From: sashiko-bot@kernel.org
To: "Catalin Marinas" <catalin.marinas@arm.com>,
"Josh Poimboeuf" <jpoimboe@kernel.org>,
"Will Deacon" <will@kernel.org>
Cc: "Ard Biesheuvel" <ardb@kernel.org>,
"Miroslav Benes" <mbenes@suse.cz>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
"Petr Mladek" <pmladek@suse.com>,
"Mark Brown" <broonie@kernel.org>,
live-patching@vger.kernel.org,
"Nick Desaulniers" <ndesaulniers@google.com>,
"Mark Rutland" <mark.rutland@arm.com>,
"Joe Lawrence" <joe.lawrence@redhat.com>,
"Kees Cook" <kees@kernel.org>,
"Nathan Chancellor" <nathan@kernel.org>,
"Song Liu" <song@kernel.org>,
linux-toolchains@vger.kernel.org
Subject: Re: [PATCH 07/12] arm64/bti: Advertise BTI in assembly objects
Date: Sat, 15 Aug 2026 05:03:02 +0000 [thread overview]
Message-ID: <20260815050302.86F851F000E9@smtp.kernel.org> (raw)
In-Reply-To: <5340f3df281bebc81aad3cd9a7471d95061b4b9d.1786768375.git.jpoimboe@kernel.org>
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
Pre-existing issues:
- [High] The patch fails to enable BTI veneers for the kernel because EFI stub and PI object files explicitly strip the property note.
--
--- Patch [7]: [PATCH 07/12] arm64/bti: Advertise BTI in assembly objects ---
commit f368db6f176a29dc1fd3803f6ac93282119ab6aa
Author: Josh Poimboeuf <jpoimboe@kernel.org>
arm64/bti: Advertise BTI in assembly objects
This commit forces the inclusion of a GNU property note with the BTI bit
into every assembly file. This is intended to ensure the linker emits BTI
veneers for >128MB kernels by ensuring all input objects have the property.
> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
> index 6b005c8fef706..4eee721c0b278 100644
> --- a/arch/arm64/Makefile
> +++ b/arch/arm64/Makefile
> @@ -23,6 +23,10 @@ ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
> LDFLAGS_vmlinux += --fix-cortex-a53-843419
> endif
>
> +ifeq ($(CONFIG_ARM64_BTI_KERNEL),y)
> +KBUILD_AFLAGS += -include $(srctree)/arch/arm64/include/asm/bti-note.h
> +endif
[Severity: High]
This isn't a bug introduced by this patch, but will this approach still
fail to emit BTI veneers for the kernel?
The GNU linker requires all input objects to have the BTI property, but
the EFI stub and PI object files explicitly strip the property note before
they are linked into vmlinux.
In drivers/firmware/efi/libstub/Makefile:
STUBCOPY_FLAGS-y += --remove-section=.note.gnu.property
And in arch/arm64/kernel/pi/Makefile:
$(obj)/%.pi.o: OBJCOPYFLAGS := --prefix-symbols=__pi_ \
--remove-section=.note.gnu.property
Since these objects are stripped of the note and linked into vmlinux,
will the linker continue to evaluate the global link with objects lacking
the BTI property, leaving the original large-kernel crash unresolved?
[ ... ]
--
Sashiko AI review · https://sashiko.dev/#/patchset/cover.1786768375.git.jpoimboe@kernel.org?part=7
next prev parent reply other threads:[~2026-08-15 5:03 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-15 4:45 [PATCH 00/12] arm64/bti: Fix kernel BTI issues with livepatch, large kernels, toolchains Josh Poimboeuf
2026-08-15 4:45 ` [PATCH 01/12] arm64/bti: Add BTI landing pad to __sdei_asm_handler() Josh Poimboeuf
2026-08-15 5:01 ` sashiko-bot
2026-08-15 4:45 ` [PATCH 02/12] arm64/module: Fix BTI exceptions caused by omitted landing pads in Clang 21 Josh Poimboeuf
2026-08-15 5:00 ` sashiko-bot
2026-08-15 9:56 ` Ard Biesheuvel
2026-08-15 4:45 ` [PATCH 03/12] arm64/bti: Fix BTI linker failures with long branches into .idmap.text Josh Poimboeuf
2026-08-15 4:45 ` [PATCH 04/12] arm64/bti: Work around ld crash caused by linker script aliases Josh Poimboeuf
2026-08-15 4:45 ` [PATCH 05/12] arm64/bti: Add link error for large kernels with BTI and unsupported toolchains Josh Poimboeuf
2026-08-15 4:45 ` [PATCH 06/12] arm64/bti: Add link error for large kernels with BTI and livepatch Josh Poimboeuf
2026-08-15 4:45 ` [PATCH 07/12] arm64/bti: Advertise BTI in assembly objects Josh Poimboeuf
2026-08-15 5:03 ` sashiko-bot [this message]
2026-08-15 4:45 ` [PATCH 08/12] arm64/bti: Enable BTI in the pi/ startup code Josh Poimboeuf
2026-08-15 4:45 ` [PATCH 09/12] efi/libstub: Preserve the GNU property note Josh Poimboeuf
2026-08-15 4:45 ` [PATCH 10/12] efi/libstub: Remove obsolete .note.gnu.property workaround Josh Poimboeuf
2026-08-15 4:45 ` [PATCH 11/12] arm64/bti: Force-enable BTI linker veneers Josh Poimboeuf
2026-08-15 5:00 ` sashiko-bot
2026-08-15 4:45 ` [PATCH 12/12] arm64/bti: Enable kernel BTI for GCC Josh Poimboeuf
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