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authorNikos Nikoleris <nikos.nikoleris@arm.com>2017-06-13 11:14:00 +0100
committerNikos Nikoleris <nikos.nikoleris@arm.com>2017-10-13 08:41:08 +0000
commitb10a0092aecbc6927e9a2336188615ed97614fd0 (patch)
treed566b7e712bb7573de3aee0599d9ea5f5c1e4127 /src/arch/arm
parent64b8feeb0e70c7e138d7e9485ccacb7fd39ae044 (diff)
downloadgem5-b10a0092aecbc6927e9a2336188615ed97614fd0.tar.xz
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>
Diffstat (limited to 'src/arch/arm')
-rw-r--r--src/arch/arm/locked_mem.hh16
1 files changed, 15 insertions, 1 deletions
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