flag, "ERROR : Returning thread$ %p has been corrupted.\n StackPointer too small.\n", thrd_src );
429        /* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) > ((uintptr_t)__get_stack(thrd_src->curr_cor)->limit) || thrd_src->corctx_flag, "ERROR : Returning thread$ %p has been corrupted.\n StackPointer too large.\n", thrd_src );
430}
431
432//-----------------------------------------------------------------------------
433// Scheduler routines
434// KERNEL ONLY
435static void __schedule_thread( thread$ * thrd, unpark_hint hint ) {
436        /* paranoid */ verify( ! __preemption_enabled() );
437        /* paranoid */ verify( ready_schedule_islocked());
438        /* paranoid */ verify( thrd );
439        /* paranoid */ verify( thrd->state != Halted );
440        /* paranoid */ verify( thrd->curr_cluster );
441        /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
442        /* paranoid */  if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
443                                        "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
444        /* paranoid */  if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
445                                        "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
446        /* paranoid */ #endif
447        /* paranoid */ verifyf( thrd->rdy_link.next == 0p, "Expected null got %p", thrd->rdy_link.next );
448        /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
449
450        if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
451
452        // Dereference the thread now because once we push it, there is not guaranteed it's still valid.
453        struct cluster * cl = thrd->curr_cluster;
454        __STATS_DEF(bool outside = hint == UNPARK_LOCAL && thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
455
456        // push the thread to the cluster ready-queue
457        push( cl, thrd, hint );
458
459        // variable thrd is no longer safe to use
460        thrd = 0xdeaddeaddeaddeadp;
461
462        // wake the cluster using the save variable.
463        __wake_one( cl );
464
465        #if !defined(__CFA_NO_STATISTICS__)
466                if( kernelTLS().this_stats ) {
467                        __tls_stats()->ready.threads.threads++;
468                        if(outside) {
469                                __tls_stats()->ready.threads.extunpark++;
470                        }
471                }
472                else {
473                        __atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
474                        __atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
475                }
476        #endif
477
478        /* paranoid */ verify( ready_schedule_islocked());
479        /* paranoid */ verify( ! __preemption_enabled() );
480}
481
482void schedule_thread$( thread$ * thrd, unpark_hint hint ) {
483        ready_schedule_lock();
484                __schedule_thread( thrd, hint );
485        ready_schedule_unlock();
486}
487
488// KERNEL ONLY
489static inline thread$ * __next_thread(cluster * this) with( *this ) {
490        /* paranoid */ verify( ! __preemption_enabled() );
491
492        ready_schedule_lock();
493                thread$ * thrd = pop_fast( this );
494        ready_schedule_unlock();
495
496        /* paranoid */ verify( ! __preemption_enabled() );
497        return thrd;
498}
499
500// KERNEL ONLY
501static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
502        /* paranoid */ verify( ! __preemption_enabled() );
503
504        ready_schedule_lock();
505                thread$ * thrd = pop_slow( this );
506        ready_schedule_unlock();
507
508        /* paranoid */ verify( ! __preemption_enabled() );
509        return thrd;
510}
511
512// KERNEL ONLY
513static inline thread$ * __next_thread_search(cluster * this) with( *this ) {
514        /* paranoid */ verify( ! __preemption_enabled() );
515
516        ready_schedule_lock();
517                thread$ * thrd = pop_search( this );
518        ready_schedule_unlock();
519
520        /* paranoid */ verify( ! __preemption_enabled() );
521        return thrd;
522}
523
524static inline bool __must_unpark( thread$ * thrd ) {
525        int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
526        switch(old_ticket) {
527                case TICKET_RUNNING:
528                        // Wake won the race, the thread will reschedule/rerun itself
529                        return false;
530                case TICKET_BLOCKED:
531                        /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
532                        /* paranoid */ verify( thrd->state == Blocked );
533                        return true;
534                default:
535                        // This makes no sense, something is wrong abort
536                        abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
537        }
538}
539
540void __kernel_unpark( thread$ * thrd, unpark_hint hint ) {
541        /* paranoid */ verify( ! __preemption_enabled() );
542        /* paranoid */ verify( ready_schedule_islocked());
543
544        if( !thrd ) return;
545
546        if(__must_unpark(thrd)) {
547                // Wake lost the race,
548                __schedule_thread( thrd, hint );
549        }
550
551        /* paranoid */ verify( ready_schedule_islocked());
552        /* paranoid */ verify( ! __preemption_enabled() );
553}
554
555void unpark( thread$ * thrd, unpark_hint hint ) libcfa_public {
556        if( !thrd ) return;
557
558        if(__must_unpark(thrd)) {
559                disable_interrupts();
560                        // Wake lost the race,
561                        schedule_thread$( thrd, hint );
562                enable_interrupts(false);
563        }
564}
565
566void park( void ) libcfa_public {
567        __disable_interrupts_checked();
568                /* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
569                returnToKernel();
570        __enable_interrupts_checked();
571}
572
573extern "C" {
574        // Leave the thread monitor
575        // last routine called by a thread.
576        // Should never return
577        void __cfactx_thrd_leave() {
578                thread$ * thrd = active_thread();
579                monitor$ * this = &thrd->self_mon;
580
581                // Lock the monitor now
582                lock( this->lock __cfaabi_dbg_ctx2 );
583
584                disable_interrupts();
585
586                /* paranoid */ verify( ! __preemption_enabled() );
587                /* paranoid */ verify( thrd->state == Active );
588                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
589                /* paranoid */ verify( kernelTLS().this_thread == thrd );
590                /* paranoid */ verify( thrd->context.SP );
591                /* paranoid */ verifyf( ((uintptr_t)thrd->context.SP) > ((uintptr_t)__get_stack(thrd->curr_cor)->limit), "ERROR : thread$ %p has been corrupted.\n StackPointer too large.\n", thrd );
592                /* paranoid */ verifyf( ((uintptr_t)thrd->context.SP) < ((uintptr_t)__get_stack(thrd->curr_cor)->base ), "ERROR : thread$ %p has been corrupted.\n StackPointer too small.\n", thrd );
593
594                if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
595                if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
596                if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
597
598                thrd->state = Halting;
599                thrd->ticket = TICKET_DEAD;
600
601                // Leave the thread
602                returnToKernel();
603
604                // Control flow should never reach here!
605                abort();
606        }
607}
608
609// KERNEL ONLY
610bool force_yield( __Preemption_Reason reason ) libcfa_public {
611        __disable_interrupts_checked();
612                thread$ * thrd = kernelTLS().this_thread;
613                /* paranoid */ verify(thrd->state == Active);
614
615                // SKULLDUGGERY: It is possible that we are preempting this thread just before
616                // it was going to park itself. If that is the case and it is already using the
617                // intrusive fields then we can't use them to preempt the thread
618                // If that is the case, abandon the preemption.
619                bool preempted = false;
620                if(thrd->rdy_link.next == 0p) {
621                        preempted = true;
622                        thrd->preempted = reason;
623                        returnToKernel();
624                }
625        __enable_interrupts_checked( false );
626        return preempted;
627}
628
629//=============================================================================================
630// Kernel Idle Sleep
631//=============================================================================================
632// Wake a thread from the front if there are any
633static void __wake_one(cluster * this) {
634        eventfd_t val;
635
636        /* paranoid */ verify( ! __preemption_enabled() );
637        /* paranoid */ verify( ready_schedule_islocked() );
638
639        // Check if there is a sleeping processor
640        struct __fd_waitctx * fdp = __atomic_load_n(&this->procs.fdw, __ATOMIC_SEQ_CST);
641
642        // If no one is sleeping: we are done
643        if( fdp == 0p ) return;
644
645        int fd = 1;
646        if( __atomic_load_n(&fdp->sem, __ATOMIC_SEQ_CST) != 1 ) {
647                fd = __atomic_exchange_n(&fdp->sem, 1, __ATOMIC_RELAXED);
648        }
649
650        switch(fd) {
651                __attribute__((unused)) int ret;
652        case 0:
653                // If the processor isn't ready to sleep then the exchange will already wake it up
654                #if !defined(__CFA_NO_STATISTICS__)
655                        if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.early++;
656                        } else { __atomic_fetch_add(&this->stats->ready.sleep.early, 1, __ATOMIC_RELAXED); }
657                #endif
658                break;
659        case 1:
660                // If someone else already said they will wake them: we are done
661                #if !defined(__CFA_NO_STATISTICS__)
662                        if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.seen++;
663                        } else { __atomic_fetch_add(&this->stats->ready.sleep.seen, 1, __ATOMIC_RELAXED); }
664                #endif
665                break;
666        default:
667                // If the processor was ready to sleep, we need to wake it up with an actual write
668                val = 1;
669                ret = eventfd_write( fd, val );
670                /* paranoid */ verifyf( ret == 0, "Expected return to be 0, was %d\n", ret );
671
672                #if !defined(__CFA_NO_STATISTICS__)
673                        if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.wakes++;
674                        } else { __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED); }
675                #endif
676                break;
677        }
678
679        /* paranoid */ verify( ready_schedule_islocked() );
680        /* paranoid */ verify( ! __preemption_enabled() );
681
682        return;
683}
684
685// Unconditionnaly wake a thread
686void __wake_proc(processor * this) {
687        /* paranoid */ verify( ! __preemption_enabled() );
688
689        __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
690
691        this->idle_wctx.sem = 1;
692
693        this->idle_wctx.wake__time = rdtscl();
694
695        eventfd_t val;
696        val = 1;
697        __attribute__((unused)) int ret = eventfd_write( this->idle_wctx.evfd, val );
698
699        /* paranoid */ verifyf( ret == 0, "Expected return to be 0, was %d\n", ret );
700        /* paranoid */ verify( ! __preemption_enabled() );
701}
702
703static void idle_sleep(processor * this) {
704        /* paranoid */ verify( this->idle_wctx.evfd != 1 );
705        /* paranoid */ verify( this->idle_wctx.evfd != 2 );
706
707        // Tell everyone we are ready to go do sleep
708        for() {
709                int expected = this->idle_wctx.sem;
710
711                // Someone already told us to wake-up! No time for a nap.
712                if(expected == 1) { return; }
713
714                // Try to mark that we are going to sleep
715                if(__atomic_compare_exchange_n(&this->idle_wctx.sem, &expected, this->idle_wctx.evfd, false,  __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ) {
716                        // Every one agreed, taking a nap
717                        break;
718                }
719        }
720
721
722        #if !defined(__CFA_NO_STATISTICS__)
723                if(this->print_halts) {
724                        __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
725                }
726        #endif
727
728        __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle_fd);
729
730        {
731                eventfd_t val;
732                ssize_t ret = read( this->idle_wctx.evfd, &val, sizeof(val) );
733                if(ret < 0) {
734                        switch((int)errno) {
735                        case EAGAIN:
736                        #if EAGAIN != EWOULDBLOCK
737                                case EWOULDBLOCK:
738                        #endif
739                        case EINTR:
740                                // No need to do anything special here, just assume it's a legitimate wake-up
741                                break;
742                        default:
743                                abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
744                        }
745                }
746        }
747
748        #if !defined(__CFA_NO_STATISTICS__)
749                if(this->print_halts) {
750                        __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
751                }
752        #endif
753}
754
755static bool mark_idle(__cluster_proc_list & this, processor & proc) {
756        __STATS__(true, ready.sleep.halts++; )
757
758        proc.idle_wctx.sem = 0;
759
760        /* paranoid */ verify( ! __preemption_enabled() );
761        if(!try_lock( this )) return false;
762                this.idle++;
763                /* paranoid */ verify( this.idle <= this.total );
764                remove(proc);
765                insert_first(this.idles, proc);
766
767                // update the pointer to the head wait context, which should now point to this proc.
768                __atomic_store_n(&this.fdw, &proc.idle_wctx, __ATOMIC_SEQ_CST);
769        unlock( this );
770        /* paranoid */ verify( ! __preemption_enabled() );
771
772        return true;
773}
774
775static void mark_awake(__cluster_proc_list & this, processor & proc) {
776        /* paranoid */ verify( ! __preemption_enabled() );
777        lock( this );
778                this.idle--;
779                /* paranoid */ verify( this.idle >= 0 );
780                remove(proc);
781                insert_last(this.actives, proc);
782
783                {
784                        // update the pointer to the head wait context
785                        struct __fd_waitctx * wctx = 0;
786                        if(!this.idles`isEmpty) wctx = &this.idles`first.idle_wctx;
787                        __atomic_store_n(&this.fdw, wctx, __ATOMIC_SEQ_CST);
788                }
789
790        unlock( this );
791        /* paranoid */ verify( ! __preemption_enabled() );
792}
793
794//=============================================================================================
795// Unexpected Terminating logic
796//=============================================================================================
797void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
798        thread$ * thrd = __cfaabi_tls.this_thread;
799
800        if(thrd) {
801                int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
802                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
803
804                if ( &thrd->self_cor != thrd->curr_cor ) {
805                        len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
806                        __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
807                }
808                else {
809                        __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
810                }
811        }
812        else {
813                int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
814                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
815        }
816}
817
818int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
819        return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
820}
821
822static __spinlock_t kernel_debug_lock;
823
824extern "C" {
825        void __cfaabi_bits_acquire() {
826                lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
827        }
828
829        void __cfaabi_bits_release() {
830                unlock( kernel_debug_lock );
831        }
832}
833
834//=============================================================================================
835// Kernel Utilities
836//=============================================================================================
837#if defined(CFA_HAVE_LINUX_IO_URING_H)
838#include "io/types.hfa"
839#endif
840
841//-----------------------------------------------------------------------------
842// Debug
843bool threading_enabled(void) __attribute__((const)) libcfa_public {
844        return true;
845}
846
847//-----------------------------------------------------------------------------
848// Statistics
849#if !defined(__CFA_NO_STATISTICS__)
850        void print_halts( processor & this ) libcfa_public {
851                this.print_halts = true;
852        }
853
854        static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
855                /* paranoid */ verify( cltr->stats );
856
857                processor * it = &list`first;
858                for(unsigned i = 0; i < count; i++) {
859                        /* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
860                        /* paranoid */ verify( it->local_data->this_stats );
861                        // __print_stats( it->local_data->this_stats, cltr->print_stats, "Processor", it->name, (void*)it );
862                        __tally_stats( cltr->stats, it->local_data->this_stats );
863                        it = &(*it)`next;
864                }
865        }
866
867        static void crawl_cluster_stats( cluster & this ) {
868                // Stop the world, otherwise stats could get really messed-up
869                // this doesn't solve all problems but does solve many
870                // so it's probably good enough
871                disable_interrupts();
872                uint_fast32_t last_size = ready_mutate_lock();
873
874                        crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
875                        crawl_list(&this, this.procs.idles  , this.procs.idle );
876
877                // Unlock the RWlock
878                ready_mutate_unlock( last_size );
879                enable_interrupts();
880        }
881
882
883        void print_stats_now( cluster & this, int flags ) libcfa_public {
884                crawl_cluster_stats( this );
885                __print_stats( this.stats, flags, "Cluster", this.name, (void*)&this );
886        }
887#endif
888// Local Variables: //
889// mode: c //
890// tab-width: 4 //
891// End: //
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