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

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