Files
gem5/src/mem/packet.cc
Geoffrey Blake b404ffde60 cache: Fix handling of LL/SC requests under contention
If a set of LL/SC requests contend on the same cache block we
can get into a situation where CPUs will deadlock if they expect
a failed SC to supply them data.  This case happens where 3 or
more cores are contending for a cache block using LL/SC and the system
is configured where 2 cores are connected to a local bus and the
third is connected to a remote bus.  If a core on the local bus
sends an SCUpgrade and the core on the remote bus sends and SCUpgrade
they will race to see who will win the SC access.  In the meantime
if the other core appends a read to one of the SCUpgrades it will expect
to be supplied data by that SCUpgrade transaction.  If it happens that
the SCUpgrade that was picked to supply the data is failed, it will
drop the appended request for data and never respond, leaving the requesting
core to deadlock.  This patch makes all SC's behave as normal stores to
prevent this case but still makes sure to check whether it can perform
the update.
2014-09-03 07:42:31 -04:00

412 lines
16 KiB
C++

/*
* Copyright (c) 2011-2014 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.
*
* Copyright (c) 2006 The Regents of The University of Michigan
* Copyright (c) 2010 Advanced Micro Devices, Inc.
* All rights reserved.
*
* 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: Ali Saidi
* Steve Reinhardt
*/
/**
* @file
* Definition of the Packet Class, a packet is a transaction occuring
* between a single level of the memory heirarchy (ie L1->L2).
*/
#include <cstring>
#include <iostream>
#include "base/cprintf.hh"
#include "base/misc.hh"
#include "base/trace.hh"
#include "mem/packet.hh"
using namespace std;
// The one downside to bitsets is that static initializers can get ugly.
#define SET1(a1) (1 << (a1))
#define SET2(a1, a2) (SET1(a1) | SET1(a2))
#define SET3(a1, a2, a3) (SET2(a1, a2) | SET1(a3))
#define SET4(a1, a2, a3, a4) (SET3(a1, a2, a3) | SET1(a4))
#define SET5(a1, a2, a3, a4, a5) (SET4(a1, a2, a3, a4) | SET1(a5))
#define SET6(a1, a2, a3, a4, a5, a6) (SET5(a1, a2, a3, a4, a5) | SET1(a6))
const MemCmd::CommandInfo
MemCmd::commandInfo[] =
{
/* InvalidCmd */
{ 0, InvalidCmd, "InvalidCmd" },
/* ReadReq */
{ SET3(IsRead, IsRequest, NeedsResponse), ReadResp, "ReadReq" },
/* ReadResp */
{ SET3(IsRead, IsResponse, HasData), InvalidCmd, "ReadResp" },
/* ReadRespWithInvalidate */
{ SET4(IsRead, IsResponse, HasData, IsInvalidate),
InvalidCmd, "ReadRespWithInvalidate" },
/* WriteReq */
{ SET5(IsWrite, NeedsExclusive, IsRequest, NeedsResponse, HasData),
WriteResp, "WriteReq" },
/* WriteResp */
{ SET3(IsWrite, NeedsExclusive, IsResponse), InvalidCmd, "WriteResp" },
/* Writeback */
{ SET4(IsWrite, NeedsExclusive, IsRequest, HasData),
InvalidCmd, "Writeback" },
/* SoftPFReq */
{ SET4(IsRead, IsRequest, IsSWPrefetch, NeedsResponse),
SoftPFResp, "SoftPFReq" },
/* HardPFReq */
{ SET4(IsRead, IsRequest, IsHWPrefetch, NeedsResponse),
HardPFResp, "HardPFReq" },
/* SoftPFResp */
{ SET4(IsRead, IsResponse, IsSWPrefetch, HasData),
InvalidCmd, "SoftPFResp" },
/* HardPFResp */
{ SET4(IsRead, IsResponse, IsHWPrefetch, HasData),
InvalidCmd, "HardPFResp" },
/* WriteInvalidateReq (currently unused, see packet.hh) */
{ SET6(IsWrite, NeedsExclusive, IsInvalidate,
IsRequest, HasData, NeedsResponse),
WriteInvalidateResp, "WriteInvalidateReq" },
/* WriteInvalidateResp (currently unused, see packet.hh) */
{ SET3(IsWrite, NeedsExclusive, IsResponse),
InvalidCmd, "WriteInvalidateResp" },
/* UpgradeReq */
{ SET5(IsInvalidate, NeedsExclusive, IsUpgrade, IsRequest, NeedsResponse),
UpgradeResp, "UpgradeReq" },
/* SCUpgradeReq: response could be UpgradeResp or UpgradeFailResp */
{ SET6(IsInvalidate, NeedsExclusive, IsUpgrade, IsLlsc,
IsRequest, NeedsResponse),
UpgradeResp, "SCUpgradeReq" },
/* UpgradeResp */
{ SET3(NeedsExclusive, IsUpgrade, IsResponse),
InvalidCmd, "UpgradeResp" },
/* SCUpgradeFailReq: generates UpgradeFailResp but still gets the data */
{ SET6(IsRead, NeedsExclusive, IsInvalidate,
IsLlsc, IsRequest, NeedsResponse),
UpgradeFailResp, "SCUpgradeFailReq" },
/* UpgradeFailResp - Behaves like a ReadExReq, but notifies an SC
* that it has failed, acquires line as Dirty*/
{ SET4(IsRead, NeedsExclusive, IsResponse, HasData),
InvalidCmd, "UpgradeFailResp" },
/* ReadExReq */
{ SET5(IsRead, NeedsExclusive, IsInvalidate, IsRequest, NeedsResponse),
ReadExResp, "ReadExReq" },
/* ReadExResp */
{ SET4(IsRead, NeedsExclusive, IsResponse, HasData),
InvalidCmd, "ReadExResp" },
/* LoadLockedReq: note that we use plain ReadResp as response, so that
* we can also use ReadRespWithInvalidate when needed */
{ SET4(IsRead, IsLlsc, IsRequest, NeedsResponse),
ReadResp, "LoadLockedReq" },
/* StoreCondReq */
{ SET6(IsWrite, NeedsExclusive, IsLlsc,
IsRequest, NeedsResponse, HasData),
StoreCondResp, "StoreCondReq" },
/* StoreCondFailReq: generates failing StoreCondResp */
{ SET6(IsWrite, NeedsExclusive, IsLlsc,
IsRequest, NeedsResponse, HasData),
StoreCondResp, "StoreCondFailReq" },
/* StoreCondResp */
{ SET4(IsWrite, NeedsExclusive, IsLlsc, IsResponse),
InvalidCmd, "StoreCondResp" },
/* SwapReq -- for Swap ldstub type operations */
{ SET6(IsRead, IsWrite, NeedsExclusive, IsRequest, HasData, NeedsResponse),
SwapResp, "SwapReq" },
/* SwapResp -- for Swap ldstub type operations */
{ SET5(IsRead, IsWrite, NeedsExclusive, IsResponse, HasData),
InvalidCmd, "SwapResp" },
/* IntReq -- for interrupts */
{ SET4(IsWrite, IsRequest, NeedsResponse, HasData),
MessageResp, "MessageReq" },
/* IntResp -- for interrupts */
{ SET2(IsWrite, IsResponse), InvalidCmd, "MessageResp" },
/* InvalidDestError -- packet dest field invalid */
{ SET2(IsResponse, IsError), InvalidCmd, "InvalidDestError" },
/* BadAddressError -- memory address invalid */
{ SET2(IsResponse, IsError), InvalidCmd, "BadAddressError" },
/* FunctionalReadError */
{ SET3(IsRead, IsResponse, IsError), InvalidCmd, "FunctionalReadError" },
/* FunctionalWriteError */
{ SET3(IsWrite, IsResponse, IsError), InvalidCmd, "FunctionalWriteError" },
/* PrintReq */
{ SET2(IsRequest, IsPrint), InvalidCmd, "PrintReq" },
/* Flush Request */
{ SET3(IsRequest, IsFlush, NeedsExclusive), InvalidCmd, "FlushReq" },
/* Invalidation Request */
{ SET3(NeedsExclusive, IsInvalidate, IsRequest),
InvalidCmd, "InvalidationReq" },
};
bool
Packet::checkFunctional(Printable *obj, Addr addr, bool is_secure, int size,
uint8_t *data)
{
Addr func_start = getAddr();
Addr func_end = getAddr() + getSize() - 1;
Addr val_start = addr;
Addr val_end = val_start + size - 1;
if (is_secure != _isSecure || func_start > val_end ||
val_start > func_end) {
// no intersection
return false;
}
// check print first since it doesn't require data
if (isPrint()) {
dynamic_cast<PrintReqState*>(senderState)->printObj(obj);
return false;
}
// if there's no data, there's no need to look further
if (!data) {
return false;
}
// offset of functional request into supplied value (could be
// negative if partial overlap)
int offset = func_start - val_start;
if (isRead()) {
if (func_start >= val_start && func_end <= val_end) {
allocate();
memcpy(getPtr<uint8_t>(), data + offset, getSize());
return true;
} else {
// Offsets and sizes to copy in case of partial overlap
int func_offset;
int val_offset;
int overlap_size;
// calculate offsets and copy sizes for the two byte arrays
if (val_start < func_start && val_end <= func_end) {
val_offset = func_start - val_start;
func_offset = 0;
overlap_size = val_end - func_start;
} else if (val_start >= func_start && val_end > func_end) {
val_offset = 0;
func_offset = val_start - func_start;
overlap_size = func_end - val_start;
} else if (val_start >= func_start && val_end <= func_end) {
val_offset = 0;
func_offset = val_start - func_start;
overlap_size = size;
} else {
panic("BUG: Missed a case for a partial functional request");
}
// Figure out how much of the partial overlap should be copied
// into the packet and not overwrite previously found bytes.
if (bytesValidStart == 0 && bytesValidEnd == 0) {
// No bytes have been copied yet, just set indices
// to found range
bytesValidStart = func_offset;
bytesValidEnd = func_offset + overlap_size;
} else {
// Some bytes have already been copied. Use bytesValid
// indices and offset values to figure out how much data
// to copy and where to copy it to.
// Indice overlap conditions to check
int a = func_offset - bytesValidStart;
int b = (func_offset + overlap_size) - bytesValidEnd;
int c = func_offset - bytesValidEnd;
int d = (func_offset + overlap_size) - bytesValidStart;
if (a >= 0 && b <= 0) {
// bytes already in pkt data array are superset of
// found bytes, will not copy any bytes
overlap_size = 0;
} else if (a < 0 && d >= 0 && b <= 0) {
// found bytes will move bytesValidStart towards 0
overlap_size = bytesValidStart - func_offset;
bytesValidStart = func_offset;
} else if (b > 0 && c <= 0 && a >= 0) {
// found bytes will move bytesValidEnd
// towards end of pkt data array
overlap_size =
(func_offset + overlap_size) - bytesValidEnd;
val_offset += bytesValidEnd - func_offset;
func_offset = bytesValidEnd;
bytesValidEnd += overlap_size;
} else if (a < 0 && b > 0) {
// Found bytes are superset of copied range. Will move
// bytesValidStart towards 0 and bytesValidEnd towards
// end of pkt data array. Need to break copy into two
// pieces so as to not overwrite previously found data.
// copy the first half
uint8_t *dest = getPtr<uint8_t>() + func_offset;
uint8_t *src = data + val_offset;
memcpy(dest, src, (bytesValidStart - func_offset));
// re-calc the offsets and indices to do the copy
// required for the second half
val_offset += (bytesValidEnd - func_offset);
bytesValidStart = func_offset;
overlap_size =
(func_offset + overlap_size) - bytesValidEnd;
func_offset = bytesValidEnd;
bytesValidEnd += overlap_size;
} else if ((c > 0 && b > 0)
|| (a < 0 && d < 0)) {
// region to be copied is discontiguous! Not supported.
panic("BUG: Discontiguous bytes found"
"for functional copying!");
}
}
assert(bytesValidEnd <= getSize());
// copy partial data into the packet's data array
uint8_t *dest = getPtr<uint8_t>() + func_offset;
uint8_t *src = data + val_offset;
memcpy(dest, src, overlap_size);
// check if we're done filling the functional access
bool done = (bytesValidStart == 0) && (bytesValidEnd == getSize());
return done;
}
} else if (isWrite()) {
if (offset >= 0) {
memcpy(data + offset, getPtr<uint8_t>(),
(min(func_end, val_end) - func_start) + 1);
} else {
// val_start > func_start
memcpy(data, getPtr<uint8_t>() - offset,
(min(func_end, val_end) - val_start) + 1);
}
} else {
panic("Don't know how to handle command %s\n", cmdString());
}
// keep going with request by default
return false;
}
void
Packet::pushSenderState(Packet::SenderState *sender_state)
{
assert(sender_state != NULL);
sender_state->predecessor = senderState;
senderState = sender_state;
}
Packet::SenderState *
Packet::popSenderState()
{
assert(senderState != NULL);
SenderState *sender_state = senderState;
senderState = sender_state->predecessor;
sender_state->predecessor = NULL;
return sender_state;
}
void
Packet::print(ostream &o, const int verbosity, const string &prefix) const
{
ccprintf(o, "%s[%x:%x] %s\n", prefix,
getAddr(), getAddr() + getSize() - 1, cmdString());
}
std::string
Packet::print() const {
ostringstream str;
print(str);
return str.str();
}
Packet::PrintReqState::PrintReqState(ostream &_os, int _verbosity)
: curPrefixPtr(new string("")), os(_os), verbosity(_verbosity)
{
labelStack.push_back(LabelStackEntry("", curPrefixPtr));
}
Packet::PrintReqState::~PrintReqState()
{
labelStack.pop_back();
assert(labelStack.empty());
delete curPrefixPtr;
}
Packet::PrintReqState::
LabelStackEntry::LabelStackEntry(const string &_label, string *_prefix)
: label(_label), prefix(_prefix), labelPrinted(false)
{
}
void
Packet::PrintReqState::pushLabel(const string &lbl, const string &prefix)
{
labelStack.push_back(LabelStackEntry(lbl, curPrefixPtr));
curPrefixPtr = new string(*curPrefixPtr);
*curPrefixPtr += prefix;
}
void
Packet::PrintReqState::popLabel()
{
delete curPrefixPtr;
curPrefixPtr = labelStack.back().prefix;
labelStack.pop_back();
assert(!labelStack.empty());
}
void
Packet::PrintReqState::printLabels()
{
if (!labelStack.back().labelPrinted) {
LabelStack::iterator i = labelStack.begin();
LabelStack::iterator end = labelStack.end();
while (i != end) {
if (!i->labelPrinted) {
ccprintf(os, "%s%s\n", *(i->prefix), i->label);
i->labelPrinted = true;
}
i++;
}
}
}
void
Packet::PrintReqState::printObj(Printable *obj)
{
printLabels();
obj->print(os, verbosity, curPrefix());
}