Re: [PATCH v7 8/8] [DO NOT MERGE] x86/kexec: Add CFI type information to relocate_kernel()

From: David Woodhouse
Date: Sat Mar 22 2025 - 07:38:52 EST


On Wed, 2025-03-19 at 08:47 -0700, Josh Poimboeuf wrote:
>
> Looking at machine_kexec(), it calls cet_disable() before the indirect
> call.  So yeah, it seems fine for relocate_kernel() to not have a CFI
> prologue or ENDBR.

Yeah. I'm just going to throw that into a branch and forget it for now.
It's just causing noise around the *actual* stuff we want to get in, to
do the exception handling.

For that, I think the only thing outstanding is to add a userspace test
based on http://david.woodhou.se/loadret.c which invokes the int3 from
the 'payload' to test it. I think this is better than doing it inside
the kernel itself, as it gives us a selftest for the kexec jump
mechanism too.

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