mem: Add HTM fields to Request
This starts the support of Hardware Transactional Memory on the mem side
* The following flags have been added:
HTM_START: The request starts a HTM transaction
HTM_COMMIT: The request commits a HTM transaction
HTM_CANCEL: The request cancels a HTM transaction
HTM_ABORT: The request aborts a HTM transaction
* The following fields have been added:
_instCount: The instruction count at the time this request is created
_htmAbortCause: The cause for HTM transaction abort
https://gem5.atlassian.net/browse/GEM5-587
Change-Id: Ic582a6566fdd23f30eb92723e629d0c4d4ca10e5
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/30316
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
diff --git a/src/mem/request.hh b/src/mem/request.hh
index 7b324dc..7f0ddcb 100644
--- a/src/mem/request.hh
+++ b/src/mem/request.hh
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2012-2013,2017-2019 ARM Limited
+ * Copyright (c) 2012-2013,2017-2020 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
@@ -56,6 +56,7 @@
#include "base/logging.hh"
#include "base/types.hh"
#include "cpu/inst_seq.hh"
+#include "mem/htm.hh"
#include "sim/core.hh"
/**
@@ -187,6 +188,42 @@
/** Bits to define the destination of a request */
DST_BITS = 0x0000003000000000,
+ /** hardware transactional memory **/
+
+ /** The request starts a HTM transaction */
+ HTM_START = 0x0000010000000000,
+
+ /** The request commits a HTM transaction */
+ HTM_COMMIT = 0x0000020000000000,
+
+ /** The request cancels a HTM transaction */
+ HTM_CANCEL = 0x0000040000000000,
+
+ /** The request aborts a HTM transaction */
+ HTM_ABORT = 0x0000080000000000,
+
+ // What is the different between HTM cancel and abort?
+ //
+ // HTM_CANCEL will originate from a user instruction, e.g.
+ // Arm's TCANCEL or x86's XABORT. This is an explicit request
+ // to end a transaction and restore from the last checkpoint.
+ //
+ // HTM_ABORT is an internally generated request used to synchronize
+ // a transaction's failure between the core and memory subsystem.
+ // If a transaction fails in the core, e.g. because an instruction
+ // within the transaction generates an exception, the core will prepare
+ // itself to stop fetching/executing more instructions and send an
+ // HTM_ABORT to the memory subsystem before restoring the checkpoint.
+ // Similarly, the transaction could fail in the memory subsystem and
+ // this will be communicated to the core via the Packet object.
+ // Once the core notices, it will do the same as the above and send
+ // a HTM_ABORT to the memory subsystem.
+ // A HTM_CANCEL sent to the memory subsystem will ultimately return
+ // to the core which in turn will send a HTM_ABORT.
+ //
+ // This separation is necessary to ensure the disjoint components
+ // of the system work correctly together.
+
/**
* These flags are *not* cleared when a Request object is
* reused (assigned a new address).
@@ -196,6 +233,9 @@
static const FlagsType STORE_NO_DATA = CACHE_BLOCK_ZERO |
CLEAN | INVALIDATE;
+ static const FlagsType HTM_CMD = HTM_START | HTM_COMMIT |
+ HTM_CANCEL | HTM_ABORT;
+
/** Master Ids that are statically allocated
* @{*/
enum : MasterID {
@@ -274,6 +314,11 @@
/** Whether or not the stream ID and substream ID is valid. */
VALID_STREAM_ID = 0x00000100,
VALID_SUBSTREAM_ID = 0x00000200,
+ // hardware transactional memory
+ /** Whether or not the abort cause is valid. */
+ VALID_HTM_ABORT_CAUSE = 0x00000400,
+ /** Whether or not the instruction count is valid. */
+ VALID_INST_COUNT = 0x00000800,
/**
* These flags are *not* cleared when a Request object is reused
* (assigned a new address).
@@ -362,6 +407,12 @@
LocalAccessor _localAccessor;
+ /** The instruction count at the time this request is created */
+ Counter _instCount = 0;
+
+ /** The cause for HTM transaction abort */
+ HtmFailureFaultCause _htmAbortCause = HtmFailureFaultCause::INVALID;
+
public:
/**
@@ -517,6 +568,21 @@
}
/**
+ * Accessor for instruction count.
+ */
+ Counter getInstCount() const
+ {
+ assert(privateFlags.isSet(VALID_INST_COUNT));
+ return _instCount;
+ }
+
+ void setInstCount(Counter val)
+ {
+ privateFlags.set(VALID_INST_COUNT);
+ _instCount = val;
+ }
+
+ /**
* Time for the TLB/table walker to successfully translate this request.
*/
Tick translateDelta = 0;
@@ -611,6 +677,24 @@
return atomicOpFunctor.get();
}
+ /**
+ * Accessor for hardware transactional memory abort cause.
+ */
+ HtmFailureFaultCause
+ getHtmAbortCause() const
+ {
+ assert(privateFlags.isSet(VALID_HTM_ABORT_CAUSE));
+ return _htmAbortCause;
+ }
+
+ void
+ setHtmAbortCause(HtmFailureFaultCause val)
+ {
+ assert(isHTMAbort());
+ privateFlags.set(VALID_HTM_ABORT_CAUSE);
+ _htmAbortCause = val;
+ }
+
/** Accessor for flags. */
Flags
getFlags()
@@ -819,6 +903,17 @@
bool isKernel() const { return _flags.isSet(KERNEL); }
bool isAtomicReturn() const { return _flags.isSet(ATOMIC_RETURN_OP); }
bool isAtomicNoReturn() const { return _flags.isSet(ATOMIC_NO_RETURN_OP); }
+ // hardware transactional memory
+ bool isHTMStart() const { return _flags.isSet(HTM_START); }
+ bool isHTMCommit() const { return _flags.isSet(HTM_COMMIT); }
+ bool isHTMCancel() const { return _flags.isSet(HTM_CANCEL); }
+ bool isHTMAbort() const { return _flags.isSet(HTM_ABORT); }
+ bool
+ isHTMCmd() const
+ {
+ return (isHTMStart() || isHTMCommit() ||
+ isHTMCancel() || isHTMAbort());
+ }
bool
isAtomic() const
