From: Josh Poimboeuf <jpoimboe@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>
Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
linux-arm-kernel@lists.infradead.org,
live-patching@vger.kernel.org, Song Liu <song@kernel.org>,
Miroslav Benes <mbenes@suse.cz>, Petr Mladek <pmladek@suse.com>,
Joe Lawrence <joe.lawrence@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Mark Brown <broonie@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Kees Cook <kees@kernel.org>,
Nathan Chancellor <nathan@kernel.org>,
linux-toolchains@vger.kernel.org
Subject: [PATCH 12/12] arm64/bti: Enable kernel BTI for GCC
Date: Fri, 14 Aug 2026 21:45:29 -0700 [thread overview]
Message-ID: <c08ef46772d364db9b904fac0861adbb3a3bd4e2.1786768375.git.jpoimboe@kernel.org> (raw)
In-Reply-To: <cover.1786768375.git.jpoimboe@kernel.org>
Commit c0a454b9044f ("arm64/bti: Disable in kernel BTI when cross
section thunks are broken") disabled in-kernel BTI for GCC because it
omits a function's BTI landing pad when it determines that a function
can only ever reached by a direct branch. The observed failure was a
module whose init text landed far enough from its core text to need a
PLT, whose "br x16" then hit a function with no "bti c".
Note that behavior isn't GCC-specific: Clang 21 has started ommitting
landing pads as well.
Now that all the known BTI bugs have been sorted out, re-enable it for
GCC.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/arm64/Kconfig | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 2687b71438661..e150807b03016 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -2114,8 +2114,6 @@ config ARM64_BTI_KERNEL
depends on CC_HAS_BRANCH_PROT_PAC_RET_BTI
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94697
depends on !CC_IS_GCC || GCC_VERSION >= 100100
- # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106671
- depends on !CC_IS_GCC
depends on (!FUNCTION_GRAPH_TRACER || DYNAMIC_FTRACE_WITH_ARGS)
help
Build the kernel with Branch Target Identification annotations
--
2.55.0
prev parent reply other threads:[~2026-08-15 4:45 UTC|newest]
Thread overview: 17+ 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 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
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 ` Josh Poimboeuf [this message]
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