This commit adds a litmus test suggested by Alan Stern that is forbidden
on fully multicopy atomic systems, but allowed on other-multicopy and
on non-multicopy atomic systems. For reference, s390 is fully multicopy
atomic, x86 and ARMv8 are other-multicopy atomic, and ARMv7 and powerpc
are non-multicopy atomic.
Suggested-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Acked-by: Andrea Parri <andrea.parri@xxxxxxxxxxxxxxxxxxxx>
---
tools/memory-model/litmus-tests/README | 9 ++++++
.../SB+rfionceonce-poonceonces.litmus | 32 +++++++++++++++++++
2 files changed, 41 insertions(+)
create mode 100644 tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus
diff --git a/tools/memory-model/litmus-tests/README b/tools/memory-model/litmus-tests/README
index 17eb9a8c222d..00140aaf58b7 100644
--- a/tools/memory-model/litmus-tests/README
+++ b/tools/memory-model/litmus-tests/README
@@ -111,6 +111,15 @@ SB+mbonceonces.litmus
SB+poonceonces.litmus
As above, but without the smp_mb() invocations.
+SB+rfionceonce-poonceonces.litmus
+ This litmus test demonstrates that LKMM is not fully multicopy
+ atomic. (Neither is it other multicopy atomic.) This litmus test
+ also demonstrates the "locations" debugging aid, which designates
+ additional registers and locations to be printed out in the dump
+ of final states in the herd7 output. Without the "locations"
+ statement, only those registers and locations mentioned in the
+ "exists" clause will be printed.
+
S+poonceonces.litmus
As below, but without the smp_wmb() and acquire load.
diff --git a/tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus b/tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus
new file mode 100644
index 000000000000..04a16603660b
--- /dev/null
+++ b/tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus
@@ -0,0 +1,32 @@
+C SB+rfionceonce-poonceonces
+
+(*
+ * Result: Sometimes
+ *
+ * This litmus test demonstrates that LKMM is not fully multicopy atomic.
+ *)
+
+{}
+
+P0(int *x, int *y)
+{
+ int r1;
+ int r2;
+
+ WRITE_ONCE(*x, 1);
+ r1 = READ_ONCE(*x);
+ r2 = READ_ONCE(*y);
+}
+
+P1(int *x, int *y)
+{
+ int r3;
+ int r4;
+
+ WRITE_ONCE(*y, 1);
+ r3 = READ_ONCE(*y);
+ r4 = READ_ONCE(*x);
+}
+
+locations [0:r1; 1:r3; x; y] (* Debug aid: Print things not in "exists". *)
+exists (0:r2=0 /\ 1:r4=0)
--
2.17.1
