/*
* Copyright (c) 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.
*
* 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: Rune Holm
* Marco Elver
*/
#ifndef __MEM_MEM_CHECKER_HH__
#define __MEM_MEM_CHECKER_HH__
#include <list>
#include <map>
#include <string>
#include <vector>
#include "base/hashmap.hh"
#include "base/misc.hh"
#include "base/types.hh"
#include "debug/MemChecker.hh"
#include "params/MemChecker.hh"
#include "sim/core.hh"
#include "sim/sim_object.hh"
/**
* MemChecker. Verifies that reads observe the values from permissible writes.
* As memory operations have a start and completion time, we consider them as
* transactions which have a start and end time. Because of this, the lifetimes
* of transactions of memory operations may be overlapping -- we assume that if
* there is overlap between writes, they could be reordered by the memory
* subsystem, and a read could any of these. For more detail, see comments of
* inExpectedData().
*
* For simplicity, the permissible values a read can observe are only dependent
* on the particular location, and we do not consider the effect of multi-byte
* reads or writes. This precludes us from discovering single-copy atomicity
* violations.
*/
class MemChecker : public SimObject
{
public:
/**
* The Serial type is used to be able to uniquely identify a transaction as
* it passes through the system. It's value is independent of any other
* system counters.
*/
typedef uint64_t Serial;
static const Serial SERIAL_INITIAL = 0; //!< Initial serial
/**
* The initial tick the system starts with. Must not be larger than the
* minimum value that curTick() could return at any time in the system's
* execution.
*/
static const Tick TICK_INITIAL = 0;
/**
* The maximum value that curTick() could ever return.
*/
static const Tick TICK_FUTURE = MaxTick;
/**
* Initial data value. No requirements.
*/
static const uint8_t DATA_INITIAL = 0x00;
/**
* The Transaction class captures the lifetimes of read and write
* operations, and the values they consumed or produced respectively.
*/
class Transaction
{
public:
Transaction(Serial _serial,
Tick _start, Tick _complete,
uint8_t _data = DATA_INITIAL)
: serial(_serial),
start(_start), complete(_complete),
data(_data)
{}
public:
Serial serial; //!< Unique identifying serial
Tick start; //!< Start tick
Tick complete; //!< Completion tick
/**
* Depending on the memory operation, the data value either represents:
* for writes, the value written upon start; for reads, the value read
* upon completion.
*/
uint8_t data;
/**
* Orders Transactions for use with std::map.
*/
bool operator<(const Transaction& rhs) const
{ return serial < rhs.serial; }
};
/**
* The WriteCluster class captures sets of writes where all writes are
* overlapping with at least one other write. Capturing writes in this way
* simplifies pruning of writes.
*/
class WriteCluster
{
public:
WriteCluster()
: start(TICK_FUTURE), complete(TICK_FUTURE),
completeMax(TICK_INITIAL), numIncomplete(0)
{}
/**
* Starts a write transaction.
*
* @param serial Unique identifier of the write.
* @param _start When the write was sent off to the memory subsystem.
* @param data The data that this write passed to the memory
* subsystem.
*/
void startWrite(Serial serial, Tick _start, uint8_t data);
/**
* Completes a write transaction.
*
* @param serial Unique identifier of a write *previously started*.
* @param _complete When the write was sent off to the memory
* subsystem.
*/
void completeWrite(Serial serial, Tick _complete);
/**
* Aborts a write transaction.
*
* @param serial Unique identifier of a write *previously started*.
*/
void abortWrite(Serial serial);
/**
* @return true if this cluster's write all completed, false otherwise.
*/
bool isComplete() const { return complete != TICK_FUTURE; }
public:
Tick start; //!< Start of earliest write in cluster
Tick complete; //!< Completion of last write in cluster
/**
* Map of Serial --> Transaction of all writes in cluster; contains
* all, in-flight or already completed.
*/
m5::hash_map<Serial, Transaction> writes;
private:
Tick completeMax;
size_t numIncomplete;
};
typedef std::list<Transaction> TransactionList;
typedef std::list<WriteCluster> WriteClusterList;
/**
* The ByteTracker keeps track of transactions for the *same byte* -- all
* outstanding reads, the completed reads (and what they observed) and write
* clusters (see WriteCluster).
*/
class ByteTracker : public Named
{
public:
ByteTracker(Addr addr = 0, const MemChecker *parent = NULL)
: Named((parent != NULL ? parent->name() : "") +
csprintf(".ByteTracker@%#llx", addr))
{
// The initial transaction has start == complete == TICK_INITIAL,
// indicating that there has been no real write to this location;
// therefore, upon checking, we do not expect any particular value.
readObservations.emplace_back(
Transaction(SERIAL_INITIAL, TICK_INITIAL, TICK_INITIAL,
DATA_INITIAL));
}
/**
* Starts a read transaction.
*
* @param serial Unique identifier for the read.
* @param start When the read was sent off to the memory subsystem.
*/
void startRead(Serial serial, Tick start);
/**
* Given a start and end time (of any read transaction), this function
* iterates through all data that such a read is expected to see. The
* data parameter is the actual value that we observed, and the
* function immediately returns true when a match is found, false
* otherwise.
*
* The set of expected data are:
*
* 1. The last value observed by a read with a completion time before
* this start time (if any).
*
* 2. The data produced by write transactions with a completion after
* the last observed read start time. Only data produced in the
* closest overlapping / earlier write cluster relative to this check
* request is considered, as writes in separate clusters are not
* reordered.
*
* @param start Start time of transaction to validate.
* @param complete End time of transaction to validate.
* @param data The value that we have actually seen.
*
* @return True if a match is found, false otherwise.
*/
bool inExpectedData(Tick start, Tick complete, uint8_t data);
/**
* Completes a read transaction that is still outstanding.
*
* @param serial Unique identifier of a read *previously started*.
* @param complete When the read got a response.
* @param data The data returned by the memory subsystem.
*/
bool completeRead(Serial serial, Tick complete, uint8_t data);
/**
* Starts a write transaction. Wrapper to startWrite of WriteCluster
* instance.
*
* @param serial Unique identifier of the write.
* @param start When the write was sent off to the memory subsystem.
* @param data The data that this write passed to the memory
* subsystem.
*/
void startWrite(Serial serial, Tick start, uint8_t data);
/**
* Completes a write transaction. Wrapper to startWrite of WriteCluster
* instance.
*
* @param serial Unique identifier of a write *previously started*.
* @param complete When the write was sent off to the memory subsystem.
*/
void completeWrite(Serial serial, Tick complete);
/**
* Aborts a write transaction. Wrapper to abortWrite of WriteCluster
* instance.
*
* @param serial Unique identifier of a write *previously started*.
*/
void abortWrite(Serial serial);
/**
* This function returns the expected data that inExpectedData iterated
* through in the last call. If inExpectedData last returned true, the
* set may be incomplete; if inExpectedData last returned false, the
* vector will contain the full set.
*
* @return Reference to internally maintained vector maintaining last
* expected data that inExpectedData iterated through.
*/
const std::vector<uint8_t>& lastExpectedData() const
{ return _lastExpectedData; }
private:
/**
* Convenience function to return the most recent incomplete write
* cluster. Instantiates new write cluster if the most recent one has
* been completed.
*
* @return The most recent incomplete write cluster.
*/
WriteCluster* getIncompleteWriteCluster();
/**
* Helper function to return an iterator to the entry of a container of
* Transaction compatible classes, before a certain tick.
*
* @param before Tick value which should be greater than the
* completion tick of the returned element.
*
* @return Iterator into container.
*/
template <class TList>
typename TList::iterator lastCompletedTransaction(TList *l, Tick before)
{
assert(!l->empty());
// Scanning backwards increases the chances of getting a match
// quicker.
auto it = l->end();
for (--it; it != l->begin() && it->complete >= before; --it);
return it;
}
/**
* Prunes no longer needed transactions. We only keep up to the last /
* most recent of each, readObservations and writeClusters, before the
* first outstanding read.
*
* It depends on the contention / overlap between memory operations to
* the same location of a particular workload how large each of them
* would grow.
*/
void pruneTransactions();
private:
/**
* Maintains a map of Serial -> Transaction for all outstanding reads.
*
* Use an ordered map here, as this makes pruneTransactions() more
* efficient (find first outstanding read).
*/
std::map<Serial, Transaction> outstandingReads;
/**
* List of completed reads, i.e. observations of reads.
*/
TransactionList readObservations;
/**
* List of write clusters for this address.
*/
WriteClusterList writeClusters;
/**
* See lastExpectedData().
*/
std::vector<uint8_t> _lastExpectedData;
};
public:
MemChecker(const MemCheckerParams *p)
: SimObject(p),
nextSerial(SERIAL_INITIAL)
{}
virtual ~MemChecker() {}
/**
* Starts a read transaction.
*
* @param start Tick this read was sent to the memory subsystem.
* @param addr Address for read.
* @param size Size of data expected.
*
* @return Serial representing the unique identifier for this transaction.
*/
Serial startRead(Tick start, Addr addr, size_t size);
/**
* Starts a write transaction.
*
* @param start Tick when this write was sent to the memory subsystem.
* @param addr Address for write.
* @param size Size of data to be written.
* @param data Pointer to size bytes, containing data to be written.
*
* @return Serial representing the unique identifier for this transaction.
*/
Serial startWrite(Tick start, Addr addr, size_t size, const uint8_t *data);
/**
* Completes a previously started read transaction.
*
* @param serial A serial of a read that was previously started and
* matches the address of the previously started read.
* @param complete Tick we received the response from the memory subsystem.
* @param addr Address for read.
* @param size Size of data received.
* @param data Pointer to size bytes, containing data received.
*
* @return True if the data we received is in the expected set, false
* otherwise.
*/
bool completeRead(Serial serial, Tick complete,
Addr addr, size_t size, uint8_t *data);
/**
* Completes a previously started write transaction.
*
* @param serial A serial of a write that was previously started and
* matches the address of the previously started write.
* @param complete Tick we received acknowledgment of completion from the
* memory subsystem.
* @param addr Address for write.
* @param size The size of the data written.
*/
void completeWrite(Serial serial, Tick complete, Addr addr, size_t size);
/**
* Aborts a previously started write transaction.
*
* @param serial A serial of a write that was previously started and
* matches the address of the previously started write.
* @param addr Address for write.
* @param size The size of the data written.
*/
void abortWrite(Serial serial, Addr addr, size_t size);
/**
* Resets the entire checker. Note that if there are transactions
* in-flight, this will cause a warning to be issued if these are completed
* after the reset. This does not reset nextSerial to avoid such a race
* condition: where a transaction started before a reset with serial S,
* then reset() was called, followed by a start of a transaction with the
* same serial S and then receive a completion of the transaction before
* the reset with serial S.
*/
void reset()
{ byte_trackers.clear(); }
/**
* Resets an address-range. This may be useful in case other unmonitored
* parts of the system caused modification to this memory, but we cannot
* track their written values.
*
* @param addr Address base.
* @param size Size of range to be invalidated.
*/
void reset(Addr addr, size_t size);
/**
* In completeRead, if an error is encountered, this does not print nor
* cause an error, but instead should be handled by the caller. However, to
* record information about the cause of an error, completeRead creates an
* errorMessage. This function returns the last error that was detected in
* completeRead.
*
* @return Reference to string of error message.
*/
const std::string& getErrorMessage() const { return errorMessage; }
private:
/**
* Returns the instance of ByteTracker for the requested location.
*/
ByteTracker* getByteTracker(Addr addr)
{
auto it = byte_trackers.find(addr);
if (it == byte_trackers.end()) {
it = byte_trackers.insert(
std::make_pair(addr, ByteTracker(addr, this))).first;
}
return &it->second;
};
private:
/**
* Detailed error message of the last violation in completeRead.
*/
std::string errorMessage;
/**
* Next distinct serial to be assigned to the next transaction to be
* started.
*/
Serial nextSerial;
/**
* Maintain a map of address --> byte-tracker. Per-byte entries are
* initialized as needed.
*
* The required space for this obviously grows with the number of distinct
* addresses used for a particular workload. The used size is independent on
* the number of nodes in the system, those may affect the size of per-byte
* tracking information.
*
* Access via getByteTracker()!
*/
m5::hash_map<Addr, ByteTracker> byte_trackers;
};
inline MemChecker::Serial
MemChecker::startRead(Tick start, Addr addr, size_t size)
{
DPRINTF(MemChecker,
"starting read: serial = %d, start = %d, addr = %#llx, "
"size = %d\n", nextSerial, start, addr , size);
for (size_t i = 0; i < size; ++i) {
getByteTracker(addr + i)->startRead(nextSerial, start);
}
return nextSerial++;
}
inline MemChecker::Serial
MemChecker::startWrite(Tick start, Addr addr, size_t size, const uint8_t *data)
{
DPRINTF(MemChecker,
"starting write: serial = %d, start = %d, addr = %#llx, "
"size = %d\n", nextSerial, start, addr, size);
for (size_t i = 0; i < size; ++i) {
getByteTracker(addr + i)->startWrite(nextSerial, start, data[i]);
}
return nextSerial++;
}
inline void
MemChecker::completeWrite(MemChecker::Serial serial, Tick complete,
Addr addr, size_t size)
{
DPRINTF(MemChecker,
"completing write: serial = %d, complete = %d, "
"addr = %#llx, size = %d\n", serial, complete, addr, size);
for (size_t i = 0; i < size; ++i) {
getByteTracker(addr + i)->completeWrite(serial, complete);
}
}
inline void
MemChecker::abortWrite(MemChecker::Serial serial, Addr addr, size_t size)
{
DPRINTF(MemChecker,
"aborting write: serial = %d, addr = %#llx, size = %d\n",
serial, addr, size);
for (size_t i = 0; i < size; ++i) {
getByteTracker(addr + i)->abortWrite(serial);
}
}
#endif // __MEM_MEM_CHECKER_HH__