From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Morse Subject: [PATCH v5 01/13] arm64: cpufeature: __this_cpu_has_cap() shouldn't stop early Date: Fri, 15 Dec 2017 15:50:49 +0000 Message-ID: <20171215155101.23505-2-james.morse@arm.com> References: <20171215155101.23505-1-james.morse@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D780C49D72 for ; Fri, 15 Dec 2017 10:49:46 -0500 (EST) Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id o18TqsNs4Mc5 for ; Fri, 15 Dec 2017 10:49:45 -0500 (EST) Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id C57F149D51 for ; Fri, 15 Dec 2017 10:49:45 -0500 (EST) In-Reply-To: <20171215155101.23505-1-james.morse@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: linux-arm-kernel@lists.infradead.org Cc: Jonathan.Zhang@cavium.com, Marc Zyngier , Catalin Marinas , Will Deacon , Dongjiu Geng , kvmarm@lists.cs.columbia.edu List-Id: kvmarm@lists.cs.columbia.edu this_cpu_has_cap() tests caps->desc not caps->matches, so it stops walking the list when it finds a 'silent' feature, instead of walking to the end of the list. Prior to v4.6's 644c2ae198412 ("arm64: cpufeature: Test 'matches' pointer to find the end of the list") we always tested desc to find the end of a capability list. This was changed for dubious things like PAN_NOT_UAO. v4.7's e3661b128e53e ("arm64: Allow a capability to be checked on single CPU") added this_cpu_has_cap() using the old desc style test. CC: Suzuki K Poulose CC: Marc Zyngier Signed-off-by: James Morse --- So far only ARM64_HAS_SYSREG_GIC_CPUIF and errata use this_cpu_has_cap(), all the errata have descriptions, and the GIC_CPUIF feature is first in the list, so its not possible to hit this with mainline. I don't think this should go to stable - this is not intended as a fix. arch/arm64/kernel/cpufeature.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index c5ba0097887f..68a49f7fb75c 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1236,8 +1236,8 @@ static bool __this_cpu_has_cap(const struct arm64_cpu_capabilities *cap_array, if (WARN_ON(preemptible())) return false; - for (caps = cap_array; caps->desc; caps++) - if (caps->capability == cap && caps->matches) + for (caps = cap_array; caps->matches; caps++) + if (caps->capability == cap) return caps->matches(caps, SCOPE_LOCAL_CPU); return false; -- 2.15.0