linux-kernel - Re: [PATCH v2 6/9] s390/module: Use s390_kernel

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Message-ID: <691690e3-b792-bac5-2080-2abfc0beb11b@redhat.com>
Date:   Thu, 30 Apr 2020 13:04:10 -0400
From:   Joe Lawrence <joe.lawrence@...hat.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Miroslav Benes <mbenes@...e.cz>,
        Gerald Schaefer <gerald.schaefer@...ibm.com>,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Jessica Yu <jeyu@...nel.org>, linux-s390@...r.kernel.org,
        heiko.carstens@...ibm.com, Vasily Gorbik <gor@...ux.ibm.com>
Subject: Re: [PATCH v2 6/9] s390/module: Use s390_kernel_write() for late
 relocations

On 4/30/20 12:48 PM, Josh Poimboeuf wrote:
> On Thu, Apr 30, 2020 at 10:38:21AM -0400, Joe Lawrence wrote:
>> On Thu, Apr 23, 2020 at 01:10:30PM -0500, Josh Poimboeuf wrote:
>> This is more of note for the future, but when/if we add livepatch
>> support on arm64 we'll need to make the very same adjustment there as
>> well.  See the following pattern:
>>
>> arch/arm64/kernel/module.c:
>>
>>    reloc_insn_movw()
>>    reloc_insn_imm()
>>    reloc_insn_adrp()
>>
>>      *place = cpu_to_le32(insn);
>>
>> maybe something like aarch64_insn_patch_text_nosync() could be used
>> there, I dunno. (It looks like ftrace and jump_labels are using that
>> interface.)
>>
>> This is outside the scope of the patchset, but I thought I'd mention it
>> as I was curious to see how other arches were currently handling their
>> relocation updates.
> 
> True... I suspect your klp-convert selftests will catch that?
> 

Indeed.  Actually I had hacked enough livepatch code support on ARM to 
see what happened when converting and loading the test patches :)

-- Joe