source: libcfa/src/concurrency/kernel.cfa @ 8bee858

pthread-emulation
Last change on this file since 8bee858 was 8bee858, checked in by Thierry Delisle <tdelisle@…>, 6 months ago

Changed io types to have trailing $ instead of leading

  • Property mode set to 100644
File size: 28.8 KB
Line 
1//
2// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// kernel.c --
8//
9// Author           : Thierry Delisle
10// Created On       : Tue Jan 17 12:27:26 2017
11// Last Modified By : Peter A. Buhr
12// Last Modified On : Mon Aug 31 07:08:20 2020
13// Update Count     : 71
14//
15
16#define __cforall_thread__
17#define _GNU_SOURCE
18
19// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
20
21#pragma GCC diagnostic push
22#pragma GCC diagnostic ignored "-Waddress-of-packed-member"
23
24//C Includes
25#include <errno.h>
26#include <stdio.h>
27#include <string.h>
28#include <signal.h>
29#include <unistd.h>
30
31extern "C" {
32        #include <sys/eventfd.h>
33        #include <sys/uio.h>
34}
35
36//CFA Includes
37#include "kernel/private.hfa"
38#include "preemption.hfa"
39#include "strstream.hfa"
40#include "device/cpu.hfa"
41#include "io/types.hfa"
42
43//Private includes
44#define __CFA_INVOKE_PRIVATE__
45#include "invoke.h"
46#pragma GCC diagnostic pop
47
48#if !defined(__CFA_NO_STATISTICS__)
49        #define __STATS_DEF( ...) __VA_ARGS__
50#else
51        #define __STATS_DEF( ...)
52#endif
53
54//-----------------------------------------------------------------------------
55// Some assembly required
56#if defined( __i386 )
57        // mxcr : SSE Status and Control bits (control bits are preserved across function calls)
58        // fcw  : X87 FPU control word (preserved across function calls)
59        #define __x87_store         \
60                uint32_t __mxcr;      \
61                uint16_t __fcw;       \
62                __asm__ volatile (    \
63                        "stmxcsr %0\n"  \
64                        "fnstcw  %1\n"  \
65                        : "=m" (__mxcr),\
66                                "=m" (__fcw)  \
67                )
68
69        #define __x87_load         \
70                __asm__ volatile (   \
71                        "fldcw  %1\n"  \
72                        "ldmxcsr %0\n" \
73                        ::"m" (__mxcr),\
74                                "m" (__fcw)  \
75                )
76
77#elif defined( __x86_64 )
78        #define __x87_store         \
79                uint32_t __mxcr;      \
80                uint16_t __fcw;       \
81                __asm__ volatile (    \
82                        "stmxcsr %0\n"  \
83                        "fnstcw  %1\n"  \
84                        : "=m" (__mxcr),\
85                                "=m" (__fcw)  \
86                )
87
88        #define __x87_load          \
89                __asm__ volatile (    \
90                        "fldcw  %1\n"   \
91                        "ldmxcsr %0\n"  \
92                        :: "m" (__mxcr),\
93                                "m" (__fcw)  \
94                )
95
96#elif defined( __arm__ )
97        #define __x87_store
98        #define __x87_load
99
100#elif defined( __aarch64__ )
101        #define __x87_store              \
102                uint32_t __fpcntl[2];    \
103                __asm__ volatile (    \
104                        "mrs x9, FPCR\n" \
105                        "mrs x10, FPSR\n"  \
106                        "stp x9, x10, %0\n"  \
107                        : "=m" (__fpcntl) : : "x9", "x10" \
108                )
109
110        #define __x87_load         \
111                __asm__ volatile (    \
112                        "ldp x9, x10, %0\n"  \
113                        "msr FPSR, x10\n"  \
114                        "msr FPCR, x9\n" \
115                : "=m" (__fpcntl) : : "x9", "x10" \
116                )
117
118#else
119        #error unsupported hardware architecture
120#endif
121
122extern thread$ * mainThread;
123extern processor * mainProcessor;
124
125//-----------------------------------------------------------------------------
126// Kernel Scheduling logic
127static thread$ * __next_thread(cluster * this);
128static thread$ * __next_thread_slow(cluster * this);
129static thread$ * __next_thread_search(cluster * this);
130static inline bool __must_unpark( thread$ * thrd ) __attribute((nonnull(1)));
131static void __run_thread(processor * this, thread$ * dst);
132static void __wake_one(cluster * cltr);
133
134static void idle_sleep(processor * proc);
135static bool mark_idle (__cluster_proc_list & idles, processor & proc);
136static void mark_awake(__cluster_proc_list & idles, processor & proc);
137
138extern bool __cfa_io_drain( processor * proc ) __attribute__((nonnull (1)));
139extern bool __cfa_io_flush( processor * ) __attribute__((nonnull (1)));
140extern void __cfa_io_idle( processor * ) __attribute__((nonnull (1)));
141
142#if defined(CFA_WITH_IO_URING_IDLE)
143        extern bool __kernel_read(processor * proc, io_future_t & future, iovec &, int fd);
144#endif
145
146extern void __disable_interrupts_hard();
147extern void __enable_interrupts_hard();
148
149
150//=============================================================================================
151// Kernel Scheduling logic
152//=============================================================================================
153//Main of the processor contexts
154void main(processorCtx_t & runner) {
155        // Because of a bug, we couldn't initialized the seed on construction
156        // Do it here
157        __cfaabi_tls.rand_seed ^= rdtscl();
158        __cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
159        __tls_rand_advance_bck();
160
161        processor * this = runner.proc;
162        verify(this);
163
164        /* paranoid */ verify( this->idle_wctx.ftr   != 0p );
165        /* paranoid */ verify( this->idle_wctx.rdbuf != 0p );
166
167        // used for idle sleep when io_uring is present
168        // mark it as already fulfilled so we know if there is a pending request or not
169        this->idle_wctx.ftr->self.ptr = 1p;
170
171        __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
172        #if !defined(__CFA_NO_STATISTICS__)
173                if( this->print_halts ) {
174                        __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
175                }
176        #endif
177
178        {
179                // Setup preemption data
180                preemption_scope scope = { this };
181
182                // if we need to run some special setup, now is the time to do it.
183                if(this->init.thrd) {
184                        this->init.thrd->curr_cluster = this->cltr;
185                        __run_thread(this, this->init.thrd);
186                }
187
188                __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
189
190                thread$ * readyThread = 0p;
191                MAIN_LOOP:
192                for() {
193                        // Check if there is pending io
194                        __cfa_io_drain( this );
195
196                        // Try to get the next thread
197                        readyThread = __next_thread( this->cltr );
198
199                        if( !readyThread ) {
200                                // there is no point in holding submissions if we are idle
201                                __IO_STATS__(true, io.flush.idle++; )
202                                __cfa_io_flush( this );
203
204                                // drain again in case something showed up
205                                __cfa_io_drain( this );
206
207                                readyThread = __next_thread( this->cltr );
208                        }
209
210                        if( !readyThread ) for(5) {
211                                readyThread = __next_thread_slow( this->cltr );
212
213                                if( readyThread ) break;
214
215                                // It's unlikely we still I/O to submit, but the arbiter could
216                                __IO_STATS__(true, io.flush.idle++; )
217                                __cfa_io_flush( this );
218
219                                // drain again in case something showed up
220                                __cfa_io_drain( this );
221                        }
222
223                        HALT:
224                        if( !readyThread ) {
225                                // Don't block if we are done
226                                if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
227
228                                // Push self to idle stack
229                                if(!mark_idle(this->cltr->procs, * this)) continue MAIN_LOOP;
230
231                                // Confirm the ready-queue is empty
232                                readyThread = __next_thread_search( this->cltr );
233                                if( readyThread ) {
234                                        // A thread was found, cancel the halt
235                                        mark_awake(this->cltr->procs, * this);
236
237                                        __STATS__(true, ready.sleep.cancels++; )
238
239                                        // continue the mai loop
240                                        break HALT;
241                                }
242
243                                idle_sleep( this );
244
245                                // We were woken up, remove self from idle
246                                mark_awake(this->cltr->procs, * this);
247
248                                // DON'T just proceed, start looking again
249                                continue MAIN_LOOP;
250                        }
251
252                        /* paranoid */ verify( readyThread );
253
254                        // Reset io dirty bit
255                        this->io.dirty = false;
256
257                        // We found a thread run it
258                        __run_thread(this, readyThread);
259
260                        // Are we done?
261                        if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
262
263                        if(__atomic_load_n(&this->io.pending, __ATOMIC_RELAXED) && !__atomic_load_n(&this->io.dirty, __ATOMIC_RELAXED)) {
264                                __IO_STATS__(true, io.flush.dirty++; )
265                                __cfa_io_flush( this );
266                        }
267                }
268
269                __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
270        }
271
272        post( this->terminated );
273
274        if(this == mainProcessor) {
275                // HACK : the coroutine context switch expects this_thread to be set
276                // and it make sense for it to be set in all other cases except here
277                // fake it
278                __cfaabi_tls.this_thread = mainThread;
279        }
280
281        __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
282}
283
284static int * __volatile_errno() __attribute__((noinline));
285static int * __volatile_errno() { asm(""); return &errno; }
286
287// KERNEL ONLY
288// runThread runs a thread by context switching
289// from the processor coroutine to the target thread
290static void __run_thread(processor * this, thread$ * thrd_dst) {
291        /* paranoid */ verify( ! __preemption_enabled() );
292        /* paranoid */ verifyf( thrd_dst->state == Ready || thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
293        /* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
294        __builtin_prefetch( thrd_dst->context.SP );
295
296        __cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
297
298        coroutine$ * proc_cor = get_coroutine(this->runner);
299
300        // set state of processor coroutine to inactive
301        verify(proc_cor->state == Active);
302        proc_cor->state = Blocked;
303
304        // Actually run the thread
305        RUNNING:  while(true) {
306                thrd_dst->preempted = __NO_PREEMPTION;
307
308                // Update global state
309                kernelTLS().this_thread = thrd_dst;
310
311                // Update the state after setting this_thread
312                // so that the debugger can find all active threads
313                // in tls storage
314                thrd_dst->state = Active;
315
316                /* paranoid */ verify( ! __preemption_enabled() );
317                /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
318                /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
319                /* paranoid */ verify( thrd_dst->context.SP );
320                /* paranoid */ verify( thrd_dst->state != Halted );
321                /* 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
322                /* 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
323                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
324
325
326
327                // set context switch to the thread that the processor is executing
328                __cfactx_switch( &proc_cor->context, &thrd_dst->context );
329                // when __cfactx_switch returns we are back in the processor coroutine
330
331
332
333                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
334                /* 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 );
335                /* 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 );
336                /* paranoid */ verify( thrd_dst->context.SP );
337                /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
338                /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
339                /* paranoid */ verify( ! __preemption_enabled() );
340
341                // We just finished running a thread, there are a few things that could have happened.
342                // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
343                // 2 - Racy case    : the thread has blocked but someone has already tried to schedule it.
344                // 4 - Preempted
345                // In case 1, we may have won a race so we can't write to the state again.
346                // In case 2, we lost the race so we now own the thread.
347
348                if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
349                        // Reset the this_thread now that we know
350                        // the state isn't active anymore
351                        kernelTLS().this_thread = 0p;
352
353                        // The thread was preempted, reschedule it and reset the flag
354                        schedule_thread$( thrd_dst, UNPARK_LOCAL );
355                        break RUNNING;
356                }
357
358                if(unlikely(thrd_dst->state == Halting)) {
359                        // Reset the this_thread now that we know
360                        // the state isn't active anymore
361                        kernelTLS().this_thread = 0p;
362
363                        // The thread has halted, it should never be scheduled/run again
364                        // finish the thread
365                        __thread_finish( thrd_dst );
366                        break RUNNING;
367                }
368
369                /* paranoid */ verify( thrd_dst->state == Active );
370                thrd_dst->state = Blocked;
371
372                // Reset the this_thread now that we know
373                // the state isn't active anymore
374                kernelTLS().this_thread = 0p;
375
376                // set state of processor coroutine to active and the thread to inactive
377                int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
378                switch(old_ticket) {
379                        case TICKET_RUNNING:
380                                // This is case 1, the regular case, nothing more is needed
381                                break RUNNING;
382                        case TICKET_UNBLOCK:
383                                __STATS__(true, ready.threads.threads++; )
384                                // This is case 2, the racy case, someone tried to run this thread before it finished blocking
385                                // In this case, just run it again.
386                                continue RUNNING;
387                        default:
388                                // This makes no sense, something is wrong abort
389                                abort();
390                }
391        }
392
393        // Just before returning to the processor, set the processor coroutine to active
394        proc_cor->state = Active;
395
396        __cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
397
398        __STATS__(true, ready.threads.threads--; )
399
400        /* paranoid */ verify( ! __preemption_enabled() );
401}
402
403// KERNEL_ONLY
404static void returnToKernel() {
405        /* paranoid */ verify( ! __preemption_enabled() );
406        coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
407        thread$ * thrd_src = kernelTLS().this_thread;
408
409        __STATS_DEF( thrd_src->last_proc = kernelTLS().this_processor; )
410
411        // Run the thread on this processor
412        {
413                int local_errno = *__volatile_errno();
414                #if defined( __i386 ) || defined( __x86_64 )
415                        __x87_store;
416                #endif
417                /* paranoid */ verify( proc_cor->context.SP );
418                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
419                __cfactx_switch( &thrd_src->context, &proc_cor->context );
420                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
421                #if defined( __i386 ) || defined( __x86_64 )
422                        __x87_load;
423                #endif
424                *__volatile_errno() = local_errno;
425        }
426
427        #if !defined(__CFA_NO_STATISTICS__)
428                /* paranoid */ verify( thrd_src->last_proc != 0p );
429                if(thrd_src->last_proc != kernelTLS().this_processor) {
430                        __tls_stats()->ready.threads.migration++;
431                }
432        #endif
433
434        /* paranoid */ verify( ! __preemption_enabled() );
435        /* 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 );
436        /* 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 );
437}
438
439//-----------------------------------------------------------------------------
440// Scheduler routines
441// KERNEL ONLY
442static void __schedule_thread( thread$ * thrd, unpark_hint hint ) {
443        /* paranoid */ verify( ! __preemption_enabled() );
444        /* paranoid */ verify( ready_schedule_islocked());
445        /* paranoid */ verify( thrd );
446        /* paranoid */ verify( thrd->state != Halted );
447        /* paranoid */ verify( thrd->curr_cluster );
448        /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
449        /* paranoid */  if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
450                                        "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
451        /* paranoid */  if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
452                                        "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
453        /* paranoid */ #endif
454        /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
455        /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
456
457        if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
458
459        // Dereference the thread now because once we push it, there is not guaranteed it's still valid.
460        struct cluster * cl = thrd->curr_cluster;
461        __STATS_DEF(bool outside = hint == UNPARK_LOCAL && thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
462
463        // push the thread to the cluster ready-queue
464        push( cl, thrd, hint );
465
466        // variable thrd is no longer safe to use
467        thrd = 0xdeaddeaddeaddeadp;
468
469        // wake the cluster using the save variable.
470        __wake_one( cl );
471
472        #if !defined(__CFA_NO_STATISTICS__)
473                if( kernelTLS().this_stats ) {
474                        __tls_stats()->ready.threads.threads++;
475                        if(outside) {
476                                __tls_stats()->ready.threads.extunpark++;
477                        }
478                }
479                else {
480                        __atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
481                        __atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
482                }
483        #endif
484
485        /* paranoid */ verify( ready_schedule_islocked());
486        /* paranoid */ verify( ! __preemption_enabled() );
487}
488
489void schedule_thread$( thread$ * thrd, unpark_hint hint ) {
490        ready_schedule_lock();
491                __schedule_thread( thrd, hint );
492        ready_schedule_unlock();
493}
494
495// KERNEL ONLY
496static inline thread$ * __next_thread(cluster * this) with( *this ) {
497        /* paranoid */ verify( ! __preemption_enabled() );
498
499        ready_schedule_lock();
500                thread$ * thrd = pop_fast( this );
501        ready_schedule_unlock();
502
503        /* paranoid */ verify( ! __preemption_enabled() );
504        return thrd;
505}
506
507// KERNEL ONLY
508static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
509        /* paranoid */ verify( ! __preemption_enabled() );
510
511        ready_schedule_lock();
512                thread$ * thrd = pop_slow( this );
513        ready_schedule_unlock();
514
515        /* paranoid */ verify( ! __preemption_enabled() );
516        return thrd;
517}
518
519// KERNEL ONLY
520static inline thread$ * __next_thread_search(cluster * this) with( *this ) {
521        /* paranoid */ verify( ! __preemption_enabled() );
522
523        ready_schedule_lock();
524                thread$ * thrd = pop_search( this );
525        ready_schedule_unlock();
526
527        /* paranoid */ verify( ! __preemption_enabled() );
528        return thrd;
529}
530
531static inline bool __must_unpark( thread$ * thrd ) {
532        int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
533        switch(old_ticket) {
534                case TICKET_RUNNING:
535                        // Wake won the race, the thread will reschedule/rerun itself
536                        return false;
537                case TICKET_BLOCKED:
538                        /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
539                        /* paranoid */ verify( thrd->state == Blocked );
540                        return true;
541                default:
542                        // This makes no sense, something is wrong abort
543                        abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
544        }
545}
546
547void __kernel_unpark( thread$ * thrd, unpark_hint hint ) {
548        /* paranoid */ verify( ! __preemption_enabled() );
549        /* paranoid */ verify( ready_schedule_islocked());
550
551        if( !thrd ) return;
552
553        if(__must_unpark(thrd)) {
554                // Wake lost the race,
555                __schedule_thread( thrd, hint );
556        }
557
558        /* paranoid */ verify( ready_schedule_islocked());
559        /* paranoid */ verify( ! __preemption_enabled() );
560}
561
562void unpark( thread$ * thrd, unpark_hint hint ) libcfa_public {
563        if( !thrd ) return;
564
565        if(__must_unpark(thrd)) {
566                disable_interrupts();
567                        // Wake lost the race,
568                        schedule_thread$( thrd, hint );
569                enable_interrupts(false);
570        }
571}
572
573void park( void ) libcfa_public {
574        __disable_interrupts_checked();
575                /* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
576                returnToKernel();
577        __enable_interrupts_checked();
578
579}
580
581extern "C" {
582        // Leave the thread monitor
583        // last routine called by a thread.
584        // Should never return
585        void __cfactx_thrd_leave() {
586                thread$ * thrd = active_thread();
587                monitor$ * this = &thrd->self_mon;
588
589                // Lock the monitor now
590                lock( this->lock __cfaabi_dbg_ctx2 );
591
592                disable_interrupts();
593
594                /* paranoid */ verify( ! __preemption_enabled() );
595                /* paranoid */ verify( thrd->state == Active );
596                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
597                /* paranoid */ verify( kernelTLS().this_thread == thrd );
598                /* paranoid */ verify( thrd->context.SP );
599                /* 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 );
600                /* 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 );
601
602                thrd->state = Halting;
603                if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
604                if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
605                if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
606
607                // Leave the thread
608                returnToKernel();
609
610                // Control flow should never reach here!
611                abort();
612        }
613}
614
615// KERNEL ONLY
616bool force_yield( __Preemption_Reason reason ) libcfa_public {
617        __disable_interrupts_checked();
618                thread$ * thrd = kernelTLS().this_thread;
619                /* paranoid */ verify(thrd->state == Active);
620
621                // SKULLDUGGERY: It is possible that we are preempting this thread just before
622                // it was going to park itself. If that is the case and it is already using the
623                // intrusive fields then we can't use them to preempt the thread
624                // If that is the case, abandon the preemption.
625                bool preempted = false;
626                if(thrd->link.next == 0p) {
627                        preempted = true;
628                        thrd->preempted = reason;
629                        returnToKernel();
630                }
631        __enable_interrupts_checked( false );
632        return preempted;
633}
634
635//=============================================================================================
636// Kernel Idle Sleep
637//=============================================================================================
638// Wake a thread from the front if there are any
639static void __wake_one(cluster * this) {
640        eventfd_t val;
641
642        /* paranoid */ verify( ! __preemption_enabled() );
643        /* paranoid */ verify( ready_schedule_islocked() );
644
645        // Check if there is a sleeping processor
646        struct __fd_waitctx * fdp = __atomic_load_n(&this->procs.fdw, __ATOMIC_SEQ_CST);
647
648        // If no one is sleeping: we are done
649        if( fdp == 0p ) return;
650
651        int fd = 1;
652        if( __atomic_load_n(&fdp->sem, __ATOMIC_SEQ_CST) != 1 ) {
653                fd = __atomic_exchange_n(&fdp->sem, 1, __ATOMIC_RELAXED);
654        }
655
656        switch(fd) {
657                __attribute__((unused)) int ret;
658        case 0:
659                // If the processor isn't ready to sleep then the exchange will already wake it up
660                #if !defined(__CFA_NO_STATISTICS__)
661                        if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.early++;
662                        } else { __atomic_fetch_add(&this->stats->ready.sleep.early, 1, __ATOMIC_RELAXED); }
663                #endif
664                break;
665        case 1:
666                // If someone else already said they will wake them: we are done
667                #if !defined(__CFA_NO_STATISTICS__)
668                        if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.seen++;
669                        } else { __atomic_fetch_add(&this->stats->ready.sleep.seen, 1, __ATOMIC_RELAXED); }
670                #endif
671                break;
672        default:
673                // If the processor was ready to sleep, we need to wake it up with an actual write
674                val = 1;
675                ret = eventfd_write( fd, val );
676                /* paranoid */ verifyf( ret == 0, "Expected return to be 0, was %d\n", ret );
677
678                #if !defined(__CFA_NO_STATISTICS__)
679                        if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.wakes++;
680                        } else { __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED); }
681                #endif
682                break;
683        }
684
685        /* paranoid */ verify( ready_schedule_islocked() );
686        /* paranoid */ verify( ! __preemption_enabled() );
687
688        return;
689}
690
691// Unconditionnaly wake a thread
692void __wake_proc(processor * this) {
693        /* paranoid */ verify( ! __preemption_enabled() );
694
695        __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
696
697        this->idle_wctx.sem = 1;
698
699        this->idle_wctx.wake__time = rdtscl();
700
701        eventfd_t val;
702        val = 1;
703        __attribute__((unused)) int ret = eventfd_write( this->idle_wctx.evfd, val );
704
705        /* paranoid */ verifyf( ret == 0, "Expected return to be 0, was %d\n", ret );
706        /* paranoid */ verify( ! __preemption_enabled() );
707}
708
709static void idle_sleep(processor * this) {
710        /* paranoid */ verify( this->idle_wctx.evfd != 1 );
711        /* paranoid */ verify( this->idle_wctx.evfd != 2 );
712
713        // Tell everyone we are ready to go do sleep
714        for() {
715                int expected = this->idle_wctx.sem;
716
717                // Someone already told us to wake-up! No time for a nap.
718                if(expected == 1) { return; }
719
720                // Try to mark that we are going to sleep
721                if(__atomic_compare_exchange_n(&this->idle_wctx.sem, &expected, this->idle_wctx.evfd, false,  __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ) {
722                        // Every one agreed, taking a nap
723                        break;
724                }
725        }
726
727
728        #if !defined(CFA_WITH_IO_URING_IDLE)
729                #if !defined(__CFA_NO_STATISTICS__)
730                        if(this->print_halts) {
731                                __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
732                        }
733                #endif
734
735                __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle_fd);
736
737                {
738                        eventfd_t val;
739                        ssize_t ret = read( this->idle_wctx.evfd, &val, sizeof(val) );
740                        if(ret < 0) {
741                                switch((int)errno) {
742                                case EAGAIN:
743                                #if EAGAIN != EWOULDBLOCK
744                                        case EWOULDBLOCK:
745                                #endif
746                                case EINTR:
747                                        // No need to do anything special here, just assume it's a legitimate wake-up
748                                        break;
749                                default:
750                                        abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
751                                }
752                        }
753                }
754
755                #if !defined(__CFA_NO_STATISTICS__)
756                        if(this->print_halts) {
757                                __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
758                        }
759                #endif
760        #else
761                __cfa_io_idle( this );
762        #endif
763}
764
765static bool mark_idle(__cluster_proc_list & this, processor & proc) {
766        __STATS__(true, ready.sleep.halts++; )
767
768        proc.idle_wctx.sem = 0;
769
770        /* paranoid */ verify( ! __preemption_enabled() );
771        if(!try_lock( this )) return false;
772                this.idle++;
773                /* paranoid */ verify( this.idle <= this.total );
774                remove(proc);
775                insert_first(this.idles, proc);
776
777                __atomic_store_n(&this.fdw, &proc.idle_wctx, __ATOMIC_SEQ_CST);
778        unlock( this );
779        /* paranoid */ verify( ! __preemption_enabled() );
780
781        return true;
782}
783
784static void mark_awake(__cluster_proc_list & this, processor & proc) {
785        /* paranoid */ verify( ! __preemption_enabled() );
786        lock( this );
787                this.idle--;
788                /* paranoid */ verify( this.idle >= 0 );
789                remove(proc);
790                insert_last(this.actives, proc);
791
792                {
793                        struct __fd_waitctx * wctx = 0;
794                        if(!this.idles`isEmpty) wctx = &this.idles`first.idle_wctx;
795                        __atomic_store_n(&this.fdw, wctx, __ATOMIC_SEQ_CST);
796                }
797
798        unlock( this );
799        /* paranoid */ verify( ! __preemption_enabled() );
800}
801
802//=============================================================================================
803// Unexpected Terminating logic
804//=============================================================================================
805void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
806        thread$ * thrd = __cfaabi_tls.this_thread;
807
808        if(thrd) {
809                int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
810                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
811
812                if ( &thrd->self_cor != thrd->curr_cor ) {
813                        len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
814                        __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
815                }
816                else {
817                        __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
818                }
819        }
820        else {
821                int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
822                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
823        }
824}
825
826int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
827        return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
828}
829
830static __spinlock_t kernel_debug_lock;
831
832extern "C" {
833        void __cfaabi_bits_acquire() {
834                lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
835        }
836
837        void __cfaabi_bits_release() {
838                unlock( kernel_debug_lock );
839        }
840}
841
842//=============================================================================================
843// Kernel Utilities
844//=============================================================================================
845#if defined(CFA_HAVE_LINUX_IO_URING_H)
846#include "io/types.hfa"
847#endif
848
849//-----------------------------------------------------------------------------
850// Debug
851bool threading_enabled(void) __attribute__((const)) libcfa_public {
852        return true;
853}
854
855//-----------------------------------------------------------------------------
856// Statistics
857#if !defined(__CFA_NO_STATISTICS__)
858        void print_halts( processor & this ) libcfa_public {
859                this.print_halts = true;
860        }
861
862        static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
863                /* paranoid */ verify( cltr->stats );
864
865                processor * it = &list`first;
866                for(unsigned i = 0; i < count; i++) {
867                        /* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
868                        /* paranoid */ verify( it->local_data->this_stats );
869                        // __print_stats( it->local_data->this_stats, cltr->print_stats, "Processor", it->name, (void*)it );
870                        __tally_stats( cltr->stats, it->local_data->this_stats );
871                        it = &(*it)`next;
872                }
873        }
874
875        static void crawl_cluster_stats( cluster & this ) {
876                // Stop the world, otherwise stats could get really messed-up
877                // this doesn't solve all problems but does solve many
878                // so it's probably good enough
879                disable_interrupts();
880                uint_fast32_t last_size = ready_mutate_lock();
881
882                        crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
883                        crawl_list(&this, this.procs.idles  , this.procs.idle );
884
885                // Unlock the RWlock
886                ready_mutate_unlock( last_size );
887                enable_interrupts();
888        }
889
890
891        void print_stats_now( cluster & this, int flags ) libcfa_public {
892                crawl_cluster_stats( this );
893                __print_stats( this.stats, flags, "Cluster", this.name, (void*)&this );
894        }
895#endif
896// Local Variables: //
897// mode: c //
898// tab-width: 4 //
899// End: //
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