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gem5 / arm / gem5 / dec0025dea92f78309d17b1840ed8449ac397d8f / . / src / cpu / minor / lsq.cc
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/*
* Copyright (c) 2013-2014,2017 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
* not be construed as granting a license to any other intellectual
* property including but not limited to intellectual property relating
* to a hardware implementation of the functionality of the software
* licensed hereunder. You may use the software subject to the license
* terms below provided that you ensure that this notice is replicated
* unmodified and in its entirety in all distributions of the software,
* modified or unmodified, in source code or in binary form.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Authors: Andrew Bardsley
*/
#include "cpu/minor/lsq.hh"
#include <iomanip>
#include <sstream>
#include "arch/locked_mem.hh"
#include "arch/mmapped_ipr.hh"
#include "cpu/minor/cpu.hh"
#include "cpu/minor/exec_context.hh"
#include "cpu/minor/execute.hh"
#include "cpu/minor/pipeline.hh"
#include "debug/Activity.hh"
#include "debug/MinorMem.hh"
namespace Minor
{
/** Returns the offset of addr into an aligned a block of size block_size */
static Addr
addrBlockOffset(Addr addr, unsigned int block_size)
{
return addr & (block_size - 1);
}
/** Returns true if the given [addr .. addr+size-1] transfer needs to be
* fragmented across a block size of block_size */
static bool
transferNeedsBurst(Addr addr, unsigned int size, unsigned int block_size)
{
return (addrBlockOffset(addr, block_size) + size) > block_size;
}
LSQ::LSQRequest::LSQRequest(LSQ &port_, MinorDynInstPtr inst_, bool isLoad_,
PacketDataPtr data_, uint64_t *res_) :
SenderState(),
port(port_),
inst(inst_),
isLoad(isLoad_),
data(data_),
packet(NULL),
request(),
fault(NoFault),
res(res_),
skipped(false),
issuedToMemory(false),
state(NotIssued)
{ }
LSQ::AddrRangeCoverage
LSQ::LSQRequest::containsAddrRangeOf(
Addr req1_addr, unsigned int req1_size,
Addr req2_addr, unsigned int req2_size)
{
/* 'end' here means the address of the byte just past the request
* blocks */
Addr req2_end_addr = req2_addr + req2_size;
Addr req1_end_addr = req1_addr + req1_size;
AddrRangeCoverage ret;
if (req1_addr >= req2_end_addr || req1_end_addr <= req2_addr)
ret = NoAddrRangeCoverage;
else if (req1_addr <= req2_addr && req1_end_addr >= req2_end_addr)
ret = FullAddrRangeCoverage;
else
ret = PartialAddrRangeCoverage;
return ret;
}
LSQ::AddrRangeCoverage
LSQ::LSQRequest::containsAddrRangeOf(LSQRequestPtr other_request)
{
return containsAddrRangeOf(request.getPaddr(), request.getSize(),
other_request->request.getPaddr(), other_request->request.getSize());
}
bool
LSQ::LSQRequest::isBarrier()
{
return inst->isInst() && inst->staticInst->isMemBarrier();
}
bool
LSQ::LSQRequest::needsToBeSentToStoreBuffer()
{
return state == StoreToStoreBuffer;
}
void
LSQ::LSQRequest::setState(LSQRequestState new_state)
{
DPRINTFS(MinorMem, (&port), "Setting state from %d to %d for request:"
" %s\n", state, new_state, *inst);
state = new_state;
}
bool
LSQ::LSQRequest::isComplete() const
{
/* @todo, There is currently only one 'completed' state. This
* may not be a good choice */
return state == Complete;
}
void
LSQ::LSQRequest::reportData(std::ostream &os) const
{
os << (isLoad ? 'R' : 'W') << ';';
inst->reportData(os);
os << ';' << state;
}
std::ostream &
operator <<(std::ostream &os, LSQ::AddrRangeCoverage coverage)
{
switch (coverage) {
case LSQ::PartialAddrRangeCoverage:
os << "PartialAddrRangeCoverage";
break;
case LSQ::FullAddrRangeCoverage:
os << "FullAddrRangeCoverage";
break;
case LSQ::NoAddrRangeCoverage:
os << "NoAddrRangeCoverage";
break;
default:
os << "AddrRangeCoverage-" << static_cast<int>(coverage);
break;
}
return os;
}
std::ostream &
operator <<(std::ostream &os, LSQ::LSQRequest::LSQRequestState state)
{
switch (state) {
case LSQ::LSQRequest::NotIssued:
os << "NotIssued";
break;
case LSQ::LSQRequest::InTranslation:
os << "InTranslation";
break;
case LSQ::LSQRequest::Translated:
os << "Translated";
break;
case LSQ::LSQRequest::Failed:
os << "Failed";
break;
case LSQ::LSQRequest::RequestIssuing:
os << "RequestIssuing";
break;
case LSQ::LSQRequest::StoreToStoreBuffer:
os << "StoreToStoreBuffer";
break;
case LSQ::LSQRequest::StoreInStoreBuffer:
os << "StoreInStoreBuffer";
break;
case LSQ::LSQRequest::StoreBufferIssuing:
os << "StoreBufferIssuing";
break;
case LSQ::LSQRequest::RequestNeedsRetry:
os << "RequestNeedsRetry";
break;
case LSQ::LSQRequest::StoreBufferNeedsRetry:
os << "StoreBufferNeedsRetry";
break;
case LSQ::LSQRequest::Complete:
os << "Complete";
break;
default:
os << "LSQRequestState-" << static_cast<int>(state);
break;
}
return os;
}
void
LSQ::clearMemBarrier(MinorDynInstPtr inst)
{
bool is_last_barrier =
inst->id.execSeqNum >= lastMemBarrier[inst->id.threadId];
DPRINTF(MinorMem, "Moving %s barrier out of store buffer inst: %s\n",
(is_last_barrier ? "last" : "a"), *inst);
if (is_last_barrier)
lastMemBarrier[inst->id.threadId] = 0;
}
void
LSQ::SingleDataRequest::finish(const Fault &fault_, RequestPtr request_,
ThreadContext *tc, BaseTLB::Mode mode)
{
fault = fault_;
port.numAccessesInDTLB--;
DPRINTFS(MinorMem, (&port), "Received translation response for"
" request: %s\n", *inst);
makePacket();
setState(Translated);
port.tryToSendToTransfers(this);
/* Let's try and wake up the processor for the next cycle */
port.cpu.wakeupOnEvent(Pipeline::ExecuteStageId);
}
void
LSQ::SingleDataRequest::startAddrTranslation()
{
ThreadContext *thread = port.cpu.getContext(
inst->id.threadId);
port.numAccessesInDTLB++;
setState(LSQ::LSQRequest::InTranslation);
DPRINTFS(MinorMem, (&port), "Submitting DTLB request\n");
/* Submit the translation request. The response will come through
* finish/markDelayed on the LSQRequest as it bears the Translation
* interface */
thread->getDTBPtr()->translateTiming(
&request, thread, this, (isLoad ? BaseTLB::Read : BaseTLB::Write));
}
void
LSQ::SingleDataRequest::retireResponse(PacketPtr packet_)
{
DPRINTFS(MinorMem, (&port), "Retiring packet\n");
packet = packet_;
packetInFlight = false;
setState(Complete);
}
void
LSQ::SplitDataRequest::finish(const Fault &fault_, RequestPtr request_,
ThreadContext *tc, BaseTLB::Mode mode)
{
fault = fault_;
port.numAccessesInDTLB--;
unsigned int M5_VAR_USED expected_fragment_index =
numTranslatedFragments;
numInTranslationFragments--;
numTranslatedFragments++;
DPRINTFS(MinorMem, (&port), "Received translation response for fragment"
" %d of request: %s\n", expected_fragment_index, *inst);
assert(request_ == fragmentRequests[expected_fragment_index]);
/* Wake up next cycle to get things going again in case the
* tryToSendToTransfers does take */
port.cpu.wakeupOnEvent(Pipeline::ExecuteStageId);
if (fault != NoFault) {
/* tryToSendToTransfers will handle the fault */
DPRINTFS(MinorMem, (&port), "Faulting translation for fragment:"
" %d of request: %s\n",
expected_fragment_index, *inst);
setState(Translated);
port.tryToSendToTransfers(this);
} else if (numTranslatedFragments == numFragments) {
makeFragmentPackets();
setState(Translated);
port.tryToSendToTransfers(this);
} else {
/* Avoid calling translateTiming from within ::finish */
assert(!translationEvent.scheduled());
port.cpu.schedule(translationEvent, curTick());
}
}
LSQ::SplitDataRequest::SplitDataRequest(LSQ &port_, MinorDynInstPtr inst_,
bool isLoad_, PacketDataPtr data_, uint64_t *res_) :
LSQRequest(port_, inst_, isLoad_, data_, res_),
translationEvent([this]{ sendNextFragmentToTranslation(); },
"translationEvent"),
numFragments(0),
numInTranslationFragments(0),
numTranslatedFragments(0),
numIssuedFragments(0),
numRetiredFragments(0),
fragmentRequests(),
fragmentPackets()
{
/* Don't know how many elements are needed until the request is
* populated by the caller. */
}
LSQ::SplitDataRequest::~SplitDataRequest()
{
for (auto i = fragmentRequests.begin();
i != fragmentRequests.end(); i++)
{
delete *i;
}
for (auto i = fragmentPackets.begin();
i != fragmentPackets.end(); i++)
{
delete *i;
}
}
void
LSQ::SplitDataRequest::makeFragmentRequests()
{
Addr base_addr = request.getVaddr();
unsigned int whole_size = request.getSize();
unsigned int line_width = port.lineWidth;
unsigned int fragment_size;
Addr fragment_addr;
/* Assume that this transfer is across potentially many block snap
* boundaries:
*
* | _|________|________|________|___ |
* | |0| 1 | 2 | 3 | 4 | |
* | |_|________|________|________|___| |
* | | | | | |
*
* The first transfer (0) can be up to lineWidth in size.
* All the middle transfers (1-3) are lineWidth in size
* The last transfer (4) can be from zero to lineWidth - 1 in size
*/
unsigned int first_fragment_offset =
addrBlockOffset(base_addr, line_width);
unsigned int last_fragment_size =
addrBlockOffset(base_addr + whole_size, line_width);
unsigned int first_fragment_size =
line_width - first_fragment_offset;
unsigned int middle_fragments_total_size =
whole_size - (first_fragment_size + last_fragment_size);
assert(addrBlockOffset(middle_fragments_total_size, line_width) == 0);
unsigned int middle_fragment_count =
middle_fragments_total_size / line_width;
numFragments = 1 /* first */ + middle_fragment_count +
(last_fragment_size == 0 ? 0 : 1);
DPRINTFS(MinorMem, (&port), "Dividing transfer into %d fragmentRequests."
" First fragment size: %d Last fragment size: %d\n",
numFragments, first_fragment_size,
(last_fragment_size == 0 ? line_width : last_fragment_size));
assert(((middle_fragment_count * line_width) +
first_fragment_size + last_fragment_size) == whole_size);
fragment_addr = base_addr;
fragment_size = first_fragment_size;
/* Just past the last address in the request */
Addr end_addr = base_addr + whole_size;
for (unsigned int fragment_index = 0; fragment_index < numFragments;
fragment_index++)
{
bool M5_VAR_USED is_last_fragment = false;
if (fragment_addr == base_addr) {
/* First fragment */
fragment_size = first_fragment_size;
} else {
if ((fragment_addr + line_width) > end_addr) {
/* Adjust size of last fragment */
fragment_size = end_addr - fragment_addr;
is_last_fragment = true;
} else {
/* Middle fragments */
fragment_size = line_width;
}
}
Request *fragment = new Request();
fragment->setContext(request.contextId());
fragment->setVirt(0 /* asid */,
fragment_addr, fragment_size, request.getFlags(),
request.masterId(),
request.getPC());
DPRINTFS(MinorMem, (&port), "Generating fragment addr: 0x%x size: %d"
" (whole request addr: 0x%x size: %d) %s\n",
fragment_addr, fragment_size, base_addr, whole_size,
(is_last_fragment ? "last fragment" : ""));
fragment_addr += fragment_size;
fragmentRequests.push_back(fragment);
}
}
void
LSQ::SplitDataRequest::makeFragmentPackets()
{
Addr base_addr = request.getVaddr();
DPRINTFS(MinorMem, (&port), "Making packets for request: %s\n", *inst);
for (unsigned int fragment_index = 0; fragment_index < numFragments;
fragment_index++)
{
Request *fragment = fragmentRequests[fragment_index];
DPRINTFS(MinorMem, (&port), "Making packet %d for request: %s"
" (%d, 0x%x)\n",
fragment_index, *inst,
(fragment->hasPaddr() ? "has paddr" : "no paddr"),
(fragment->hasPaddr() ? fragment->getPaddr() : 0));
Addr fragment_addr = fragment->getVaddr();
unsigned int fragment_size = fragment->getSize();
uint8_t *request_data = NULL;
if (!isLoad) {
/* Split data for Packets. Will become the property of the
* outgoing Packets */
request_data = new uint8_t[fragment_size];
std::memcpy(request_data, data + (fragment_addr - base_addr),
fragment_size);
}
assert(fragment->hasPaddr());
PacketPtr fragment_packet =
makePacketForRequest(*fragment, isLoad, this, request_data);
fragmentPackets.push_back(fragment_packet);
/* Accumulate flags in parent request */
request.setFlags(fragment->getFlags());
}
/* Might as well make the overall/response packet here */
/* Get the physical address for the whole request/packet from the first
* fragment */
request.setPaddr(fragmentRequests[0]->getPaddr());
makePacket();
}
void
LSQ::SplitDataRequest::startAddrTranslation()
{
setState(LSQ::LSQRequest::InTranslation);
makeFragmentRequests();
numInTranslationFragments = 0;
numTranslatedFragments = 0;
/* @todo, just do these in sequence for now with
* a loop of:
* do {
* sendNextFragmentToTranslation ; translateTiming ; finish
* } while (numTranslatedFragments != numFragments);
*/
/* Do first translation */
sendNextFragmentToTranslation();
}
PacketPtr
LSQ::SplitDataRequest::getHeadPacket()
{
assert(numIssuedFragments < numFragments);
return fragmentPackets[numIssuedFragments];
}
void
LSQ::SplitDataRequest::stepToNextPacket()
{
assert(numIssuedFragments < numFragments);
numIssuedFragments++;
}
void
LSQ::SplitDataRequest::retireResponse(PacketPtr response)
{
assert(numRetiredFragments < numFragments);
DPRINTFS(MinorMem, (&port), "Retiring fragment addr: 0x%x size: %d"
" offset: 0x%x (retired fragment num: %d) %s\n",
response->req->getVaddr(), response->req->getSize(),
request.getVaddr() - response->req->getVaddr(),
numRetiredFragments,
(fault == NoFault ? "" : fault->name()));
numRetiredFragments++;
if (skipped) {
/* Skip because we already knew the request had faulted or been
* skipped */
DPRINTFS(MinorMem, (&port), "Skipping this fragment\n");
} else if (response->isError()) {
/* Mark up the error and leave to execute to handle it */
DPRINTFS(MinorMem, (&port), "Fragment has an error, skipping\n");
setSkipped();
packet->copyError(response);
} else {
if (isLoad) {
if (!data) {
/* For a split transfer, a Packet must be constructed
* to contain all returning data. This is that packet's
* data */
data = new uint8_t[request.getSize()];
}
/* Populate the portion of the overall response data represented
* by the response fragment */
std::memcpy(
data + (response->req->getVaddr() - request.getVaddr()),
response->getConstPtr<uint8_t>(),
response->req->getSize());
}
}
/* Complete early if we're skipping are no more in-flight accesses */
if (skipped && !hasPacketsInMemSystem()) {
DPRINTFS(MinorMem, (&port), "Completed skipped burst\n");
setState(Complete);
if (packet->needsResponse())
packet->makeResponse();
}
if (numRetiredFragments == numFragments)
setState(Complete);
if (!skipped && isComplete()) {
DPRINTFS(MinorMem, (&port), "Completed burst %d\n", packet != NULL);
DPRINTFS(MinorMem, (&port), "Retired packet isRead: %d isWrite: %d"
" needsResponse: %d packetSize: %s requestSize: %s responseSize:"
" %s\n", packet->isRead(), packet->isWrite(),
packet->needsResponse(), packet->getSize(), request.getSize(),
response->getSize());
/* A request can become complete by several paths, this is a sanity
* check to make sure the packet's data is created */
if (!data) {
data = new uint8_t[request.getSize()];
}
if (isLoad) {
DPRINTFS(MinorMem, (&port), "Copying read data\n");
std::memcpy(packet->getPtr<uint8_t>(), data, request.getSize());
}
packet->makeResponse();
}
/* Packets are all deallocated together in ~SplitLSQRequest */
}
void
LSQ::SplitDataRequest::sendNextFragmentToTranslation()
{
unsigned int fragment_index = numTranslatedFragments;
ThreadContext *thread = port.cpu.getContext(
inst->id.threadId);
DPRINTFS(MinorMem, (&port), "Submitting DTLB request for fragment: %d\n",
fragment_index);
port.numAccessesInDTLB++;
numInTranslationFragments++;
thread->getDTBPtr()->translateTiming(
fragmentRequests[fragment_index], thread, this, (isLoad ?
BaseTLB::Read : BaseTLB::Write));
}
bool
LSQ::StoreBuffer::canInsert() const
{
/* @todo, support store amalgamation */
return slots.size() < numSlots;
}
void
LSQ::StoreBuffer::deleteRequest(LSQRequestPtr request)
{
auto found = std::find(slots.begin(), slots.end(), request);
if (found != slots.end()) {
DPRINTF(MinorMem, "Deleting request: %s %s %s from StoreBuffer\n",
request, *found, *(request->inst));
slots.erase(found);
delete request;
}
}
void
LSQ::StoreBuffer::insert(LSQRequestPtr request)
{
if (!canInsert()) {
warn("%s: store buffer insertion without space to insert from"
" inst: %s\n", name(), *(request->inst));
}
DPRINTF(MinorMem, "Pushing store: %s into store buffer\n", request);
numUnissuedAccesses++;
if (request->state != LSQRequest::Complete)
request->setState(LSQRequest::StoreInStoreBuffer);
slots.push_back(request);
/* Let's try and wake up the processor for the next cycle to step
* the store buffer */
lsq.cpu.wakeupOnEvent(Pipeline::ExecuteStageId);
}
LSQ::AddrRangeCoverage
LSQ::StoreBuffer::canForwardDataToLoad(LSQRequestPtr request,
unsigned int &found_slot)
{
unsigned int slot_index = slots.size() - 1;
auto i = slots.rbegin();
AddrRangeCoverage ret = NoAddrRangeCoverage;
/* Traverse the store buffer in reverse order (most to least recent)
* and try to find a slot whose address range overlaps this request */
while (ret == NoAddrRangeCoverage && i != slots.rend()) {
LSQRequestPtr slot = *i;
/* Cache maintenance instructions go down via the store path *
* but they carry no data and they shouldn't be considered for
* forwarding */
if (slot->packet &&
slot->inst->id.threadId == request->inst->id.threadId &&
!slot->packet->req->isCacheMaintenance()) {
AddrRangeCoverage coverage = slot->containsAddrRangeOf(request);
if (coverage != NoAddrRangeCoverage) {
DPRINTF(MinorMem, "Forwarding: slot: %d result: %s thisAddr:"
" 0x%x thisSize: %d slotAddr: 0x%x slotSize: %d\n",
slot_index, coverage,
request->request.getPaddr(), request->request.getSize(),
slot->request.getPaddr(), slot->request.getSize());
found_slot = slot_index;
ret = coverage;
}
}
i++;
slot_index--;
}
return ret;
}
/** Fill the given packet with appropriate date from slot slot_number */
void
LSQ::StoreBuffer::forwardStoreData(LSQRequestPtr load,
unsigned int slot_number)
{
assert(slot_number < slots.size());
assert(load->packet);
assert(load->isLoad);
LSQRequestPtr store = slots[slot_number];
assert(store->packet);
assert(store->containsAddrRangeOf(load) == FullAddrRangeCoverage);
Addr load_addr = load->request.getPaddr();
Addr store_addr = store->request.getPaddr();
Addr addr_offset = load_addr - store_addr;
unsigned int load_size = load->request.getSize();
DPRINTF(MinorMem, "Forwarding %d bytes for addr: 0x%x from store buffer"
" slot: %d addr: 0x%x addressOffset: 0x%x\n",
load_size, load_addr, slot_number,
store_addr, addr_offset);
void *load_packet_data = load->packet->getPtr<void>();
void *store_packet_data = store->packet->getPtr<uint8_t>() + addr_offset;
std::memcpy(load_packet_data, store_packet_data, load_size);
}
void
LSQ::StoreBuffer::countIssuedStore(LSQRequestPtr request)
{
/* Barriers are accounted for as they are cleared from
* the queue, not after their transfers are complete */
if (!request->isBarrier())
numUnissuedAccesses--;
}
void
LSQ::StoreBuffer::step()
{
DPRINTF(MinorMem, "StoreBuffer step numUnissuedAccesses: %d\n",
numUnissuedAccesses);
if (numUnissuedAccesses != 0 && lsq.state == LSQ::MemoryRunning) {
/* Clear all the leading barriers */
while (!slots.empty() &&
slots.front()->isComplete() && slots.front()->isBarrier())
{
LSQRequestPtr barrier = slots.front();
DPRINTF(MinorMem, "Clearing barrier for inst: %s\n",
*(barrier->inst));
numUnissuedAccesses--;
lsq.clearMemBarrier(barrier->inst);
slots.pop_front();
delete barrier;
}
auto i = slots.begin();
bool issued = true;
unsigned int issue_count = 0;
/* Skip trying if the memory system is busy */
if (lsq.state == LSQ::MemoryNeedsRetry)
issued = false;
/* Try to issue all stores in order starting from the head
* of the queue. Responses are allowed to be retired
* out of order */
while (issued &&
issue_count < storeLimitPerCycle &&
lsq.canSendToMemorySystem() &&
i != slots.end())
{
LSQRequestPtr request = *i;
DPRINTF(MinorMem, "Considering request: %s, sentAllPackets: %d"
" state: %s\n",
*(request->inst), request->sentAllPackets(),
request->state);
if (request->isBarrier() && request->isComplete()) {
/* Give up at barriers */
issued = false;
} else if (!(request->state == LSQRequest::StoreBufferIssuing &&
request->sentAllPackets()))
{
DPRINTF(MinorMem, "Trying to send request: %s to memory"
" system\n", *(request->inst));
if (lsq.tryToSend(request)) {
countIssuedStore(request);
issue_count++;
} else {
/* Don't step on to the next store buffer entry if this
* one hasn't issued all its packets as the store
* buffer must still enforce ordering */
issued = false;
}
}
i++;
}
}
}
void
LSQ::completeMemBarrierInst(MinorDynInstPtr inst,
bool committed)
{
if (committed) {
/* Not already sent to the store buffer as a store request? */
if (!inst->inStoreBuffer) {
/* Insert an entry into the store buffer to tick off barriers
* until there are none in flight */
storeBuffer.insert(new BarrierDataRequest(*this, inst));
}
} else {
/* Clear the barrier anyway if it wasn't actually committed */
clearMemBarrier(inst);
}
}
void
LSQ::StoreBuffer::minorTrace() const
{
unsigned int size = slots.size();
unsigned int i = 0;
std::ostringstream os;
while (i < size) {
LSQRequestPtr request = slots[i];
request->reportData(os);
i++;
if (i < numSlots)
os << ',';
}
while (i < numSlots) {
os << '-';
i++;
if (i < numSlots)
os << ',';
}
MINORTRACE("addr=%s num_unissued_stores=%d\n", os.str(),
numUnissuedAccesses);
}
void
LSQ::tryToSendToTransfers(LSQRequestPtr request)
{
if (state == MemoryNeedsRetry) {
DPRINTF(MinorMem, "Request needs retry, not issuing to"
" memory until retry arrives\n");
return;
}
if (request->state == LSQRequest::InTranslation) {
DPRINTF(MinorMem, "Request still in translation, not issuing to"
" memory\n");
return;
}
assert(request->state == LSQRequest::Translated ||
request->state == LSQRequest::RequestIssuing ||
request->state == LSQRequest::Failed ||
request->state == LSQRequest::Complete);
if (requests.empty() || requests.front() != request) {
DPRINTF(MinorMem, "Request not at front of requests queue, can't"
" issue to memory\n");
return;
}
if (transfers.unreservedRemainingSpace() == 0) {
DPRINTF(MinorMem, "No space to insert request into transfers"
" queue\n");
return;
}
if (request->isComplete() || request->state == LSQRequest::Failed) {
DPRINTF(MinorMem, "Passing a %s transfer on to transfers"
" queue\n", (request->isComplete() ? "completed" : "failed"));
request->setState(LSQRequest::Complete);
request->setSkipped();
moveFromRequestsToTransfers(request);
return;
}
if (!execute.instIsRightStream(request->inst)) {
/* Wrong stream, try to abort the transfer but only do so if
* there are no packets in flight */
if (request->hasPacketsInMemSystem()) {
DPRINTF(MinorMem, "Request's inst. is from the wrong stream,"
" waiting for responses before aborting request\n");
} else {
DPRINTF(MinorMem, "Request's inst. is from the wrong stream,"
" aborting request\n");
request->setState(LSQRequest::Complete);
request->setSkipped();
moveFromRequestsToTransfers(request);
}
return;
}
if (request->fault != NoFault) {
if (request->inst->staticInst->isPrefetch()) {
DPRINTF(MinorMem, "Not signalling fault for faulting prefetch\n");
}
DPRINTF(MinorMem, "Moving faulting request into the transfers"
" queue\n");
request->setState(LSQRequest::Complete);
request->setSkipped();
moveFromRequestsToTransfers(request);
return;
}
bool is_load = request->isLoad;
bool is_llsc = request->request.isLLSC();
bool is_swap = request->request.isSwap();
bool bufferable = !(request->request.isStrictlyOrdered() ||
is_llsc || is_swap);
if (is_load) {
if (numStoresInTransfers != 0) {
DPRINTF(MinorMem, "Load request with stores still in transfers"
" queue, stalling\n");
return;
}
} else {
/* Store. Can it be sent to the store buffer? */
if (bufferable && !request->request.isMmappedIpr()) {
request->setState(LSQRequest::StoreToStoreBuffer);
moveFromRequestsToTransfers(request);
DPRINTF(MinorMem, "Moving store into transfers queue\n");
return;
}
}
/* Check if this is the head instruction (and so must be executable as
* its stream sequence number was checked above) for loads which must
* not be speculatively issued and stores which must be issued here */
if (!bufferable) {
if (!execute.instIsHeadInst(request->inst)) {
DPRINTF(MinorMem, "Memory access not the head inst., can't be"
" sure it can be performed, not issuing\n");
return;
}
unsigned int forwarding_slot = 0;
if (storeBuffer.canForwardDataToLoad(request, forwarding_slot) !=
NoAddrRangeCoverage)
{
DPRINTF(MinorMem, "Memory access can receive forwarded data"
" from the store buffer, need to wait for store buffer to"
" drain\n");
return;
}
}
/* True: submit this packet to the transfers queue to be sent to the
* memory system.
* False: skip the memory and push a packet for this request onto
* requests */
bool do_access = true;
if (!is_llsc) {
/* Check for match in the store buffer */
if (is_load) {
unsigned int forwarding_slot = 0;
AddrRangeCoverage forwarding_result =
storeBuffer.canForwardDataToLoad(request,
forwarding_slot);
switch (forwarding_result) {
case FullAddrRangeCoverage:
/* Forward data from the store buffer into this request and
* repurpose this request's packet into a response packet */
storeBuffer.forwardStoreData(request, forwarding_slot);
request->packet->makeResponse();
/* Just move between queues, no access */
do_access = false;
break;
case PartialAddrRangeCoverage:
DPRINTF(MinorMem, "Load partly satisfied by store buffer"
" data. Must wait for the store to complete\n");
return;
break;
case NoAddrRangeCoverage:
DPRINTF(MinorMem, "No forwardable data from store buffer\n");
/* Fall through to try access */
break;
}
}
} else {
if (!canSendToMemorySystem()) {
DPRINTF(MinorMem, "Can't send request to memory system yet\n");
return;
}
SimpleThread &thread = *cpu.threads[request->inst->id.threadId];
TheISA::PCState old_pc = thread.pcState();
ExecContext context(cpu, thread, execute, request->inst);
/* Handle LLSC requests and tests */
if (is_load) {
TheISA::handleLockedRead(&context, &request->request);
} else {
do_access = TheISA::handleLockedWrite(&context,
&request->request, cacheBlockMask);
if (!do_access) {
DPRINTF(MinorMem, "Not perfoming a memory "
"access for store conditional\n");
}
}
thread.pcState(old_pc);
}
/* See the do_access comment above */
if (do_access) {
if (!canSendToMemorySystem()) {
DPRINTF(MinorMem, "Can't send request to memory system yet\n");
return;
}
/* Remember if this is an access which can't be idly
* discarded by an interrupt */
if (!bufferable && !request->issuedToMemory) {
numAccessesIssuedToMemory++;
request->issuedToMemory = true;
}
if (tryToSend(request)) {
moveFromRequestsToTransfers(request);
}
} else {
request->setState(LSQRequest::Complete);
moveFromRequestsToTransfers(request);
}
}
bool
LSQ::tryToSend(LSQRequestPtr request)
{
bool ret = false;
if (!canSendToMemorySystem()) {
DPRINTF(MinorMem, "Can't send request: %s yet, no space in memory\n",
*(request->inst));
} else {
PacketPtr packet = request->getHeadPacket();
DPRINTF(MinorMem, "Trying to send request: %s addr: 0x%x\n",
*(request->inst), packet->req->getVaddr());
/* The sender state of the packet *must* be an LSQRequest
* so the response can be correctly handled */
assert(packet->findNextSenderState<LSQRequest>());
if (request->request.isMmappedIpr()) {
ThreadContext *thread =
cpu.getContext(cpu.contextToThread(
request->request.contextId()));
if (request->isLoad) {
DPRINTF(MinorMem, "IPR read inst: %s\n", *(request->inst));
TheISA::handleIprRead(thread, packet);
} else {
DPRINTF(MinorMem, "IPR write inst: %s\n", *(request->inst));
TheISA::handleIprWrite(thread, packet);
}
request->stepToNextPacket();
ret = request->sentAllPackets();
if (!ret) {
DPRINTF(MinorMem, "IPR access has another packet: %s\n",
*(request->inst));
}
if (ret)
request->setState(LSQRequest::Complete);
else
request->setState(LSQRequest::RequestIssuing);
} else if (dcachePort.sendTimingReq(packet)) {
DPRINTF(MinorMem, "Sent data memory request\n");
numAccessesInMemorySystem++;
request->stepToNextPacket();
ret = request->sentAllPackets();
switch (request->state) {
case LSQRequest::Translated:
case LSQRequest::RequestIssuing:
/* Fully or partially issued a request in the transfers
* queue */
request->setState(LSQRequest::RequestIssuing);
break;
case LSQRequest::StoreInStoreBuffer:
case LSQRequest::StoreBufferIssuing:
/* Fully or partially issued a request in the store
* buffer */
request->setState(LSQRequest::StoreBufferIssuing);
break;
default:
assert(false);
break;
}
state = MemoryRunning;
} else {
DPRINTF(MinorMem,
"Sending data memory request - needs retry\n");
/* Needs to be resent, wait for that */
state = MemoryNeedsRetry;
retryRequest = request;
switch (request->state) {
case LSQRequest::Translated:
case LSQRequest::RequestIssuing:
request->setState(LSQRequest::RequestNeedsRetry);
break;
case LSQRequest::StoreInStoreBuffer:
case LSQRequest::StoreBufferIssuing:
request->setState(LSQRequest::StoreBufferNeedsRetry);
break;
default:
assert(false);
break;
}
}
}
if (ret)
threadSnoop(request);
return ret;
}
void
LSQ::moveFromRequestsToTransfers(LSQRequestPtr request)
{
assert(!requests.empty() && requests.front() == request);
assert(transfers.unreservedRemainingSpace() != 0);
/* Need to count the number of stores in the transfers
* queue so that loads know when their store buffer forwarding
* results will be correct (only when all those stores
* have reached the store buffer) */
if (!request->isLoad)
numStoresInTransfers++;
requests.pop();
transfers.push(request);
}
bool
LSQ::canSendToMemorySystem()
{
return state == MemoryRunning &&
numAccessesInMemorySystem < inMemorySystemLimit;
}
bool
LSQ::recvTimingResp(PacketPtr response)
{
LSQRequestPtr request =
safe_cast<LSQRequestPtr>(response->popSenderState());
DPRINTF(MinorMem, "Received response packet inst: %s"
" addr: 0x%x cmd: %s\n",
*(request->inst), response->getAddr(),
response->cmd.toString());
numAccessesInMemorySystem--;
if (response->isError()) {
DPRINTF(MinorMem, "Received error response packet: %s\n",
*request->inst);
}
switch (request->state) {
case LSQRequest::RequestIssuing:
case LSQRequest::RequestNeedsRetry:
/* Response to a request from the transfers queue */
request->retireResponse(response);
DPRINTF(MinorMem, "Has outstanding packets?: %d %d\n",
request->hasPacketsInMemSystem(), request->isComplete());
break;
case LSQRequest::StoreBufferIssuing:
case LSQRequest::StoreBufferNeedsRetry:
/* Response to a request from the store buffer */
request->retireResponse(response);
/* Remove completed requests unless they are barriers (which will
* need to be removed in order */
if (request->isComplete()) {
if (!request->isBarrier()) {
storeBuffer.deleteRequest(request);
} else {
DPRINTF(MinorMem, "Completed transfer for barrier: %s"
" leaving the request as it is also a barrier\n",
*(request->inst));
}
}
break;
default:
/* Shouldn't be allowed to receive a response from another
* state */
assert(false);
break;
}
/* We go to idle even if there are more things in the requests queue
* as it's the job of step to actually step us on to the next
* transaction */
/* Let's try and wake up the processor for the next cycle */
cpu.wakeupOnEvent(Pipeline::ExecuteStageId);
/* Never busy */
return true;
}
void
LSQ::recvReqRetry()
{
DPRINTF(MinorMem, "Received retry request\n");
assert(state == MemoryNeedsRetry);
switch (retryRequest->state) {
case LSQRequest::RequestNeedsRetry:
/* Retry in the requests queue */
retryRequest->setState(LSQRequest::Translated);
break;
case LSQRequest::StoreBufferNeedsRetry:
/* Retry in the store buffer */
retryRequest->setState(LSQRequest::StoreInStoreBuffer);
break;
default:
assert(false);
}
/* Set state back to MemoryRunning so that the following
* tryToSend can actually send. Note that this won't
* allow another transfer in as tryToSend should
* issue a memory request and either succeed for this
* request or return the LSQ back to MemoryNeedsRetry */
state = MemoryRunning;
/* Try to resend the request */
if (tryToSend(retryRequest)) {
/* Successfully sent, need to move the request */
switch (retryRequest->state) {
case LSQRequest::RequestIssuing:
/* In the requests queue */
moveFromRequestsToTransfers(retryRequest);
break;
case LSQRequest::StoreBufferIssuing:
/* In the store buffer */
storeBuffer.countIssuedStore(retryRequest);
break;
default:
assert(false);
break;
}
retryRequest = NULL;
}
}
LSQ::LSQ(std::string name_, std::string dcache_port_name_,
MinorCPU &cpu_, Execute &execute_,
unsigned int in_memory_system_limit, unsigned int line_width,
unsigned int requests_queue_size, unsigned int transfers_queue_size,
unsigned int store_buffer_size,
unsigned int store_buffer_cycle_store_limit) :
Named(name_),
cpu(cpu_),
execute(execute_),
dcachePort(dcache_port_name_, *this, cpu_),
lastMemBarrier(cpu.numThreads, 0),
state(MemoryRunning),
inMemorySystemLimit(in_memory_system_limit),
lineWidth((line_width == 0 ? cpu.cacheLineSize() : line_width)),
requests(name_ + ".requests", "addr", requests_queue_size),
transfers(name_ + ".transfers", "addr", transfers_queue_size),
storeBuffer(name_ + ".storeBuffer",
*this, store_buffer_size, store_buffer_cycle_store_limit),
numAccessesInMemorySystem(0),
numAccessesInDTLB(0),
numStoresInTransfers(0),
numAccessesIssuedToMemory(0),
retryRequest(NULL),
cacheBlockMask(~(cpu_.cacheLineSize() - 1))
{
if (in_memory_system_limit < 1) {
fatal("%s: executeMaxAccessesInMemory must be >= 1 (%d)\n", name_,
in_memory_system_limit);
}
if (store_buffer_cycle_store_limit < 1) {
fatal("%s: executeLSQMaxStoreBufferStoresPerCycle must be"
" >= 1 (%d)\n", name_, store_buffer_cycle_store_limit);
}
if (requests_queue_size < 1) {
fatal("%s: executeLSQRequestsQueueSize must be"
" >= 1 (%d)\n", name_, requests_queue_size);
}
if (transfers_queue_size < 1) {
fatal("%s: executeLSQTransfersQueueSize must be"
" >= 1 (%d)\n", name_, transfers_queue_size);
}
if (store_buffer_size < 1) {
fatal("%s: executeLSQStoreBufferSize must be"
" >= 1 (%d)\n", name_, store_buffer_size);
}
if ((lineWidth & (lineWidth - 1)) != 0) {
fatal("%s: lineWidth: %d must be a power of 2\n", name(), lineWidth);
}
}
LSQ::~LSQ()
{ }
LSQ::LSQRequest::~LSQRequest()
{
if (packet)
delete packet;
if (data)
delete [] data;
}
/**
* Step the memory access mechanism on to its next state. In reality, most
* of the stepping is done by the callbacks on the LSQ but this
* function is responsible for issuing memory requests lodged in the
* requests queue.
*/
void
LSQ::step()
{
/* Try to move address-translated requests between queues and issue
* them */
if (!requests.empty())
tryToSendToTransfers(requests.front());
storeBuffer.step();
}
LSQ::LSQRequestPtr
LSQ::findResponse(MinorDynInstPtr inst)
{
LSQ::LSQRequestPtr ret = NULL;
if (!transfers.empty()) {
LSQRequestPtr request = transfers.front();
/* Same instruction and complete access or a store that's
* capable of being moved to the store buffer */
if (request->inst->id == inst->id) {
bool complete = request->isComplete();
bool can_store = storeBuffer.canInsert();
bool to_store_buffer = request->state ==
LSQRequest::StoreToStoreBuffer;
if ((complete && !(request->isBarrier() && !can_store)) ||
(to_store_buffer && can_store))
{
ret = request;
}
}
}
if (ret) {
DPRINTF(MinorMem, "Found matching memory response for inst: %s\n",
*inst);
} else {
DPRINTF(MinorMem, "No matching memory response for inst: %s\n",
*inst);
}
return ret;
}
void
LSQ::popResponse(LSQ::LSQRequestPtr response)
{
assert(!transfers.empty() && transfers.front() == response);
transfers.pop();
if (!response->isLoad)
numStoresInTransfers--;
if (response->issuedToMemory)
numAccessesIssuedToMemory--;
if (response->state != LSQRequest::StoreInStoreBuffer) {
DPRINTF(MinorMem, "Deleting %s request: %s\n",
(response->isLoad ? "load" : "store"),
*(response->inst));
delete response;
}
}
void
LSQ::sendStoreToStoreBuffer(LSQRequestPtr request)
{
assert(request->state == LSQRequest::StoreToStoreBuffer);
DPRINTF(MinorMem, "Sending store: %s to store buffer\n",
*(request->inst));
request->inst->inStoreBuffer = true;
storeBuffer.insert(request);
}
bool
LSQ::isDrained()
{
return requests.empty() && transfers.empty() &&
storeBuffer.isDrained();
}
bool
LSQ::needsToTick()
{
bool ret = false;
if (canSendToMemorySystem()) {
bool have_translated_requests = !requests.empty() &&
requests.front()->state != LSQRequest::InTranslation &&
transfers.unreservedRemainingSpace() != 0;
ret = have_translated_requests ||
storeBuffer.numUnissuedStores() != 0;
}
if (ret)
DPRINTF(Activity, "Need to tick\n");
return ret;
}
void
LSQ::pushRequest(MinorDynInstPtr inst, bool isLoad, uint8_t *data,
unsigned int size, Addr addr, Request::Flags flags,
uint64_t *res)
{
bool needs_burst = transferNeedsBurst(addr, size, lineWidth);
LSQRequestPtr request;
/* Copy given data into the request. The request will pass this to the
* packet and then it will own the data */
uint8_t *request_data = NULL;
DPRINTF(MinorMem, "Pushing request (%s) addr: 0x%x size: %d flags:"
" 0x%x%s lineWidth : 0x%x\n",
(isLoad ? "load" : "store"), addr, size, flags,
(needs_burst ? " (needs burst)" : ""), lineWidth);
if (!isLoad) {
/* request_data becomes the property of a ...DataRequest (see below)
* and destroyed by its destructor */
request_data = new uint8_t[size];
if (flags & Request::STORE_NO_DATA) {
/* For cache zeroing, just use zeroed data */
std::memset(request_data, 0, size);
} else {
std::memcpy(request_data, data, size);
}
}
if (needs_burst) {
request = new SplitDataRequest(
*this, inst, isLoad, request_data, res);
} else {
request = new SingleDataRequest(
*this, inst, isLoad, request_data, res);
}
if (inst->traceData)
inst->traceData->setMem(addr, size, flags);
int cid = cpu.threads[inst->id.threadId]->getTC()->contextId();
request->request.setContext(cid);
request->request.setVirt(0 /* asid */,
addr, size, flags, cpu.dataMasterId(),
/* I've no idea why we need the PC, but give it */
inst->pc.instAddr());
requests.push(request);
request->startAddrTranslation();
}
void
LSQ::pushFailedRequest(MinorDynInstPtr inst)
{
LSQRequestPtr request = new FailedDataRequest(*this, inst);
requests.push(request);
}
void
LSQ::minorTrace() const
{
MINORTRACE("state=%s in_tlb_mem=%d/%d stores_in_transfers=%d"
" lastMemBarrier=%d\n",
state, numAccessesInDTLB, numAccessesInMemorySystem,
numStoresInTransfers, lastMemBarrier[0]);
requests.minorTrace();
transfers.minorTrace();
storeBuffer.minorTrace();
}
LSQ::StoreBuffer::StoreBuffer(std::string name_, LSQ &lsq_,
unsigned int store_buffer_size,
unsigned int store_limit_per_cycle) :
Named(name_), lsq(lsq_),
numSlots(store_buffer_size),
storeLimitPerCycle(store_limit_per_cycle),
slots(),
numUnissuedAccesses(0)
{
}
PacketPtr
makePacketForRequest(Request &request, bool isLoad,
Packet::SenderState *sender_state, PacketDataPtr data)
{
PacketPtr ret = isLoad ? Packet::createRead(&request)
: Packet::createWrite(&request);
if (sender_state)
ret->pushSenderState(sender_state);
if (isLoad) {
ret->allocate();
} else if (!request.isCacheMaintenance()) {
// CMOs are treated as stores but they don't have data. All
// stores otherwise need to allocate for data.
ret->dataDynamic(data);
}
return ret;
}
void
LSQ::issuedMemBarrierInst(MinorDynInstPtr inst)
{
assert(inst->isInst() && inst->staticInst->isMemBarrier());
assert(inst->id.execSeqNum > lastMemBarrier[inst->id.threadId]);
/* Remember the barrier. We only have a notion of one
* barrier so this may result in some mem refs being
* delayed if they are between barriers */
lastMemBarrier[inst->id.threadId] = inst->id.execSeqNum;
}
void
LSQ::LSQRequest::makePacket()
{
/* Make the function idempotent */
if (packet)
return;
// if the translation faulted, do not create a packet
if (fault != NoFault) {
assert(packet == NULL);
return;
}
packet = makePacketForRequest(request, isLoad, this, data);
/* Null the ret data so we know not to deallocate it when the
* ret is destroyed. The data now belongs to the ret and
* the ret is responsible for its destruction */
data = NULL;
}
std::ostream &
operator <<(std::ostream &os, LSQ::MemoryState state)
{
switch (state) {
case LSQ::MemoryRunning:
os << "MemoryRunning";
break;
case LSQ::MemoryNeedsRetry:
os << "MemoryNeedsRetry";
break;
default:
os << "MemoryState-" << static_cast<int>(state);
break;
}
return os;
}
void
LSQ::recvTimingSnoopReq(PacketPtr pkt)
{
/* LLSC operations in Minor can't be speculative and are executed from
* the head of the requests queue. We shouldn't need to do more than
* this action on snoops. */
for (ThreadID tid = 0; tid < cpu.numThreads; tid++) {
if (cpu.getCpuAddrMonitor(tid)->doMonitor(pkt)) {
cpu.wakeup(tid);
}
}
if (pkt->isInvalidate() || pkt->isWrite()) {
for (ThreadID tid = 0; tid < cpu.numThreads; tid++) {
TheISA::handleLockedSnoop(cpu.getContext(tid), pkt,
cacheBlockMask);
}
}
}
void
LSQ::threadSnoop(LSQRequestPtr request)
{
/* LLSC operations in Minor can't be speculative and are executed from
* the head of the requests queue. We shouldn't need to do more than
* this action on snoops. */
ThreadID req_tid = request->inst->id.threadId;
PacketPtr pkt = request->packet;
for (ThreadID tid = 0; tid < cpu.numThreads; tid++) {
if (tid != req_tid) {
if (cpu.getCpuAddrMonitor(tid)->doMonitor(pkt)) {
cpu.wakeup(tid);
}
if (pkt->isInvalidate() || pkt->isWrite()) {
TheISA::handleLockedSnoop(cpu.getContext(tid), pkt,
cacheBlockMask);
}
}
}
}
}