linux-kernel - [PATCH memory-model 2/3] tools/memory-model: Add atomic

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Date: Tue,  4 Jun 2024 15:14:18 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org,
	kernel-team@...a.com,
	mingo@...nel.org
Cc: stern@...land.harvard.edu,
	parri.andrea@...il.com,
	will@...nel.org,
	peterz@...radead.org,
	boqun.feng@...il.com,
	npiggin@...il.com,
	dhowells@...hat.com,
	j.alglave@....ac.uk,
	luc.maranget@...ia.fr,
	akiyks@...il.com,
	Puranjay Mohan <puranjay@...nel.org>,
	"Paul E . McKenney" <paulmck@...nel.org>,
	Daniel Lustig <dlustig@...dia.com>,
	Joel Fernandes <joel@...lfernandes.org>
Subject: [PATCH memory-model 2/3] tools/memory-model: Add atomic_andnot() with its variants

From: Puranjay Mohan <puranjay@...nel.org>

Pull-855[1] added the support of atomic_andnot() to the herd tool. Use
this to add the implementation in the LKMM. All of the ordering variants
are also added.

Here is a small litmus-test that uses this operation:

C andnot

{
atomic_t u = ATOMIC_INIT(7);
}

P0(atomic_t *u)
{

        r0 = atomic_fetch_andnot(3, u);
        r1 = READ_ONCE(*u);
}

exists (0:r0=7 /\ 0:r1=4)

Test andnot Allowed
States 1
0:r0=7; 0:r1=4;
Ok
Witnesses
Positive: 1 Negative: 0
Condition exists (0:r0=7 /\ 0:r1=4)
Observation andnot Always 1 0
Time andnot 0.00
Hash=78f011a0b5a0c65fa1cf106fcd62c845

[1] https://github.com/herd/herdtools7/pull/855

Signed-off-by: Puranjay Mohan <puranjay@...nel.org>
Acked-by: Andrea Parri <parri.andrea@...il.com>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
Cc: Alan Stern <stern@...land.harvard.edu>
Cc: Will Deacon <will@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Nicholas Piggin <npiggin@...il.com>
Cc: David Howells <dhowells@...hat.com>
Cc: Jade Alglave <j.alglave@....ac.uk>
Cc: Luc Maranget <luc.maranget@...ia.fr>
Cc: Akira Yokosawa <akiyks@...il.com>
Cc: Daniel Lustig <dlustig@...dia.com>
Cc: Joel Fernandes <joel@...lfernandes.org>
Cc: <linux-arch@...r.kernel.org>
---
 tools/memory-model/linux-kernel.def | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/memory-model/linux-kernel.def b/tools/memory-model/linux-kernel.def
index d1f11930ec512..a12b96c547b7a 100644
--- a/tools/memory-model/linux-kernel.def
+++ b/tools/memory-model/linux-kernel.def
@@ -70,6 +70,7 @@ atomic_or(V,X)  { __atomic_op(X,|,V); }
 atomic_xor(V,X) { __atomic_op(X,^,V); }
 atomic_inc(X)   { __atomic_op(X,+,1); }
 atomic_dec(X)   { __atomic_op(X,-,1); }
+atomic_andnot(V,X) { __atomic_op(X,&~,V); }
 
 atomic_add_return(V,X) __atomic_op_return{mb}(X,+,V)
 atomic_add_return_relaxed(V,X) __atomic_op_return{once}(X,+,V)
@@ -138,3 +139,8 @@ atomic_add_negative(V,X) __atomic_op_return{mb}(X,+,V) < 0
 atomic_add_negative_relaxed(V,X) __atomic_op_return{once}(X,+,V) < 0
 atomic_add_negative_acquire(V,X) __atomic_op_return{acquire}(X,+,V) < 0
 atomic_add_negative_release(V,X) __atomic_op_return{release}(X,+,V) < 0
+
+atomic_fetch_andnot(V,X) __atomic_fetch_op{mb}(X,&~,V)
+atomic_fetch_andnot_acquire(V,X) __atomic_fetch_op{acquire}(X,&~,V)
+atomic_fetch_andnot_release(V,X) __atomic_fetch_op{release}(X,&~,V)
+atomic_fetch_andnot_relaxed(V,X) __atomic_fetch_op{once}(X,&~,V)
-- 
2.40.1