Hello everyone,
Hope all is well. I am working on implementing an fsm that would dynamically
insert lfence instruction during one of the state transitions. I’ve implemented
the fsm in the decode stage.
Here is how I tried inserting the lfence instruction inside the decodeInsts
function of o3 core:
// Line 680 in decode_impl.hh
// My code begins
DynInstPtr lfence_inst = buildInst(tid, StaticInst::nopStaticInstPtr,
NULL, inst->pcState(), inst->pcState(),
false);
lfence_inst->staticInst->setFlag(IsReadBarrier);
lfence_inst->staticInst->setFlag(IsSerializeAfter);
toRename->insts[toRenameIndex] = lfence_inst;
++(toRename->size);
++toRenameIndex;
// My code ends
where buildInst function is similar to buildInst function defined in
fetch_impl.hh:
template<class Impl>
typename Impl::DynInstPtr
DefaultDecode<Impl>::buildInst(ThreadID tid, StaticInstPtr staticInst,
StaticInstPtr curMacroop, TheISA::PCState thisPC,
TheISA::PCState nextPC, bool trace)
{
// Get a sequence number.
InstSeqNum seq = cpu->getAndIncrementInstSeq();
// Create a new DynInst from the instruction fetched.
DynInstPtr instruction =
new DynInst(staticInst, curMacroop, thisPC, nextPC, seq, cpu);
instruction->setTid(tid);
instruction->setThreadState(cpu->thread[tid]);
DPRINTF(Decode, "[tid:%i] Instruction PC %#x (%d) created "
"[sn:%lli].\n", tid, thisPC.instAddr(),
thisPC.microPC(), seq);
DPRINTF(Decode, "[tid:%i] Instruction is: %s\n", tid,
instruction->staticInst->
disassemble(thisPC.instAddr()));
#if TRACING_ON
if (trace) {
instruction->traceData =
cpu->getTracer()->getInstRecord(curTick(), cpu->tcBase(tid),
instruction->staticInst, thisPC, curMacroop);
}
#else
instruction->traceData = NULL;
#endif
// Add instruction to the CPU's list of instructions.
instruction->setInstListIt(cpu->addInst(instruction));
return instruction;
}
When I try running it on a test program, I get segmentation fault:
info: Entering event queue @ 0. Starting simulation...
gem5 has encountered a segmentation fault!
While there are obvious problems with this code (this and next PC being same
and wrong), I was wondering if you could give some directions. Do I have the
right idea? Or should I be doing something completely different?
Any type of feedback would be much appreciated.
Best regards,
George Klimiashvili
_______________________________________________
gem5-users mailing list -- [email protected]
To unsubscribe send an email to [email protected]
%(web_page_url)slistinfo%(cgiext)s/%(_internal_name)s
