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/*
* Copyright (c) 2017 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.
*/
#ifndef __FUTEX_MAP_HH__
#define __FUTEX_MAP_HH__
#include <unordered_map>
#include <unordered_set>
#include <cpu/thread_context.hh>
namespace gem5
{
/**
* FutexKey class defines an unique identifier for a particular futex in the
* system. The tgid and an address are the unique values needed as the key.
*/
class FutexKey
{
public:
uint64_t addr;
uint64_t tgid;
FutexKey(uint64_t addr_in, uint64_t tgid_in);
bool operator==(const FutexKey &in) const;
};
} // namespace gem5
namespace std
{
/**
* The unordered_map structure needs the parenthesis operator defined for
* std::hash if a user defined key is used. Our key is is user defined
* so we need to provide the hash functor.
*/
template <>
struct hash<gem5::FutexKey>
{
size_t operator()(const gem5::FutexKey& in) const
{
size_t hash = 65521;
for (int i = 0; i < sizeof(uint64_t) / sizeof(size_t); i++) {
hash ^= (size_t)(in.addr >> sizeof(size_t) * i) ^
(size_t)(in.tgid >> sizeof(size_t) * i);
}
return hash;
}
};
} // namespace std
namespace gem5
{
/**
* WaiterState defines internal state of a waiter thread. The state
* includes a pointer to the thread's context and its associated bitmask.
*/
class WaiterState
{
public:
ThreadContext* tc;
int bitmask;
/**
* this constructor is used if futex ops with bitset are used
*/
WaiterState(ThreadContext* _tc, int _bitmask);
/**
* return true if the bit-wise AND of the wakeup_bitmask given by
* a waking thread and this thread's internal bitmask is non-zero
*/
bool checkMask(int wakeup_bitmask) const;
};
typedef std::list<WaiterState> WaiterList;
/**
* FutexMap class holds a map of all futexes used in the system
*/
class FutexMap : public std::unordered_map<FutexKey, WaiterList>
{
public:
/** Inserts a futex into the map with one waiting TC */
void suspend(Addr addr, uint64_t tgid, ThreadContext *tc);
/** Wakes up at most count waiting threads on a futex */
int wakeup(Addr addr, uint64_t tgid, int count);
void suspend_bitset(Addr addr, uint64_t tgid, ThreadContext *tc,
int bitmask);
int wakeup_bitset(Addr addr, uint64_t tgid, int bitmask);
/**
* This operation wakes a given number (val) of waiters. If there are
* more threads waiting than woken, they are removed from the wait
* queue of the futex pointed to by addr1 and added to the wait queue
* of the futex pointed to by addr2. The number of waiter moved is
* capped by count2 (misused timeout parameter).
*
* The return value is the number of waiters that are woken or
* requeued.
*/
int requeue(Addr addr1, uint64_t tgid, int count, int count2, Addr addr2);
/**
* Determine if the given thread context is currently waiting on a
* futex wait operation on any of the futexes tracked by this FutexMap.
*/
bool is_waiting(ThreadContext *tc);
private:
std::unordered_set<ThreadContext *> waitingTcs;
};
} // namespace gem5
#endif // __FUTEX_MAP_HH__