linux-kernel - Re: [PATCH 3/9] arm64: mm: install SError abort handler

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Message-ID: <710c4142-ae20-9715-3e51-910a2073a64e@gmail.com>
Date:   Fri, 24 Mar 2017 10:53:48 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Mark Rutland <mark.rutland@....com>,
        Doug Berger <opendmb@...il.com>
Cc:     catalin.marinas@....com, robh+dt@...nel.org, will.deacon@....com,
        computersforpeace@...il.com, gregory.0xf0@...il.com,
        f.fainelli@...il.com, bcm-kernel-feedback-list@...adcom.com,
        wangkefeng.wang@...wei.com, james.morse@....com,
        vladimir.murzin@....com, panand@...hat.com, andre.przywara@....com,
        cmetcalf@...lanox.com, mingo@...nel.org,
        sandeepa.s.prabhu@...il.com, shijie.huang@....com,
        linus.walleij@...aro.org, treding@...dia.com, jonathanh@...dia.com,
        olof@...om.net, mirza.krak@...il.com, suzuki.poulose@....com,
        bgolaszewski@...libre.com, horms+renesas@...ge.net.au,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 3/9] arm64: mm: install SError abort handler

On 03/24/2017 10:35 AM, Mark Rutland wrote:
> On Fri, Mar 24, 2017 at 09:48:40AM -0700, Doug Berger wrote:
>> On 03/24/2017 08:16 AM, Mark Rutland wrote:
>>> On Fri, Mar 24, 2017 at 07:46:26AM -0700, Doug Berger wrote:
> 
>> If you would consider an alternative implementation where we scrap
>> the SError handler (i.e. maintain the ugliness in our downstream
>> kernel) in favor of a more gentle user mode crash on SError that
>> allows the kernel the opportunity to service the interrupt for
>> diagnostic purposes I could try to repackage that.
> 
> If this is just for diagnostic purposes, I believe you can register a
> panic notifier, which can then read from the bus. The panic will occur,
> but you'll have the opportunity to log some information to dmesg.

And crash the kernel? That sounds awful, FWIW the ARM/Linux kernel is
able to recover just fine from user-space accessing e.g: invalid
physical addresses in the GISB register space, bringing the same level
of functionality to ARM64/Linux sounds reasonable to me.
-- 
Florian