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
  34 #include <cpu/thread_context.hh>
  35
  36 /**
  37  * FutexKey class defines an unique identifier for a particular futex in the
  38  * system. The tgid and an address are the unique values needed as the key.
  39  */
  40 class FutexKey {
  41   public:
  42     uint64_t addr;
  43     uint64_t tgid;
  44
  45     FutexKey(uint64_t addr_in, uint64_t tgid_in);
  46
  47     bool operator==(const FutexKey &in) const;
  48 };
  49
  50 namespace std {
  51     /**
  52      * The unordered_map structure needs the parenthesis operator defined for
  53      * std::hash if a user defined key is used. Our key is is user defined
  54      * so we need to provide the hash functor.
  55      */
  56     template <>
  57     struct hash<FutexKey>
  58     {
  59         size_t operator()(const FutexKey& in) const;
  60     };
  61 }
  62
  63 /**
  64  * WaiterState defines internal state of a waiter thread. The state
  65  * includes a pointer to the thread's context and its associated bitmask.
  66  */
  67 class WaiterState {
  68   public:
  69     ThreadContext* tc;
  70     int bitmask;
  71
  72     /**
  73      * this constructor is used if futex ops with bitset are used
  74      */
  75     WaiterState(ThreadContext* _tc, int _bitmask);
  76
  77     /**
  78      * if bitset is not defined, just set bitmask to 0xffffffff
  79      */
  80     WaiterState(ThreadContext* _tc);
  81
  82     /**
  83      * return true if the bit-wise AND of the wakeup_bitmask given by
  84      * a waking thread and this thread's internal bitmask is non-zero
  85      */
  86     bool checkMask(int wakeup_bitmask) const;
  87 };
  88
  89 typedef std::list<WaiterState> WaiterList;
  90
  91 /**
  92  * FutexMap class holds a map of all futexes used in the system
  93  */
  94 class FutexMap : public std::unordered_map<FutexKey, WaiterList>
  95 {
  96   public:
  97     /** Inserts a futex into the map with one waiting TC */
  98     void suspend(Addr addr, uint64_t tgid, ThreadContext *tc);
  99
 100     /** Wakes up at most count waiting threads on a futex */
 101     int wakeup(Addr addr, uint64_t tgid, int count);
 102
 103     void suspend_bitset(Addr addr, uint64_t tgid, ThreadContext *tc,
 104                    int bitmask);
 105
 106     int wakeup_bitset(Addr addr, uint64_t tgid, int bitmask);
 107
 108     /**
 109      * This operation wakes a given number (val) of waiters. If there are
 110      * more threads waiting than woken, they are removed from the wait
 111      * queue of the futex pointed to by addr1 and added to the wait queue
 112      * of the futex pointed to by addr2. The number of waiter moved is
 113      * capped by count2 (misused timeout parameter).
 114      *
 115      * The return value is the number of waiters that are woken or
 116      * requeued.
 117      */
 118     int requeue(Addr addr1, uint64_t tgid, int count, int count2, Addr addr2);
 119 };
 120
 121 #endif // __FUTEX_MAP_HH__