Merge tag 'lkmm-scripting.2023.04.07a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull Linux Kernel Memory Model scripting updates from Paul McKenney:
 "This improves litmus-test documentation and improves the ability to do
  before/after tests on the https://github.com/paulmckrcu/litmus repo"

* tag 'lkmm-scripting.2023.04.07a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (32 commits)
  tools/memory-model: Remove out-of-date SRCU documentation
  tools/memory-model: Document LKMM test procedure
  tools/memory-model: Use "grep -E" instead of "egrep"
  tools/memory-model: Use "-unroll 0" to keep --hw runs finite
  tools/memory-model: Make judgelitmus.sh handle scripted Result: tag
  tools/memory-model: Add data-race capabilities to judgelitmus.sh
  tools/memory-model: Add checktheselitmus.sh to run specified litmus tests
  tools/memory-model: Repair parseargs.sh header comment
  tools/memory-model:  Add "--" to parseargs.sh for additional arguments
  tools/memory-model: Make history-check scripts use mselect7
  tools/memory-model: Make checkghlitmus.sh use mselect7
  tools/memory-model: Fix scripting --jobs argument
  tools/memory-model: Implement --hw support for checkghlitmus.sh
  tools/memory-model: Add -v flag to jingle7 runs
  tools/memory-model: Make runlitmus.sh check for jingle errors
  tools/memory-model: Allow herd to deduce CPU type
  tools/memory-model: Keep assembly-language litmus tests
  tools/memory-model: Move from .AArch64.litmus.out to .litmus.AArch.out
  tools/memory-model: Make runlitmus.sh generate .litmus.out for --hw
  tools/memory-model: Split runlitmus.sh out of checklitmus.sh
  ...

4 files changed, 191 insertions, 0 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..bfb7ba4316d6
--- /dev/null
+++ b/Documentation/litmus-tests/locking/DCL-broken.litmus
@@ -0,0 +1,54 @@
+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;
+}
+
+P0(int *flag, int *data, spinlock_t *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, spinlock_t *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;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..d1b60bcb0c8f
--- /dev/null
+++ b/Documentation/litmus-tests/locking/DCL-fixed.litmus
@@ -0,0 +1,55 @@
+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;
+}
+
+P0(int *flag, int *data, spinlock_t *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, spinlock_t *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;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..b7ef30cedfe5
--- /dev/null
+++ b/Documentation/litmus-tests/locking/RM-broken.litmus
@@ -0,0 +1,41 @@
+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 x;
+	atomic_t y;
+}
+
+P0(int *x, atomic_t *y, spinlock_t *lck)
+{
+	int r2;
+
+	spin_lock(lck);
+	r2 = atomic_inc_return(y);
+	WRITE_ONCE(*x, 1);
+	spin_unlock(lck);
+}
+
+P1(int *x, atomic_t *y, spinlock_t *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;0:r2;1:r0;1:r1;1:r2]
+filter (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..b62817559616
--- /dev/null
+++ b/Documentation/litmus-tests/locking/RM-fixed.litmus
@@ -0,0 +1,41 @@
+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 x;
+	atomic_t y;
+}
+
+P0(int *x, atomic_t *y, spinlock_t *lck)
+{
+	int r2;
+
+	spin_lock(lck);
+	r2 = atomic_inc_return(y);
+	WRITE_ONCE(*x, 1);
+	spin_unlock(lck);
+}
+
+P1(int *x, atomic_t *y, spinlock_t *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;0:r2;1:r0;1:r1;1:r2]
+filter (1:r0=0 /\ 1:r1=1)
+exists (1:r2=1)