by Masahiro Yamada

[permalink] [raw]

Subject: Re: [PATCH 08/10] kbuild: do not include include/config/auto.conf from shell scripts

On Mon, Dec 13, 2021 at 10:34 PM Nicolas Schier <[email protected]> wrote:
>
> 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/[email protected]/
> > [3]: https://lore.kernel.org/all/[email protected]/
> > Signed-off-by: Masahiro Yamada <[email protected]>
> > ---
> >
> > 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:

Ah, right.
I missed to fix up this hunk somehow...

Thanks for the view.

>
> 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="$needed_symbols module_layout"
> fi
>
>
> For the other hunks:
>
> Reviewed-by: Nicolas Schier <[email protected]>
>
>
> >
> > -ksym_wl=
> > -if [ -n "$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
> >

--
Best Regards
Masahiro Yamada