source: libcfa/src/concurrency/kernel.cfa @ 210b8b3

arm-ehenumforall-pointer-decayjacob/cs343-translationnew-astnew-ast-unique-exprpthread-emulationqualifiedEnum
Last change on this file since 210b8b3 was 210b8b3, checked in by Thierry Delisle <tdelisle@…>, 3 years ago

Added checks that the stack pointer is consistent when running and returning from a thread

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File size: 30.9 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
18//C Includes
19#include <stddef.h>
20#include <errno.h>
21#include <string.h>
22extern "C" {
23#include <stdio.h>
24#include <fenv.h>
25#include <sys/resource.h>
26#include <signal.h>
27#include <unistd.h>
28#include <limits.h>                                                                             // PTHREAD_STACK_MIN
29#include <sys/mman.h>                                                                   // mprotect
30}
31
32//CFA Includes
33#include "time.hfa"
34#include "kernel_private.hfa"
35#include "preemption.hfa"
36#include "startup.hfa"
37
38//Private includes
39#define __CFA_INVOKE_PRIVATE__
40#include "invoke.h"
41
42//-----------------------------------------------------------------------------
43// Some assembly required
44#if defined( __i386 )
45        #define CtxGet( ctx )        \
46                __asm__ volatile (     \
47                        "movl %%esp,%0\n"\
48                        "movl %%ebp,%1\n"\
49                        : "=rm" (ctx.SP),\
50                                "=rm" (ctx.FP) \
51                )
52
53        // mxcr : SSE Status and Control bits (control bits are preserved across function calls)
54        // fcw  : X87 FPU control word (preserved across function calls)
55        #define __x87_store         \
56                uint32_t __mxcr;      \
57                uint16_t __fcw;       \
58                __asm__ volatile (    \
59                        "stmxcsr %0\n"  \
60                        "fnstcw  %1\n"  \
61                        : "=m" (__mxcr),\
62                                "=m" (__fcw)  \
63                )
64
65        #define __x87_load         \
66                __asm__ volatile (   \
67                        "fldcw  %1\n"  \
68                        "ldmxcsr %0\n" \
69                        ::"m" (__mxcr),\
70                                "m" (__fcw)  \
71                )
72
73#elif defined( __x86_64 )
74        #define CtxGet( ctx )        \
75                __asm__ volatile (     \
76                        "movq %%rsp,%0\n"\
77                        "movq %%rbp,%1\n"\
78                        : "=rm" (ctx.SP),\
79                                "=rm" (ctx.FP) \
80                )
81
82        #define __x87_store         \
83                uint32_t __mxcr;      \
84                uint16_t __fcw;       \
85                __asm__ volatile (    \
86                        "stmxcsr %0\n"  \
87                        "fnstcw  %1\n"  \
88                        : "=m" (__mxcr),\
89                                "=m" (__fcw)  \
90                )
91
92        #define __x87_load          \
93                __asm__ volatile (    \
94                        "fldcw  %1\n"   \
95                        "ldmxcsr %0\n"  \
96                        :: "m" (__mxcr),\
97                                "m" (__fcw)  \
98                )
99
100
101#elif defined( __ARM_ARCH )
102#define CtxGet( ctx ) __asm__ ( \
103                "mov %0,%%sp\n"   \
104                "mov %1,%%r11\n"   \
105        : "=rm" (ctx.SP), "=rm" (ctx.FP) )
106#else
107        #error unknown hardware architecture
108#endif
109
110//-----------------------------------------------------------------------------
111//Start and stop routine for the kernel, declared first to make sure they run first
112static void __kernel_startup (void) __attribute__(( constructor( STARTUP_PRIORITY_KERNEL ) ));
113static void __kernel_shutdown(void) __attribute__(( destructor ( STARTUP_PRIORITY_KERNEL ) ));
114
115//-----------------------------------------------------------------------------
116// Kernel storage
117KERNEL_STORAGE(cluster,         mainCluster);
118KERNEL_STORAGE(processor,       mainProcessor);
119KERNEL_STORAGE($thread, mainThread);
120KERNEL_STORAGE(__stack_t,       mainThreadCtx);
121
122cluster     * mainCluster;
123processor   * mainProcessor;
124$thread * mainThread;
125
126extern "C" {
127        struct { __dllist_t(cluster) list; __spinlock_t lock; } __cfa_dbg_global_clusters;
128}
129
130size_t __page_size = 0;
131
132//-----------------------------------------------------------------------------
133// Global state
134thread_local struct KernelThreadData kernelTLS __attribute__ ((tls_model ( "initial-exec" ))) = {
135        NULL,                                                                                           // cannot use 0p
136        NULL,
137        { 1, false, false },
138        6u //this should be seeded better but due to a bug calling rdtsc doesn't work
139};
140
141//-----------------------------------------------------------------------------
142// Struct to steal stack
143struct current_stack_info_t {
144        __stack_t * storage;                                                            // pointer to stack object
145        void * base;                                                                            // base of stack
146        void * limit;                                                                           // stack grows towards stack limit
147        void * context;                                                                         // address of cfa_context_t
148};
149
150void ?{}( current_stack_info_t & this ) {
151        __stack_context_t ctx;
152        CtxGet( ctx );
153        this.base = ctx.FP;
154
155        rlimit r;
156        getrlimit( RLIMIT_STACK, &r);
157        size_t size = r.rlim_cur;
158
159        this.limit = (void *)(((intptr_t)this.base) - size);
160        this.context = &storage_mainThreadCtx;
161}
162
163//-----------------------------------------------------------------------------
164// Main thread construction
165
166void ?{}( $coroutine & this, current_stack_info_t * info) with( this ) {
167        stack.storage = info->storage;
168        with(*stack.storage) {
169                limit     = info->limit;
170                base      = info->base;
171        }
172        __attribute__((may_alias)) intptr_t * istorage = (intptr_t*) &stack.storage;
173        *istorage |= 0x1;
174        name = "Main Thread";
175        state = Start;
176        starter = 0p;
177        last = 0p;
178        cancellation = 0p;
179}
180
181void ?{}( $thread & this, current_stack_info_t * info) with( this ) {
182        state = Start;
183        self_cor{ info };
184        curr_cor = &self_cor;
185        curr_cluster = mainCluster;
186        self_mon.owner = &this;
187        self_mon.recursion = 1;
188        self_mon_p = &self_mon;
189        next = 0p;
190
191        node.next = 0p;
192        node.prev = 0p;
193        doregister(curr_cluster, this);
194
195        monitors{ &self_mon_p, 1, (fptr_t)0 };
196}
197
198//-----------------------------------------------------------------------------
199// Processor coroutine
200void ?{}(processorCtx_t & this) {
201
202}
203
204// Construct the processor context of non-main processors
205static void ?{}(processorCtx_t & this, processor * proc, current_stack_info_t * info) {
206        (this.__cor){ info };
207        this.proc = proc;
208}
209
210static void * __invoke_processor(void * arg);
211
212void ?{}(processor & this, const char name[], cluster & cltr) with( this ) {
213        this.name = name;
214        this.cltr = &cltr;
215        terminated{ 0 };
216        destroyer = 0p;
217        do_terminate = false;
218        preemption_alarm = 0p;
219        pending_preemption = false;
220        runner.proc = &this;
221
222        idleLock{};
223
224        __cfaabi_dbg_print_safe("Kernel : Starting core %p\n", &this);
225
226        this.stack = __create_pthread( &this.kernel_thread, __invoke_processor, (void *)&this );
227
228        __cfaabi_dbg_print_safe("Kernel : core %p started\n", &this);
229}
230
231void ^?{}(processor & this) with( this ){
232        if( ! __atomic_load_n(&do_terminate, __ATOMIC_ACQUIRE) ) {
233                __cfaabi_dbg_print_safe("Kernel : core %p signaling termination\n", &this);
234
235                __atomic_store_n(&do_terminate, true, __ATOMIC_RELAXED);
236                wake( &this );
237
238                P( terminated );
239                verify( kernelTLS.this_processor != &this);
240        }
241
242        pthread_join( kernel_thread, 0p );
243        free( this.stack );
244}
245
246void ?{}(cluster & this, const char name[], Duration preemption_rate) with( this ) {
247        this.name = name;
248        this.preemption_rate = preemption_rate;
249        ready_queue{};
250        ready_queue_lock{};
251
252        procs{ __get };
253        idles{ __get };
254        threads{ __get };
255
256        doregister(this);
257}
258
259void ^?{}(cluster & this) {
260        unregister(this);
261}
262
263//=============================================================================================
264// Kernel Scheduling logic
265//=============================================================================================
266static $thread * __next_thread(cluster * this);
267static void __run_thread(processor * this, $thread * dst);
268static void __halt(processor * this);
269
270//Main of the processor contexts
271void main(processorCtx_t & runner) {
272        // Because of a bug, we couldn't initialized the seed on construction
273        // Do it here
274        kernelTLS.rand_seed ^= rdtscl();
275
276        processor * this = runner.proc;
277        verify(this);
278
279        __cfaabi_dbg_print_safe("Kernel : core %p starting\n", this);
280
281        doregister(this->cltr, this);
282
283        {
284                // Setup preemption data
285                preemption_scope scope = { this };
286
287                __cfaabi_dbg_print_safe("Kernel : core %p started\n", this);
288
289                $thread * readyThread = 0p;
290                for( unsigned int spin_count = 0; ! __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST); spin_count++ ) {
291                        readyThread = __next_thread( this->cltr );
292
293                        if(readyThread) {
294                                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
295                                /* paranoid */ verifyf( readyThread->state == Inactive || readyThread->state == Start || readyThread->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", readyThread->state, readyThread->preempted);
296                                /* paranoid */ verifyf( readyThread->next == 0p, "Expected null got %p", readyThread->next );
297
298                                __run_thread(this, readyThread);
299
300                                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
301
302                                spin_count = 0;
303                        } else {
304                                // spin(this, &spin_count);
305                                __halt(this);
306                        }
307                }
308
309                __cfaabi_dbg_print_safe("Kernel : core %p stopping\n", this);
310        }
311
312        unregister(this->cltr, this);
313
314        V( this->terminated );
315
316        __cfaabi_dbg_print_safe("Kernel : core %p terminated\n", this);
317}
318
319static int * __volatile_errno() __attribute__((noinline));
320static int * __volatile_errno() { asm(""); return &errno; }
321
322// KERNEL ONLY
323// runThread runs a thread by context switching
324// from the processor coroutine to the target thread
325static void __run_thread(processor * this, $thread * thrd_dst) {
326        $coroutine * proc_cor = get_coroutine(this->runner);
327
328        // Update global state
329        kernelTLS.this_thread = thrd_dst;
330
331        // set state of processor coroutine to inactive
332        verify(proc_cor->state == Active);
333        proc_cor->state = Inactive;
334
335        // Actually run the thread
336        RUNNING:  while(true) {
337                if(unlikely(thrd_dst->preempted)) {
338                        thrd_dst->preempted = __NO_PREEMPTION;
339                        verify(thrd_dst->state == Active || thrd_dst->state == Rerun);
340                } else {
341                        verify(thrd_dst->state == Start || thrd_dst->state == Primed || thrd_dst->state == Inactive);
342                        thrd_dst->state = Active;
343                }
344
345                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
346                /* 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
347                /* 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
348
349                // set context switch to the thread that the processor is executing
350                verify( thrd_dst->context.SP );
351                __cfactx_switch( &proc_cor->context, &thrd_dst->context );
352                // when __cfactx_switch returns we are back in the processor coroutine
353
354                /* 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 );
355                /* 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 );
356                /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
357
358
359                // We just finished running a thread, there are a few things that could have happened.
360                // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
361                // 2 - Racy case    : the thread has blocked but someone has already tried to schedule it.
362                // 3 - Polite Racy case : the thread has blocked, someone has already tried to schedule it, but the thread is nice and wants to go through the ready-queue any way
363                // 4 - Preempted
364                // In case 1, we may have won a race so we can't write to the state again.
365                // In case 2, we lost the race so we now own the thread.
366                // In case 3, we lost the race but can just reschedule the thread.
367
368                if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
369                        // The thread was preempted, reschedule it and reset the flag
370                        __schedule_thread( thrd_dst );
371                        break RUNNING;
372                }
373
374                // set state of processor coroutine to active and the thread to inactive
375                static_assert(sizeof(thrd_dst->state) == sizeof(int));
376                enum coroutine_state old_state = __atomic_exchange_n(&thrd_dst->state, Inactive, __ATOMIC_SEQ_CST);
377                switch(old_state) {
378                        case Halted:
379                                // The thread has halted, it should never be scheduled/run again, leave it back to Halted and move on
380                                thrd_dst->state = Halted;
381
382                                // We may need to wake someone up here since
383                                unpark( this->destroyer );
384                                this->destroyer = 0p;
385                                break RUNNING;
386                        case Active:
387                                // This is case 1, the regular case, nothing more is needed
388                                break RUNNING;
389                        case Rerun:
390                                // This is case 2, the racy case, someone tried to run this thread before it finished blocking
391                                // In this case, just run it again.
392                                continue RUNNING;
393                        default:
394                                // This makes no sense, something is wrong abort
395                                abort("Finished running a thread that was Inactive/Start/Primed %d\n", old_state);
396                }
397        }
398
399        // Just before returning to the processor, set the processor coroutine to active
400        proc_cor->state = Active;
401}
402
403// KERNEL_ONLY
404void returnToKernel() {
405        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
406        $coroutine * proc_cor = get_coroutine(kernelTLS.this_processor->runner);
407        $thread * thrd_src = kernelTLS.this_thread;
408
409        // Run the thread on this processor
410        {
411                int local_errno = *__volatile_errno();
412                #if defined( __i386 ) || defined( __x86_64 )
413                        __x87_store;
414                #endif
415                verify( proc_cor->context.SP );
416                __cfactx_switch( &thrd_src->context, &proc_cor->context );
417                #if defined( __i386 ) || defined( __x86_64 )
418                        __x87_load;
419                #endif
420                *__volatile_errno() = local_errno;
421        }
422
423        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
424        /* 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 );
425        /* 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 );
426}
427
428// KERNEL_ONLY
429// Context invoker for processors
430// This is the entry point for processors (kernel threads)
431// It effectively constructs a coroutine by stealing the pthread stack
432static void * __invoke_processor(void * arg) {
433        processor * proc = (processor *) arg;
434        kernelTLS.this_processor = proc;
435        kernelTLS.this_thread    = 0p;
436        kernelTLS.preemption_state.[enabled, disable_count] = [false, 1];
437        // SKULLDUGGERY: We want to create a context for the processor coroutine
438        // which is needed for the 2-step context switch. However, there is no reason
439        // to waste the perfectly valid stack create by pthread.
440        current_stack_info_t info;
441        __stack_t ctx;
442        info.storage = &ctx;
443        (proc->runner){ proc, &info };
444
445        __cfaabi_dbg_print_safe("Coroutine : created stack %p\n", get_coroutine(proc->runner)->stack.storage);
446
447        //Set global state
448        kernelTLS.this_thread = 0p;
449
450        //We now have a proper context from which to schedule threads
451        __cfaabi_dbg_print_safe("Kernel : core %p created (%p, %p)\n", proc, &proc->runner, &ctx);
452
453        // SKULLDUGGERY: Since the coroutine doesn't have its own stack, we can't
454        // resume it to start it like it normally would, it will just context switch
455        // back to here. Instead directly call the main since we already are on the
456        // appropriate stack.
457        get_coroutine(proc->runner)->state = Active;
458        main( proc->runner );
459        get_coroutine(proc->runner)->state = Halted;
460
461        // Main routine of the core returned, the core is now fully terminated
462        __cfaabi_dbg_print_safe("Kernel : core %p main ended (%p)\n", proc, &proc->runner);
463
464        return 0p;
465}
466
467static void Abort( int ret, const char func[] ) {
468        if ( ret ) {                                                                            // pthread routines return errno values
469                abort( "%s : internal error, error(%d) %s.", func, ret, strerror( ret ) );
470        } // if
471} // Abort
472
473void * __create_pthread( pthread_t * pthread, void * (*start)(void *), void * arg ) {
474        pthread_attr_t attr;
475
476        Abort( pthread_attr_init( &attr ), "pthread_attr_init" ); // initialize attribute
477
478        size_t stacksize;
479        // default stack size, normally defined by shell limit
480        Abort( pthread_attr_getstacksize( &attr, &stacksize ), "pthread_attr_getstacksize" );
481        assert( stacksize >= PTHREAD_STACK_MIN );
482
483        void * stack;
484        __cfaabi_dbg_debug_do(
485                stack = memalign( __page_size, stacksize + __page_size );
486                // pthread has no mechanism to create the guard page in user supplied stack.
487                if ( mprotect( stack, __page_size, PROT_NONE ) == -1 ) {
488                        abort( "mprotect : internal error, mprotect failure, error(%d) %s.", errno, strerror( errno ) );
489                } // if
490        );
491        __cfaabi_dbg_no_debug_do(
492                stack = malloc( stacksize );
493        );
494
495        Abort( pthread_attr_setstack( &attr, stack, stacksize ), "pthread_attr_setstack" );
496
497        Abort( pthread_create( pthread, &attr, start, arg ), "pthread_create" );
498        return stack;
499}
500
501// KERNEL_ONLY
502static void __kernel_first_resume( processor * this ) {
503        $thread * src = mainThread;
504        $coroutine * dst = get_coroutine(this->runner);
505
506        verify( ! kernelTLS.preemption_state.enabled );
507
508        kernelTLS.this_thread->curr_cor = dst;
509        __stack_prepare( &dst->stack, 65000 );
510        __cfactx_start(main, dst, this->runner, __cfactx_invoke_coroutine);
511
512        verify( ! kernelTLS.preemption_state.enabled );
513
514        dst->last = &src->self_cor;
515        dst->starter = dst->starter ? dst->starter : &src->self_cor;
516
517        // set state of current coroutine to inactive
518        src->state = src->state == Halted ? Halted : Inactive;
519
520        // context switch to specified coroutine
521        verify( dst->context.SP );
522        __cfactx_switch( &src->context, &dst->context );
523        // when __cfactx_switch returns we are back in the src coroutine
524
525        mainThread->curr_cor = &mainThread->self_cor;
526
527        // set state of new coroutine to active
528        src->state = Active;
529
530        verify( ! kernelTLS.preemption_state.enabled );
531}
532
533// KERNEL_ONLY
534static void __kernel_last_resume( processor * this ) {
535        $coroutine * src = &mainThread->self_cor;
536        $coroutine * dst = get_coroutine(this->runner);
537
538        verify( ! kernelTLS.preemption_state.enabled );
539        verify( dst->starter == src );
540        verify( dst->context.SP );
541
542        // context switch to the processor
543        __cfactx_switch( &src->context, &dst->context );
544}
545
546//-----------------------------------------------------------------------------
547// Scheduler routines
548// KERNEL ONLY
549void __schedule_thread( $thread * thrd ) with( *thrd->curr_cluster ) {
550        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
551        /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
552        /* paranoid */ if( thrd->state == Inactive || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
553                          "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
554        /* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active || thrd->state == Rerun,
555                          "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
556        /* paranoid */ #endif
557        /* paranoid */ verifyf( thrd->next == 0p, "Expected null got %p", thrd->next );
558
559        lock  ( ready_queue_lock __cfaabi_dbg_ctx2 );
560        bool was_empty = !(ready_queue != 0);
561        append( ready_queue, thrd );
562        unlock( ready_queue_lock );
563
564        if(was_empty) {
565                lock      (proc_list_lock __cfaabi_dbg_ctx2);
566                if(idles) {
567                        wake_fast(idles.head);
568                }
569                unlock    (proc_list_lock);
570        }
571        else if( struct processor * idle = idles.head ) {
572                wake_fast(idle);
573        }
574
575        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
576}
577
578// KERNEL ONLY
579static $thread * __next_thread(cluster * this) with( *this ) {
580        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
581
582        lock( ready_queue_lock __cfaabi_dbg_ctx2 );
583        $thread * head = pop_head( ready_queue );
584        unlock( ready_queue_lock );
585
586        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
587        return head;
588}
589
590void unpark( $thread * thrd ) {
591        if( !thrd ) return;
592
593        disable_interrupts();
594        static_assert(sizeof(thrd->state) == sizeof(int));
595        enum coroutine_state old_state = __atomic_exchange_n(&thrd->state, Rerun, __ATOMIC_SEQ_CST);
596        switch(old_state) {
597                case Active:
598                        // Wake won the race, the thread will reschedule/rerun itself
599                        break;
600                case Inactive:
601                        /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
602
603                        // Wake lost the race,
604                        thrd->state = Inactive;
605                        __schedule_thread( thrd );
606                        break;
607                case Rerun:
608                        abort("More than one thread attempted to schedule thread %p\n", thrd);
609                        break;
610                case Halted:
611                case Start:
612                case Primed:
613                default:
614                        // This makes no sense, something is wrong abort
615                        abort();
616        }
617        enable_interrupts( __cfaabi_dbg_ctx );
618}
619
620void park( void ) {
621        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
622        disable_interrupts();
623        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
624        /* paranoid */ verify( kernelTLS.this_thread->preempted == __NO_PREEMPTION );
625
626        returnToKernel();
627
628        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
629        enable_interrupts( __cfaabi_dbg_ctx );
630        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
631
632}
633
634// KERNEL ONLY
635void __leave_thread() {
636        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
637        returnToKernel();
638        abort();
639}
640
641// KERNEL ONLY
642bool force_yield( __Preemption_Reason reason ) {
643        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
644        disable_interrupts();
645        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
646
647        $thread * thrd = kernelTLS.this_thread;
648        /* paranoid */ verify(thrd->state == Active || thrd->state == Rerun);
649
650        // SKULLDUGGERY: It is possible that we are preempting this thread just before
651        // it was going to park itself. If that is the case and it is already using the
652        // intrusive fields then we can't use them to preempt the thread
653        // If that is the case, abandon the preemption.
654        bool preempted = false;
655        if(thrd->next == 0p) {
656                preempted = true;
657                thrd->preempted = reason;
658                returnToKernel();
659        }
660
661        /* paranoid */ verify( ! kernelTLS.preemption_state.enabled );
662        enable_interrupts_noPoll();
663        /* paranoid */ verify( kernelTLS.preemption_state.enabled );
664
665        return preempted;
666}
667
668//=============================================================================================
669// Kernel Setup logic
670//=============================================================================================
671//-----------------------------------------------------------------------------
672// Kernel boot procedures
673static void __kernel_startup(void) {
674        verify( ! kernelTLS.preemption_state.enabled );
675        __cfaabi_dbg_print_safe("Kernel : Starting\n");
676
677        __page_size = sysconf( _SC_PAGESIZE );
678
679        __cfa_dbg_global_clusters.list{ __get };
680        __cfa_dbg_global_clusters.lock{};
681
682        // Initialize the main cluster
683        mainCluster = (cluster *)&storage_mainCluster;
684        (*mainCluster){"Main Cluster"};
685
686        __cfaabi_dbg_print_safe("Kernel : Main cluster ready\n");
687
688        // Start by initializing the main thread
689        // SKULLDUGGERY: the mainThread steals the process main thread
690        // which will then be scheduled by the mainProcessor normally
691        mainThread = ($thread *)&storage_mainThread;
692        current_stack_info_t info;
693        info.storage = (__stack_t*)&storage_mainThreadCtx;
694        (*mainThread){ &info };
695
696        __cfaabi_dbg_print_safe("Kernel : Main thread ready\n");
697
698
699
700        // Construct the processor context of the main processor
701        void ?{}(processorCtx_t & this, processor * proc) {
702                (this.__cor){ "Processor" };
703                this.__cor.starter = 0p;
704                this.proc = proc;
705        }
706
707        void ?{}(processor & this) with( this ) {
708                name = "Main Processor";
709                cltr = mainCluster;
710                terminated{ 0 };
711                do_terminate = false;
712                preemption_alarm = 0p;
713                pending_preemption = false;
714                kernel_thread = pthread_self();
715
716                runner{ &this };
717                __cfaabi_dbg_print_safe("Kernel : constructed main processor context %p\n", &runner);
718        }
719
720        // Initialize the main processor and the main processor ctx
721        // (the coroutine that contains the processing control flow)
722        mainProcessor = (processor *)&storage_mainProcessor;
723        (*mainProcessor){};
724
725        //initialize the global state variables
726        kernelTLS.this_processor = mainProcessor;
727        kernelTLS.this_thread    = mainThread;
728
729        // Enable preemption
730        kernel_start_preemption();
731
732        // Add the main thread to the ready queue
733        // once resume is called on mainProcessor->runner the mainThread needs to be scheduled like any normal thread
734        __schedule_thread(mainThread);
735
736        // SKULLDUGGERY: Force a context switch to the main processor to set the main thread's context to the current UNIX
737        // context. Hence, the main thread does not begin through __cfactx_invoke_thread, like all other threads. The trick here is that
738        // mainThread is on the ready queue when this call is made.
739        __kernel_first_resume( kernelTLS.this_processor );
740
741
742
743        // THE SYSTEM IS NOW COMPLETELY RUNNING
744        __cfaabi_dbg_print_safe("Kernel : Started\n--------------------------------------------------\n\n");
745
746        verify( ! kernelTLS.preemption_state.enabled );
747        enable_interrupts( __cfaabi_dbg_ctx );
748        verify( TL_GET( preemption_state.enabled ) );
749}
750
751static void __kernel_shutdown(void) {
752        __cfaabi_dbg_print_safe("\n--------------------------------------------------\nKernel : Shutting down\n");
753
754        verify( TL_GET( preemption_state.enabled ) );
755        disable_interrupts();
756        verify( ! kernelTLS.preemption_state.enabled );
757
758        // SKULLDUGGERY: Notify the mainProcessor it needs to terminates.
759        // When its coroutine terminates, it return control to the mainThread
760        // which is currently here
761        __atomic_store_n(&mainProcessor->do_terminate, true, __ATOMIC_RELEASE);
762        __kernel_last_resume( kernelTLS.this_processor );
763        mainThread->self_cor.state = Halted;
764
765        // THE SYSTEM IS NOW COMPLETELY STOPPED
766
767        // Disable preemption
768        kernel_stop_preemption();
769
770        // Destroy the main processor and its context in reverse order of construction
771        // These were manually constructed so we need manually destroy them
772        ^(*mainProcessor){};
773
774        // Final step, destroy the main thread since it is no longer needed
775        // Since we provided a stack to this taxk it will not destroy anything
776        /* paranoid */ verify(mainThread->self_cor.stack.storage == (__stack_t*)(((uintptr_t)&storage_mainThreadCtx)| 0x1));
777        ^(*mainThread){};
778
779        ^(__cfa_dbg_global_clusters.list){};
780        ^(__cfa_dbg_global_clusters.lock){};
781
782        __cfaabi_dbg_print_safe("Kernel : Shutdown complete\n");
783}
784
785//=============================================================================================
786// Kernel Quiescing
787//=============================================================================================
788static void __halt(processor * this) with( *this ) {
789        // verify( ! __atomic_load_n(&do_terminate, __ATOMIC_SEQ_CST) );
790
791        with( *cltr ) {
792                lock      (proc_list_lock __cfaabi_dbg_ctx2);
793                remove    (procs, *this);
794                push_front(idles, *this);
795                unlock    (proc_list_lock);
796        }
797
798        __cfaabi_dbg_print_safe("Kernel : Processor %p ready to sleep\n", this);
799
800        wait( idleLock );
801
802        __cfaabi_dbg_print_safe("Kernel : Processor %p woke up and ready to run\n", this);
803
804        with( *cltr ) {
805                lock      (proc_list_lock __cfaabi_dbg_ctx2);
806                remove    (idles, *this);
807                push_front(procs, *this);
808                unlock    (proc_list_lock);
809        }
810}
811
812//=============================================================================================
813// Unexpected Terminating logic
814//=============================================================================================
815static __spinlock_t kernel_abort_lock;
816static bool kernel_abort_called = false;
817
818void * kernel_abort(void) __attribute__ ((__nothrow__)) {
819        // abort cannot be recursively entered by the same or different processors because all signal handlers return when
820        // the globalAbort flag is true.
821        lock( kernel_abort_lock __cfaabi_dbg_ctx2 );
822
823        // first task to abort ?
824        if ( kernel_abort_called ) {                    // not first task to abort ?
825                unlock( kernel_abort_lock );
826
827                sigset_t mask;
828                sigemptyset( &mask );
829                sigaddset( &mask, SIGALRM );            // block SIGALRM signals
830                sigaddset( &mask, SIGUSR1 );            // block SIGALRM signals
831                sigsuspend( &mask );                            // block the processor to prevent further damage during abort
832                _exit( EXIT_FAILURE );                          // if processor unblocks before it is killed, terminate it
833        }
834        else {
835                kernel_abort_called = true;
836                unlock( kernel_abort_lock );
837        }
838
839        return kernelTLS.this_thread;
840}
841
842void kernel_abort_msg( void * kernel_data, char * abort_text, int abort_text_size ) {
843        $thread * thrd = kernel_data;
844
845        if(thrd) {
846                int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
847                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
848
849                if ( &thrd->self_cor != thrd->curr_cor ) {
850                        len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
851                        __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
852                }
853                else {
854                        __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
855                }
856        }
857        else {
858                int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
859                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
860        }
861}
862
863int kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
864        return get_coroutine(kernelTLS.this_thread) == get_coroutine(mainThread) ? 4 : 2;
865}
866
867static __spinlock_t kernel_debug_lock;
868
869extern "C" {
870        void __cfaabi_bits_acquire() {
871                lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
872        }
873
874        void __cfaabi_bits_release() {
875                unlock( kernel_debug_lock );
876        }
877}
878
879//=============================================================================================
880// Kernel Utilities
881//=============================================================================================
882//-----------------------------------------------------------------------------
883// Locks
884void  ?{}( semaphore & this, int count = 1 ) {
885        (this.lock){};
886        this.count = count;
887        (this.waiting){};
888}
889void ^?{}(semaphore & this) {}
890
891void P(semaphore & this) with( this ){
892        lock( lock __cfaabi_dbg_ctx2 );
893        count -= 1;
894        if ( count < 0 ) {
895                // queue current task
896                append( waiting, kernelTLS.this_thread );
897
898                // atomically release spin lock and block
899                unlock( lock );
900                park();
901        }
902        else {
903            unlock( lock );
904        }
905}
906
907void V(semaphore & this) with( this ) {
908        $thread * thrd = 0p;
909        lock( lock __cfaabi_dbg_ctx2 );
910        count += 1;
911        if ( count <= 0 ) {
912                // remove task at head of waiting list
913                thrd = pop_head( waiting );
914        }
915
916        unlock( lock );
917
918        // make new owner
919        unpark( thrd );
920}
921
922//-----------------------------------------------------------------------------
923// Global Queues
924void doregister( cluster     & cltr ) {
925        lock      ( __cfa_dbg_global_clusters.lock __cfaabi_dbg_ctx2);
926        push_front( __cfa_dbg_global_clusters.list, cltr );
927        unlock    ( __cfa_dbg_global_clusters.lock );
928}
929
930void unregister( cluster     & cltr ) {
931        lock  ( __cfa_dbg_global_clusters.lock __cfaabi_dbg_ctx2);
932        remove( __cfa_dbg_global_clusters.list, cltr );
933        unlock( __cfa_dbg_global_clusters.lock );
934}
935
936void doregister( cluster * cltr, $thread & thrd ) {
937        lock      (cltr->thread_list_lock __cfaabi_dbg_ctx2);
938        cltr->nthreads += 1;
939        push_front(cltr->threads, thrd);
940        unlock    (cltr->thread_list_lock);
941}
942
943void unregister( cluster * cltr, $thread & thrd ) {
944        lock  (cltr->thread_list_lock __cfaabi_dbg_ctx2);
945        remove(cltr->threads, thrd );
946        cltr->nthreads -= 1;
947        unlock(cltr->thread_list_lock);
948}
949
950void doregister( cluster * cltr, processor * proc ) {
951        lock      (cltr->proc_list_lock __cfaabi_dbg_ctx2);
952        cltr->nprocessors += 1;
953        push_front(cltr->procs, *proc);
954        unlock    (cltr->proc_list_lock);
955}
956
957void unregister( cluster * cltr, processor * proc ) {
958        lock  (cltr->proc_list_lock __cfaabi_dbg_ctx2);
959        remove(cltr->procs, *proc );
960        cltr->nprocessors -= 1;
961        unlock(cltr->proc_list_lock);
962}
963
964//-----------------------------------------------------------------------------
965// Debug
966__cfaabi_dbg_debug_do(
967        extern "C" {
968                void __cfaabi_dbg_record(__spinlock_t & this, const char prev_name[]) {
969                        this.prev_name = prev_name;
970                        this.prev_thrd = kernelTLS.this_thread;
971                }
972        }
973)
974
975//-----------------------------------------------------------------------------
976// Debug
977bool threading_enabled(void) __attribute__((const)) {
978        return true;
979}
980// Local Variables: //
981// mode: c //
982// tab-width: 4 //
983// End: //
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