syscall-emul: Rewrite system call exit code

The changeset does a major refactor on the exit, exit_group, and
futex system calls regarding exit functionality.

A FutexMap class and related structures are added into a new
file. This increases code clarity by encapsulating the futex
operations and the futex state into an object.

Several exit conditions were added to allow the simulator to end
processes under certain conditions. Also, the simulation only
exits now when all processes have finished executing.

Change-Id: I1ee244caa9b5586fe7375e5b9b50fd3959b9655e
Reviewed-on: https://gem5-review.googlesource.com/2269
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

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__