/*
- * Copyright (c) 2013-2015 ARM Limited
+ * Copyright (c) 2013-2017 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
* (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: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
+ * Authors: Stephan Diestelhorst
*/
/**
* @file
- * Definition of a snoop filter.
+ * Implementation of a snoop filter.
*/
-#include "base/misc.hh"
+#include "mem/snoop_filter.hh"
+
+#include "base/logging.hh"
#include "base/trace.hh"
#include "debug/SnoopFilter.hh"
-#include "mem/snoop_filter.hh"
#include "sim/system.hh"
void
std::pair<SnoopFilter::SnoopList, Cycles>
SnoopFilter::lookupRequest(const Packet* cpkt, const SlavePort& slave_port)
{
- DPRINTF(SnoopFilter, "%s: packet src %s addr 0x%x cmd %s\n",
- __func__, slave_port.name(), cpkt->getAddr(), cpkt->cmdString());
+ DPRINTF(SnoopFilter, "%s: src %s packet %s\n", __func__,
+ slave_port.name(), cpkt->print());
- // Ultimately we should check if the packet came from an
- // allocating source, not just if the port is snooping
- bool allocate = !cpkt->req->isUncacheable() && slave_port.isSnooping();
+ // check if the packet came from a cache
+ bool allocate = !cpkt->req->isUncacheable() && slave_port.isSnooping() &&
+ cpkt->fromCache();
Addr line_addr = cpkt->getBlockAddr(linesize);
+ if (cpkt->isSecure()) {
+ line_addr |= LineSecure;
+ }
SnoopMask req_port = portToMask(slave_port);
reqLookupResult = cachedLocations.find(line_addr);
bool is_hit = (reqLookupResult != cachedLocations.end());
lookupLatency);
if (cpkt->needsResponse()) {
- if (!cpkt->memInhibitAsserted()) {
+ if (!cpkt->cacheResponding()) {
// Max one request per address per port
panic_if(sf_item.requested & req_port, "double request :( " \
"SF value %x.%x\n", sf_item.requested, sf_item.holder);
__func__, sf_item.requested, sf_item.holder);
}
} else { // if (!cpkt->needsResponse())
- assert(cpkt->evictingBlock());
+ assert(cpkt->isEviction());
// make sure that the sender actually had the line
panic_if(!(sf_item.holder & req_port), "requester %x is not a " \
"holder :( SF value %x.%x\n", req_port,
}
void
-SnoopFilter::finishRequest(bool will_retry, const Packet* cpkt)
+SnoopFilter::finishRequest(bool will_retry, Addr addr, bool is_secure)
{
if (reqLookupResult != cachedLocations.end()) {
// since we rely on the caller, do a basic check to ensure
// that finishRequest is being called following lookupRequest
- assert(reqLookupResult->first == cpkt->getBlockAddr(linesize));
+ Addr line_addr = (addr & ~(Addr(linesize - 1)));
+ if (is_secure) {
+ line_addr |= LineSecure;
+ }
+ assert(reqLookupResult->first == line_addr);
if (will_retry) {
// Undo any changes made in lookupRequest to the snoop filter
// entry if the request will come again. retryItem holds
std::pair<SnoopFilter::SnoopList, Cycles>
SnoopFilter::lookupSnoop(const Packet* cpkt)
{
- DPRINTF(SnoopFilter, "%s: packet addr 0x%x cmd %s\n",
- __func__, cpkt->getAddr(), cpkt->cmdString());
+ DPRINTF(SnoopFilter, "%s: packet %s\n", __func__, cpkt->print());
assert(cpkt->isRequest());
- // Broadcast / filter upward snoops
- const bool filter_upward = true; // @todo: Make configurable
-
- if (!filter_upward)
- return snoopAll(lookupLatency);
-
Addr line_addr = cpkt->getBlockAddr(linesize);
+ if (cpkt->isSecure()) {
+ line_addr |= LineSecure;
+ }
auto sf_it = cachedLocations.find(line_addr);
bool is_hit = (sf_it != cachedLocations.end());
"snoop filter exceeded capacity of %d cache blocks\n",
maxEntryCount);
- // If the snoop filter has no entry and its an uncacheable
- // request, do not create a new snoop filter entry, simply return
- // a NULL portlist.
- if (!is_hit && cpkt->req->isUncacheable())
+ // If the snoop filter has no entry, simply return a NULL
+ // portlist, there is no point creating an entry only to remove it
+ // later
+ if (!is_hit)
return snoopDown(lookupLatency);
- // If no hit in snoop filter create a new element and update iterator
- if (!is_hit)
- sf_it = cachedLocations.emplace(line_addr, SnoopItem()).first;
SnoopItem& sf_item = sf_it->second;
DPRINTF(SnoopFilter, "%s: old SF value %x.%x\n",
SnoopMask interested = (sf_item.holder | sf_item.requested);
totSnoops++;
- if (is_hit) {
- // Single bit set -> value is a power of two
- if (isPow2(interested))
- hitSingleSnoops++;
- else
- hitMultiSnoops++;
- }
+ // Single bit set -> value is a power of two
+ if (isPow2(interested))
+ hitSingleSnoops++;
+ else
+ hitMultiSnoops++;
+
// ReadEx and Writes require both invalidation and exlusivity, while reads
// require neither. Writebacks on the other hand require exclusivity but
// not the invalidation. Previously Writebacks did not generate upward
- // snoops so this was never an aissue. Now that Writebacks generate snoops
- // we need to special case for Writebacks.
- assert(cpkt->cmd == MemCmd::Writeback || cpkt->req->isUncacheable() ||
- (cpkt->isInvalidate() == cpkt->needsExclusive()));
+ // snoops so this was never an issue. Now that Writebacks generate snoops
+ // we need a special case for Writebacks. Additionally cache maintenance
+ // operations can generate snoops as they clean and/or invalidate all
+ // caches down to the specified point of reference.
+ assert(cpkt->isWriteback() || cpkt->req->isUncacheable() ||
+ (cpkt->isInvalidate() == cpkt->needsWritable()) ||
+ cpkt->req->isCacheMaintenance());
if (cpkt->isInvalidate() && !sf_item.requested) {
// Early clear of the holder, if no other request is currently going on
// @todo: This should possibly be updated even though we do not filter
const SlavePort& rsp_port,
const SlavePort& req_port)
{
- DPRINTF(SnoopFilter, "%s: packet rsp %s req %s addr 0x%x cmd %s\n",
- __func__, rsp_port.name(), req_port.name(), cpkt->getAddr(),
- cpkt->cmdString());
+ DPRINTF(SnoopFilter, "%s: rsp %s req %s packet %s\n",
+ __func__, rsp_port.name(), req_port.name(), cpkt->print());
assert(cpkt->isResponse());
- assert(cpkt->memInhibitAsserted());
+ assert(cpkt->cacheResponding());
- // Ultimately we should check if the packet came from an
- // allocating source, not just if the port is snooping
- bool allocate = !cpkt->req->isUncacheable() && req_port.isSnooping();
- if (!allocate)
+ // if this snoop response is due to an uncacheable request, or is
+ // being turned into a normal response, there is nothing more to
+ // do
+ if (cpkt->req->isUncacheable() || !req_port.isSnooping()) {
return;
+ }
Addr line_addr = cpkt->getBlockAddr(linesize);
+ if (cpkt->isSecure()) {
+ line_addr |= LineSecure;
+ }
SnoopMask rsp_mask = portToMask(rsp_port);
SnoopMask req_mask = portToMask(req_port);
SnoopItem& sf_item = cachedLocations[line_addr];
panic_if(!(sf_item.requested & req_mask), "SF value %x.%x missing "\
"the original request\n", sf_item.requested, sf_item.holder);
- // Update the residency of the cache line.
- if (cpkt->needsExclusive() || !cpkt->sharedAsserted()) {
- DPRINTF(SnoopFilter, "%s: dropping %x because needs: %i shared: %i "\
- "SF val: %x.%x\n", __func__, rsp_mask,
- cpkt->needsExclusive(), cpkt->sharedAsserted(),
+ // If the snoop response has no sharers the line is passed in
+ // Modified state, and we know that there are no other copies, or
+ // they will all be invalidated imminently
+ if (!cpkt->hasSharers()) {
+ DPRINTF(SnoopFilter,
+ "%s: dropping %x because non-shared snoop "
+ "response SF val: %x.%x\n", __func__, rsp_mask,
sf_item.requested, sf_item.holder);
-
- sf_item.holder &= ~rsp_mask;
- // The snoop filter does not see any ACKs from non-responding sharers
- // that have been invalidated :( So below assert would be nice, but..
- //assert(sf_item.holder == 0);
sf_item.holder = 0;
}
- assert(cpkt->cmd != MemCmd::Writeback);
+ assert(!cpkt->isWriteback());
+ // @todo Deal with invalidating responses
sf_item.holder |= req_mask;
sf_item.requested &= ~req_mask;
assert(sf_item.requested | sf_item.holder);
SnoopFilter::updateSnoopForward(const Packet* cpkt,
const SlavePort& rsp_port, const MasterPort& req_port)
{
- DPRINTF(SnoopFilter, "%s: packet rsp %s req %s addr 0x%x cmd %s\n",
- __func__, rsp_port.name(), req_port.name(), cpkt->getAddr(),
- cpkt->cmdString());
+ DPRINTF(SnoopFilter, "%s: rsp %s req %s packet %s\n",
+ __func__, rsp_port.name(), req_port.name(), cpkt->print());
+
+ assert(cpkt->isResponse());
+ assert(cpkt->cacheResponding());
Addr line_addr = cpkt->getBlockAddr(linesize);
+ if (cpkt->isSecure()) {
+ line_addr |= LineSecure;
+ }
auto sf_it = cachedLocations.find(line_addr);
- if (sf_it == cachedLocations.end())
- sf_it = cachedLocations.emplace(line_addr, SnoopItem()).first;
- SnoopItem& sf_item = sf_it->second;
- SnoopMask rsp_mask M5_VAR_USED = portToMask(rsp_port);
+ bool is_hit = sf_it != cachedLocations.end();
- assert(cpkt->isResponse());
- assert(cpkt->memInhibitAsserted());
+ // Nothing to do if it is not a hit
+ if (!is_hit)
+ return;
+
+ SnoopItem& sf_item = sf_it->second;
DPRINTF(SnoopFilter, "%s: old SF value %x.%x\n",
__func__, sf_item.requested, sf_item.holder);
- // Remote (to this snoop filter) snoops update the filter already when they
- // arrive from below, because we may not see any response.
- if (cpkt->needsExclusive()) {
- // If the request to this snoop response hit an in-flight transaction,
- // the holder was not reset -> no assertion & do that here, now!
- //assert(sf_item.holder == 0);
+ // If the snoop response has no sharers the line is passed in
+ // Modified state, and we know that there are no other copies, or
+ // they will all be invalidated imminently
+ if (!cpkt->hasSharers()) {
sf_item.holder = 0;
}
DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n",
__func__, sf_item.requested, sf_item.holder);
eraseIfNullEntry(sf_it);
+
}
void
SnoopFilter::updateResponse(const Packet* cpkt, const SlavePort& slave_port)
{
- DPRINTF(SnoopFilter, "%s: packet src %s addr 0x%x cmd %s\n",
- __func__, slave_port.name(), cpkt->getAddr(), cpkt->cmdString());
+ DPRINTF(SnoopFilter, "%s: src %s packet %s\n",
+ __func__, slave_port.name(), cpkt->print());
assert(cpkt->isResponse());
- // Ultimately we should check if the packet came from an
- // allocating source, not just if the port is snooping
- bool allocate = !cpkt->req->isUncacheable() && slave_port.isSnooping();
- if (!allocate)
+ // we only allocate if the packet actually came from a cache, but
+ // start by checking if the port is snooping
+ if (cpkt->req->isUncacheable() || !slave_port.isSnooping())
return;
+ // next check if we actually allocated an entry
Addr line_addr = cpkt->getBlockAddr(linesize);
+ if (cpkt->isSecure()) {
+ line_addr |= LineSecure;
+ }
+ auto sf_it = cachedLocations.find(line_addr);
+ if (sf_it == cachedLocations.end())
+ return;
+
SnoopMask slave_mask = portToMask(slave_port);
- SnoopItem& sf_item = cachedLocations[line_addr];
+ SnoopItem& sf_item = sf_it->second;
DPRINTF(SnoopFilter, "%s: old SF value %x.%x\n",
__func__, sf_item.requested, sf_item.holder);
panic_if(!(sf_item.requested & slave_mask), "SF value %x.%x missing "\
"request bit\n", sf_item.requested, sf_item.holder);
- // Update the residency of the cache line. Here we assume that the
- // line has been zapped in all caches that are not the responder.
- if (cpkt->needsExclusive() || !cpkt->sharedAsserted())
- sf_item.holder = 0;
- sf_item.holder |= slave_mask;
sf_item.requested &= ~slave_mask;
- assert(sf_item.holder | sf_item.requested);
+ // Update the residency of the cache line.
+
+ if (cpkt->req->isCacheMaintenance()) {
+ // A cache clean response does not carry any data so it
+ // shouldn't change the holders, unless it is invalidating.
+ if (cpkt->isInvalidate()) {
+ sf_item.holder &= ~slave_mask;
+ }
+ eraseIfNullEntry(sf_it);
+ } else {
+ // Any other response implies that a cache above will have the
+ // block.
+ sf_item.holder |= slave_mask;
+ assert(sf_item.holder | sf_item.requested);
+ }
DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n",
__func__, sf_item.requested, sf_item.holder);
}
void
SnoopFilter::regStats()
{
+ SimObject::regStats();
+
totRequests
.name(name() + ".tot_requests")
.desc("Total number of requests made to the snoop filter.");
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