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tools/memory-model: Add litmus test for full multicopy atomicity

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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@rowland.harvard.edu>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akiyks@gmail.com
Cc: boqun.feng@gmail.com
Cc: dhowells@redhat.com
Cc: j.alglave@ucl.ac.uk
Cc: linux-arch@vger.kernel.org
Cc: luc.maranget@inria.fr
Cc: npiggin@gmail.com
Cc: parri.andrea@gmail.com
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/20180716180605.16115-1-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Paul E. McKenney 2018-07-16 11:05:52 -07:00 committed by Ingo Molnar
parent 52b544bd38
commit b464818978
2 changed files with 41 additions and 0 deletions
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9
tools/memory-model/litmus-tests/README
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@ -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.

32
tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus Normal file
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@ -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)