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Date: Mon, 13 Dec 2021 14:17:07 +0100
From: Nicolas Schier <n.schier@....de>
To: Masahiro Yamada <masahiroy@...nel.org>
Cc: linux-kbuild@...r.kernel.org,
Michal Simek <michal.simek@...inx.com>,
linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
David Howells <dhowells@...hat.com>,
David Woodhouse <dwmw2@...radead.org>,
keyrings@...r.kernel.org, Richard Weinberger <richard@....at>
Subject: Re: [PATCH 08/10] kbuild: do not include include/config/auto.conf
from shell scripts
On Mon, Dec 13, 2021 at 04:29:39AM +0900, Masahiro Yamada wrote:
> Richard Weinberger pointed out the risk of sourcing the kernel config
> from shell scripts [1], and proposed some patches [2], [3]. It is a good
> point, but it took a long time because I was wondering how to fix this.
>
> This commit goes with simple grep approach because there are only a few
> scripts including the kernel configuration.
>
> scripts/link_vmlinux.sh has references to a bunch of CONFIG options,
> all of which are boolean. I added is_enabled() helper as
> scripts/package/{mkdebian,builddeb} do.
>
> scripts/gen_autoksyms.sh uses 'eval', stating "to expand the whitelist
> path". I removed it since it is the issue we are trying to fix.
>
> I was a bit worried about the cost of invoking the grep command over
> again. I extracted the grep parts from it, and measured the cost. It
> was approximately 0.03 sec, which I hope is acceptable.
>
> [test code]
>
> $ cat test-grep.sh
> #!/bin/sh
>
> is_enabled() {
> grep -q "^$1=y" include/config/auto.conf
> }
>
> is_enabled CONFIG_LTO_CLANG
> is_enabled CONFIG_LTO_CLANG
> is_enabled CONFIG_STACK_VALIDATION
> is_enabled CONFIG_UNWINDER_ORC
> is_enabled CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
> is_enabled CONFIG_VMLINUX_VALIDATION
> is_enabled CONFIG_FRAME_POINTER
> is_enabled CONFIG_GCOV_KERNEL
> is_enabled CONFIG_LTO_CLANG
> is_enabled CONFIG_RETPOLINE
> is_enabled CONFIG_X86_SMAP
> is_enabled CONFIG_LTO_CLANG
> is_enabled CONFIG_VMLINUX_MAP
> is_enabled CONFIG_KALLSYMS_ALL
> is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU
> is_enabled CONFIG_KALLSYMS_BASE_RELATIVE
> is_enabled CONFIG_DEBUG_INFO_BTF
> is_enabled CONFIG_KALLSYMS
> is_enabled CONFIG_DEBUG_INFO_BTF
> is_enabled CONFIG_BPF
> is_enabled CONFIG_BUILDTIME_TABLE_SORT
> is_enabled CONFIG_KALLSYMS
>
> $ time ./test-grep.sh
> real 0m0.036s
> user 0m0.027s
> sys m0.009s
>
> [1]: https://lore.kernel.org/all/1919455.eZKeABUfgV@blindfold/
> [2]: https://lore.kernel.org/all/20180219092245.26404-1-richard@nod.at/
> [3]: https://lore.kernel.org/all/20210920213957.1064-2-richard@nod.at/
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> ---
>
> scripts/gen_autoksyms.sh | 6 ++---
> scripts/link-vmlinux.sh | 47 ++++++++++++++++++++--------------------
> scripts/setlocalversion | 9 ++++----
> 3 files changed, 30 insertions(+), 32 deletions(-)
>
> diff --git a/scripts/gen_autoksyms.sh b/scripts/gen_autoksyms.sh
> index 6ed0d225c8b1..12ffb01f13cb 100755
> --- a/scripts/gen_autoksyms.sh
> +++ b/scripts/gen_autoksyms.sh
> @@ -26,10 +26,8 @@ if [ -n "$CONFIG_MODVERSIONS" ]; then
> needed_symbols="$needed_symbols module_layout"
> fi
As kernel test robot pointed out, gen_autoksyms.sh still sources
include/config/auto.conf. What about this:
diff --git a/scripts/gen_autoksyms.sh b/scripts/gen_autoksyms.sh
index 31872d95468b..be9ee250200e 100755
--- a/scripts/gen_autoksyms.sh
+++ b/scripts/gen_autoksyms.sh
@@ -16,13 +16,11 @@ case "$KBUILD_VERBOSE" in
;;
esac
-# We need access to CONFIG_ symbols
-. include/config/auto.conf
needed_symbols=
# Special case for modversions (see modpost.c)
-if [ -n "$CONFIG_MODVERSIONS" ]; then
+if grep -qe "^CONFIG_MODVERSIONS=y" include/config/auto.conf; then
needed_symbols="$needed_symbols module_layout"
fi
For the other hunks:
Reviewed-by: Nicolas Schier <n.schier@....de>
>
> -ksym_wl=
> -if [ -n "$CONFIG_UNUSED_KSYMS_WHITELIST" ]; then
> - # Use 'eval' to expand the whitelist path and check if it is relative
> - eval ksym_wl="$CONFIG_UNUSED_KSYMS_WHITELIST"
> +ksym_wl=$(sed -n 's/^CONFIG_UNUSED_KSYMS_WHITELIST="\(.*\)"$/\1/p' include/config/auto.conf)
> +if [ -n "$ksym_wl" ]; then
> [ "${ksym_wl}" != "${ksym_wl#/}" ] || ksym_wl="$abs_srctree/$ksym_wl"
> if [ ! -f "$ksym_wl" ] || [ ! -r "$ksym_wl" ]; then
> echo "ERROR: '$ksym_wl' whitelist file not found" >&2
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index 5cdd9bc5c385..a4b61a2f65db 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -34,6 +34,10 @@ LD="$1"
> KBUILD_LDFLAGS="$2"
> LDFLAGS_vmlinux="$3"
>
> +is_enabled() {
> + grep -q "^$1=y" include/config/auto.conf
> +}
> +
> # Nice output in kbuild format
> # Will be supressed by "make -s"
> info()
> @@ -80,11 +84,11 @@ modpost_link()
> ${KBUILD_VMLINUX_LIBS} \
> --end-group"
>
> - if [ -n "${CONFIG_LTO_CLANG}" ]; then
> + if is_enabled CONFIG_LTO_CLANG; then
> gen_initcalls
> lds="-T .tmp_initcalls.lds"
>
> - if [ -n "${CONFIG_MODVERSIONS}" ]; then
> + if is_enabled CONFIG_MODVERSIONS; then
> gen_symversions
> lds="${lds} -T .tmp_symversions.lds"
> fi
> @@ -104,21 +108,21 @@ objtool_link()
> local objtoolcmd;
> local objtoolopt;
>
> - if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then
> + if is_enabled CONFIG_LTO_CLANG && is_enabled CONFIG_STACK_VALIDATION; then
> # Don't perform vmlinux validation unless explicitly requested,
> # but run objtool on vmlinux.o now that we have an object file.
> - if [ -n "${CONFIG_UNWINDER_ORC}" ]; then
> + if is_enabled CONFIG_UNWINDER_ORC; then
> objtoolcmd="orc generate"
> fi
>
> objtoolopt="${objtoolopt} --duplicate"
>
> - if [ -n "${CONFIG_FTRACE_MCOUNT_USE_OBJTOOL}" ]; then
> + if is_enabled CONFIG_FTRACE_MCOUNT_USE_OBJTOOL; then
> objtoolopt="${objtoolopt} --mcount"
> fi
> fi
>
> - if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
> + if is_enabled CONFIG_VMLINUX_VALIDATION; then
> objtoolopt="${objtoolopt} --noinstr"
> fi
>
> @@ -127,16 +131,16 @@ objtool_link()
> objtoolcmd="check"
> fi
> objtoolopt="${objtoolopt} --vmlinux"
> - if [ -z "${CONFIG_FRAME_POINTER}" ]; then
> + if ! is_enabled CONFIG_FRAME_POINTER; then
> objtoolopt="${objtoolopt} --no-fp"
> fi
> - if [ -n "${CONFIG_GCOV_KERNEL}" ] || [ -n "${CONFIG_LTO_CLANG}" ]; then
> + if is_enabled CONFIG_GCOV_KERNEL || is_enabled CONFIG_LTO_CLANG; then
> objtoolopt="${objtoolopt} --no-unreachable"
> fi
> - if [ -n "${CONFIG_RETPOLINE}" ]; then
> + if is_enabled CONFIG_RETPOLINE; then
> objtoolopt="${objtoolopt} --retpoline"
> fi
> - if [ -n "${CONFIG_X86_SMAP}" ]; then
> + if is_enabled CONFIG_X86_SMAP; then
> objtoolopt="${objtoolopt} --uaccess"
> fi
> info OBJTOOL ${1}
> @@ -161,7 +165,7 @@ vmlinux_link()
> # skip output file argument
> shift
>
> - if [ -n "${CONFIG_LTO_CLANG}" ]; then
> + if is_enabled CONFIG_LTO_CLANG; then
> # Use vmlinux.o instead of performing the slow LTO link again.
> objs=vmlinux.o
> libs=
> @@ -189,7 +193,7 @@ vmlinux_link()
> ldflags="${ldflags} ${wl}--strip-debug"
> fi
>
> - if [ -n "${CONFIG_VMLINUX_MAP}" ]; then
> + if is_enabled CONFIG_VMLINUX_MAP; then
> ldflags="${ldflags} ${wl}-Map=${output}.map"
> fi
>
> @@ -239,15 +243,15 @@ kallsyms()
> {
> local kallsymopt;
>
> - if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
> + if is_enabled CONFIG_KALLSYMS_ALL; then
> kallsymopt="${kallsymopt} --all-symbols"
> fi
>
> - if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
> + if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then
> kallsymopt="${kallsymopt} --absolute-percpu"
> fi
>
> - if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
> + if is_enabled CONFIG_KALLSYMS_BASE_RELATIVE; then
> kallsymopt="${kallsymopt} --base-relative"
> fi
>
> @@ -312,9 +316,6 @@ if [ "$1" = "clean" ]; then
> exit 0
> fi
>
> -# We need access to CONFIG_ symbols
> -. include/config/auto.conf
> -
> # Update version
> info GEN .version
> if [ -r .version ]; then
> @@ -343,7 +344,7 @@ tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
> tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
>
> btf_vmlinux_bin_o=""
> -if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
> +if is_enabled CONFIG_DEBUG_INFO_BTF; then
> btf_vmlinux_bin_o=.btf.vmlinux.bin.o
> if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
> echo >&2 "Failed to generate BTF for vmlinux"
> @@ -355,7 +356,7 @@ fi
> kallsymso=""
> kallsymso_prev=""
> kallsyms_vmlinux=""
> -if [ -n "${CONFIG_KALLSYMS}" ]; then
> +if is_enabled CONFIG_KALLSYMS; then
>
> # kallsyms support
> # Generate section listing all symbols and add it into vmlinux
> @@ -395,12 +396,12 @@ fi
> vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
>
> # fill in BTF IDs
> -if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
> +if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then
> info BTFIDS vmlinux
> ${RESOLVE_BTFIDS} vmlinux
> fi
>
> -if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
> +if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then
> info SORTTAB vmlinux
> if ! sorttable vmlinux; then
> echo >&2 Failed to sort kernel tables
> @@ -412,7 +413,7 @@ info SYSMAP System.map
> mksysmap vmlinux System.map
>
> # step a (see comment above)
> -if [ -n "${CONFIG_KALLSYMS}" ]; then
> +if is_enabled CONFIG_KALLSYMS; then
> mksysmap ${kallsyms_vmlinux} .tmp_System.map
>
> if ! cmp -s System.map .tmp_System.map; then
> diff --git a/scripts/setlocalversion b/scripts/setlocalversion
> index 6b54e46a0f12..d06137405190 100755
> --- a/scripts/setlocalversion
> +++ b/scripts/setlocalversion
> @@ -111,9 +111,7 @@ if $scm_only; then
> exit
> fi
>
> -if test -e include/config/auto.conf; then
> - . include/config/auto.conf
> -else
> +if ! test -e include/config/auto.conf; then
> echo "Error: kernelrelease not valid - run 'make prepare' to update it" >&2
> exit 1
> fi
> @@ -125,10 +123,11 @@ if test ! "$srctree" -ef .; then
> fi
>
> # CONFIG_LOCALVERSION and LOCALVERSION (if set)
> -res="${res}${CONFIG_LOCALVERSION}${LOCALVERSION}"
> +config_localversion=$(sed -n 's/^CONFIG_LOCALVERSION="\(.*\)"$/\1/p' include/config/auto.conf)
> +res="${res}${config_localversion}${LOCALVERSION}"
>
> # scm version string if not at a tagged commit
> -if test "$CONFIG_LOCALVERSION_AUTO" = "y"; then
> +if grep -q "^CONFIG_LOCALVERSION_AUTO=y$" include/config/auto.conf; then
> # full scm version string
> res="$res$(scm_version)"
> elif [ "${LOCALVERSION+set}" != "set" ]; then
> --
> 2.32.0
>
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