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From: sashiko-bot@kernel.org
Subject: Re: [PATCH] arm64: kexec: mark machine_kexec() __nocfi
Reply-To: sashiko-reviews@lists.linux.dev
To: "Nick Desaulniers" <ndesaulniers@google.com>, "Catalin Marinas" <catalin.marinas@arm.com>, "Will
 Deacon" <will@kernel.org>, "Nathan Chancellor" <nathan@kernel.org>, "Bill
 Wendling" <morbo@google.com>, "Ben Cressey" <ben@cressey.dev>, "Mark
 Rutland" <mark.rutland@arm.com>, "Justin Stitt" <justinstitt@google.com>, "Pasha
 Tatashin" <pasha.tatashin@soleen.com>
Cc: llvm@lists.linux.dev, stable@vger.kernel.org, kexec@lists.infradead.org, "David
 Woodhouse" <dwmw@amazon.co.uk>, linux-arm-kernel@lists.infradead.org, "Sami
 Tolvanen" <samitolvanen@google.com>, linux-kernel@vger.kernel.org, "Kees
 Cook" <kees@kernel.org>
In-Reply-To: <20260924-arm64-kexec-nocfi-v1-1-bbae2e2eadc8@cressey.dev>
References: <20260924-arm64-kexec-nocfi-v1-1-bbae2e2eadc8@cressey.dev>
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Date: Thu, 24 Sep 2026 22:48:05 +0000
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> When the loaded image needs relocation, machine_kexec() makes an
> indirect call into the copy of arm64_relocate_new_kernel in the control
> page:
>=20
> 	kernel_reloc =3D (void *)kimage->arch.kern_reloc;
> 	kernel_reloc(kimage);
>=20
> With CONFIG_CFI=3Dy the kCFI check on this call loads a type hash from
> kern_reloc - 4. arm64_relocate_new_kernel is SYM_CODE_START and carries
> no hash. Its copy also sits at the start of the control page, which is
> all that TTBR0 maps at this point, so the load faults and the kernel
> oopses after "Bye!" instead of entering the new kernel:
>=20
>  Unable to handle kernel paging request at virtual address 00000000544bff=
fc
>  Internal error: Oops: 0000000096000007 [#1]  SMP
> [ ... ]
> ("x86/kexec: Mark machine_kexec() with __nocfi") did on x86.
>=20
> Fixes: efc2d0f20a9d ("arm64: kexec: keep MMU enabled during kexec relocat=
ion")
> Cc: stable@vger.kernel.org
> Signed-off-by: Ben Cressey <ben@cressey.dev>

Sashiko has reviewed this patch and found no issues. It looks great!

--=20
Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260924-arm64-kexe=
c-nocfi-v1-1-bbae2e2eadc8@cressey.dev?part=3D1