Date:   Tue, 30 Nov 2021 12:44:27 +0100
In-Reply-To: <20211130114433.2580590-1-elver@google.com>
Message-Id: <20211130114433.2580590-20-elver@google.com>
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References: <20211130114433.2580590-1-elver@google.com>
Subject: [PATCH v3 19/25] x86/qspinlock, kcsan: Instrument barrier of pv_queued_spin_unlock()
From:   Marco Elver <elver@google.com>
To:     elver@google.com, "Paul E. McKenney" <paulmck@kernel.org>
Cc:     Alexander Potapenko <glider@google.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        Borislav Petkov <bp@alien8.de>,
        Dmitry Vyukov <dvyukov@google.com>,
        Ingo Molnar <mingo@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Waiman Long <longman@redhat.com>,
        Will Deacon <will@kernel.org>, kasan-dev@googlegroups.com,
        linux-arch@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, llvm@lists.linux.dev, x86@kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

If CONFIG_PARAVIRT_SPINLOCKS=y, queued_spin_unlock() is implemented
using pv_queued_spin_unlock() which is entirely inline asm based. As
such, we do not receive any KCSAN barrier instrumentation via regular
atomic operations.

Add the missing KCSAN barrier instrumentation for the
CONFIG_PARAVIRT_SPINLOCKS case.

Signed-off-by: Marco Elver <elver@google.com>
---
 arch/x86/include/asm/qspinlock.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/include/asm/qspinlock.h b/arch/x86/include/asm/qspinlock.h
index d86ab942219c..d87451df480b 100644
--- a/arch/x86/include/asm/qspinlock.h
+++ b/arch/x86/include/asm/qspinlock.h
@@ -53,6 +53,7 @@ static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
 
 static inline void queued_spin_unlock(struct qspinlock *lock)
 {
+	kcsan_release();
 	pv_queued_spin_unlock(lock);
 }
 
-- 
2.34.0.rc2.393.gf8c9666880-goog