1/*
2 * Copyright 2018 Google, Inc.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met: redistributions of source code must retain the above copyright
7 * notice, this list of conditions and the following disclaimer;
8 * redistributions in binary form must reproduce the above copyright
9 * notice, this list of conditions and the following disclaimer in the
10 * documentation and/or other materials provided with the distribution;
11 * neither the name of the copyright holders nor the names of its
12 * contributors may be used to endorse or promote products derived from
13 * this software without specific prior written permission.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
18 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
19 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
21 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
25 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 *
27 * Authors: Gabe Black
28 */
29
30#include "systemc/core/scheduler.hh"
31
32#include "base/fiber.hh"
33#include "base/logging.hh"
34#include "sim/eventq.hh"
35#include "sim/sim_exit.hh"
36#include "systemc/core/kernel.hh"
37#include "systemc/core/sc_main_fiber.hh"
38#include "systemc/ext/core/messages.hh"
39#include "systemc/ext/core/sc_main.hh"
40#include "systemc/ext/utils/sc_report.hh"
41#include "systemc/ext/utils/sc_report_handler.hh"
42#include "systemc/utils/report.hh"
43#include "systemc/utils/tracefile.hh"
44
45namespace sc_gem5
46{
47
48Scheduler::Scheduler() :
49    eq(nullptr), readyEvent(this, false, ReadyPriority),
50    pauseEvent(this, false, PausePriority),
51    stopEvent(this, false, StopPriority), _throwUp(nullptr),
52    starvationEvent(this, false, StarvationPriority),
53    _elaborationDone(false), _started(false), _stopNow(false),
54    _status(StatusOther), maxTick(::MaxTick),
55    maxTickEvent(this, false, MaxTickPriority),
56    timeAdvancesEvent(this, false, TimeAdvancesPriority), _numCycles(0),
57    _changeStamp(0), _current(nullptr), initDone(false), runToTime(true),
58    runOnce(false)
59{}
60
61Scheduler::~Scheduler()
62{
63    // Clear out everything that belongs to us to make sure nobody tries to
64    // clear themselves out after the scheduler goes away.
65    clear();
66}
67
68void
69Scheduler::clear()
70{
71    // Delta notifications.
72    while (!deltas.empty())
73        deltas.front()->deschedule();
74
75    // Timed notifications.
76    for (auto &tsp: timeSlots) {
77        TimeSlot *&ts = tsp.second;
78        while (!ts->events.empty())
79            ts->events.front()->deschedule();
80        deschedule(ts);
81    }
82    timeSlots.clear();
83
84    // gem5 events.
85    if (readyEvent.scheduled())
86        deschedule(&readyEvent);
87    if (pauseEvent.scheduled())
88        deschedule(&pauseEvent);
89    if (stopEvent.scheduled())
90        deschedule(&stopEvent);
91    if (starvationEvent.scheduled())
92        deschedule(&starvationEvent);
93    if (maxTickEvent.scheduled())
94        deschedule(&maxTickEvent);
95    if (timeAdvancesEvent.scheduled())
96        deschedule(&timeAdvancesEvent);
97
98    Process *p;
99    while ((p = initList.getNext()))
100        p->popListNode();
101    while ((p = readyListMethods.getNext()))
102        p->popListNode();
103    while ((p = readyListThreads.getNext()))
104        p->popListNode();
105
106    Channel *c;
107    while ((c = updateList.getNext()))
108        c->popListNode();
109}
110
111void
112Scheduler::initPhase()
113{
114    runUpdate();
115
116    for (Process *p = initList.getNext(); p; p = initList.getNext()) {
117        p->popListNode();
118
119        if (p->dontInitialize()) {
120            if (!p->hasStaticSensitivities() && !p->internal()) {
121                SC_REPORT_WARNING(sc_core::SC_ID_DISABLE_WILL_ORPHAN_PROCESS_,
122                        p->name());
123            }
124        } else {
125            p->ready();
126        }
127    }
128
129    runDelta();
130
131    for (auto ets: eventsToSchedule)
132        eq->schedule(ets.first, ets.second);
133    eventsToSchedule.clear();
134
135    if (_started) {
136        if (!runToTime && starved())
137            scheduleStarvationEvent();
138        kernel->status(::sc_core::SC_RUNNING);
139    }
140
141    initDone = true;
142
143    status(StatusOther);
144
145    scheduleTimeAdvancesEvent();
146}
147
148void
149Scheduler::reg(Process *p)
150{
151    if (initDone) {
152        // If not marked as dontInitialize, mark as ready.
153        if (!p->dontInitialize())
154            p->ready();
155    } else {
156        // Otherwise, record that this process should be initialized once we
157        // get there.
158        initList.pushLast(p);
159    }
160}
161
162void
163Scheduler::yield()
164{
165    // Pull a process from the active list.
166    _current = getNextReady();
167    if (!_current) {
168        // There are no more processes, so return control to evaluate.
169        Fiber::primaryFiber()->run();
170    } else {
171        _current->popListNode();
172        _current->scheduled(false);
173        // Switch to whatever Fiber is supposed to run this process. All
174        // Fibers which aren't running should be parked at this line.
175        _current->fiber()->run();
176        // If the current process needs to be manually started, start it.
177        if (_current && _current->needsStart()) {
178            _current->needsStart(false);
179            // If a process hasn't started yet, "resetting" it just starts it
180            // and signals its reset event.
181            if (_current->inReset())
182                _current->resetEvent().notify();
183            try {
184                _current->run();
185            } catch (...) {
186                throwUp();
187            }
188        }
189    }
190    if (_current && !_current->needsStart()) {
191        if (_current->excWrapper) {
192            auto ew = _current->excWrapper;
193            _current->excWrapper = nullptr;
194            ew->throw_it();
195        } else if (_current->inReset()) {
196            _current->reset(false);
197        }
198    }
199}
200
201void
202Scheduler::ready(Process *p)
203{
204    if (_stopNow)
205        return;
206
207    p->scheduled(true);
208
209    if (p->procKind() == ::sc_core::SC_METHOD_PROC_)
210        readyListMethods.pushLast(p);
211    else
212        readyListThreads.pushLast(p);
213
214    if (!inEvaluate())
215        scheduleReadyEvent();
216}
217
218void
219Scheduler::resume(Process *p)
220{
221    if (initDone)
222        ready(p);
223    else
224        initList.pushLast(p);
225}
226
227bool
228listContains(ListNode *list, ListNode *target)
229{
230    ListNode *n = list->nextListNode;
231    while (n != list)
232        if (n == target)
233            return true;
234    return false;
235}
236
237bool
238Scheduler::suspend(Process *p)
239{
240    bool was_ready;
241    if (initDone) {
242        // After initialization, check if we're on a ready list.
243        was_ready = (p->nextListNode != nullptr);
244        p->popListNode();
245    } else {
246        // Nothing is ready before init.
247        was_ready = false;
248    }
249    return was_ready;
250}
251
252void
253Scheduler::requestUpdate(Channel *c)
254{
255    updateList.pushLast(c);
256    if (!inEvaluate())
257        scheduleReadyEvent();
258}
259
260void
261Scheduler::asyncRequestUpdate(Channel *c)
262{
263    std::lock_guard<std::mutex> lock(asyncListMutex);
264    asyncUpdateList.pushLast(c);
265}
266
267void
268Scheduler::scheduleReadyEvent()
269{
270    // Schedule the evaluate and update phases.
271    if (!readyEvent.scheduled()) {
272        schedule(&readyEvent);
273        if (starvationEvent.scheduled())
274            deschedule(&starvationEvent);
275    }
276}
277
278void
279Scheduler::scheduleStarvationEvent()
280{
281    if (!starvationEvent.scheduled()) {
282        schedule(&starvationEvent);
283        if (readyEvent.scheduled())
284            deschedule(&readyEvent);
285    }
286}
287
288void
289Scheduler::runReady()
290{
291    scheduleTimeAdvancesEvent();
292
293    bool empty = readyListMethods.empty() && readyListThreads.empty();
294    lastReadyTick = getCurTick();
295
296    // The evaluation phase.
297    status(StatusEvaluate);
298    do {
299        yield();
300    } while (getNextReady());
301    _current = nullptr;
302
303    if (!empty) {
304        _numCycles++;
305        _changeStamp++;
306    }
307
308    if (_stopNow) {
309        status(StatusOther);
310        return;
311    }
312
313    runUpdate();
314    if (!traceFiles.empty())
315        trace(true);
316    runDelta();
317
318    if (!runToTime && starved())
319        scheduleStarvationEvent();
320
321    if (runOnce)
322        schedulePause();
323
324    status(StatusOther);
325}
326
327void
328Scheduler::runUpdate()
329{
330    status(StatusUpdate);
331    {
332        std::lock_guard<std::mutex> lock(asyncListMutex);
333        Channel *channel;
334        while ((channel = asyncUpdateList.getNext()) != nullptr)
335            updateList.pushLast(channel);
336    }
337
338    try {
339        Channel *channel = updateList.getNext();
340        while (channel) {
341            channel->popListNode();
342            channel->update();
343            channel = updateList.getNext();
344        }
345    } catch (...) {
346        throwUp();
347    }
348}
349
350void
351Scheduler::runDelta()
352{
353    status(StatusDelta);
354
355    try {
356        while (!deltas.empty())
357            deltas.back()->run();
358    } catch (...) {
359        throwUp();
360    }
361}
362
363void
364Scheduler::pause()
365{
366    status(StatusPaused);
367    kernel->status(::sc_core::SC_PAUSED);
368    runOnce = false;
369    if (scMainFiber.called()) {
370        if (!scMainFiber.finished())
371            scMainFiber.run();
372    } else {
373        if (scMainFiber.finished())
374            fatal("Pausing systemc after sc_main completed.");
375        else
376            exitSimLoopNow("systemc pause");
377    }
378}
379
380void
381Scheduler::stop()
382{
383    status(StatusStopped);
384    kernel->stop();
385
386    clear();
387
388    runOnce = false;
389    if (scMainFiber.called()) {
390        if (!scMainFiber.finished())
391            scMainFiber.run();
392    } else {
393        if (scMainFiber.finished())
394            fatal("Stopping systemc after sc_main completed.");
395        else
396            exitSimLoopNow("systemc stop");
397    }
398}
399
400void
401Scheduler::start(Tick max_tick, bool run_to_time)
402{
403    _started = true;
404    status(StatusOther);
405    runToTime = run_to_time;
406
407    maxTick = max_tick;
408    lastReadyTick = getCurTick();
409
410    if (initDone) {
411        if (!runToTime && starved())
412            scheduleStarvationEvent();
413        kernel->status(::sc_core::SC_RUNNING);
414    }
415
416    schedule(&maxTickEvent, maxTick);
417    scheduleTimeAdvancesEvent();
418
419    // Return to gem5 to let it run events, etc.
420    Fiber::primaryFiber()->run();
421
422    if (pauseEvent.scheduled())
423        deschedule(&pauseEvent);
424    if (stopEvent.scheduled())
425        deschedule(&stopEvent);
426    if (maxTickEvent.scheduled())
427        deschedule(&maxTickEvent);
428    if (starvationEvent.scheduled())
429        deschedule(&starvationEvent);
430
431    if (_throwUp) {
432        const ::sc_core::sc_report *to_throw = _throwUp;
433        _throwUp = nullptr;
434        throw *to_throw;
435    }
436}
437
438void
439Scheduler::oneCycle()
440{
441    runOnce = true;
442    scheduleReadyEvent();
443    start(::MaxTick, false);
444}
445
446void
447Scheduler::schedulePause()
448{
449    if (pauseEvent.scheduled())
450        return;
451
452    schedule(&pauseEvent);
453}
454
455void
456Scheduler::throwUp()
457{
458    if (scMainFiber.called() && !scMainFiber.finished()) {
459        ::sc_core::sc_report report = reportifyException();
460        _throwUp = &report;
461        status(StatusOther);
462        scMainFiber.run();
463    } else {
464        reportHandlerProc(reportifyException(),
465                ::sc_core::sc_report_handler::get_catch_actions());
466    }
467}
468
469void
470Scheduler::scheduleStop(bool finish_delta)
471{
472    if (stopEvent.scheduled())
473        return;
474
475    if (!finish_delta) {
476        _stopNow = true;
477        // If we're not supposed to finish the delta cycle, flush all
478        // pending activity.
479        clear();
480    }
481    schedule(&stopEvent);
482}
483
484void
485Scheduler::trace(bool delta)
486{
487    for (auto tf: traceFiles)
488        tf->trace(delta);
489}
490
491Scheduler scheduler;
492Process *getCurrentProcess() { return scheduler.current(); }
493
494namespace {
495
496void
497throwingReportHandler(const ::sc_core::sc_report &r,
498                      const ::sc_core::sc_actions &)
499{
500    throw r;
501}
502
503} // anonymous namespace
504
505const ::sc_core::sc_report
506reportifyException()
507{
508    ::sc_core::sc_report_handler_proc old_handler = reportHandlerProc;
509    ::sc_core::sc_report_handler::set_handler(&throwingReportHandler);
510
511    try {
512        try {
513            // Rethrow the current exception so we can catch it and throw an
514            // sc_report instead if it's not a type we recognize/can handle.
515            throw;
516        } catch (const ::sc_core::sc_report &) {
517            // It's already a sc_report, so nothing to do.
518            throw;
519        } catch (const ::sc_core::sc_unwind_exception &) {
520            panic("Kill/reset exception escaped a Process::run()");
521        } catch (const std::exception &e) {
522            SC_REPORT_ERROR(
523                    sc_core::SC_ID_SIMULATION_UNCAUGHT_EXCEPTION_, e.what());
524        } catch (const char *msg) {
525            SC_REPORT_ERROR(
526                    sc_core::SC_ID_SIMULATION_UNCAUGHT_EXCEPTION_, msg);
527        } catch (...) {
528            SC_REPORT_ERROR(
529                    sc_core::SC_ID_SIMULATION_UNCAUGHT_EXCEPTION_,
530                    "UNKNOWN EXCEPTION");
531        }
532    } catch (const ::sc_core::sc_report &r) {
533        ::sc_core::sc_report_handler::set_handler(old_handler);
534        return r;
535    }
536    panic("No exception thrown in reportifyException.");
537}
538
539} // namespace sc_gem5
540