src/sim/futex_map.hh

   1 /*
   2  * Copyright (c) 2017 Advanced Micro Devices, Inc.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 #ifndef __FUTEX_MAP_HH__
  30 #define __FUTEX_MAP_HH__
  31
  32 #include <unordered_map>
  33 #include <unordered_set>
  34
  35 #include <cpu/thread_context.hh>
  36
  37 /**
  38  * FutexKey class defines an unique identifier for a particular futex in the
  39  * system. The tgid and an address are the unique values needed as the key.
  40  */
  41 class FutexKey {
  42   public:
  43     uint64_t addr;
  44     uint64_t tgid;
  45
  46     FutexKey(uint64_t addr_in, uint64_t tgid_in);
  47
  48     bool operator==(const FutexKey &in) const;
  49 };
  50
  51 namespace std {
  52     /**
  53      * The unordered_map structure needs the parenthesis operator defined for
  54      * std::hash if a user defined key is used. Our key is is user defined
  55      * so we need to provide the hash functor.
  56      */
  57     template <>
  58     struct hash<FutexKey>
  59     {
  60         size_t operator()(const FutexKey& in) const;
  61     };
  62 }
  63
  64 /**
  65  * WaiterState defines internal state of a waiter thread. The state
  66  * includes a pointer to the thread's context and its associated bitmask.
  67  */
  68 class WaiterState {
  69   public:
  70     ThreadContext* tc;
  71     int bitmask;
  72
  73     /**
  74      * this constructor is used if futex ops with bitset are used
  75      */
  76     WaiterState(ThreadContext* _tc, int _bitmask);
  77
  78     /**
  79      * return true if the bit-wise AND of the wakeup_bitmask given by
  80      * a waking thread and this thread's internal bitmask is non-zero
  81      */
  82     bool checkMask(int wakeup_bitmask) const;
  83 };
  84
  85 typedef std::list<WaiterState> WaiterList;
  86
  87 /**
  88  * FutexMap class holds a map of all futexes used in the system
  89  */
  90 class FutexMap : public std::unordered_map<FutexKey, WaiterList>
  91 {
  92   public:
  93     /** Inserts a futex into the map with one waiting TC */
  94     void suspend(Addr addr, uint64_t tgid, ThreadContext *tc);
  95
  96     /** Wakes up at most count waiting threads on a futex */
  97     int wakeup(Addr addr, uint64_t tgid, int count);
  98
  99     void suspend_bitset(Addr addr, uint64_t tgid, ThreadContext *tc,
 100                    int bitmask);
 101
 102     int wakeup_bitset(Addr addr, uint64_t tgid, int bitmask);
 103
 104     /**
 105      * This operation wakes a given number (val) of waiters. If there are
 106      * more threads waiting than woken, they are removed from the wait
 107      * queue of the futex pointed to by addr1 and added to the wait queue
 108      * of the futex pointed to by addr2. The number of waiter moved is
 109      * capped by count2 (misused timeout parameter).
 110      *
 111      * The return value is the number of waiters that are woken or
 112      * requeued.
 113      */
 114     int requeue(Addr addr1, uint64_t tgid, int count, int count2, Addr addr2);
 115
 116     /**
 117      * Determine if the given thread context is currently waiting on a
 118      * futex wait operation on any of the futexes tracked by this FutexMap.
 119      */
 120     bool is_waiting(ThreadContext *tc);
 121
 122   private:
 123
 124     std::unordered_set<ThreadContext *> waitingTcs;
 125 };
 126
 127 #endif // __FUTEX_MAP_HH__