Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git

21 files changed, 915 insertions, 88 deletions

diff --git a/Documentation/litmus-tests/locking/DCL-broken.litmus b/Documentation/litmus-tests/locking/DCL-broken.litmus
new file mode 100644
index 000000000000..cfaa25ff82b1
--- /dev/null
+++ b/Documentation/litmus-tests/locking/DCL-broken.litmus
@@ -0,0 +1,55 @@
+C DCL-broken
+
+(*
+ * Result: Sometimes
+ *
+ * This litmus test demonstrates more than just locking is required to
+ * correctly implement double-checked locking.
+ *)
+
+{
+	int flag;
+	int data;
+	int lck;
+}
+
+P0(int *flag, int *data, int *lck)
+{
+	int r0;
+	int r1;
+	int r2;
+
+	r0 = READ_ONCE(*flag);
+	if (r0 == 0) {
+		spin_lock(lck);
+		r1 = READ_ONCE(*flag);
+		if (r1 == 0) {
+			WRITE_ONCE(*data, 1);
+			WRITE_ONCE(*flag, 1);
+		}
+		spin_unlock(lck);
+	}
+	r2 = READ_ONCE(*data);
+}
+
+P1(int *flag, int *data, int *lck)
+{
+	int r0;
+	int r1;
+	int r2;
+
+	r0 = READ_ONCE(*flag);
+	if (r0 == 0) {
+		spin_lock(lck);
+		r1 = READ_ONCE(*flag);
+		if (r1 == 0) {
+			WRITE_ONCE(*data, 1);
+			WRITE_ONCE(*flag, 1);
+		}
+		spin_unlock(lck);
+	}
+	r2 = READ_ONCE(*data);
+}
+
+locations [flag;data;lck;0:r0;0:r1;1:r0;1:r1]
+exists (0:r2=0 \/ 1:r2=0)
diff --git a/Documentation/litmus-tests/locking/DCL-fixed.litmus b/Documentation/litmus-tests/locking/DCL-fixed.litmus
new file mode 100644
index 000000000000..579d6c246f16
--- /dev/null
+++ b/Documentation/litmus-tests/locking/DCL-fixed.litmus
@@ -0,0 +1,56 @@
+C DCL-fixed
+
+(*
+ * Result: Never
+ *
+ * This litmus test demonstrates that double-checked locking can be
+ * reliable given proper use of smp_load_acquire() and smp_store_release()
+ * in addition to the locking.
+ *)
+
+{
+	int flag;
+	int data;
+	int lck;
+}
+
+P0(int *flag, int *data, int *lck)
+{
+	int r0;
+	int r1;
+	int r2;
+
+	r0 = smp_load_acquire(flag);
+	if (r0 == 0) {
+		spin_lock(lck);
+		r1 = READ_ONCE(*flag);
+		if (r1 == 0) {
+			WRITE_ONCE(*data, 1);
+			smp_store_release(flag, 1);
+		}
+		spin_unlock(lck);
+	}
+	r2 = READ_ONCE(*data);
+}
+
+P1(int *flag, int *data, int *lck)
+{
+	int r0;
+	int r1;
+	int r2;
+
+	r0 = smp_load_acquire(flag);
+	if (r0 == 0) {
+		spin_lock(lck);
+		r1 = READ_ONCE(*flag);
+		if (r1 == 0) {
+			WRITE_ONCE(*data, 1);
+			smp_store_release(flag, 1);
+		}
+		spin_unlock(lck);
+	}
+	r2 = READ_ONCE(*data);
+}
+
+locations [flag;data;lck;0:r0;0:r1;1:r0;1:r1]
+exists (0:r2=0 \/ 1:r2=0)
diff --git a/Documentation/litmus-tests/locking/RM-broken.litmus b/Documentation/litmus-tests/locking/RM-broken.litmus
new file mode 100644
index 000000000000..c586ae4b547d
--- /dev/null
+++ b/Documentation/litmus-tests/locking/RM-broken.litmus
@@ -0,0 +1,42 @@
+C RM-broken
+
+(*
+ * Result: DEADLOCK
+ *
+ * This litmus test demonstrates that the old "roach motel" approach
+ * to locking, where code can be freely moved into critical sections,
+ * cannot be used in the Linux kernel.
+ *)
+
+{
+	int lck;
+	int x;
+	int y;
+}
+
+P0(int *x, int *y, int *lck)
+{
+	int r2;
+
+	spin_lock(lck);
+	r2 = atomic_inc_return(y);
+	WRITE_ONCE(*x, 1);
+	spin_unlock(lck);
+}
+
+P1(int *x, int *y, int *lck)
+{
+	int r0;
+	int r1;
+	int r2;
+
+	spin_lock(lck);
+	r0 = READ_ONCE(*x);
+	r1 = READ_ONCE(*x);
+	r2 = atomic_inc_return(y);
+	spin_unlock(lck);
+}
+
+locations [x;lck;0:r2;1:r0;1:r1;1:r2]
+filter (y=2 /\ 1:r0=0 /\ 1:r1=1)
+exists (1:r2=1)
diff --git a/Documentation/litmus-tests/locking/RM-fixed.litmus b/Documentation/litmus-tests/locking/RM-fixed.litmus
new file mode 100644
index 000000000000..672856736b42
--- /dev/null
+++ b/Documentation/litmus-tests/locking/RM-fixed.litmus
@@ -0,0 +1,42 @@
+C RM-fixed
+
+(*
+ * Result: Never
+ *
+ * This litmus test demonstrates that the old "roach motel" approach
+ * to locking, where code can be freely moved into critical sections,
+ * cannot be used in the Linux kernel.
+ *)
+
+{
+	int lck;
+	int x;
+	int y;
+}
+
+P0(int *x, int *y, int *lck)
+{
+	int r2;
+
+	spin_lock(lck);
+	r2 = atomic_inc_return(y);
+	WRITE_ONCE(*x, 1);
+	spin_unlock(lck);
+}
+
+P1(int *x, int *y, int *lck)
+{
+	int r0;
+	int r1;
+	int r2;
+
+	r0 = READ_ONCE(*x);
+	r1 = READ_ONCE(*x);
+	spin_lock(lck);
+	r2 = atomic_inc_return(y);
+	spin_unlock(lck);
+}
+
+locations [x;lck;0:r2;1:r0;1:r1;1:r2]
+filter (y=2 /\ 1:r0=0 /\ 1:r1=1)
+exists (1:r2=1)
diff --git a/tools/memory-model/Documentation/locking.txt b/tools/memory-model/Documentation/locking.txt
new file mode 100644
index 000000000000..4e05c6d53ab7
--- /dev/null
+++ b/tools/memory-model/Documentation/locking.txt
@@ -0,0 +1,320 @@
+Locking
+=======
+
+Locking is well-known and the common use cases are straightforward: Any
+CPU holding a given lock sees any changes previously seen or made by any
+CPU before it previously released that same lock.  This last sentence
+is the only part of this document that most developers will need to read.
+
+However, developers who would like to also access lock-protected shared
+variables outside of their corresponding locks should continue reading.
+
+
+Locking and Prior Accesses
+--------------------------
+
+The basic rule of locking is worth repeating:
+
+	Any CPU holding a given lock sees any changes previously seen
+	or made by any CPU before it previously released that same lock.
+
+Note that this statement is a bit stronger than "Any CPU holding a
+given lock sees all changes made by any CPU during the time that CPU was
+previously holding this same lock".  For example, consider the following
+pair of code fragments:
+
+	/* See MP+polocks.litmus. */
+	void CPU0(void)
+	{
+		WRITE_ONCE(x, 1);
+		spin_lock(&mylock);
+		WRITE_ONCE(y, 1);
+		spin_unlock(&mylock);
+	}
+
+	void CPU1(void)
+	{
+		spin_lock(&mylock);
+		r0 = READ_ONCE(y);
+		spin_unlock(&mylock);
+		r1 = READ_ONCE(x);
+	}
+
+The basic rule guarantees that if CPU0() acquires mylock before CPU1(),
+then both r0 and r1 must be set to the value 1.  This also has the
+consequence that if the final value of r0 is equal to 1, then the final
+value of r1 must also be equal to 1.  In contrast, the weaker rule would
+say nothing about the final value of r1.
+
+
+Locking and Subsequent Accesses
+-------------------------------
+
+The converse to the basic rule also holds:  Any CPU holding a given
+lock will not see any changes that will be made by any CPU after it
+subsequently acquires this same lock.  This converse statement is
+illustrated by the following litmus test:
+
+	/* See MP+porevlocks.litmus. */
+	void CPU0(void)
+	{
+		r0 = READ_ONCE(y);
+		spin_lock(&mylock);
+		r1 = READ_ONCE(x);
+		spin_unlock(&mylock);
+	}
+
+	void CPU1(void)
+	{
+		spin_lock(&mylock);
+		WRITE_ONCE(x, 1);
+		spin_unlock(&mylock);
+		WRITE_ONCE(y, 1);
+	}
+
+This converse to the basic rule guarantees that if CPU0() acquires
+mylock before CPU1(), then both r0 and r1 must be set to the value 0.
+This also has the consequence that if the final value of r1 is equal
+to 0, then the final value of r0 must also be equal to 0.  In contrast,
+the weaker rule would say nothing about the final value of r0.
+
+These examples show only a single pair of CPUs, but the effects of the
+locking basic rule extend across multiple acquisitions of a given lock
+across multiple CPUs.
+
+
+Double-Checked Locking
+----------------------
+
+It is well known that more than just a lock is required to make
+double-checked locking work correctly,  This litmus test illustrates
+one incorrect approach:
+
+	/* See Documentation/litmus-tests/locking/DCL-broken.litmus. */
+	P0(int *flag, int *data, int *lck)
+	{
+		int r0;
+		int r1;
+		int r2;
+
+		r0 = READ_ONCE(*flag);
+		if (r0 == 0) {
+			spin_lock(lck);
+			r1 = READ_ONCE(*flag);
+			if (r1 == 0) {
+				WRITE_ONCE(*data, 1);
+				WRITE_ONCE(*flag, 1);
+			}
+			spin_unlock(lck);
+		}
+		r2 = READ_ONCE(*data);
+	}
+	/* P1() is the exactly the same as P0(). */
+
+There are two problems.  First, there is no ordering between the first
+READ_ONCE() of "flag" and the READ_ONCE() of "data".  Second, there is
+no ordering between the two WRITE_ONCE() calls.  It should therefore be
+no surprise that "r2" can be zero, and a quick herd7 run confirms this.
+
+One way to fix this is to use smp_load_acquire() and smp_store_release()
+as shown in this corrected version:
+
+	/* See Documentation/litmus-tests/locking/DCL-fixed.litmus. */
+	P0(int *flag, int *data, int *lck)
+	{
+		int r0;
+		int r1;
+		int r2;
+
+		r0 = smp_load_acquire(flag);
+		if (r0 == 0) {
+			spin_lock(lck);
+			r1 = READ_ONCE(*flag);
+			if (r1 == 0) {
+				WRITE_ONCE(*data, 1);
+				smp_store_release(flag, 1);
+			}
+			spin_unlock(lck);
+		}
+		r2 = READ_ONCE(*data);
+	}
+	/* P1() is the exactly the same as P0(). */
+
+The smp_load_acquire() guarantees that its load from "flags" will
+be ordered before the READ_ONCE() from data, thus solving the first
+problem.  The smp_store_release() guarantees that its store will be
+ordered after the WRITE_ONCE() to "data", solving the second problem.
+The smp_store_release() pairs with the smp_load_acquire(), thus ensuring
+that the ordering provided by each actually takes effect.  Again, a
+quick herd7 run confirms this.
+
+In short, if you access a lock-protected variable without holding the
+corresponding lock, you will need to provide additional ordering, in
+this case, via the smp_load_acquire() and the smp_store_release().
+
+
+Ordering Provided by a Lock to CPUs Not Holding That Lock
+---------------------------------------------------------
+
+It is not necessarily the case that accesses ordered by locking will be
+seen as ordered by CPUs not holding that lock.  Consider this example:
+
+	/* See Z6.0+pooncelock+pooncelock+pombonce.litmus. */
+	void CPU0(void)
+	{
+		spin_lock(&mylock);
+		WRITE_ONCE(x, 1);
+		WRITE_ONCE(y, 1);
+		spin_unlock(&mylock);
+	}
+
+	void CPU1(void)
+	{
+		spin_lock(&mylock);
+		r0 = READ_ONCE(y);
+		WRITE_ONCE(z, 1);
+		spin_unlock(&mylock);
+	}
+
+	void CPU2(void)
+	{
+		WRITE_ONCE(z, 2);
+		smp_mb();
+		r1 = READ_ONCE(x);
+	}
+
+Counter-intuitive though it might be, it is quite possible to have
+the final value of r0 be 1, the final value of z be 2, and the final
+value of r1 be 0.  The reason for this surprising outcome is that CPU2()
+never acquired the lock, and thus did not fully benefit from the lock's
+ordering properties.
+
+Ordering can be extended to CPUs not holding the lock by careful use
+of smp_mb__after_spinlock():
+
+	/* See Z6.0+pooncelock+poonceLock+pombonce.litmus. */
+	void CPU0(void)
+	{
+		spin_lock(&mylock);
+		WRITE_ONCE(x, 1);
+		WRITE_ONCE(y, 1);
+		spin_unlock(&mylock);
+	}
+
+	void CPU1(void)
+	{
+		spin_lock(&mylock);
+		smp_mb__after_spinlock();
+		r0 = READ_ONCE(y);
+		WRITE_ONCE(z, 1);
+		spin_unlock(&mylock);
+	}
+
+	void CPU2(void)
+	{
+		WRITE_ONCE(z, 2);
+		smp_mb();
+		r1 = READ_ONCE(x);
+	}
+
+This addition of smp_mb__after_spinlock() strengthens the lock
+acquisition sufficiently to rule out the counter-intuitive outcome.
+In other words, the addition of the smp_mb__after_spinlock() prohibits
+the counter-intuitive result where the final value of r0 is 1, the final
+value of z is 2, and the final value of r1 is 0.
+
+
+No Roach-Motel Locking!
+-----------------------
+
+This example requires familiarity with the herd7 "filter" clause, so
+please read up on that topic in litmus-tests.txt.
+
+It is tempting to allow memory-reference instructions to be pulled
+into a critical section, but this cannot be allowed in the general case.
+For example, consider a spin loop preceding a lock-based critical section.
+Now, herd7 does not model spin loops, but we can emulate one with two
+loads, with a "filter" clause to constrain the first to return the
+initial value and the second to return the updated value, as shown below:
+
+	/* See Documentation/litmus-tests/locking/RM-fixed.litmus. */
+	P0(int *x, int *y, int *lck)
+	{
+		int r2;
+
+		spin_lock(lck);
+		r2 = atomic_inc_return(y);
+		WRITE_ONCE(*x, 1);
+		spin_unlock(lck);
+	}
+
+	P1(int *x, int *y, int *lck)
+	{
+		int r0;
+		int r1;
+		int r2;
+
+		r0 = READ_ONCE(*x);
+		r1 = READ_ONCE(*x);
+		spin_lock(lck);
+		r2 = atomic_inc_return(y);
+		spin_unlock(lck);
+	}
+
+	filter (y=2 /\ 1:r0=0 /\ 1:r1=1)
+	exists (1:r2=1)
+
+The variable "x" is the control variable for the emulated spin loop.
+P0() sets it to "1" while holding the lock, and P1() emulates the
+spin loop by reading it twice, first into "1:r0" (which should get the
+initial value "0") and then into "1:r1" (which should get the updated
+value "1").
+
+The purpose of the variable "y" is to reject deadlocked executions.
+Only those executions where the final value of "y" have avoided deadlock.
+
+The "filter" clause takes all this into account, constraining "y" to
+equal "2", "1:r0" to equal "0", and "1:r1" to equal 1.
+
+Then the "exists" clause checks to see if P1() acquired its lock first,
+which should not happen given the filter clause because P0() updates
+"x" while holding the lock.  And herd7 confirms this.
+
+But suppose that the compiler was permitted to reorder the spin loop
+into P1()'s critical section, like this:
+
+	/* See Documentation/litmus-tests/locking/RM-broken.litmus. */
+	P0(int *x, int *y, int *lck)
+	{
+		int r2;
+
+		spin_lock(lck);
+		r2 = atomic_inc_return(y);
+		WRITE_ONCE(*x, 1);
+		spin_unlock(lck);
+	}
+
+	P1(int *x, int *y, int *lck)
+	{
+		int r0;
+		int r1;
+		int r2;
+
+		spin_lock(lck);
+		r0 = READ_ONCE(*x);
+		r1 = READ_ONCE(*x);
+		r2 = atomic_inc_return(y);
+		spin_unlock(lck);
+	}
+
+	locations [x;lck;0:r2;1:r0;1:r1;1:r2]
+	filter (y=2 /\ 1:r0=0 /\ 1:r1=1)
+	exists (1:r2=1)
+
+If "1:r0" is equal to "0", "1:r1" can never equal "1" because P0()
+cannot update "x" while P1() holds the lock.  And herd7 confirms this,
+showing zero executions matching the "filter" criteria.
+
+And this is why Linux-kernel lock and unlock primitives must prevent
+code from entering critical sections.  It is not sufficient to only
+prevent code from leaving them.
diff --git a/tools/memory-model/litmus-tests/.gitignore b/tools/memory-model/litmus-tests/.gitignore
index c492a1ddad91..19c379cf069d 100644
--- a/tools/memory-model/litmus-tests/.gitignore
+++ b/tools/memory-model/litmus-tests/.gitignore
@@ -1,2 +1,2 @@
 # SPDX-License-Identifier: GPL-2.0-only
-*.litmus.out
+*.litmus.*
diff --git a/tools/memory-model/scripts/README b/tools/memory-model/scripts/README
index 095c7eb36f9f..cc2c4e5be9ec 100644
--- a/tools/memory-model/scripts/README
+++ b/tools/memory-model/scripts/README
@@ -27,6 +27,14 @@ checklitmushist.sh
 checklitmus.sh
 
 	Check a single litmus test against its "Result:" expected result.
+	Not intended to for manual use.
+
+checktheselitmus.sh
+
+	Check the specified list of litmus tests against their "Result:"
+	expected results.  This takes optional parseargs.sh arguments,
+	followed by "--" followed by pathnames starting from the current
+	directory.
 
 cmplitmushist.sh
 
@@ -43,10 +51,10 @@ initlitmushist.sh
 
 judgelitmus.sh
 
-	Given a .litmus file and its .litmus.out herd7 output, check the
-	.litmus.out file against the .litmus file's "Result:" comment to
-	judge whether the test ran correctly.  Not normally run manually,
-	provided instead for use by other scripts.
+	Given a .litmus file and its herd7 output, check the output file
+	against the .litmus file's "Result:" comment to judge whether
+	the test ran correctly.  Not normally run manually, provided
+	instead for use by other scripts.
 
 newlitmushist.sh
 
diff --git a/tools/memory-model/scripts/checkalllitmus.sh b/tools/memory-model/scripts/checkalllitmus.sh
index 3c0c7fbbd223..2d3ee850a839 100755
--- a/tools/memory-model/scripts/checkalllitmus.sh
+++ b/tools/memory-model/scripts/checkalllitmus.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 # SPDX-License-Identifier: GPL-2.0+
 #
 # Run herd7 tests on all .litmus files in the litmus-tests directory
@@ -8,6 +8,11 @@
 # "^^^".  It also outputs verification results to a file whose name is
 # that of the specified litmus test, but with ".out" appended.
 #
+# If the --hw argument is specified, this script translates the .litmus
+# C-language file to the specified type of assembly and verifies that.
+# But in this case, litmus tests using complex synchronization (such as
+# locking, RCU, and SRCU) are cheerfully ignored.
+#
 # Usage:
 #	checkalllitmus.sh
 #
@@ -17,7 +22,7 @@
 #
 # Copyright IBM Corporation, 2018
 #
-# Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+# Author: Paul E. McKenney <paulmck@linux.ibm.com>
 
 . scripts/parseargs.sh
 
@@ -30,29 +35,23 @@ else
 	exit 255
 fi
 
-# Create any new directories that have appeared in the github litmus
-# repo since the last run.
+# Create any new directories that have appeared in the litmus-tests
+# directory since the last run.
 if test "$LKMM_DESTDIR" != "."
 then
 	find $litmusdir -type d -print |
 	( cd "$LKMM_DESTDIR"; sed -e 's/^/mkdir -p /' | sh )
 fi
 
-# Find the checklitmus script.  If it is not where we expect it, then
-# assume that the caller has the PATH environment variable set
-# appropriately.
-if test -x scripts/checklitmus.sh
-then
-	clscript=scripts/checklitmus.sh
-else
-	clscript=checklitmus.sh
-fi
-
 # Run the script on all the litmus tests in the specified directory
 ret=0
 for i in $litmusdir/*.litmus
 do
-	if ! $clscript $i
+	if test -n "$LKMM_HW_MAP_FILE" && ! scripts/simpletest.sh $i
+	then
+		continue
+	fi
+	if ! scripts/checklitmus.sh $i
 	then
 		ret=1
 	fi
diff --git a/tools/memory-model/scripts/checkghlitmus.sh b/tools/memory-model/scripts/checkghlitmus.sh
index 6589fbb6f653..cedd0290b73f 100755
--- a/tools/memory-model/scripts/checkghlitmus.sh
+++ b/tools/memory-model/scripts/checkghlitmus.sh
@@ -10,6 +10,7 @@
 # parseargs.sh scripts for arguments.
 
 . scripts/parseargs.sh
+. scripts/hwfnseg.sh
 
 T=/tmp/checkghlitmus.sh.$$
 trap 'rm -rf $T' 0
@@ -32,19 +33,19 @@ then
 	( cd "$LKMM_DESTDIR"; sed -e 's/^/mkdir -p /' | sh )
 fi
 
-# Create a list of the C-language litmus tests previously run.
-( cd $LKMM_DESTDIR; find litmus -name '*.litmus.out' -print ) |
-	sed -e 's/\.out$//' |
+# Create a list of the specified litmus tests previously run.
+( cd $LKMM_DESTDIR; find litmus -name "*.litmus${hwfnseg}.out" -print ) |
+	sed -e "s/${hwfnseg}"'\.out$//' |
 	xargs -r egrep -l '^ \* Result: (Never|Sometimes|Always|DEADLOCK)' |
 	xargs -r grep -L "^P${LKMM_PROCS}"> $T/list-C-already
 
 # Create a list of C-language litmus tests with "Result:" commands and
 # no more than the specified number of processes.
-find litmus -name '*.litmus' -exec grep -l -m 1 "^C " {} \; > $T/list-C
+find litmus -name '*.litmus' -print | mselect7 -arch C > $T/list-C
 xargs < $T/list-C -r egrep -l '^ \* Result: (Never|Sometimes|Always|DEADLOCK)' > $T/list-C-result
 xargs < $T/list-C-result -r grep -L "^P${LKMM_PROCS}" > $T/list-C-result-short
 
-# Form list of tests without corresponding .litmus.out files
+# Form list of tests without corresponding .out files
 sort $T/list-C-already $T/list-C-result-short | uniq -u > $T/list-C-needed
 
 # Run any needed tests.
diff --git a/tools/memory-model/scripts/checklitmus.sh b/tools/memory-model/scripts/checklitmus.sh
index 11461ed40b5e..4c1d0cf0ddad 100755
--- a/tools/memory-model/scripts/checklitmus.sh
+++ b/tools/memory-model/scripts/checklitmus.sh
@@ -1,10 +1,8 @@
 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0+
 #
-# Run a herd7 test and invokes judgelitmus.sh to check the result against
-# a "Result:" comment within the litmus test.  It also outputs verification
-# results to a file whose name is that of the specified litmus test, but
-# with ".out" appended.
+# Invokes runlitmus.sh and judgelitmus.sh on its arguments to run the
+# specified litmus test and pass judgment on the results.
 #
 # Usage:
 #	checklitmus.sh file.litmus
@@ -15,20 +13,7 @@
 #
 # Copyright IBM Corporation, 2018
 #
-# Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+# Author: Paul E. McKenney <paulmck@linux.ibm.com>
 
-litmus=$1
-herdoptions=${LKMM_HERD_OPTIONS--conf linux-kernel.cfg}
-
-if test -f "$litmus" -a -r "$litmus"
-then
-	:
-else
-	echo ' --- ' error: \"$litmus\" is not a readable file
-	exit 255
-fi
-
-echo Herd options: $herdoptions > $LKMM_DESTDIR/$litmus.out
-/usr/bin/time $LKMM_TIMEOUT_CMD herd7 $herdoptions $litmus >> $LKMM_DESTDIR/$litmus.out 2>&1
-
-scripts/judgelitmus.sh $litmus
+scripts/runlitmus.sh $1
+scripts/judgelitmus.sh $1
diff --git a/tools/memory-model/scripts/checklitmushist.sh b/tools/memory-model/scripts/checklitmushist.sh
index 1d210ffb7c8a..406ecfc0aee4 100755
--- a/tools/memory-model/scripts/checklitmushist.sh
+++ b/tools/memory-model/scripts/checklitmushist.sh
@@ -12,7 +12,7 @@
 #
 # Copyright IBM Corporation, 2018
 #
-# Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+# Author: Paul E. McKenney <paulmck@linux.ibm.com>
 
 . scripts/parseargs.sh
 
diff --git a/tools/memory-model/scripts/checktheselitmus.sh b/tools/memory-model/scripts/checktheselitmus.sh
new file mode 100755
index 000000000000..10eeb5ecea6d
--- /dev/null
+++ b/tools/memory-model/scripts/checktheselitmus.sh
@@ -0,0 +1,43 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Invokes checklitmus.sh on its arguments to run the specified litmus
+# test and pass judgment on the results.
+#
+# Usage:
+#	checktheselitmus.sh -- [ file1.litmus [ file2.litmus ... ] ]
+#
+# Run this in the directory containing the memory model, specifying the
+# pathname of the litmus test to check.  The usual parseargs.sh arguments
+# can be specified prior to the "--".
+#
+# This script is intended for use with pathnames that start from the
+# tools/memory-model directory.  If some of the pathnames instead start at
+# the root directory, they all must do so and the "--destdir /" parseargs.sh
+# argument must be specified prior to the "--".  Alternatively, some other
+# "--destdir" argument can be supplied as long as the needed subdirectories
+# are populated.
+#
+# Copyright IBM Corporation, 2018
+#
+# Author: Paul E. McKenney <paulmck@linux.ibm.com>
+
+. scripts/parseargs.sh
+
+ret=0
+for i in "$@"
+do
+	if scripts/checklitmus.sh $i
+	then
+		:
+	else
+		ret=1
+	fi
+done
+if test "$ret" -ne 0
+then
+	echo " ^^^ VERIFICATION MISMATCHES" 1>&2
+else
+	echo All litmus tests verified as was expected. 1>&2
+fi
+exit $ret
diff --git a/tools/memory-model/scripts/cmplitmushist.sh b/tools/memory-model/scripts/cmplitmushist.sh
index 0f498aeeccf5..ca1ac8b64614 100755
--- a/tools/memory-model/scripts/cmplitmushist.sh
+++ b/tools/memory-model/scripts/cmplitmushist.sh
@@ -12,12 +12,49 @@ trap 'rm -rf $T' 0
 mkdir $T
 
 # comparetest oldpath newpath
+badmacnam=0
+timedout=0
 perfect=0
 obsline=0
 noobsline=0
 obsresult=0
 badcompare=0
 comparetest () {
+	if grep -q ': Unknown macro ' $1 || grep -q ': Unknown macro ' $2
+	then
+		if grep -q ': Unknown macro ' $1
+		then
+			badname=`grep ': Unknown macro ' $1 |
+				sed -e 's/^.*: Unknown macro //' |
+				sed -e 's/ (User error).*$//'`
+			echo 'Current LKMM version does not know "'$badname'"' $1
+		fi
+		if grep -q ': Unknown macro ' $2
+		then
+			badname=`grep ': Unknown macro ' $2 |
+				sed -e 's/^.*: Unknown macro //' |
+				sed -e 's/ (User error).*$//'`
+			echo 'Current LKMM version does not know "'$badname'"' $2
+		fi
+		badmacnam=`expr "$badmacnam" + 1`
+		return 0
+	elif grep -q '^Command exited with non-zero status 124' $1 ||
+	     grep -q '^Command exited with non-zero status 124' $2
+	then
+		if grep -q '^Command exited with non-zero status 124' $1 &&
+		   grep -q '^Command exited with non-zero status 124' $2
+		then
+			echo Both runs timed out: $2
+		elif grep -q '^Command exited with non-zero status 124' $1
+		then
+			echo Old run timed out: $2
+		elif grep -q '^Command exited with non-zero status 124' $2
+		then
+			echo New run timed out: $2
+		fi
+		timedout=`expr "$timedout" + 1`
+		return 0
+	fi
 	grep -v 'maxresident)k\|minor)pagefaults\|^Time' $1 > $T/oldout
 	grep -v 'maxresident)k\|minor)pagefaults\|^Time' $2 > $T/newout
 	if cmp -s $T/oldout $T/newout && grep -q '^Observation' $1
@@ -38,7 +75,7 @@ comparetest () {
 			return 0
 		fi
 	else
-		echo Missing Observation line "(e.g., herd7 timeout)": $2
+		echo Missing Observation line "(e.g., syntax error)": $2
 		noobsline=`expr "$noobsline" + 1`
 		return 0
 	fi
@@ -72,12 +109,20 @@ then
 fi
 if test "$noobsline" -ne 0
 then
-	echo Missing Observation line "(e.g., herd7 timeout)": $noobsline 1>&2
+	echo Missing Observation line "(e.g., syntax error)": $noobsline 1>&2
 fi
 if test "$obsresult" -ne 0
 then
 	echo Matching Observation Always/Sometimes/Never result: $obsresult 1>&2
 fi
+if test "$timedout" -ne 0
+then
+	echo "!!!" Timed out: $timedout 1>&2
+fi
+if test "$badmacnam" -ne 0
+then
+	echo "!!!" Unknown primitive: $badmacnam 1>&2
+fi
 if test "$badcompare" -ne 0
 then
 	echo "!!!" Result changed: $badcompare 1>&2
diff --git a/tools/memory-model/scripts/hwfnseg.sh b/tools/memory-model/scripts/hwfnseg.sh
new file mode 100755
index 000000000000..580c3281181c
--- /dev/null
+++ b/tools/memory-model/scripts/hwfnseg.sh
@@ -0,0 +1,20 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Generate the hardware extension to the litmus-test filename, or the
+# empty string if this is an LKMM run.  The extension is placed in
+# the shell variable hwfnseg.
+#
+# Usage:
+#	. hwfnseg.sh
+#
+# Copyright IBM Corporation, 2019
+#
+# Author: Paul E. McKenney <paulmck@linux.ibm.com>
+
+if test -z "$LKMM_HW_MAP_FILE"
+then
+	hwfnseg=
+else
+	hwfnseg=".$LKMM_HW_MAP_FILE"
+fi
diff --git a/tools/memory-model/scripts/initlitmushist.sh b/tools/memory-model/scripts/initlitmushist.sh
index 956b6957484d..31ea782955d3 100755
--- a/tools/memory-model/scripts/initlitmushist.sh
+++ b/tools/memory-model/scripts/initlitmushist.sh
@@ -60,7 +60,7 @@ fi
 
 # Create a list of the C-language litmus tests with no more than the
 # specified number of processes (per the --procs argument).
-find litmus -name '*.litmus' -exec grep -l -m 1 "^C " {} \; > $T/list-C
+find litmus -name '*.litmus' -print | mselect7 -arch C > $T/list-C
 xargs < $T/list-C -r grep -L "^P${LKMM_PROCS}" > $T/list-C-short
 
 scripts/runlitmushist.sh < $T/list-C-short
diff --git a/tools/memory-model/scripts/judgelitmus.sh b/tools/memory-model/scripts/judgelitmus.sh
index 0cc63875e395..1ec5d89fcfbb 100755
--- a/tools/memory-model/scripts/judgelitmus.sh
+++ b/tools/memory-model/scripts/judgelitmus.sh
@@ -1,9 +1,22 @@
 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0+
 #
-# Given a .litmus test and the corresponding .litmus.out file, check
-# the .litmus.out file against the "Result:" comment to judge whether
-# the test ran correctly.
+# Given a .litmus test and the corresponding litmus output file, check
+# the .litmus.out file against the "Result:" comment to judge whether the
+# test ran correctly.  If the --hw argument is omitted, check against the
+# LKMM output, which is assumed to be in file.litmus.out. If either a
+# "DATARACE" marker in the "Result:" comment or a "Flag data-race" marker
+# in the LKMM output is present, the other must also be as well, at least
+# for litmus tests having a "Result:" comment. In this case, a failure of
+# the Always/Sometimes/Never portion of the "Result:" prediction will be
+# noted, but forgiven.
+#
+# If the --hw argument is provided, this is assumed to be a hardware
+# test, and the output is assumed to be in file.litmus.HW.out, where
+# "HW" is the --hw argument. In addition, non-Sometimes verification
+# results will be noted, but forgiven.  Furthermore, if there is no
+# "Result:" comment but there is an LKMM .litmus.out file, the observation
+# in that file will be used to judge the assembly-language verification.
 #
 # Usage:
 #	judgelitmus.sh file.litmus
@@ -13,7 +26,7 @@
 #
 # Copyright IBM Corporation, 2018
 #
-# Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+# Author: Paul E. McKenney <paulmck@linux.ibm.com>
 
 litmus=$1
 
@@ -24,55 +37,120 @@ else
 	echo ' --- ' error: \"$litmus\" is not a readable file
 	exit 255
 fi
-if test -f "$LKMM_DESTDIR/$litmus".out -a -r "$LKMM_DESTDIR/$litmus".out
+if test -z "$LKMM_HW_MAP_FILE"
+then
+	litmusout=$litmus.out
+	lkmmout=
+else
+	litmusout="`echo $litmus |
+		sed -e 's/\.litmus$/.litmus.'${LKMM_HW_MAP_FILE}'/'`.out"
+	lkmmout=$litmus.out
+fi
+if test -f "$LKMM_DESTDIR/$litmusout" -a -r "$LKMM_DESTDIR/$litmusout"
 then
 	:
 else
-	echo ' --- ' error: \"$LKMM_DESTDIR/$litmus\".out is not a readable file
+	echo ' --- ' error: \"$LKMM_DESTDIR/$litmusout is not a readable file
 	exit 255
 fi
-if grep -q '^ \* Result: ' $litmus
+if grep -q '^Flag data-race$' "$LKMM_DESTDIR/$litmusout"
+then
+	datarace_modeled=1
+fi
+if grep -q '^[( ]\* Result: ' $litmus
+then
+	outcome=`grep -m 1 '^[( ]\* Result: ' $litmus | awk '{ print $3 }'`
+	if grep -m1 '^[( ]\* Result: .* DATARACE' $litmus
+	then
+		datarace_predicted=1
+	fi
+	if test -n "$datarace_predicted" -a -z "$datarace_modeled" -a -z "$LKMM_HW_MAP_FILE"
+	then
+		echo '!!! Predicted data race not modeled' $litmus
+		exit 252
+	elif test -z "$datarace_predicted" -a -n "$datarace_modeled"
+	then
+		# Note that hardware models currently don't model data races
+		echo '!!! Unexpected data race modeled' $litmus
+		exit 253
+	fi
+elif test -n "$LKMM_HW_MAP_FILE" && grep -q '^Observation' $LKMM_DESTDIR/$lkmmout > /dev/null 2>&1
 then
-	outcome=`grep -m 1 '^ \* Result: ' $litmus | awk '{ print $3 }'`
+	outcome=`grep -m 1 '^Observation ' $LKMM_DESTDIR/$lkmmout | awk '{ print $3 }'`
 else
 	outcome=specified
 fi
 
-grep '^Observation' $LKMM_DESTDIR/$litmus.out
-if grep -q '^Observation' $LKMM_DESTDIR/$litmus.out
+grep '^Observation' $LKMM_DESTDIR/$litmusout
+if grep -q '^Observation' $LKMM_DESTDIR/$litmusout
 then
 	:
+elif grep ': Unknown macro ' $LKMM_DESTDIR/$litmusout
+then
+	badname=`grep ': Unknown macro ' $LKMM_DESTDIR/$litmusout |
+		sed -e 's/^.*: Unknown macro //' |
+		sed -e 's/ (User error).*$//'`
+	badmsg=' !!! Current LKMM version does not know "'$badname'"'" $litmus"
+	echo $badmsg
+	if ! grep -q '!!!' $LKMM_DESTDIR/$litmusout
+	then
+		echo ' !!! '$badmsg >> $LKMM_DESTDIR/$litmusout 2>&1
+	fi
+	exit 254
+elif grep '^Command exited with non-zero status 124' $LKMM_DESTDIR/$litmusout
+then
+	echo ' !!! Timeout' $litmus
+	if ! grep -q '!!!' $LKMM_DESTDIR/$litmusout
+	then
+		echo ' !!! Timeout' >> $LKMM_DESTDIR/$litmusout 2>&1
+	fi
+	exit 124
 else
 	echo ' !!! Verification error' $litmus
-	if ! grep -q '!!!' $LKMM_DESTDIR/$litmus.out
+	if ! grep -q '!!!' $LKMM_DESTDIR/$litmusout
 	then
-		echo ' !!! Verification error' >> $LKMM_DESTDIR/$litmus.out 2>&1
+		echo ' !!! Verification error' >> $LKMM_DESTDIR/$litmusout 2>&1
 	fi
 	exit 255
 fi
 if test "$outcome" = DEADLOCK
 then
-	if grep '^Observation' $LKMM_DESTDIR/$litmus.out | grep -q 'Never 0 0$'
+	if grep '^Observation' $LKMM_DESTDIR/$litmusout | grep -q 'Never 0 0$'
 	then
 		ret=0
 	else
 		echo " !!! Unexpected non-$outcome verification" $litmus
-		if ! grep -q '!!!' $LKMM_DESTDIR/$litmus.out
+		if ! grep -q '!!!' $LKMM_DESTDIR/$litmusout
 		then
-			echo " !!! Unexpected non-$outcome verification" >> $LKMM_DESTDIR/$litmus.out 2>&1
+			echo " !!! Unexpected non-$outcome verification" >> $LKMM_DESTDIR/$litmusout 2>&1
 		fi
 		ret=1
 	fi
-elif grep '^Observation' $LKMM_DESTDIR/$litmus.out | grep -q $outcome || test "$outcome" = Maybe
+elif grep '^Observation' $LKMM_DESTDIR/$litmusout | grep -q 'Never 0 0$'
+then
+	echo " !!! Unexpected non-$outcome deadlock" $litmus
+	if ! grep -q '!!!' $LKMM_DESTDIR/$litmusout
+	then
+		echo " !!! Unexpected non-$outcome deadlock" $litmus >> $LKMM_DESTDIR/$litmusout 2>&1
+	fi
+	ret=1
+elif grep '^Observation' $LKMM_DESTDIR/$litmusout | grep -q $outcome || test "$outcome" = Maybe
 then
 	ret=0
 else
-	echo " !!! Unexpected non-$outcome verification" $litmus
-	if ! grep -q '!!!' $LKMM_DESTDIR/$litmus.out
+	if test \( -n "$LKMM_HW_MAP_FILE" -a "$outcome" = Sometimes \) -o -n "$datarace_modeled"
 	then
-		echo " !!! Unexpected non-$outcome verification" >> $LKMM_DESTDIR/$litmus.out 2>&1
+		flag="--- Forgiven"
+		ret=0
+	else
+		flag="!!! Unexpected"
+		ret=1
+	fi
+	echo " $flag non-$outcome verification" $litmus
+	if ! grep -qe "$flag" $LKMM_DESTDIR/$litmusout
+	then
+		echo " $flag non-$outcome verification" >> $LKMM_DESTDIR/$litmusout 2>&1
 	fi
-	ret=1
 fi
-tail -2 $LKMM_DESTDIR/$litmus.out | head -1
+tail -2 $LKMM_DESTDIR/$litmusout | head -1
 exit $ret
diff --git a/tools/memory-model/scripts/newlitmushist.sh b/tools/memory-model/scripts/newlitmushist.sh
index 991f8f814881..25235e2049cf 100755
--- a/tools/memory-model/scripts/newlitmushist.sh
+++ b/tools/memory-model/scripts/newlitmushist.sh
@@ -12,7 +12,7 @@
 #
 # Copyright IBM Corporation, 2018
 #
-# Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+# Author: Paul E. McKenney <paulmck@linux.ibm.com>
 
 . scripts/parseargs.sh
 
@@ -43,7 +43,7 @@ fi
 
 # Form full list of litmus tests with no more than the specified
 # number of processes (per the --procs argument).
-find litmus -name '*.litmus' -exec grep -l -m 1 "^C " {} \; > $T/list-C-all
+find litmus -name '*.litmus' -print | mselect7 -arch C > $T/list-C-all
 xargs < $T/list-C-all -r grep -L "^P${LKMM_PROCS}" > $T/list-C-short
 
 # Form list of new tests.  Note: This does not handle litmus-test deletion!
diff --git a/tools/memory-model/scripts/parseargs.sh b/tools/memory-model/scripts/parseargs.sh
index 40f52080fdbd..08ded5909860 100755
--- a/tools/memory-model/scripts/parseargs.sh
+++ b/tools/memory-model/scripts/parseargs.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0+
 #
-# the corresponding .litmus.out file, and does not judge the result.
+# Parse arguments common to the various scripts.
 #
 # . scripts/parseargs.sh
 #
@@ -9,7 +9,7 @@
 #
 # Copyright IBM Corporation, 2018
 #
-# Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+# Author: Paul E. McKenney <paulmck@linux.ibm.com>
 
 T=/tmp/parseargs.sh.$$
 mkdir $T
@@ -27,6 +27,7 @@ initparam () {
 
 initparam LKMM_DESTDIR "."
 initparam LKMM_HERD_OPTIONS "-conf linux-kernel.cfg"
+initparam LKMM_HW_MAP_FILE ""
 initparam LKMM_JOBS `getconf _NPROCESSORS_ONLN`
 initparam LKMM_PROCS "3"
 initparam LKMM_TIMEOUT "1m"
@@ -37,10 +38,11 @@ usagehelp () {
 	echo "Usage $scriptname [ arguments ]"
 	echo "      --destdir path (place for .litmus.out, default by .litmus)"
 	echo "      --herdopts -conf linux-kernel.cfg ..."
+	echo "      --hw AArch64"
 	echo "      --jobs N (number of jobs, default one per CPU)"
 	echo "      --procs N (litmus tests with at most this many processes)"
 	echo "      --timeout N (herd7 timeout (e.g., 10s, 1m, 2hr, 1d, '')"
-	echo "Defaults: --destdir '$LKMM_DESTDIR_DEF' --herdopts '$LKMM_HERD_OPTIONS_DEF' --jobs '$LKMM_JOBS_DEF' --procs '$LKMM_PROCS_DEF' --timeout '$LKMM_TIMEOUT_DEF'"
+	echo "Defaults: --destdir '$LKMM_DESTDIR_DEF' --herdopts '$LKMM_HERD_OPTIONS_DEF' --hw '$LKMM_HW_MAP_FILE' --jobs '$LKMM_JOBS_DEF' --procs '$LKMM_PROCS_DEF' --timeout '$LKMM_TIMEOUT_DEF'"
 	exit 1
 }
 
@@ -81,7 +83,7 @@ do
 			echo "Cannot create directory --destdir '$LKMM_DESTDIR'"
 			usage
 		fi
-		if test -d "$LKMM_DESTDIR" -a -w "$LKMM_DESTDIR" -a -x "$LKMM_DESTDIR"
+		if test -d "$LKMM_DESTDIR" -a -x "$LKMM_DESTDIR"
 		then
 			:
 		else
@@ -95,6 +97,11 @@ do
 		LKMM_HERD_OPTIONS="$2"
 		shift
 		;;
+	--hw)
+		checkarg --hw "(.map file architecture name)" "$#" "$2" '^[A-Za-z0-9_-]\+' '^--'
+		LKMM_HW_MAP_FILE="$2"
+		shift
+		;;
 	-j[1-9]*)
 		njobs="`echo $1 | sed -e 's/^-j//'`"
 		trailchars="`echo $njobs | sed -e 's/[0-9]\+\(.*\)$/\1/'`"
@@ -106,7 +113,7 @@ do
 		LKMM_JOBS="`echo $njobs | sed -e 's/^\([0-9]\+\).*$/\1/'`"
 		;;
 	--jobs|--job|-j)
-		checkarg --jobs "(number)" "$#" "$2" '^[1-9][0-9]\+$' '^--'
+		checkarg --jobs "(number)" "$#" "$2" '^[1-9][0-9]*$' '^--'
 		LKMM_JOBS="$2"
 		shift
 		;;
@@ -120,6 +127,10 @@ do
 		LKMM_TIMEOUT="$2"
 		shift
 		;;
+	--)
+		shift
+		break
+		;;
 	*)
 		echo Unknown argument $1
 		usage
diff --git a/tools/memory-model/scripts/runlitmus.sh b/tools/memory-model/scripts/runlitmus.sh
new file mode 100755
index 000000000000..94608d4b6502
--- /dev/null
+++ b/tools/memory-model/scripts/runlitmus.sh
@@ -0,0 +1,80 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Without the -hw argument, runs a herd7 test and outputs verification
+# results to a file whose name is that of the specified litmus test,
+# but with ".out" appended.
+#
+# If the --hw argument is specified, this script translates the .litmus
+# C-language file to the specified type of assembly and verifies that.
+# But in this case, litmus tests using complex synchronization (such as
+# locking, RCU, and SRCU) are cheerfully ignored.
+#
+# Either way, return the status of the herd7 command.
+#
+# Usage:
+#	runlitmus.sh file.litmus
+#
+# Run this in the directory containing the memory model, specifying the
+# pathname of the litmus test to check.  The caller is expected to have
+# properly set up the LKMM environment variables.
+#
+# Copyright IBM Corporation, 2019
+#
+# Author: Paul E. McKenney <paulmck@linux.ibm.com>
+
+litmus=$1
+if test -f "$litmus" -a -r "$litmus"
+then
+	:
+else
+	echo ' !!! ' error: \"$litmus\" is not a readable file
+	exit 255
+fi
+
+if test -z "$LKMM_HW_MAP_FILE" -o ! -e $LKMM_DESTDIR/$litmus.out
+then
+	# LKMM run
+	herdoptions=${LKMM_HERD_OPTIONS--conf linux-kernel.cfg}
+	echo Herd options: $herdoptions > $LKMM_DESTDIR/$litmus.out
+	/usr/bin/time $LKMM_TIMEOUT_CMD herd7 $herdoptions $litmus >> $LKMM_DESTDIR/$litmus.out 2>&1
+	ret=$?
+	if test -z "$LKMM_HW_MAP_FILE"
+	then
+		exit $ret
+	fi
+	echo " --- " Automatically generated LKMM output for '"'--hw $LKMM_HW_MAP_FILE'"' run
+fi
+
+# Hardware run
+
+T=/tmp/checklitmushw.sh.$$
+trap 'rm -rf $T' 0 2
+mkdir $T
+
+# Generate filenames
+mapfile="Linux2${LKMM_HW_MAP_FILE}.map"
+themefile="$T/${LKMM_HW_MAP_FILE}.theme"
+herdoptions="-model $LKMM_HW_CAT_FILE"
+hwlitmus=`echo $litmus | sed -e 's/\.litmus$/.litmus.'${LKMM_HW_MAP_FILE}'/'`
+hwlitmusfile=`echo $hwlitmus | sed -e 's,^.*/,,'`
+
+# Don't run on litmus tests with complex synchronization
+if ! scripts/simpletest.sh $litmus
+then
+	echo ' --- ' error: \"$litmus\" contains locking, RCU, or SRCU
+	exit 254
+fi
+
+# Generate the assembly code and run herd7 on it.
+gen_theme7 -n 10 -map $mapfile -call Linux.call > $themefile
+jingle7 -v -theme $themefile $litmus > $LKMM_DESTDIR/$hwlitmus 2> $T/$hwlitmusfile.jingle7.out
+if grep -q "Generated 0 tests" $T/$hwlitmusfile.jingle7.out
+then
+	echo ' !!! ' jingle7 failed, errors in $hwlitmus.err
+	cp $T/$hwlitmusfile.jingle7.out $LKMM_DESTDIR/$hwlitmus.err
+	exit 253
+fi
+/usr/bin/time $LKMM_TIMEOUT_CMD herd7 -unroll 0 $LKMM_DESTDIR/$hwlitmus > $LKMM_DESTDIR/$hwlitmus.out 2>&1
+
+exit $?
diff --git a/tools/memory-model/scripts/runlitmushist.sh b/tools/memory-model/scripts/runlitmushist.sh
index 6ed376f495bb..c6c2bdc67a50 100755
--- a/tools/memory-model/scripts/runlitmushist.sh
+++ b/tools/memory-model/scripts/runlitmushist.sh
@@ -13,7 +13,9 @@
 #
 # Copyright IBM Corporation, 2018
 #
-# Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+# Author: Paul E. McKenney <paulmck@linux.ibm.com>
+
+. scripts/hwfnseg.sh
 
 T=/tmp/runlitmushist.sh.$$
 trap 'rm -rf $T' 0
@@ -30,15 +32,12 @@ fi
 # Prefixes for per-CPU scripts
 for ((i=0;i<$LKMM_JOBS;i++))
 do
-	echo dir="$LKMM_DESTDIR" > $T/$i.sh
 	echo T=$T >> $T/$i.sh
-	echo herdoptions=\"$LKMM_HERD_OPTIONS\" >> $T/$i.sh
 	cat << '___EOF___' >> $T/$i.sh
 	runtest () {
-		echo ' ... ' /usr/bin/time $LKMM_TIMEOUT_CMD herd7 $herdoptions $1 '>' $dir/$1.out '2>&1'
-		if /usr/bin/time $LKMM_TIMEOUT_CMD herd7 $herdoptions $1 > $dir/$1.out 2>&1
+		if scripts/runlitmus.sh $1
 		then
-			if ! grep -q '^Observation ' $dir/$1.out
+			if ! grep -q '^Observation ' $LKMM_DESTDIR/$1$2.out
 			then
 				echo ' !!! Herd failed, no Observation:' $1
 			fi
@@ -47,10 +46,16 @@ do
 			if test "$exitcode" -eq 124
 			then
 				exitmsg="timed out"
+			elif test "$exitcode" -eq 253
+			then
+				exitmsg=
 			else
 				exitmsg="failed, exit code $exitcode"
 			fi
-			echo ' !!! Herd' ${exitmsg}: $1
+			if test -n "$exitmsg"
+			then
+				echo ' !!! Herd' ${exitmsg}: $1
+			fi
 		fi
 	}
 ___EOF___
@@ -59,11 +64,13 @@ done
 awk -v q="'" -v b='\\' '
 {
 	print "echo `grep " q "^P[0-9]" b "+(" q " " $0 " | tail -1 | sed -e " q "s/^P" b "([0-9]" b "+" b ")(.*$/" b "1/" q "` " $0
-}' | bash |
-sort -k1n |
-awk -v ncpu=$LKMM_JOBS -v t=$T '
+}' | sh | sort -k1n |
+awk -v dq='"' -v hwfnseg="$hwfnseg" -v ncpu="$LKMM_JOBS" -v t="$T" '
 {
-	print "runtest " $2 >> t "/" NR % ncpu ".sh";
+	print "if test -z " dq hwfnseg dq " || scripts/simpletest.sh " dq $2 dq
+	print "then"
+	print "\techo runtest " dq $2 dq " " hwfnseg " >> " t "/" NR % ncpu ".sh";
+	print "fi"
 }
 
 END {
diff --git a/tools/memory-model/scripts/simpletest.sh b/tools/memory-model/scripts/simpletest.sh
new file mode 100755
index 000000000000..7edc5d361665
--- /dev/null
+++ b/tools/memory-model/scripts/simpletest.sh
@@ -0,0 +1,35 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Give zero status if this is a simple test and non-zero otherwise.
+# Simple tests do not contain locking, RCU, or SRCU.
+#
+# Usage:
+#	simpletest.sh file.litmus
+#
+# Copyright IBM Corporation, 2019
+#
+# Author: Paul E. McKenney <paulmck@linux.ibm.com>
+
+
+litmus=$1
+
+if test -f "$litmus" -a -r "$litmus"
+then
+	:
+else
+	echo ' --- ' error: \"$litmus\" is not a readable file
+	exit 255
+fi
+exclude="^[[:space:]]*\("
+exclude="${exclude}spin_lock(\|spin_unlock(\|spin_trylock(\|spin_is_locked("
+exclude="${exclude}\|rcu_read_lock(\|rcu_read_unlock("
+exclude="${exclude}\|synchronize_rcu(\|synchronize_rcu_expedited("
+exclude="${exclude}\|srcu_read_lock(\|srcu_read_unlock("
+exclude="${exclude}\|synchronize_srcu(\|synchronize_srcu_expedited("
+exclude="${exclude}\)"
+if grep -q $exclude $litmus
+then
+	exit 255
+fi
+exit 0