linux-kernel - Re: [PATCH v2 11/11] ARC: [plat-eznps] Handle memory error as an exception

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <ef177e34-e2ac-2e05-c136-e5b213687911@synopsys.com>
Date:   Wed, 7 Jun 2017 09:15:49 -0700
From:   Vineet Gupta <Vineet.Gupta1@...opsys.com>
To:     Noam Camus <noamca@...lanox.com>,
        "linux-snps-arc@...ts.infradead.org" 
        <linux-snps-arc@...ts.infradead.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Elad Kanfi <eladkan@...lanox.com>
Subject: Re: [PATCH v2 11/11] ARC: [plat-eznps] Handle memory error as an
 exception

On 06/07/2017 04:14 AM, Noam Camus wrote:
>>>> +config EZNPS_MEM_ERROR
>>>> +       bool "ARC-EZchip Memory error as an exception"
>>>> +       depends on ARC_PLAT_EZNPS
>>>> +       default n
>>> So you set default to "n" - thus by default it works for the simulator not silicon ?
>> Correct, this way I "align" Sim environment to react as close as possible to how it work with silicon.
> Sorry, but It is not correct.
> Default is for silicon where it is naturally emits machine check and unlike simulator do not need OS to redirect the ISR L2 to machine check handler.
> Above motivation of "align" is true, but default is silicon and not sim, as I wrote in my original configuration help.
> Please re-update this CONFIG help section.



So NPS *hardware* generates exception, jumps to vector mem_service(), which you 
redirect to the machine check handler - which simply panics.
But this redirection is under EZNPS_MEM_ERROR, which you have defaulted to "n". So 
how is the default working for hardware ? Doesn't it need to be "y"

BTW it seems your patch is wrong otherwise too. So the userspace bus error will go 
to machine check handler which currently just panic's. You really want to kill the 
user space process and continue, thus need to call do_memory_error()

-Vineet