learning_gem5: Adds the simple MemObject code

Adding more code from Learning gem5 Part II

See http://learning.gem5.org/book/part2/memoryobject.html

Change-Id: Iaa9480c5cdbe4090364f02e81dc1d0a0ddac392a
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/5022
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>

4 files changed, 558 insertions, 0 deletions

diff --git a/src/learning_gem5/part2/SConscript b/src/learning_gem5/part2/SConscript
index 35d14ecce..f4605f39d 100644
--- a/src/learning_gem5/part2/SConscript
+++ b/src/learning_gem5/part2/SConscript
@@ -31,9 +31,12 @@ Import('*')
 
 SimObject('SimpleObject.py')
 SimObject('HelloObject.py')
+SimObject('SimpleMemobj.py')
 
 Source('simple_object.cc')
 Source('hello_object.cc')
 Source('goodbye_object.cc')
+Source('simple_memobj.cc')
 
 DebugFlag('HelloExample', "For Learning gem5 Part 2. Simple example debug flag")
+DebugFlag('SimpleMemobj', "For Learning gem5 Part 2.")
diff --git a/src/learning_gem5/part2/SimpleMemobj.py b/src/learning_gem5/part2/SimpleMemobj.py
new file mode 100644
index 000000000..414e2c7f6
--- /dev/null
+++ b/src/learning_gem5/part2/SimpleMemobj.py
@@ -0,0 +1,39 @@
+# -*- coding: utf-8 -*-
+# Copyright (c) 2017 Jason Lowe-Power
+# 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: Jason Lowe-Power
+
+from m5.params import *
+from MemObject import MemObject
+
+class SimpleMemobj(MemObject):
+    type = 'SimpleMemobj'
+    cxx_header = "learning_gem5/part2/simple_memobj.hh"
+
+    inst_port = SlavePort("CPU side port, receives requests")
+    data_port = SlavePort("CPU side port, receives requests")
+    mem_side = MasterPort("Memory side port, sends requests")
diff --git a/src/learning_gem5/part2/simple_memobj.cc b/src/learning_gem5/part2/simple_memobj.cc
new file mode 100644
index 000000000..cb4d3d8db
--- /dev/null
+++ b/src/learning_gem5/part2/simple_memobj.cc
@@ -0,0 +1,251 @@
+/*
+ * Copyright (c) 2017 Jason Lowe-Power
+ * 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: Jason Lowe-Power
+ */
+
+#include "learning_gem5/part2/simple_memobj.hh"
+
+#include "debug/SimpleMemobj.hh"
+
+SimpleMemobj::SimpleMemobj(SimpleMemobjParams *params) :
+    MemObject(params),
+    instPort(params->name + ".inst_port", this),
+    dataPort(params->name + ".data_port", this),
+    memPort(params->name + ".mem_side", this),
+    blocked(false)
+{
+}
+
+BaseMasterPort&
+SimpleMemobj::getMasterPort(const std::string& if_name, PortID idx)
+{
+    panic_if(idx != InvalidPortID, "This object doesn't support vector ports");
+
+    // This is the name from the Python SimObject declaration (SimpleMemobj.py)
+    if (if_name == "mem_side") {
+        return memPort;
+    } else {
+        // pass it along to our super class
+        return MemObject::getMasterPort(if_name, idx);
+    }
+}
+
+BaseSlavePort&
+SimpleMemobj::getSlavePort(const std::string& if_name, PortID idx)
+{
+    panic_if(idx != InvalidPortID, "This object doesn't support vector ports");
+
+    // This is the name from the Python SimObject declaration in SimpleCache.py
+    if (if_name == "inst_port") {
+        return instPort;
+    } else if (if_name == "data_port") {
+        return dataPort;
+    } else {
+        // pass it along to our super class
+        return MemObject::getSlavePort(if_name, idx);
+    }
+}
+
+void
+SimpleMemobj::CPUSidePort::sendPacket(PacketPtr pkt)
+{
+    // Note: This flow control is very simple since the memobj is blocking.
+
+    panic_if(blockedPacket != nullptr, "Should never try to send if blocked!");
+
+    // If we can't send the packet across the port, store it for later.
+    if (!sendTimingResp(pkt)) {
+        blockedPacket = pkt;
+    }
+}
+
+AddrRangeList
+SimpleMemobj::CPUSidePort::getAddrRanges() const
+{
+    return owner->getAddrRanges();
+}
+
+void
+SimpleMemobj::CPUSidePort::trySendRetry()
+{
+    if (needRetry && blockedPacket == nullptr) {
+        // Only send a retry if the port is now completely free
+        needRetry = false;
+        DPRINTF(SimpleMemobj, "Sending retry req for %d\n", id);
+        sendRetryReq();
+    }
+}
+
+void
+SimpleMemobj::CPUSidePort::recvFunctional(PacketPtr pkt)
+{
+    // Just forward to the memobj.
+    return owner->handleFunctional(pkt);
+}
+
+bool
+SimpleMemobj::CPUSidePort::recvTimingReq(PacketPtr pkt)
+{
+    // Just forward to the memobj.
+    if (!owner->handleRequest(pkt)) {
+        needRetry = true;
+        return false;
+    } else {
+        return true;
+    }
+}
+
+void
+SimpleMemobj::CPUSidePort::recvRespRetry()
+{
+    // We should have a blocked packet if this function is called.
+    assert(blockedPacket != nullptr);
+
+    // Grab the blocked packet.
+    PacketPtr pkt = blockedPacket;
+    blockedPacket = nullptr;
+
+    // Try to resend it. It's possible that it fails again.
+    sendPacket(pkt);
+}
+
+void
+SimpleMemobj::MemSidePort::sendPacket(PacketPtr pkt)
+{
+    // Note: This flow control is very simple since the memobj is blocking.
+
+    panic_if(blockedPacket != nullptr, "Should never try to send if blocked!");
+
+    // If we can't send the packet across the port, store it for later.
+    if (!sendTimingReq(pkt)) {
+        blockedPacket = pkt;
+    }
+}
+
+bool
+SimpleMemobj::MemSidePort::recvTimingResp(PacketPtr pkt)
+{
+    // Just forward to the memobj.
+    return owner->handleResponse(pkt);
+}
+
+void
+SimpleMemobj::MemSidePort::recvReqRetry()
+{
+    // We should have a blocked packet if this function is called.
+    assert(blockedPacket != nullptr);
+
+    // Grab the blocked packet.
+    PacketPtr pkt = blockedPacket;
+    blockedPacket = nullptr;
+
+    // Try to resend it. It's possible that it fails again.
+    sendPacket(pkt);
+}
+
+void
+SimpleMemobj::MemSidePort::recvRangeChange()
+{
+    owner->sendRangeChange();
+}
+
+bool
+SimpleMemobj::handleRequest(PacketPtr pkt)
+{
+    if (blocked) {
+        // There is currently an outstanding request. Stall.
+        return false;
+    }
+
+    DPRINTF(SimpleMemobj, "Got request for addr %#x\n", pkt->getAddr());
+
+    // This memobj is now blocked waiting for the response to this packet.
+    blocked = true;
+
+    // Simply forward to the memory port
+    memPort.sendPacket(pkt);
+
+    return true;
+}
+
+bool
+SimpleMemobj::handleResponse(PacketPtr pkt)
+{
+    assert(blocked);
+    DPRINTF(SimpleMemobj, "Got response for addr %#x\n", pkt->getAddr());
+
+    // The packet is now done. We're about to put it in the port, no need for
+    // this object to continue to stall.
+    // We need to free the resource before sending the packet in case the CPU
+    // tries to send another request immediately (e.g., in the same callchain).
+    blocked = false;
+
+    // Simply forward to the memory port
+    if (pkt->req->isInstFetch()) {
+        instPort.sendPacket(pkt);
+    } else {
+        dataPort.sendPacket(pkt);
+    }
+
+    // For each of the cpu ports, if it needs to send a retry, it should do it
+    // now since this memory object may be unblocked now.
+    instPort.trySendRetry();
+    dataPort.trySendRetry();
+
+    return true;
+}
+
+void
+SimpleMemobj::handleFunctional(PacketPtr pkt)
+{
+    // Just pass this on to the memory side to handle for now.
+    memPort.sendFunctional(pkt);
+}
+
+AddrRangeList
+SimpleMemobj::getAddrRanges() const
+{
+    DPRINTF(SimpleMemobj, "Sending new ranges\n");
+    // Just use the same ranges as whatever is on the memory side.
+    return memPort.getAddrRanges();
+}
+
+void
+SimpleMemobj::sendRangeChange()
+{
+    instPort.sendRangeChange();
+    dataPort.sendRangeChange();
+}
+
+
+
+SimpleMemobj*
+SimpleMemobjParams::create()
+{
+    return new SimpleMemobj(this);
+}
diff --git a/src/learning_gem5/part2/simple_memobj.hh b/src/learning_gem5/part2/simple_memobj.hh
new file mode 100644
index 000000000..a44d4336c
--- /dev/null
+++ b/src/learning_gem5/part2/simple_memobj.hh
@@ -0,0 +1,265 @@
+/*
+ * Copyright (c) 2017 Jason Lowe-Power
+ * 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: Jason Lowe-Power
+ */
+
+#ifndef __LEARNING_GEM5_PART2_SIMPLE_MEMOBJ_HH__
+#define __LEARNING_GEM5_PART2_SIMPLE_MEMOBJ_HH__
+
+#include "mem/mem_object.hh"
+#include "params/SimpleMemobj.hh"
+
+/**
+ * A very simple memory object. Current implementation doesn't even cache
+ * anything it just forwards requests and responses.
+ * This memobj is fully blocking (not non-blocking). Only a single request can
+ * be outstanding at a time.
+ */
+class SimpleMemobj : public MemObject
+{
+  private:
+
+    /**
+     * Port on the CPU-side that receives requests.
+     * Mostly just forwards requests to the owner.
+     * Part of a vector of ports. One for each CPU port (e.g., data, inst)
+     */
+    class CPUSidePort : public SlavePort
+    {
+      private:
+        /// The object that owns this object (SimpleMemobj)
+        SimpleMemobj *owner;
+
+        /// True if the port needs to send a retry req.
+        bool needRetry;
+
+        /// If we tried to send a packet and it was blocked, store it here
+        PacketPtr blockedPacket;
+
+      public:
+        /**
+         * Constructor. Just calls the superclass constructor.
+         */
+        CPUSidePort(const std::string& name, SimpleMemobj *owner) :
+            SlavePort(name, owner), owner(owner), needRetry(false),
+            blockedPacket(nullptr)
+        { }
+
+        /**
+         * Send a packet across this port. This is called by the owner and
+         * all of the flow control is hanled in this function.
+         *
+         * @param packet to send.
+         */
+        void sendPacket(PacketPtr pkt);
+
+        /**
+         * Get a list of the non-overlapping address ranges the owner is
+         * responsible for. All slave ports must override this function
+         * and return a populated list with at least one item.
+         *
+         * @return a list of ranges responded to
+         */
+        AddrRangeList getAddrRanges() const override;
+
+        /**
+         * Send a retry to the peer port only if it is needed. This is called
+         * from the SimpleMemobj whenever it is unblocked.
+         */
+        void trySendRetry();
+
+      protected:
+        /**
+         * Receive an atomic request packet from the master port.
+         * No need to implement in this simple memobj.
+         */
+        Tick recvAtomic(PacketPtr pkt) override
+        { panic("recvAtomic unimpl."); }
+
+        /**
+         * Receive a functional request packet from the master port.
+         * Performs a "debug" access updating/reading the data in place.
+         *
+         * @param packet the requestor sent.
+         */
+        void recvFunctional(PacketPtr pkt) override;
+
+        /**
+         * Receive a timing request from the master port.
+         *
+         * @param the packet that the requestor sent
+         * @return whether this object can consume the packet. If false, we
+         *         will call sendRetry() when we can try to receive this
+         *         request again.
+         */
+        bool recvTimingReq(PacketPtr pkt) override;
+
+        /**
+         * Called by the master port if sendTimingResp was called on this
+         * slave port (causing recvTimingResp to be called on the master
+         * port) and was unsuccesful.
+         */
+        void recvRespRetry() override;
+    };
+
+    /**
+     * Port on the memory-side that receives responses.
+     * Mostly just forwards requests to the owner
+     */
+    class MemSidePort : public MasterPort
+    {
+      private:
+        /// The object that owns this object (SimpleMemobj)
+        SimpleMemobj *owner;
+
+        /// If we tried to send a packet and it was blocked, store it here
+        PacketPtr blockedPacket;
+
+      public:
+        /**
+         * Constructor. Just calls the superclass constructor.
+         */
+        MemSidePort(const std::string& name, SimpleMemobj *owner) :
+            MasterPort(name, owner), owner(owner), blockedPacket(nullptr)
+        { }
+
+        /**
+         * Send a packet across this port. This is called by the owner and
+         * all of the flow control is hanled in this function.
+         *
+         * @param packet to send.
+         */
+        void sendPacket(PacketPtr pkt);
+
+      protected:
+        /**
+         * Receive a timing response from the slave port.
+         */
+        bool recvTimingResp(PacketPtr pkt) override;
+
+        /**
+         * Called by the slave port if sendTimingReq was called on this
+         * master port (causing recvTimingReq to be called on the slave
+         * port) and was unsuccesful.
+         */
+        void recvReqRetry() override;
+
+        /**
+         * Called to receive an address range change from the peer slave
+         * port. The default implementation ignores the change and does
+         * nothing. Override this function in a derived class if the owner
+         * needs to be aware of the address ranges, e.g. in an
+         * interconnect component like a bus.
+         */
+        void recvRangeChange() override;
+    };
+
+    /**
+     * Handle the request from the CPU side
+     *
+     * @param requesting packet
+     * @return true if we can handle the request this cycle, false if the
+     *         requestor needs to retry later
+     */
+    bool handleRequest(PacketPtr pkt);
+
+    /**
+     * Handle the respone from the memory side
+     *
+     * @param responding packet
+     * @return true if we can handle the response this cycle, false if the
+     *         responder needs to retry later
+     */
+    bool handleResponse(PacketPtr pkt);
+
+    /**
+     * Handle a packet functionally. Update the data on a write and get the
+     * data on a read.
+     *
+     * @param packet to functionally handle
+     */
+    void handleFunctional(PacketPtr pkt);
+
+    /**
+     * Return the address ranges this memobj is responsible for. Just use the
+     * same as the next upper level of the hierarchy.
+     *
+     * @return the address ranges this memobj is responsible for
+     */
+    AddrRangeList getAddrRanges() const;
+
+    /**
+     * Tell the CPU side to ask for our memory ranges.
+     */
+    void sendRangeChange();
+
+    /// Instantiation of the CPU-side ports
+    CPUSidePort instPort;
+    CPUSidePort dataPort;
+
+    /// Instantiation of the memory-side port
+    MemSidePort memPort;
+
+    /// True if this is currently blocked waiting for a response.
+    bool blocked;
+
+  public:
+
+    /** constructor
+     */
+    SimpleMemobj(SimpleMemobjParams *params);
+
+    /**
+     * Get a master port with a given name and index. This is used at
+     * binding time and returns a reference to a protocol-agnostic
+     * base master port.
+     *
+     * @param if_name Port name
+     * @param idx Index in the case of a VectorPort
+     *
+     * @return A reference to the given port
+     */
+    BaseMasterPort& getMasterPort(const std::string& if_name,
+                                  PortID idx = InvalidPortID) override;
+
+    /**
+     * Get a slave port with a given name and index. This is used at
+     * binding time and returns a reference to a protocol-agnostic
+     * base master port.
+     *
+     * @param if_name Port name
+     * @param idx Index in the case of a VectorPort
+     *
+     * @return A reference to the given port
+     */
+    BaseSlavePort& getSlavePort(const std::string& if_name,
+                                PortID idx = InvalidPortID) override;
+};
+
+
+#endif // __LEARNING_GEM5_PART2_SIMPLE_MEMOBJ_HH__