src/sim/futex_map.cc

   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 #include <debug/Thread.hh>
  30 #include <sim/futex_map.hh>
  31
  32 FutexKey::FutexKey(uint64_t addr_in, uint64_t tgid_in)
  33         : addr(addr_in), tgid(tgid_in) {}
  34
  35 bool
  36 FutexKey::operator==(const FutexKey &in) const
  37 {
  38     return addr == in.addr && tgid == in.tgid;
  39 }
  40
  41 namespace std {
  42     size_t hash<FutexKey>::operator()(const FutexKey& in) const
  43     {
  44         size_t hash = 65521;
  45         for (int i = 0; i < sizeof(uint64_t) / sizeof(size_t); i++) {
  46             hash ^= (size_t)(in.addr >> sizeof(size_t) * i) ^
  47                     (size_t)(in.tgid >> sizeof(size_t) * i);
  48         }
  49         return hash;
  50     }
  51 }
  52
  53 WaiterState::WaiterState(ThreadContext* _tc, int _bitmask)
  54       : tc(_tc), bitmask(_bitmask) { }
  55
  56 WaiterState::WaiterState(ThreadContext* _tc)
  57       : tc(_tc), bitmask(0xffffffff) { }
  58
  59 bool
  60 WaiterState::checkMask(int wakeup_bitmask) const
  61 {
  62     return bitmask & wakeup_bitmask;
  63 }
  64
  65 void
  66 FutexMap::suspend(Addr addr, uint64_t tgid, ThreadContext *tc)
  67 {
  68     FutexKey key(addr, tgid);
  69     auto it = find(key);
  70
  71     if (it == end()) {
  72         WaiterList waiterList {WaiterState(tc)};
  73         insert({key, waiterList});
  74     } else {
  75         it->second.push_back(WaiterState(tc));
  76     }
  77
  78     /** Suspend the thread context */
  79     tc->suspend();
  80 }
  81
  82 int
  83 FutexMap::wakeup(Addr addr, uint64_t tgid, int count)
  84 {
  85     FutexKey key(addr, tgid);
  86     auto it = find(key);
  87
  88     if (it == end())
  89         return 0;
  90
  91     int woken_up = 0;
  92     auto &waiterList = it->second;
  93
  94     while (!waiterList.empty() && woken_up < count) {
  95         // Threads may be woken up by access to locked
  96         // memory addresses outside of syscalls, so we
  97         // must only count threads that were actually
  98         // woken up by this syscall.
  99         auto& tc = waiterList.front().tc;
 100         if (tc->status() == ThreadContext::Suspended) {
 101             tc->activate();
 102             woken_up++;
 103         }
 104         waiterList.pop_front();
 105     }
 106
 107     if (waiterList.empty())
 108         erase(it);
 109
 110     return woken_up;
 111 }
 112
 113 void
 114 FutexMap::suspend_bitset(Addr addr, uint64_t tgid, ThreadContext *tc,
 115                int bitmask)
 116 {
 117     FutexKey key(addr, tgid);
 118     auto it = find(key);
 119
 120     if (it == end()) {
 121         WaiterList waiterList {WaiterState(tc, bitmask)};
 122         insert({key, waiterList});
 123     } else {
 124         it->second.push_back(WaiterState(tc, bitmask));
 125     }
 126
 127     /** Suspend the thread context */
 128     tc->suspend();
 129 }
 130
 131 int
 132 FutexMap::wakeup_bitset(Addr addr, uint64_t tgid, int bitmask)
 133 {
 134     FutexKey key(addr, tgid);
 135     auto it = find(key);
 136
 137     if (it == end())
 138         return 0;
 139
 140     int woken_up = 0;
 141
 142     auto &waiterList = it->second;
 143     auto iter = waiterList.begin();
 144
 145     while (iter != waiterList.end()) {
 146         WaiterState& waiter = *iter;
 147
 148         if (waiter.checkMask(bitmask)) {
 149             waiter.tc->activate();
 150             iter = waiterList.erase(iter);
 151             woken_up++;
 152         } else {
 153             ++iter;
 154         }
 155     }
 156
 157     if (waiterList.empty())
 158         erase(it);
 159
 160     return woken_up;
 161 }
 162
 163 int
 164 FutexMap::requeue(Addr addr1, uint64_t tgid, int count, int count2, Addr addr2)
 165 {
 166     FutexKey key1(addr1, tgid);
 167     auto it1 = find(key1);
 168
 169     if (it1 == end())
 170         return 0;
 171
 172     int woken_up = 0;
 173     auto &waiterList1 = it1->second;
 174
 175     while (!waiterList1.empty() && woken_up < count) {
 176         waiterList1.front().tc->activate();
 177         waiterList1.pop_front();
 178         woken_up++;
 179     }
 180
 181     WaiterList tmpList;
 182     int requeued = 0;
 183
 184     while (!waiterList1.empty() && requeued < count2) {
 185       auto w = waiterList1.front();
 186       waiterList1.pop_front();
 187       tmpList.push_back(w);
 188       requeued++;
 189     }
 190
 191     FutexKey key2(addr2, tgid);
 192     auto it2 = find(key2);
 193
 194     if (it2 == end() && requeued > 0) {
 195         insert({key2, tmpList});
 196     } else {
 197         it2->second.insert(it2->second.end(),
 198                            tmpList.begin(), tmpList.end());
 199     }
 200
 201     if (waiterList1.empty())
 202         erase(it1);
 203
 204     return woken_up + requeued;
 205 }