From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
rostedt@goodmis.org, "Paul E. McKenney" <paulmck@kernel.org>,
Neeraj Upadhyay <quic_neeraju@quicinc.com>,
Frederic Weisbecker <frederic@kernel.org>,
Boqun Feng <boqun.feng@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
John Ogness <john.ogness@linutronix.de>,
Petr Mladek <pmladek@suse.com>,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3 rcu 06/11] arch/arm64: Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option
Date: Wed, 19 Oct 2022 15:58:41 -0700 [thread overview]
Message-ID: <20221019225846.2501109-6-paulmck@kernel.org> (raw)
In-Reply-To: <20221019225838.GA2500612@paulmck-ThinkPad-P17-Gen-1>
The arm64 architecture uses either an LL/SC loop (old systems) or an LSE
stadd instruction (new systems) to implement this_cpu_add(), both of which
are NMI safe. This means that the old and more-efficient srcu_read_lock()
may be used in NMI context, without the need for srcu_read_lock_nmisafe().
Therefore, add the new Kconfig option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS to
arch/arm64/Kconfig, which will cause NEED_SRCU_NMI_SAFE to be deselected,
thus preserving the current srcu_read_lock() behavior.
Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/
Suggested-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>
Cc: <linux-arm-kernel@lists.infradead.org>
---
arch/arm64/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 505c8a1ccbe0c..099ee812f3f18 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -31,6 +31,7 @@ config ARM64
select ARCH_HAS_KCOV
select ARCH_HAS_KEEPINITRD
select ARCH_HAS_MEMBARRIER_SYNC_CORE
+ select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
select ARCH_HAS_PTE_DEVMAP
select ARCH_HAS_PTE_SPECIAL
--
2.31.1.189.g2e36527f23
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parent reply other threads:[~2022-10-19 23:00 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20221019225838.GA2500612@paulmck-ThinkPad-P17-Gen-1>]
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