source: libcfa/src/concurrency/kernel.cfa @ a7b486b

arm-ehjacob/cs343-translationnew-astnew-ast-unique-expr
Last change on this file since a7b486b was a7b486b, checked in by Thierry Delisle <tdelisle@…>, 19 months ago

Added verify to run_thread, which would inexplicably have failed in the last build failure

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File size: 35.2 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 : Tue Feb  4 13:03:15 2020
13// Update Count     : 58
14//
15
16#define __cforall_thread__
17// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
18
19//C Includes
20#include <stddef.h>
21#include <errno.h>
22#include <string.h>
23extern "C" {
24#include <stdio.h>
25#include <fenv.h>
26#include <sys/resource.h>
27#include <signal.h>
28#include <unistd.h>
29#include <limits.h>                                                                             // PTHREAD_STACK_MIN
30#include <sys/mman.h>                                                                   // mprotect
31}
32
33//CFA Includes
34#include "time.hfa"
35#include "kernel_private.hfa"
36#include "preemption.hfa"
37#include "startup.hfa"
38
39//Private includes
40#define __CFA_INVOKE_PRIVATE__
41#include "invoke.h"
42
43
44//-----------------------------------------------------------------------------
45// Some assembly required
46#if defined( __i386 )
47        #define CtxGet( ctx )        \
48                __asm__ volatile (     \
49                        "movl %%esp,%0\n"\
50                        "movl %%ebp,%1\n"\
51                        : "=rm" (ctx.SP),\
52                                "=rm" (ctx.FP) \
53                )
54
55        // mxcr : SSE Status and Control bits (control bits are preserved across function calls)
56        // fcw  : X87 FPU control word (preserved across function calls)
57        #define __x87_store         \
58                uint32_t __mxcr;      \
59                uint16_t __fcw;       \
60                __asm__ volatile (    \
61                        "stmxcsr %0\n"  \
62                        "fnstcw  %1\n"  \
63                        : "=m" (__mxcr),\
64                                "=m" (__fcw)  \
65                )
66
67        #define __x87_load         \
68                __asm__ volatile (   \
69                        "fldcw  %1\n"  \
70                        "ldmxcsr %0\n" \
71                        ::"m" (__mxcr),\
72                                "m" (__fcw)  \
73                )
74
75#elif defined( __x86_64 )
76        #define CtxGet( ctx )        \
77                __asm__ volatile (     \
78                        "movq %%rsp,%0\n"\
79                        "movq %%rbp,%1\n"\
80                        : "=rm" (ctx.SP),\
81                                "=rm" (ctx.FP) \
82                )
83
84        #define __x87_store         \
85                uint32_t __mxcr;      \
86                uint16_t __fcw;       \
87                __asm__ volatile (    \
88                        "stmxcsr %0\n"  \
89                        "fnstcw  %1\n"  \
90                        : "=m" (__mxcr),\
91                                "=m" (__fcw)  \
92                )
93
94        #define __x87_load          \
95                __asm__ volatile (    \
96                        "fldcw  %1\n"   \
97                        "ldmxcsr %0\n"  \
98                        :: "m" (__mxcr),\
99                                "m" (__fcw)  \
100                )
101
102
103#elif defined( __ARM_ARCH )
104#define CtxGet( ctx ) __asm__ ( \
105                "mov %0,%%sp\n"   \
106                "mov %1,%%r11\n"   \
107        : "=rm" (ctx.SP), "=rm" (ctx.FP) )
108#else
109        #error unknown hardware architecture
110#endif
111
112//-----------------------------------------------------------------------------
113//Start and stop routine for the kernel, declared first to make sure they run first
114static void __kernel_startup (void) __attribute__(( constructor( STARTUP_PRIORITY_KERNEL ) ));
115static void __kernel_shutdown(void) __attribute__(( destructor ( STARTUP_PRIORITY_KERNEL ) ));
116
117//-----------------------------------------------------------------------------
118// Kernel Scheduling logic
119static $thread * __next_thread(cluster * this);
120static void __run_thread(processor * this, $thread * dst);
121static $thread * __halt(processor * this);
122static bool __wake_one(cluster * cltr, bool was_empty);
123static bool __wake_proc(processor *);
124
125//-----------------------------------------------------------------------------
126// Kernel storage
127KERNEL_STORAGE(cluster,         mainCluster);
128KERNEL_STORAGE(processor,       mainProcessor);
129KERNEL_STORAGE($thread, mainThread);
130KERNEL_STORAGE(__stack_t,       mainThreadCtx);
131
132cluster     * mainCluster;
133processor   * mainProcessor;
134$thread * mainThread;
135
136extern "C" {
137        struct { __dllist_t(cluster) list; __spinlock_t lock; } __cfa_dbg_global_clusters;
138}
139
140size_t __page_size = 0;
141
142//-----------------------------------------------------------------------------
143// Global state
144thread_local struct KernelThreadData kernelTLS __attribute__ ((tls_model ( "initial-exec" ))) = {
145        NULL,                                                                                           // cannot use 0p
146        NULL,
147        { 1, false, false },
148        6u //this should be seeded better but due to a bug calling rdtsc doesn't work
149};
150
151//-----------------------------------------------------------------------------
152// Struct to steal stack
153struct current_stack_info_t {
154        __stack_t * storage;                                                            // pointer to stack object
155        void * base;                                                                            // base of stack
156        void * limit;                                                                           // stack grows towards stack limit
157        void * context;                                                                         // address of cfa_context_t
158};
159
160void ?{}( current_stack_info_t & this ) {
161        __stack_context_t ctx;
162        CtxGet( ctx );
163        this.base = ctx.FP;
164
165        rlimit r;
166        getrlimit( RLIMIT_STACK, &r);
167        size_t size = r.rlim_cur;
168
169        this.limit = (void *)(((intptr_t)this.base) - size);
170        this.context = &storage_mainThreadCtx;
171}
172
173//-----------------------------------------------------------------------------
174// Main thread construction
175
176void ?{}( $coroutine & this, current_stack_info_t * info) with( this ) {
177        stack.storage = info->storage;
178        with(*stack.storage) {
179                limit     = info->limit;
180                base      = info->base;
181        }
182        __attribute__((may_alias)) intptr_t * istorage = (intptr_t*) &stack.storage;
183        *istorage |= 0x1;
184        name = "Main Thread";
185        state = Start;
186        starter = 0p;
187        last = 0p;
188        cancellation = 0p;
189}
190
191void ?{}( $thread & this, current_stack_info_t * info) with( this ) {
192        state = Start;
193        self_cor{ info };
194        curr_cor = &self_cor;
195        curr_cluster = mainCluster;
196        self_mon.owner = &this;
197        self_mon.recursion = 1;
198        self_mon_p = &self_mon;
199        next = 0p;
200
201        node.next = 0p;
202        node.prev = 0p;
203        doregister(curr_cluster, this);
204
205        monitors{ &self_mon_p, 1, (fptr_t)0 };
206}
207
208//-----------------------------------------------------------------------------
209// Processor coroutine
210void ?{}(processorCtx_t & this) {
211
212}
213
214// Construct the processor context of non-main processors
215static void ?{}(processorCtx_t & this, processor * proc, current_stack_info_t * info) {
216        (this.__cor){ info };
217        this.proc = proc;
218}
219
220static void * __invoke_processor(void * arg);
221
222void ?{}(processor & this, const char name[], cluster & cltr) with( this ) {
223        this.name = name;
224        this.cltr = &cltr;
225        terminated{ 0 };
226        destroyer = 0p;
227        do_terminate = false;
228        preemption_alarm = 0p;
229        pending_preemption = false;
230        runner.proc = &this;
231
232        idle{};
233
234        __cfadbg_print_safe(runtime_core, "Kernel : Starting core %p\n", &this);
235
236        this.stack = __create_pthread( &this.kernel_thread, __invoke_processor, (void *)&this );
237
238        __cfadbg_print_safe(runtime_core, "Kernel : core %p created\n", &this);
239}
240
241void ^?{}(processor & this) with( this ){
242        if( ! __atomic_load_n(&do_terminate, __ATOMIC_ACQUIRE) ) {
243                __cfadbg_print_safe(runtime_core, "Kernel : core %p signaling termination\n", &this);
244
245                __atomic_store_n(&do_terminate, true, __ATOMIC_RELAXED);
246                __wake_proc( &this );
247
248                P( terminated );
249                verify( kernelTLS.this_processor != &this);
250        }
251
252        int err = pthread_join( kernel_thread, 0p );
253        if( err != 0 ) abort("KERNEL ERROR: joining processor %p caused error %s\n", &this, strerror(err));
254
255        free( this.stack );
256}
257
258void ?{}(cluster & this, const char name[], Duration preemption_rate, int io_flags) with( this ) {
259        this.name = name;
260        this.preemption_rate = preemption_rate;
261        ready_queue{};
262        ready_queue_lock{};
263
264        #if !defined(__CFA_NO_STATISTICS__)
265                print_stats = false;
266        #endif
267
268        procs{ __get };
269        idles{ __get };
270        threads{ __get };
271
272        __kernel_io_startup( this, io_flags, &this == mainCluster );
273
274        doregister(this);
275}
276
277void ^?{}(cluster & this) {
278        __kernel_io_shutdown( this, &this == mainCluster );
279
280        unregister(this);
281}
282
283//=============================================================================================
284// Kernel Scheduling logic
285//=============================================================================================
286//Main of the processor contexts
287void main(processorCtx_t & runner) {
288        // Because of a bug, we couldn't initialized the seed on construction
289        // Do it here
290        kernelTLS.rand_seed ^= rdtscl();
291
292        processor * this = runner.proc;
293        verify(this);
294
295        __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
296
297        doregister(this->cltr, this);
298
299        {
300                // Setup preemption data
301                preemption_scope scope = { this };
302
303                __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
304
305                $thread * readyThread = 0p;
306                for( unsigned int spin_count = 0; ! __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST); spin_count++ ) {
307                        // Try to get the next thread
308                        readyThread = __next_thread( this->cltr );
309
310                        // If no ready thread
311                        if( readyThread == 0p ) {
312                                // Block until a thread is ready
313                                readyThread = __halt(this);
314                        }
315
316                        // Check if we actually found a thread
317                        if( readyThread ) {
318                                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
319                                /* paranoid */ verifyf( readyThread->state == Ready || readyThread->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", readyThread->state, readyThread->preempted);
320                                /* paranoid */ verifyf( readyThread->next == 0p, "Expected null got %p", readyThread->next );
321
322                                // We found a thread run it
323                                __run_thread(this, readyThread);
324
325                                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
326                        }
327                }
328
329                __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
330        }
331
332        unregister(this->cltr, this);
333
334        V( this->terminated );
335
336        __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
337
338        // HACK : the coroutine context switch expects this_thread to be set
339        // and it make sense for it to be set in all other cases except here
340        // fake it
341        if( this == mainProcessor ) kernelTLS.this_thread = mainThread;
342}
343
344static int * __volatile_errno() __attribute__((noinline));
345static int * __volatile_errno() { asm(""); return &errno; }
346
347// KERNEL ONLY
348// runThread runs a thread by context switching
349// from the processor coroutine to the target thread
350static void __run_thread(processor * this, $thread * thrd_dst) {
351        $coroutine * proc_cor = get_coroutine(this->runner);
352
353        // Update global state
354        kernelTLS.this_thread = thrd_dst;
355
356        // set state of processor coroutine to inactive
357        verify(proc_cor->state == Active);
358        proc_cor->state = Blocked;
359
360        // Actually run the thread
361        RUNNING:  while(true) {
362                if(unlikely(thrd_dst->preempted)) {
363                        thrd_dst->preempted = __NO_PREEMPTION;
364                        verify(thrd_dst->state == Active  || thrd_dst->state == Rerun);
365                } else {
366                        verify(thrd_dst->state == Blocked || thrd_dst->state == Ready); // Ready means scheduled normally, blocked means rerun
367                        thrd_dst->state = Active;
368                }
369
370                __cfaabi_dbg_debug_do(
371                        thrd_dst->park_stale   = true;
372                        thrd_dst->unpark_stale = true;
373                )
374
375                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
376                /* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
377                /* 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
378                /* 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
379
380                // set context switch to the thread that the processor is executing
381                verify( thrd_dst->context.SP );
382                __cfactx_switch( &proc_cor->context, &thrd_dst->context );
383                // when __cfactx_switch returns we are back in the processor coroutine
384
385                /* 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 );
386                /* 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 );
387                /* paranoid */ verify( kernelTLS.this_thread == thrd_dst );
388                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
389
390
391                // We just finished running a thread, there are a few things that could have happened.
392                // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
393                // 2 - Racy case    : the thread has blocked but someone has already tried to schedule it.
394                // 4 - Preempted
395                // In case 1, we may have won a race so we can't write to the state again.
396                // In case 2, we lost the race so we now own the thread.
397
398                if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
399                        // The thread was preempted, reschedule it and reset the flag
400                        __schedule_thread( thrd_dst );
401                        break RUNNING;
402                }
403
404                // set state of processor coroutine to active and the thread to inactive
405                static_assert(sizeof(thrd_dst->state) == sizeof(int));
406                enum coroutine_state old_state = __atomic_exchange_n(&thrd_dst->state, Blocked, __ATOMIC_SEQ_CST);
407                __cfaabi_dbg_debug_do( thrd_dst->park_result = old_state; )
408                switch(old_state) {
409                        case Halted:
410                                // The thread has halted, it should never be scheduled/run again, leave it back to Halted and move on
411                                thrd_dst->state = Halted;
412
413                                // We may need to wake someone up here since
414                                unpark( this->destroyer __cfaabi_dbg_ctx2 );
415                                this->destroyer = 0p;
416                                break RUNNING;
417                        case Active:
418                                // This is case 1, the regular case, nothing more is needed
419                                break RUNNING;
420                        case Rerun:
421                                // This is case 2, the racy case, someone tried to run this thread before it finished blocking
422                                // In this case, just run it again.
423                                continue RUNNING;
424                        default:
425                                // This makes no sense, something is wrong abort
426                                abort("Finished running a thread that was Blocked/Start/Primed %d\n", old_state);
427                }
428        }
429
430        // Just before returning to the processor, set the processor coroutine to active
431        proc_cor->state = Active;
432        kernelTLS.this_thread = 0p;
433}
434
435// KERNEL_ONLY
436void returnToKernel() {
437        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
438        $coroutine * proc_cor = get_coroutine(kernelTLS.this_processor->runner);
439        $thread * thrd_src = kernelTLS.this_thread;
440
441        // Run the thread on this processor
442        {
443                int local_errno = *__volatile_errno();
444                #if defined( __i386 ) || defined( __x86_64 )
445                        __x87_store;
446                #endif
447                verify( proc_cor->context.SP );
448                __cfactx_switch( &thrd_src->context, &proc_cor->context );
449                #if defined( __i386 ) || defined( __x86_64 )
450                        __x87_load;
451                #endif
452                *__volatile_errno() = local_errno;
453        }
454
455        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
456        /* 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 );
457        /* 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 );
458}
459
460// KERNEL_ONLY
461// Context invoker for processors
462// This is the entry point for processors (kernel threads)
463// It effectively constructs a coroutine by stealing the pthread stack
464static void * __invoke_processor(void * arg) {
465        processor * proc = (processor *) arg;
466        kernelTLS.this_processor = proc;
467        kernelTLS.this_thread    = 0p;
468        kernelTLS.preemption_state.[enabled, disable_count] = [false, 1];
469        // SKULLDUGGERY: We want to create a context for the processor coroutine
470        // which is needed for the 2-step context switch. However, there is no reason
471        // to waste the perfectly valid stack create by pthread.
472        current_stack_info_t info;
473        __stack_t ctx;
474        info.storage = &ctx;
475        (proc->runner){ proc, &info };
476
477        __cfaabi_dbg_print_safe("Coroutine : created stack %p\n", get_coroutine(proc->runner)->stack.storage);
478
479        //Set global state
480        kernelTLS.this_thread = 0p;
481
482        //We now have a proper context from which to schedule threads
483        __cfadbg_print_safe(runtime_core, "Kernel : core %p created (%p, %p)\n", proc, &proc->runner, &ctx);
484
485        // SKULLDUGGERY: Since the coroutine doesn't have its own stack, we can't
486        // resume it to start it like it normally would, it will just context switch
487        // back to here. Instead directly call the main since we already are on the
488        // appropriate stack.
489        get_coroutine(proc->runner)->state = Active;
490        main( proc->runner );
491        get_coroutine(proc->runner)->state = Halted;
492
493        // Main routine of the core returned, the core is now fully terminated
494        __cfadbg_print_safe(runtime_core, "Kernel : core %p main ended (%p)\n", proc, &proc->runner);
495
496        return 0p;
497}
498
499static void Abort( int ret, const char func[] ) {
500        if ( ret ) {                                                                            // pthread routines return errno values
501                abort( "%s : internal error, error(%d) %s.", func, ret, strerror( ret ) );
502        } // if
503} // Abort
504
505void * __create_pthread( pthread_t * pthread, void * (*start)(void *), void * arg ) {
506        pthread_attr_t attr;
507
508        Abort( pthread_attr_init( &attr ), "pthread_attr_init" ); // initialize attribute
509
510        size_t stacksize;
511        // default stack size, normally defined by shell limit
512        Abort( pthread_attr_getstacksize( &attr, &stacksize ), "pthread_attr_getstacksize" );
513        assert( stacksize >= PTHREAD_STACK_MIN );
514
515        void * stack;
516        __cfaabi_dbg_debug_do(
517                stack = memalign( __page_size, stacksize + __page_size );
518                // pthread has no mechanism to create the guard page in user supplied stack.
519                if ( mprotect( stack, __page_size, PROT_NONE ) == -1 ) {
520                        abort( "mprotect : internal error, mprotect failure, error(%d) %s.", errno, strerror( errno ) );
521                } // if
522        );
523        __cfaabi_dbg_no_debug_do(
524                stack = malloc( stacksize );
525        );
526
527        Abort( pthread_attr_setstack( &attr, stack, stacksize ), "pthread_attr_setstack" );
528
529        Abort( pthread_create( pthread, &attr, start, arg ), "pthread_create" );
530        return stack;
531}
532
533// KERNEL_ONLY
534static void __kernel_first_resume( processor * this ) {
535        $thread * src = mainThread;
536        $coroutine * dst = get_coroutine(this->runner);
537
538        verify( ! kernelTLS.preemption_state.enabled );
539
540        kernelTLS.this_thread->curr_cor = dst;
541        __stack_prepare( &dst->stack, 65000 );
542        __cfactx_start(main, dst, this->runner, __cfactx_invoke_coroutine);
543
544        verify( ! kernelTLS.preemption_state.enabled );
545
546        dst->last = &src->self_cor;
547        dst->starter = dst->starter ? dst->starter : &src->self_cor;
548
549        // make sure the current state is still correct
550        /* paranoid */ verify(src->state == Ready);
551
552        // context switch to specified coroutine
553        verify( dst->context.SP );
554        __cfactx_switch( &src->context, &dst->context );
555        // when __cfactx_switch returns we are back in the src coroutine
556
557        mainThread->curr_cor = &mainThread->self_cor;
558
559        // make sure the current state has been update
560        /* paranoid */ verify(src->state == Active);
561
562        verify( ! kernelTLS.preemption_state.enabled );
563}
564
565// KERNEL_ONLY
566static void __kernel_last_resume( processor * this ) {
567        $coroutine * src = &mainThread->self_cor;
568        $coroutine * dst = get_coroutine(this->runner);
569
570        verify( ! kernelTLS.preemption_state.enabled );
571        verify( dst->starter == src );
572        verify( dst->context.SP );
573
574        // SKULLDUGGERY in debug the processors check that the
575        // stack is still within the limit of the stack limits after running a thread.
576        // that check doesn't make sense if we context switch to the processor using the
577        // coroutine semantics. Since this is a special case, use the current context
578        // info to populate these fields.
579        __cfaabi_dbg_debug_do(
580                __stack_context_t ctx;
581                CtxGet( ctx );
582                mainThread->context.SP = ctx.SP;
583                mainThread->context.FP = ctx.FP;
584        )
585
586        // context switch to the processor
587        __cfactx_switch( &src->context, &dst->context );
588}
589
590//-----------------------------------------------------------------------------
591// Scheduler routines
592// KERNEL ONLY
593void __schedule_thread( $thread * thrd ) with( *thrd->curr_cluster ) {
594        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
595        /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
596        /* paranoid */ if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
597                          "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
598        /* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active || thrd->state == Rerun,
599                          "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
600        /* paranoid */ #endif
601        /* paranoid */ verifyf( thrd->next == 0p, "Expected null got %p", thrd->next );
602
603        if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
604
605        lock  ( ready_queue_lock __cfaabi_dbg_ctx2 );
606        bool was_empty = !(ready_queue != 0);
607        append( ready_queue, thrd );
608        unlock( ready_queue_lock );
609
610        __wake_one(thrd->curr_cluster, was_empty);
611
612        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
613}
614
615// KERNEL ONLY
616static $thread * __next_thread(cluster * this) with( *this ) {
617        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
618
619        lock( ready_queue_lock __cfaabi_dbg_ctx2 );
620        $thread * head = pop_head( ready_queue );
621        unlock( ready_queue_lock );
622
623        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
624        return head;
625}
626
627// KERNEL ONLY unpark with out disabling interrupts
628void __unpark( $thread * thrd __cfaabi_dbg_ctx_param2 ) {
629        static_assert(sizeof(thrd->state) == sizeof(int));
630
631        // record activity
632        __cfaabi_dbg_record_thrd( *thrd, false, caller );
633
634        enum coroutine_state old_state = __atomic_exchange_n(&thrd->state, Rerun, __ATOMIC_SEQ_CST);
635        __cfaabi_dbg_debug_do( thrd->unpark_result = old_state; )
636        switch(old_state) {
637                case Active:
638                        // Wake won the race, the thread will reschedule/rerun itself
639                        break;
640                case Blocked:
641                        /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
642
643                        // Wake lost the race,
644                        thrd->state = Blocked;
645                        __schedule_thread( thrd );
646                        break;
647                case Rerun:
648                        abort("More than one thread attempted to schedule thread %p\n", thrd);
649                        break;
650                case Halted:
651                case Start:
652                case Primed:
653                default:
654                        // This makes no sense, something is wrong abort
655                        abort();
656        }
657}
658
659void unpark( $thread * thrd __cfaabi_dbg_ctx_param2 ) {
660        if( !thrd ) return;
661
662        disable_interrupts();
663        __unpark( thrd __cfaabi_dbg_ctx_fwd2 );
664        enable_interrupts( __cfaabi_dbg_ctx );
665}
666
667void park( __cfaabi_dbg_ctx_param ) {
668        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
669        disable_interrupts();
670        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
671        /* paranoid */ verify( kernelTLS.this_thread->preempted == __NO_PREEMPTION );
672
673        // record activity
674        __cfaabi_dbg_record_thrd( *kernelTLS.this_thread, true, caller );
675
676        returnToKernel();
677
678        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
679        enable_interrupts( __cfaabi_dbg_ctx );
680        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
681
682}
683
684// KERNEL ONLY
685void __leave_thread() {
686        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
687        returnToKernel();
688        abort();
689}
690
691// KERNEL ONLY
692bool force_yield( __Preemption_Reason reason ) {
693        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
694        disable_interrupts();
695        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
696
697        $thread * thrd = kernelTLS.this_thread;
698        /* paranoid */ verify(thrd->state == Active || thrd->state == Rerun);
699
700        // SKULLDUGGERY: It is possible that we are preempting this thread just before
701        // it was going to park itself. If that is the case and it is already using the
702        // intrusive fields then we can't use them to preempt the thread
703        // If that is the case, abandon the preemption.
704        bool preempted = false;
705        if(thrd->next == 0p) {
706                preempted = true;
707                thrd->preempted = reason;
708                returnToKernel();
709        }
710
711        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
712        enable_interrupts_noPoll();
713        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
714
715        return preempted;
716}
717
718//=============================================================================================
719// Kernel Setup logic
720//=============================================================================================
721//-----------------------------------------------------------------------------
722// Kernel boot procedures
723static void __kernel_startup(void) {
724        verify( ! kernelTLS.preemption_state.enabled );
725        __cfadbg_print_safe(runtime_core, "Kernel : Starting\n");
726
727        __page_size = sysconf( _SC_PAGESIZE );
728
729        __cfa_dbg_global_clusters.list{ __get };
730        __cfa_dbg_global_clusters.lock{};
731
732        // Initialize the main cluster
733        mainCluster = (cluster *)&storage_mainCluster;
734        (*mainCluster){"Main Cluster"};
735
736        __cfadbg_print_safe(runtime_core, "Kernel : Main cluster ready\n");
737
738        // Start by initializing the main thread
739        // SKULLDUGGERY: the mainThread steals the process main thread
740        // which will then be scheduled by the mainProcessor normally
741        mainThread = ($thread *)&storage_mainThread;
742        current_stack_info_t info;
743        info.storage = (__stack_t*)&storage_mainThreadCtx;
744        (*mainThread){ &info };
745
746        __cfadbg_print_safe(runtime_core, "Kernel : Main thread ready\n");
747
748
749
750        // Construct the processor context of the main processor
751        void ?{}(processorCtx_t & this, processor * proc) {
752                (this.__cor){ "Processor" };
753                this.__cor.starter = 0p;
754                this.proc = proc;
755        }
756
757        void ?{}(processor & this) with( this ) {
758                name = "Main Processor";
759                cltr = mainCluster;
760                terminated{ 0 };
761                do_terminate = false;
762                preemption_alarm = 0p;
763                pending_preemption = false;
764                kernel_thread = pthread_self();
765
766                runner{ &this };
767                __cfadbg_print_safe(runtime_core, "Kernel : constructed main processor context %p\n", &runner);
768        }
769
770        // Initialize the main processor and the main processor ctx
771        // (the coroutine that contains the processing control flow)
772        mainProcessor = (processor *)&storage_mainProcessor;
773        (*mainProcessor){};
774
775        //initialize the global state variables
776        kernelTLS.this_processor = mainProcessor;
777        kernelTLS.this_thread    = mainThread;
778
779        // Enable preemption
780        kernel_start_preemption();
781
782        // Add the main thread to the ready queue
783        // once resume is called on mainProcessor->runner the mainThread needs to be scheduled like any normal thread
784        __schedule_thread(mainThread);
785
786        // SKULLDUGGERY: Force a context switch to the main processor to set the main thread's context to the current UNIX
787        // context. Hence, the main thread does not begin through __cfactx_invoke_thread, like all other threads. The trick here is that
788        // mainThread is on the ready queue when this call is made.
789        __kernel_first_resume( kernelTLS.this_processor );
790
791
792        // THE SYSTEM IS NOW COMPLETELY RUNNING
793
794
795        // Now that the system is up, finish creating systems that need threading
796        __kernel_io_finish_start( *mainCluster );
797
798
799        __cfadbg_print_safe(runtime_core, "Kernel : Started\n--------------------------------------------------\n\n");
800
801        verify( ! kernelTLS.preemption_state.enabled );
802        enable_interrupts( __cfaabi_dbg_ctx );
803        verify( TL_GET( preemption_state.enabled ) );
804}
805
806static void __kernel_shutdown(void) {
807        //Before we start shutting things down, wait for systems that need threading to shutdown
808        __kernel_io_prepare_stop( *mainCluster );
809
810        /* paranoid */ verify( TL_GET( preemption_state.enabled ) );
811        disable_interrupts();
812        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
813
814        __cfadbg_print_safe(runtime_core, "\n--------------------------------------------------\nKernel : Shutting down\n");
815
816        // SKULLDUGGERY: Notify the mainProcessor it needs to terminates.
817        // When its coroutine terminates, it return control to the mainThread
818        // which is currently here
819        __atomic_store_n(&mainProcessor->do_terminate, true, __ATOMIC_RELEASE);
820        __kernel_last_resume( kernelTLS.this_processor );
821        mainThread->self_cor.state = Halted;
822
823        // THE SYSTEM IS NOW COMPLETELY STOPPED
824
825        // Disable preemption
826        kernel_stop_preemption();
827
828        // Destroy the main processor and its context in reverse order of construction
829        // These were manually constructed so we need manually destroy them
830        void ^?{}(processor & this) with( this ){
831                /* paranoid */ verify( this.do_terminate == true );
832        }
833
834        ^(*mainProcessor){};
835
836        // Final step, destroy the main thread since it is no longer needed
837        // Since we provided a stack to this taxk it will not destroy anything
838        /* paranoid */ verify(mainThread->self_cor.stack.storage == (__stack_t*)(((uintptr_t)&storage_mainThreadCtx)| 0x1));
839        ^(*mainThread){};
840
841        ^(*mainCluster){};
842
843        ^(__cfa_dbg_global_clusters.list){};
844        ^(__cfa_dbg_global_clusters.lock){};
845
846        __cfadbg_print_safe(runtime_core, "Kernel : Shutdown complete\n");
847}
848
849//=============================================================================================
850// Kernel Idle Sleep
851//=============================================================================================
852static $thread * __halt(processor * this) with( *this ) {
853        if( do_terminate ) return 0p;
854
855        // First, lock the cluster idle
856        lock( cltr->idle_lock __cfaabi_dbg_ctx2 );
857
858        // Check if we can find a thread
859        if( $thread * found = __next_thread( cltr ) ) {
860                unlock( cltr->idle_lock );
861                return found;
862        }
863
864        // Move this processor from the active list to the idle list
865        move_to_front(cltr->procs, cltr->idles, *this);
866
867        // Unlock the idle lock so we don't go to sleep with a lock
868        unlock    (cltr->idle_lock);
869
870        // We are ready to sleep
871        __cfadbg_print_safe(runtime_core, "Kernel : Processor %p ready to sleep\n", this);
872        wait( idle );
873
874        // We have woken up
875        __cfadbg_print_safe(runtime_core, "Kernel : Processor %p woke up and ready to run\n", this);
876
877        // Get ourself off the idle list
878        with( *cltr ) {
879                lock  (idle_lock __cfaabi_dbg_ctx2);
880                move_to_front(idles, procs, *this);
881                unlock(idle_lock);
882        }
883
884        // Don't check the ready queue again, we may not be in a position to run a thread
885        return 0p;
886}
887
888// Wake a thread from the front if there are any
889static bool __wake_one(cluster * this, __attribute__((unused)) bool force) {
890        // if we don't want to force check if we know it's false
891        // if( !this->idles.head && !force ) return false;
892
893        // First, lock the cluster idle
894        lock( this->idle_lock __cfaabi_dbg_ctx2 );
895
896        // Check if there is someone to wake up
897        if( !this->idles.head ) {
898                // Nope unlock and return false
899                unlock( this->idle_lock );
900                return false;
901        }
902
903        // Wake them up
904        __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this->idles.head);
905        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
906        post( this->idles.head->idle );
907
908        // Unlock and return true
909        unlock( this->idle_lock );
910        return true;
911}
912
913// Unconditionnaly wake a thread
914static bool __wake_proc(processor * this) {
915        __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
916
917        disable_interrupts();
918                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
919                bool ret = post( this->idle );
920        enable_interrupts( __cfaabi_dbg_ctx );
921
922        return ret;
923}
924
925//=============================================================================================
926// Unexpected Terminating logic
927//=============================================================================================
928static __spinlock_t kernel_abort_lock;
929static bool kernel_abort_called = false;
930
931void * kernel_abort(void) __attribute__ ((__nothrow__)) {
932        // abort cannot be recursively entered by the same or different processors because all signal handlers return when
933        // the globalAbort flag is true.
934        lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
935
936        // first task to abort ?
937        if ( kernel_abort_called ) {                    // not first task to abort ?
938                unlock( kernel_abort_lock );
939
940                sigset_t mask;
941                sigemptyset( &mask );
942                sigaddset( &mask, SIGALRM );            // block SIGALRM signals
943                sigaddset( &mask, SIGUSR1 );            // block SIGALRM signals
944                sigsuspend( &mask );                            // block the processor to prevent further damage during abort
945                _exit( EXIT_FAILURE );                          // if processor unblocks before it is killed, terminate it
946        }
947        else {
948                kernel_abort_called = true;
949                unlock( kernel_abort_lock );
950        }
951
952        return kernelTLS.this_thread;
953}
954
955void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
956        $thread * thrd = kernel_data;
957
958        if(thrd) {
959                int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
960                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
961
962                if ( &thrd->self_cor != thrd->curr_cor ) {
963                        len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
964                        __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
965                }
966                else {
967                        __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
968                }
969        }
970        else {
971                int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
972                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
973        }
974}
975
976int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
977        return get_coroutine(kernelTLS.this_thread) == get_coroutine(mainThread) ? 4 : 2;
978}
979
980static __spinlock_t kernel_debug_lock;
981
982extern "C" {
983        void __cfaabi_bits_acquire() {
984                lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
985        }
986
987        void __cfaabi_bits_release() {
988                unlock( kernel_debug_lock );
989        }
990}
991
992//=============================================================================================
993// Kernel Utilities
994//=============================================================================================
995//-----------------------------------------------------------------------------
996// Locks
997void  ?{}( semaphore & this, int count = 1 ) {
998        (this.lock){};
999        this.count = count;
1000        (this.waiting){};
1001}
1002void ^?{}(semaphore & this) {}
1003
1004bool P(semaphore & this) with( this ){
1005        lock( lock __cfaabi_dbg_ctx2 );
1006        count -= 1;
1007        if ( count < 0 ) {
1008                // queue current task
1009                append( waiting, kernelTLS.this_thread );
1010
1011                // atomically release spin lock and block
1012                unlock( lock );
1013                park( __cfaabi_dbg_ctx );
1014                return true;
1015        }
1016        else {
1017            unlock( lock );
1018            return false;
1019        }
1020}
1021
1022bool V(semaphore & this) with( this ) {
1023        $thread * thrd = 0p;
1024        lock( lock __cfaabi_dbg_ctx2 );
1025        count += 1;
1026        if ( count <= 0 ) {
1027                // remove task at head of waiting list
1028                thrd = pop_head( waiting );
1029        }
1030
1031        unlock( lock );
1032
1033        // make new owner
1034        unpark( thrd __cfaabi_dbg_ctx2 );
1035
1036        return thrd != 0p;
1037}
1038
1039bool V(semaphore & this, unsigned diff) with( this ) {
1040        $thread * thrd = 0p;
1041        lock( lock __cfaabi_dbg_ctx2 );
1042        int release = max(-count, (int)diff);
1043        count += diff;
1044        for(release) {
1045                unpark( pop_head( waiting ) __cfaabi_dbg_ctx2 );
1046        }
1047
1048        unlock( lock );
1049
1050        return thrd != 0p;
1051}
1052
1053//-----------------------------------------------------------------------------
1054// Global Queues
1055void doregister( cluster     & cltr ) {
1056        lock      ( __cfa_dbg_global_clusters.lock __cfaabi_dbg_ctx2);
1057        push_front( __cfa_dbg_global_clusters.list, cltr );
1058        unlock    ( __cfa_dbg_global_clusters.lock );
1059}
1060
1061void unregister( cluster     & cltr ) {
1062        lock  ( __cfa_dbg_global_clusters.lock __cfaabi_dbg_ctx2);
1063        remove( __cfa_dbg_global_clusters.list, cltr );
1064        unlock( __cfa_dbg_global_clusters.lock );
1065}
1066
1067void doregister( cluster * cltr, $thread & thrd ) {
1068        lock      (cltr->thread_list_lock __cfaabi_dbg_ctx2);
1069        cltr->nthreads += 1;
1070        push_front(cltr->threads, thrd);
1071        unlock    (cltr->thread_list_lock);
1072}
1073
1074void unregister( cluster * cltr, $thread & thrd ) {
1075        lock  (cltr->thread_list_lock __cfaabi_dbg_ctx2);
1076        remove(cltr->threads, thrd );
1077        cltr->nthreads -= 1;
1078        unlock(cltr->thread_list_lock);
1079}
1080
1081void doregister( cluster * cltr, processor * proc ) {
1082        lock      (cltr->idle_lock __cfaabi_dbg_ctx2);
1083        cltr->nprocessors += 1;
1084        push_front(cltr->procs, *proc);
1085        unlock    (cltr->idle_lock);
1086}
1087
1088void unregister( cluster * cltr, processor * proc ) {
1089        lock  (cltr->idle_lock __cfaabi_dbg_ctx2);
1090        remove(cltr->procs, *proc );
1091        cltr->nprocessors -= 1;
1092        unlock(cltr->idle_lock);
1093}
1094
1095//-----------------------------------------------------------------------------
1096// Debug
1097__cfaabi_dbg_debug_do(
1098        extern "C" {
1099                void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
1100                        this.prev_name = prev_name;
1101                        this.prev_thrd = kernelTLS.this_thread;
1102                }
1103
1104                void __cfaabi_dbg_record_thrd($thread & this, bool park, const char prev_name[]) {
1105                        if(park) {
1106                                this.park_caller   = prev_name;
1107                                this.park_stale    = false;
1108                        }
1109                        else {
1110                                this.unpark_caller = prev_name;
1111                                this.unpark_stale  = false;
1112                        }
1113                }
1114        }
1115)
1116
1117//-----------------------------------------------------------------------------
1118// Debug
1119bool threading_enabled(void) __attribute__((const)) {
1120        return true;
1121}
1122// Local Variables: //
1123// mode: c //
1124// tab-width: 4 //
1125// End: //
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