linux-kernel - Re: [PATCH v3 00/10] livepatch,module: Remove .klp.arch and module_disable

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Date:   Mon, 27 Apr 2020 12:52:43 -0400
From:   Joe Lawrence <joe.lawrence@...hat.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>, live-patching@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Jessica Yu <jeyu@...nel.org>
Subject: Re: [PATCH v3 00/10] livepatch,module: Remove .klp.arch and
 module_disable_ro()

On Mon, Apr 27, 2020 at 08:22:03AM -0400, Joe Lawrence wrote:
> On 4/25/20 7:07 AM, Josh Poimboeuf wrote:
> > v3:
> > - klp: split klp_write_relocations() into object/section specific
> >    functions [joe]
> > - s390: fix plt/got writes [joe]
> > - s390: remove text_mutex usage [mbenes]
> > - x86: do text_poke_sync() before releasing text_mutex [peterz]
> > - split x86 text_mutex changes into separate patch [mbenes]
> > 
> > v2:
> > - add vmlinux.ko check [peterz]
> > - remove 'klp_object' forward declaration [mbenes]
> > - use text_mutex [jeyu]
> > - fix documentation TOC [jeyu]
> > - fix s390 issues [mbenes]
> > - upstream kpatch-build now supports this
> >    (though it's only enabled for Linux >= 5.8)
> > 
> > These patches add simplifications and improvements for some issues Peter
> > found six months ago, as part of his non-writable text code (W^X)
> > cleanups.
> > 
> > Highlights:
> > 
> > - Remove the livepatch arch-specific .klp.arch sections, which were used
> >    to do paravirt patching and alternatives patching for livepatch
> >    replacement code.
> > 
> > - Add support for jump labels in patched code.

Nit: support for the hopefully common cases anyway: jump labels whose
keys are not going to require late-module klp-relocation (defined in an
unloaded module).

> > 
> > - Remove the last module_disable_ro() usage.
> > 
> > For more background, see this thread:
> > 
> >    https://lkml.kernel.org/r/20191021135312.jbbxsuipxldocdjk@treble
> > 
> > This has been tested with kpatch-build integration tests and klp-convert
> > selftests.
> > 
> 
> Hi Josh,
> 
> I've added some late module patching tests for klp-convert as well as
> extended the existing ones.  I'll put them on-top of v3 and give it some
> test runs today (x86, ppc64le, s390x) and report back.

Ok all three arches look good with the klp-convert WIP tests.  For
reference, I pushed the combined branch up to github [1] if anyone else
wants to see the klp-relocations in action first hand.

For the series:
Acked-by: Joe Lawrence <joe.lawrence@...hat.com>


[1] https://github.com/joe-lawrence/linux/tree/jp-v3-klp-convert

-- Joe