Re: [PATCH 0/8] unwind, arm64: add sframe unwinder for kernel

Puranjay Mohan <[email protected]> Thu, 13 Feb 2025 07:53:27 +0000

Newsgroups	org.kernel.vger.linux-toolchains,org.infradead.lists.linux-arm-kernel,org.kernel.vger.linux-kernel,org.kernel.vger.live-patching
Message-ID	<[email protected]>

Song Liu <[email protected]> writes:

> On Wed, Feb 12, 2025 at 11:26 PM Puranjay Mohan <[email protected]> wrote:
>>
>> Song Liu <[email protected]> writes:
>>
>> > On Wed, Feb 12, 2025 at 4:10 PM Indu Bhagat <[email protected]> wrote:
>> >>
>> >> On 2/12/25 3:32 PM, Song Liu wrote:
>> >> > I run some tests with this set and my RFC set [1]. Most of
>> >> > the test is done with kpatch-build. I tested both Puranjay's
>> >> > version [3] and my version [4].
>> >> >
>> >> > For gcc 14.2.1, I have seen the following issue with this
>> >> > test [2]. This happens with both upstream and 6.13.2.
>> >> > The livepatch loaded fine, but the system spilled out the
>> >> > following warning quickly.
>> >> >
>> >>
>> >> In presence of the issue
>> >> https://sourceware.org/bugzilla/show_bug.cgi?id=32666, I'd expect bad
>> >> data in SFrame section.  Which may be causing this symptom?
>> >>
>> >> To be clear, the issue affects loaded kernel modules.  I cannot tell for
>> >> certain - is there module loading involved in your test ?
>> >
>> > The KLP is a module, I guess that is also affected?
>> >
>> > During kpatch-build, we added some logic to drop the .sframe section.
>> > I guess this is wrong, as we need the .sframe section when we apply
>> > the next KLP. However, I don't think the issue is caused by missing
>> > .sframe section.
>>
>> Hi, I did the same testing and did not get the Warning.
>>
>> I am testing on the 6.12.11 kernel with GCC 11.4.1.
>
> Could you please also try kernel 6.13.2?
>
>> Just to verify, the patch we are testing is:
>
> Yes, this is the test patch.
>>
>> --- >8 ---
> [...]
>> --- 8< ---
>>
>> P.S. - I have a downstream patch for create-diff-object to generate .sframe sections for
>> livepatch module, will add it to the PR after some cleanups.
>
> Yeah, I think the .sframe section is still needed.
>

Hi Song,

Can you try with this:
https://github.com/puranjaymohan/kpatch/tree/arm64_wip

This has the .sframe logic patch, but it looks as if I wrote that code
in a 30 minute leetcode interview. I need to refactor it before I send
it for review with the main PR.

Can you test with this branch with your setup?

Thanks,
Puranjay

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