Messages in this thread | | | Subject | Re: [PATCH] [stable 4.9] arm64: Add work around for Arm Cortex-A55 Erratum 1024718 | From | Suzuki K Poulose <> | Date | Fri, 11 May 2018 17:06:20 +0100 |
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On 11/05/18 16:47, Greg KH wrote: > On Fri, May 11, 2018 at 02:51:15PM +0100, Suzuki K Poulose wrote: >> commit ece1397cbc89c51914fae1aec729539cfd8bd62b upstream >> >> Some variants of the Arm Cortex-55 cores (r0p0, r0p1, r1p0) suffer >> from an erratum 1024718, which causes incorrect updates when DBM/AP >> bits in a page table entry is modified without a break-before-make >> sequence. The work around is to disable the hardware DBM feature >> on the affected cores. The hardware Access Flag management features >> is not affected. >> >> The hardware DBM feature is a non-conflicting capability, i.e, the >> kernel could handle cores using the feature and those without having >> the features running at the same time. So this work around is detected >> at early boot time, rather than delaying it until the CPUs are brought >> up into the kernel with MMU turned on. This also avoids other complexities >> with late CPUs turning online, with or without the hardware DBM features. >> >> Cc: stable@vger.kernel.org # v4.9 >> Cc: Catalin Marinas <catalin.marinas@arm.com> >> Cc: Mark Rutland <mark.rutland@arm.com> >> Cc: Will Deacon <will.deacon@arm.com> >> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> >> --- >> Note: The upstream commit is on top of a reworked capability >> infrastructure for arm64 heterogeneous systems, which allows >> delaying the CPU model checks. This backport is based on the >> original version of the patch [0], which checks the affected >> CPU models during the early boot. >> >> [0] https://lkml.kernel.org/r/20180116102323.3470-1-suzuki.poulose@arm.com > > Now applied, thanks.
Greg,
I have the backport for v4.4 ready. But it needs to cherry-pick a commit (commit 30b5ba5cf33 : arm64: introduce mov_q macro to move a constant into a 64-bit register) which adds the assembly helper and that seems to result in a conflict with an obvious resolution. What do you prefer in this case ?
1) Go ahead with the cherry-pick
Or
2) Fold the pre-req patch (which is about 30 lines of changes) in the back port
Cheers Suzuki
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