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Diffstat (limited to 'src/sim/futex_map.hh')
-rw-r--r-- | src/sim/futex_map.hh | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/src/sim/futex_map.hh b/src/sim/futex_map.hh new file mode 100644 index 000000000..998f8d481 --- /dev/null +++ b/src/sim/futex_map.hh @@ -0,0 +1,135 @@ +/* + * 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. + * + * Authors: Brandon Potter + * Steve Reinhardt + * Alexandru Dutu + */ + +#ifndef __FUTEX_MAP_HH__ +#define __FUTEX_MAP_HH__ + +#include <unordered_map> + +#include <cpu/thread_context.hh> + +/** + * 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) + : addr(addr_in), tgid(tgid_in) + { + } + + bool + operator==(const FutexKey &in) const + { + return addr == in.addr && tgid == in.tgid; + } +}; + +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<FutexKey> + { + size_t operator()(const 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; + } + }; +} + +typedef std::list<ThreadContext *> ThreadContextList; + +/** + * FutexMap class holds a map of all futexes used in the system + */ +class FutexMap : public std::unordered_map<FutexKey, ThreadContextList> +{ + public: + /** Inserts a futex into the map with one waiting TC */ + void + suspend(Addr addr, uint64_t tgid, ThreadContext *tc) + { + FutexKey key(addr, tgid); + auto it = find(key); + + if (it == end()) { + ThreadContextList tcList {tc}; + insert({key, tcList}); + } else { + it->second.push_back(tc); + } + + /** Suspend the thread context */ + tc->suspend(); + } + + /** Wakes up at most count waiting threads on a futex */ + int + wakeup(Addr addr, uint64_t tgid, int count) + { + FutexKey key(addr, tgid); + auto it = find(key); + + if (it == end()) + return 0; + + int woken_up = 0; + auto &tcList = it->second; + + while (!tcList.empty() && woken_up < count) { + tcList.front()->activate(); + tcList.pop_front(); + woken_up++; + } + + if (tcList.empty()) + erase(it); + + return woken_up; + } + +}; + +#endif // __FUTEX_MAP_HH__ |