linux-kernel - Re: [PATCH v3 0/2] arm64: livepatch: Enable livepatch without sframe

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Message-ID: <CADBMgpzPyW+EnB3A1Hr=LQGhuen4pUuJ0QYa44nH0qfQ9TFaSQ@mail.gmail.com>
Date: Mon, 19 May 2025 10:11:04 -0700
From: Dylan Hatch <dylanbhatch@...gle.com>
To: Mark Rutland <mark.rutland@....com>
Cc: Song Liu <song@...nel.org>, Petr Mladek <pmladek@...e.com>, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-toolchains@...r.kernel.org, live-patching@...r.kernel.org, 
	indu.bhagat@...cle.com, puranjay@...nel.org, wnliu@...gle.com, 
	irogers@...gle.com, joe.lawrence@...hat.com, jpoimboe@...nel.org, 
	peterz@...radead.org, roman.gushchin@...ux.dev, rostedt@...dmis.org, 
	will@...nel.org, kernel-team@...a.com
Subject: Re: [PATCH v3 0/2] arm64: livepatch: Enable livepatch without sframe

> FWIW: I reviewed the patch above ([1]) already but didn't hear anything
> back.

Sorry for the delay on this, last week was busier than expected on my
end. I'm aiming to send the revised patch within the next couple of
days.

On Mon, May 19, 2025 at 9:40 AM Mark Rutland <mark.rutland@....com> wrote:
> I've had a quick look at [1], and IIUC that's a hard prerequisite for
> livepatching, as without it the kernel *will* crash if it attempts a
> late module relocation.
>

This is correct. In both module-patch scenarios (module is loaded
first, or patch is loaded first) the relocations on the livepatch
module occur after it is already RX-only, so a crash is inevitable
with the current relocation code.

Thanks,
Dylan