From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5172239FCB5; Fri, 28 Aug 2026 04:51:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787892720; cv=none; b=jpiE/LO7h/+u1QRYm61gtCkk1PxLvvlPrTLlBqqR3HR0/T9gZ32v4/oKfKOGLw6oWq/j+OYKPLsw62wzXAOXLdDYdz6K6SbkABtce7N8z4OadgS/ROMoA4CxKD6Vg8S1GhmmjU5k7dA6uckWqqr+oFbLuJC9rKcBNsaiBFZ8lzU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787892720; c=relaxed/simple; bh=r51T4P/rePhfM/0/IsK0LWWu3w+gTjlFU0r3fYOHz7o=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Z1r/u2Yt1X8q/efa+m8u+3l8ivAe9yxYPpas3c4+IPSPYDeaUjFMeBGf0gHgD6Vh/LdvWtCEFQdgqAETeInf9wrxvE3fOCeWPcxshI2lCfymXyUFSN9JJH+bpL2J7W0GueHEUOV3k+CBKZ4yk4ez4zRRZ4vC2pdLhB7tROjuqww= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=S5cwkEl6; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="S5cwkEl6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 790171F000E9; Fri, 28 Aug 2026 04:51:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787892718; bh=JLcwD228BFGDz2UbxvWm/M8XG/wbxrG8XtJnHllKHiU=; h=From:To:Cc:Subject:Date; b=S5cwkEl6i22cVOutVosqw5pQe2jboNowcTzr9X3CZN7OadXEcavVUMZQpk1zKwh76 V7S7DgJpFMuqpXIQ1DRw4+EynLkqwPcGAno2ZU2p8fj74DCWRYm4xfJ2C00EcTeDah JnVAk62wzyQ2ChbifNO7/NVpFx/Yk/v9FGgJImQnF2qAb4yonXLshCdSz6F1+sr5zz OzmW2gxrMa8OM2k50OMtXNt1dekelY0oMyyfeqXEjpyFvLHTx+oXta7Nep36JkrYiR 6E8gSHlpgnHQ/y6mdHw/7ULM8hJbnUtA9PjoTrJKdfJtobD4mTvK/NO9whWJi1q0K2 dDPetPWEctstA== From: Josh Poimboeuf To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Gary Guo , rust-for-linux@vger.kernel.org, Ard Biesheuvel , Miguel Ojeda , Nathan Chancellor , Nicolas Schier , linux-kbuild@vger.kernel.org, Huacai Chen Subject: [PATCH 00/27] objtool: dynamically detect noreturns Date: Thu, 27 Aug 2026 21:51:29 -0700 Message-ID: X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The C and rust manual noreturn lists are a maintenance nightmare. Get rid of them by taking advantage of the fact that objtool can run on linked objects (vmlinux.o and modules) and can thus detect noreturns dynamically: 1) When features are enabled which require the noreturn knowledge (i.e., control flow analysis) always defer objtool to run on linked objects. That obsoletes most of noreturns.h. (patch 12) 2) For noreturn functions which are exported by vmlinux, dynamically write their names to a file which is then read by objtool running on modules. That obsoletes most of the remaining noreturns.h entries and the entirety of is_rust_noreturn(). (patch 24) 3) For the (four) noreturn functions which are exported by modules, manually annotate them at their declaration sites with a new ANNOTATE_EXPORTED_NORETURN(). That removes the last few stragglers in noreturns.h. (patch 26) Josh Poimboeuf (27): objtool: Remove obsolete noreturns.h entries kbuild: Add CONFIG_OBJTOOL_DEFERRED kbuild: Add CONFIG_OBJTOOL_CONTROL_FLOW objtool: Fix dead end detection for sibling calls objtool: Refactor the noreturn/dead-end detection objtool: Ignore traps after noreturn calls in STT_CODE objtool: Make .discard.stack_frame_non_standard non-allocatable efi/libstub: Drop .discard.addressable from the stub objects efi/loongarch: Mark loongarch efi_boot_kernel() non-standard for objtool objtool: Add ANNOTATE_IGNORE_NORETURN() LoongArch: Annotate reboot and kexec paths as returnable kbuild: Defer running objtool to link time for all CFG features rust: Annotate the intrinsic stubs as returnable panic: Mark abort() __noreturn x86/xen: Ignore noreturn status of weak mem_map_via_hcall() objtool: Detect noreturns in weak functions x86/entry: Make rewind_stack_and_make_dead() a real function x86/xen: Make xen_cpu_bringup_again() a real function x86/xen: Make xen_start_kernel() noreturn x86/boot: Rework how pi startup symbols get exposed to vmlinux objtool: Fix noreturn detection for non-sibling jumps to SYM_CODE objtool: Add options to write/read exported noreturns to/from a file kbuild: Do the per-module objtool pass right before linking kbuild: Generate the noreturn list and validate modules against it objtool: Add ANNOTATE_EXPORTED_NORETURN() objtool: Annotate all module-exported noreturns and remove noreturns.h objtool: Warn about missing/stale ANNOTATE_EXPORTED_NORETURN() usage Makefile | 8 + arch/arc/kernel/traps.c | 4 +- arch/arm/kernel/traps.c | 2 +- arch/loongarch/kernel/machine_kexec.c | 2 + arch/loongarch/kernel/reset.c | 4 + arch/x86/boot/startup/Makefile | 16 +- arch/x86/boot/startup/exports.h | 14 - arch/x86/boot/startup/unprefix.syms | 13 + arch/x86/entry/entry_64.S | 7 +- arch/x86/kernel/vmlinux.lds.S | 2 - arch/x86/platform/pvh/enlighten.c | 1 + arch/x86/xen/enlighten_pv.c | 5 +- arch/x86/xen/xen-head.S | 5 +- arch/x86/xen/xen-ops.h | 2 +- drivers/firmware/efi/libstub/Makefile | 4 + drivers/firmware/efi/libstub/loongarch.c | 8 + drivers/message/fusion/mptbase.h | 2 + include/kunit/test.h | 1 + include/kunit/try-catch.h | 2 + include/linux/annotate.h | 24 ++ include/linux/objtool.h | 13 +- include/linux/objtool_types.h | 1 + include/linux/panic.h | 2 +- include/linux/rtc/ds1685.h | 2 + kernel/exit.c | 2 +- lib/Kconfig.debug | 14 + lib/Kconfig.ubsan | 2 +- rust/.gitignore | 1 + rust/Makefile | 17 + scripts/.gitignore | 1 + scripts/Makefile.build | 31 +- scripts/Makefile.lib | 4 +- scripts/Makefile.modfinal | 35 +- scripts/Makefile.vmlinux_o | 13 +- scripts/link-vmlinux.sh | 3 +- scripts/livepatch/klp-build | 4 +- tools/include/linux/objtool_types.h | 1 + tools/objtool/Documentation/objtool.txt | 30 +- tools/objtool/builtin-check.c | 12 + tools/objtool/check.c | 435 +++++++++++++++++------ tools/objtool/include/objtool/builtin.h | 2 + tools/objtool/include/objtool/elf.h | 4 + tools/objtool/klp-diff.c | 32 ++ tools/objtool/noreturns.h | 55 --- 44 files changed, 584 insertions(+), 258 deletions(-) delete mode 100644 arch/x86/boot/startup/exports.h create mode 100644 arch/x86/boot/startup/unprefix.syms delete mode 100644 tools/objtool/noreturns.h -- 2.55.0