From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- scripts/dtc/dtx_diff | 361 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 361 insertions(+) create mode 100755 scripts/dtc/dtx_diff (limited to 'scripts/dtc/dtx_diff') diff --git a/scripts/dtc/dtx_diff b/scripts/dtc/dtx_diff new file mode 100755 index 000000000..f2bbde4bb --- /dev/null +++ b/scripts/dtc/dtx_diff @@ -0,0 +1,361 @@ +#! /bin/bash +# SPDX-License-Identifier: GPL-2.0-only + +# Copyright (C) 2015 Frank Rowand +# + + +usage() { + + # use spaces instead of tabs in the usage message + cat >&2 <tmp_dtx_1.dts + `basename $0` ARCH=arch_of_dtx_2 DTx_2 >tmp_dtx_2.dts + `basename $0` tmp_dtx_1.dts tmp_dtx_2.dts + rm tmp_dtx_1.dts tmp_dtx_2.dts + + If DTx_1 and DTx_2 are in different directories, then this script will + add the path of DTx_1 and DTx_2 to the include paths. If DTx_2 includes + a local file that exists in both the path of DTx_1 and DTx_2 then the + file in the path of DTx_1 will incorrectly be included. Possible + workaround: + + `basename $0` DTx_1 >tmp_dtx_1.dts + `basename $0` DTx_2 >tmp_dtx_2.dts + `basename $0` tmp_dtx_1.dts tmp_dtx_2.dts + rm tmp_dtx_1.dts tmp_dtx_2.dts + +eod +} + + +compile_to_dts() { + + dtx="$1" + dtc_include="$2" + + if [ -d "${dtx}" ] ; then + + # ----- input is file tree + + if ( ! ${DTC} -I fs ${dtx} ) ; then + exit 3 + fi + + elif [ -f "${dtx}" ] && [ -r "${dtx}" ] ; then + + magic=`hexdump -n 4 -e '/1 "%02x"' ${dtx}` + if [ "${magic}" = "d00dfeed" ] ; then + + # ----- input is FDT (binary blob) + + if ( ! ${DTC} -I dtb ${dtx} ) ; then + exit 3 + fi + + return + + fi + + # ----- input is DTS (source) + + if ( cpp ${cpp_flags} -x assembler-with-cpp ${dtx} \ + | ${DTC} ${dtc_include} -I dts ) ; then + return + fi + + echo "" >&2 + echo "Possible hints to resolve the above error:" >&2 + echo " (hints might not fix the problem)" >&2 + + hint_given=0 + + if [ "${ARCH}" = "" ] ; then + hint_given=1 + echo "" >&2 + echo " shell variable \$ARCH not set" >&2 + fi + + dtx_arch=`echo "/${dtx}" | sed -e 's|.*/arch/||' -e 's|/.*||'` + + if [ "${dtx_arch}" != "" -a "${dtx_arch}" != "${ARCH}" ] ; then + hint_given=1 + echo "" >&2 + echo " architecture ${dtx_arch} is in file path," >&2 + echo " but does not match shell variable \$ARCH" >&2 + echo " >>\$ARCH<< is: >>${ARCH}<<" >&2 + fi + + if [ ! -d ${srctree}/arch/${ARCH} ] ; then + hint_given=1 + echo "" >&2 + echo " ${srctree}/arch/${ARCH}/ does not exist" >&2 + echo " Is \$ARCH='${ARCH}' correct?" >&2 + echo " Possible fix: use '-s' option" >&2 + + git_root=`git rev-parse --show-toplevel 2>/dev/null` + if [ -d ${git_root}/arch/ ] ; then + echo " Possible fix: use '-S' option" >&2 + fi + fi + + if [ $hint_given = 0 ] ; then + echo "" >&2 + echo " No hints available." >&2 + fi + + echo "" >&2 + + exit 3 + + else + echo "" >&2 + echo "ERROR: ${dtx} does not exist or is not readable" >&2 + echo "" >&2 + exit 2 + fi + +} + + +# ----- start of script + +annotate="" +cmd_diff=0 +diff_flags="-u" +diff_color="" +dtx_file_1="" +dtx_file_2="" +dtc_sort="-s" +help=0 +srctree="" + + +while [ $# -gt 0 ] ; do + + case $1 in + + -c | --color ) + if diff --color /dev/null /dev/null 2>/dev/null ; then + diff_color="--color=always" + fi + shift + ;; + + -f ) + diff_flags="--unified=999999" + shift + ;; + + -h | -help | --help ) + help=1 + shift + ;; + + -s ) + srctree="$2" + shift 2 + ;; + + -S ) + git_root=`git rev-parse --show-toplevel 2>/dev/null` + srctree="${git_root}" + shift + ;; + + -T | --annotate ) + if [ "${annotate}" = "" ] ; then + annotate="-T" + elif [ "${annotate}" = "-T" ] ; then + annotate="-T -T" + fi + shift + ;; + -u ) + dtc_sort="" + shift + ;; + + *) + if [ "${dtx_file_1}" = "" ] ; then + dtx_file_1="$1" + elif [ "${dtx_file_2}" = "" ] ; then + dtx_file_2="$1" + else + echo "" >&2 + echo "ERROR: Unexpected parameter: $1" >&2 + echo "" >&2 + exit 2 + fi + shift + ;; + + esac + +done + +if [ "${srctree}" = "" ] ; then + srctree="." +fi + +if [ "${dtx_file_2}" != "" ]; then + cmd_diff=1 +fi + +if (( ${help} )) ; then + usage + exit 1 +fi + +# this must follow check for ${help} +if [ "${dtx_file_1}" = "" ]; then + echo "" >&2 + echo "ERROR: parameter DTx required" >&2 + echo "" >&2 + exit 2 +fi + + +# ----- prefer dtc from linux kernel, allow fallback to dtc in $PATH + +if [ "${KBUILD_OUTPUT:0:2}" = ".." ] ; then + __KBUILD_OUTPUT="${srctree}/${KBUILD_OUTPUT}" +elif [ "${KBUILD_OUTPUT}" = "" ] ; then + __KBUILD_OUTPUT="." +else + __KBUILD_OUTPUT="${KBUILD_OUTPUT}" +fi + +DTC="${__KBUILD_OUTPUT}/scripts/dtc/dtc" + +if [ ! -x ${DTC} ] ; then + __DTC="dtc" + if grep -q "^CONFIG_DTC=y" ${__KBUILD_OUTPUT}/.config 2>/dev/null; then + make_command=' + make scripts' + else + make_command=' + Enable CONFIG_DTC in the kernel configuration + make scripts' + fi + if ( ! which ${__DTC} >/dev/null ) ; then + + # use spaces instead of tabs in the error message + cat >&2 <