mem: Signal the local monitor when clearing the global monitor

ARM systems require the coordination of the global and local
monitors. When the system is run without caches the global monitor is
implemented in the abstract memory object. This change adds a callback
from the abstract memory that notifies the local monitor when the
global monitor is cleared.

Additionally, for ARM systems the local monitor signals the event
register and wakes the thread context up. Subsequent wait-for-event
(WFE) instructions will be immediately signaled.

Change-Id: If6c038f3a6bea7239ba4258f07f39c7f9a30500b
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/3760
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

10 files changed, 196 insertions, 104 deletions

diff --git a/src/arch/alpha/locked_mem.hh b/src/arch/alpha/locked_mem.hh
index 7998cbdf1..ba577e8cb 100644
--- a/src/arch/alpha/locked_mem.hh
+++ b/src/arch/alpha/locked_mem.hh
@@ -135,6 +135,13 @@ handleLockedWrite(XC *xc, Request *req, Addr cacheBlockMask)
     return true;
 }
 
+template <class XC>
+inline void
+globalClearExclusive(XC *xc)
+{
+    xc->getCpuPtr()->wakeup(xc->threadId());
+}
+
 } // namespace AlphaISA
 
 #endif // __ARCH_ALPHA_LOCKED_MEM_HH__
diff --git a/src/arch/arm/locked_mem.hh b/src/arch/arm/locked_mem.hh
index 8aa181245..2fcbc4a92 100644
--- a/src/arch/arm/locked_mem.hh
+++ b/src/arch/arm/locked_mem.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012-2013 ARM Limited
+ * Copyright (c) 2012-2013,2017 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -148,6 +148,20 @@ handleLockedWrite(XC *xc, Request *req, Addr cacheBlockMask)
     return true;
 }
 
+template <class XC>
+inline void
+globalClearExclusive(XC *xc)
+{
+    // A spinlock would typically include a Wait For Event (WFE) to
+    // conserve energy. The ARMv8 architecture specifies that an event
+    // is automatically generated when clearing the exclusive monitor
+    // to wake up the processor in WFE.
+    DPRINTF(LLSC,"Clearing lock and signaling sev\n");
+    xc->setMiscReg(MISCREG_LOCKFLAG, false);
+    // Implement ARMv8 WFE/SEV semantics
+    xc->setMiscReg(MISCREG_SEV_MAILBOX, true);
+    xc->getCpuPtr()->wakeup(xc->threadId());
+}
 
 } // namespace ArmISA
 
diff --git a/src/arch/generic/locked_mem.hh b/src/arch/generic/locked_mem.hh
new file mode 100644
index 000000000..68a4ff540
--- /dev/null
+++ b/src/arch/generic/locked_mem.hh
@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2017 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * Copyright (c) 2006 The Regents of The University of Michigan
+ * 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: Steve Reinhardt
+ */
+
+#ifndef __ARCH_GENERIC_LOCKED_MEM_HH__
+#define __ARCH_GENERIC_LOCKED_MEM_HH__
+
+/**
+ * @file
+ *
+ * Generic helper functions for locked memory accesses.
+ */
+
+#include "config/the_isa.hh"
+#include "mem/packet.hh"
+#include "mem/request.hh"
+
+namespace TheISA
+{
+template <class XC>
+inline void
+handleLockedSnoop(XC *xc, PacketPtr pkt, Addr cacheBlockMask)
+{
+}
+
+template <class XC>
+inline void
+handleLockedRead(XC *xc, Request *req)
+{
+}
+
+template <class XC>
+inline void
+handleLockedSnoopHit(XC *xc)
+{
+}
+
+
+template <class XC>
+inline bool
+handleLockedWrite(XC *xc, Request *req, Addr cacheBlockMask)
+{
+    return true;
+}
+
+template <class XC>
+inline void
+globalClearExclusive(XC *xc)
+{
+}
+
+} // namespace Generic ISA
+
+#endif
diff --git a/src/arch/mips/locked_mem.hh b/src/arch/mips/locked_mem.hh
index a1d89de99..61c689955 100644
--- a/src/arch/mips/locked_mem.hh
+++ b/src/arch/mips/locked_mem.hh
@@ -139,6 +139,13 @@ handleLockedWrite(XC *xc, Request *req, Addr cacheBlockMask)
     return true;
 }
 
+template <class XC>
+inline void
+globalClearExclusive(XC *xc)
+{
+    xc->getCpuPtr()->wakeup(xc->threadId());
+}
+
 } // namespace MipsISA
 
 #endif
diff --git a/src/arch/null/locked_mem.hh b/src/arch/null/locked_mem.hh
new file mode 100644
index 000000000..f5ecaf7dc
--- /dev/null
+++ b/src/arch/null/locked_mem.hh
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2017 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * Copyright (c) 2006 The Regents of The University of Michigan
+ * 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: Steve Reinhardt
+ */
+
+#ifndef __ARCH_NULL_LOCKED_MEM_HH__
+#define __ARCH_NULL_LOCKED_MEM_HH__
+
+/**
+ * @file
+ *
+ * ISA-specific helper functions for locked memory accesses.
+ */
+
+#include "arch/generic/locked_mem.hh"
+
+#endif
diff --git a/src/arch/power/locked_mem.hh b/src/arch/power/locked_mem.hh
index d962f9aff..d7abc64f0 100644
--- a/src/arch/power/locked_mem.hh
+++ b/src/arch/power/locked_mem.hh
@@ -41,37 +41,6 @@
  * ISA-specific helper functions for locked memory accesses.
  */
 
-#include "mem/packet.hh"
-#include "mem/request.hh"
-
-namespace PowerISA
-{
-
-template <class XC>
-inline void
-handleLockedSnoop(XC *xc, PacketPtr pkt, Addr cacheBlockMask)
-{
-}
-
-template <class XC>
-inline void
-handleLockedRead(XC *xc, Request *req)
-{
-}
-
-template <class XC>
-inline void
-handleLockedSnoopHit(XC *xc)
-{
-}
-
-template <class XC>
-inline bool
-handleLockedWrite(XC *xc, Request *req, Addr cacheBlockMask)
-{
-    return true;
-}
-
-} // namespace PowerISA
+#include "arch/generic/locked_mem.hh"
 
 #endif // __ARCH_POWER_LOCKED_MEM_HH__
diff --git a/src/arch/riscv/locked_mem.hh b/src/arch/riscv/locked_mem.hh
index d7fc0ca5a..f334385b1 100644
--- a/src/arch/riscv/locked_mem.hh
+++ b/src/arch/riscv/locked_mem.hh
@@ -126,6 +126,13 @@ handleLockedWrite(XC *xc, Request *req, Addr cacheBlockMask)
     return true;
 }
 
+template <class XC>
+inline void
+globalClearExclusive(XC *xc)
+{
+    xc->getCpuPtr()->wakeup(xc->threadId());
+}
+
 } // namespace RiscvISA
 
 #endif // __ARCH_RISCV_LOCKED_MEM_HH__
diff --git a/src/arch/sparc/locked_mem.hh b/src/arch/sparc/locked_mem.hh
index b28179481..90760d586 100644
--- a/src/arch/sparc/locked_mem.hh
+++ b/src/arch/sparc/locked_mem.hh
@@ -37,38 +37,6 @@
  * ISA-specific helper functions for locked memory accesses.
  */
 
-#include "mem/packet.hh"
-#include "mem/request.hh"
-
-namespace SparcISA
-{
-template <class XC>
-inline void
-handleLockedSnoop(XC *xc, PacketPtr pkt, Addr cacheBlockMask)
-{
-}
-
-template <class XC>
-inline void
-handleLockedRead(XC *xc, Request *req)
-{
-}
-
-template <class XC>
-inline void
-handleLockedSnoopHit(XC *xc)
-{
-}
-
-
-template <class XC>
-inline bool
-handleLockedWrite(XC *xc, Request *req, Addr cacheBlockMask)
-{
-    return true;
-}
-
-
-} // namespace SparcISA
+#include "arch/generic/locked_mem.hh"
 
 #endif
diff --git a/src/arch/x86/locked_mem.hh b/src/arch/x86/locked_mem.hh
index 51cfb2ea3..0a746eb4e 100644
--- a/src/arch/x86/locked_mem.hh
+++ b/src/arch/x86/locked_mem.hh
@@ -37,35 +37,6 @@
  * ISA-specific helper functions for locked memory accesses.
  */
 
-#include "mem/packet.hh"
-#include "mem/request.hh"
-
-namespace X86ISA
-{
-    template <class XC>
-    inline void
-    handleLockedSnoop(XC *xc, PacketPtr pkt, Addr cacheBlockMask)
-    {
-    }
-
-    template <class XC>
-    inline void
-    handleLockedRead(XC *xc, Request *req)
-    {
-    }
-
-    template <class XC>
-    inline bool
-    handleLockedWrite(XC *xc, Request *req, Addr cacheBlockMask)
-    {
-        return true;
-    }
-
-    template <class XC>
-    inline void
-    handleLockedSnoopHit(XC *xc)
-    {
-    }
-}
+#include "arch/generic/locked_mem.hh"
 
 #endif // __ARCH_X86_LOCKEDMEM_HH__
diff --git a/src/mem/abstract_mem.cc b/src/mem/abstract_mem.cc
index e05296c3e..13a0873cb 100644
--- a/src/mem/abstract_mem.cc
+++ b/src/mem/abstract_mem.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2012 ARM Limited
+ * Copyright (c) 2010-2012,2017 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -46,6 +46,7 @@
 
 #include <vector>
 
+#include "arch/locked_mem.hh"
 #include "cpu/base.hh"
 #include "cpu/thread_context.hh"
 #include "debug/LLSC.hh"
@@ -272,13 +273,12 @@ AbstractMemory::checkLockedAddrList(PacketPtr pkt)
             if (i->addr == paddr) {
                 DPRINTF(LLSC, "Erasing lock record: context %d addr %#x\n",
                         i->contextId, paddr);
-                // For ARM, a spinlock would typically include a Wait
-                // For Event (WFE) to conserve energy. The ARMv8
-                // architecture specifies that an event is
-                // automatically generated when clearing the exclusive
-                // monitor to wake up the processor in WFE.
-                ThreadContext* ctx = system()->getThreadContext(i->contextId);
-                ctx->getCpuPtr()->wakeup(ctx->threadId());
+                ContextID owner_cid = i->contextId;
+                ContextID requester_cid = pkt->req->contextId();
+                if (owner_cid != requester_cid) {
+                    ThreadContext* ctx = system()->getThreadContext(owner_cid);
+                    TheISA::globalClearExclusive(ctx);
+                }
                 i = lockedAddrList.erase(i);
             } else {
                 i++;
@@ -387,6 +387,9 @@ AbstractMemory::access(PacketPtr pkt)
     } else if (pkt->isRead()) {
         assert(!pkt->isWrite());
         if (pkt->isLLSC()) {
+            assert(!pkt->fromCache());
+            // if the packet is not coming from a cache then we have
+            // to do the LL/SC tracking here
             trackLoadLocked(pkt);
         }
         if (pmemAddr)