From mboxrd@z Thu Jan 1 00:00:00 1970 From: james.morse@arm.com (James Morse) Date: Mon, 15 Jan 2018 19:38:54 +0000 Subject: [PATCH v6 01/13] arm64: cpufeature: __this_cpu_has_cap() shouldn't stop early In-Reply-To: <20180115193906.30053-1-james.morse@arm.com> References: <20180115193906.30053-1-james.morse@arm.com> Message-ID: <20180115193906.30053-2-james.morse@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 Reviewed-by: Suzuki K Poulose --- 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 9ef84d0def9a..d88cd0e88606 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1303,8 +1303,8 @@ 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; -- 2.15.1