mirror of
https://github.com/torvalds/linux.git
synced 2024-11-24 05:02:12 +00:00
1518c633df
CONFIG_TRIM_UNUSED_KSYMS currently removes all unused exported symbols from ksymtab. This works really well when using in-tree drivers, but cannot be used in its current form if some of them are out-of-tree. Indeed, even if the list of symbols required by out-of-tree drivers is known at compile time, the only solution today to guarantee these don't get trimmed is to set CONFIG_TRIM_UNUSED_KSYMS=n. This not only wastes space, but also makes it difficult to control the ABI usable by vendor modules in distribution kernels such as Android. Being able to control the kernel ABI surface is particularly useful to ship a unique Generic Kernel Image (GKI) for all vendors, which is a first step in the direction of getting all vendors to contribute their code upstream. As such, attempt to improve the situation by enabling users to specify a symbol 'whitelist' at compile time. Any symbol specified in this whitelist will be kept exported when CONFIG_TRIM_UNUSED_KSYMS is set, even if it has no in-tree user. The whitelist is defined as a simple text file, listing symbols, one per line. Acked-by: Jessica Yu <jeyu@kernel.org> Acked-by: Nicolas Pitre <nico@fluxnic.net> Tested-by: Matthias Maennich <maennich@google.com> Reviewed-by: Matthias Maennich <maennich@google.com> Signed-off-by: Quentin Perret <qperret@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
105 lines
3.0 KiB
Bash
Executable File
105 lines
3.0 KiB
Bash
Executable File
#!/bin/sh
|
|
# SPDX-License-Identifier: GPL-2.0-only
|
|
|
|
# Script to create/update include/generated/autoksyms.h and dependency files
|
|
#
|
|
# Copyright: (C) 2016 Linaro Limited
|
|
# Created by: Nicolas Pitre, January 2016
|
|
#
|
|
|
|
# Create/update the include/generated/autoksyms.h file from the list
|
|
# of all module's needed symbols as recorded on the second line of *.mod files.
|
|
#
|
|
# For each symbol being added or removed, the corresponding dependency
|
|
# file's timestamp is updated to force a rebuild of the affected source
|
|
# file. All arguments passed to this script are assumed to be a command
|
|
# to be exec'd to trigger a rebuild of those files.
|
|
|
|
set -e
|
|
|
|
cur_ksyms_file="include/generated/autoksyms.h"
|
|
new_ksyms_file="include/generated/autoksyms.h.tmpnew"
|
|
|
|
info() {
|
|
if [ "$quiet" != "silent_" ]; then
|
|
printf " %-7s %s\n" "$1" "$2"
|
|
fi
|
|
}
|
|
|
|
info "CHK" "$cur_ksyms_file"
|
|
|
|
# Use "make V=1" to debug this script.
|
|
case "$KBUILD_VERBOSE" in
|
|
*1*)
|
|
set -x
|
|
;;
|
|
esac
|
|
|
|
# We need access to CONFIG_ symbols
|
|
. include/config/auto.conf
|
|
|
|
ksym_wl=/dev/null
|
|
if [ -n "$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}" != "${ksym_wl#/}" ] || ksym_wl="$abs_srctree/$ksym_wl"
|
|
if [ ! -f "$ksym_wl" ] || [ ! -r "$ksym_wl" ]; then
|
|
echo "ERROR: '$ksym_wl' whitelist file not found" >&2
|
|
exit 1
|
|
fi
|
|
fi
|
|
|
|
# Generate a new ksym list file with symbols needed by the current
|
|
# set of modules.
|
|
cat > "$new_ksyms_file" << EOT
|
|
/*
|
|
* Automatically generated file; DO NOT EDIT.
|
|
*/
|
|
|
|
EOT
|
|
sed 's/ko$/mod/' modules.order |
|
|
xargs -n1 sed -n -e '2{s/ /\n/g;/^$/!p;}' -- |
|
|
cat - "$ksym_wl" |
|
|
sort -u |
|
|
sed -e 's/\(.*\)/#define __KSYM_\1 1/' >> "$new_ksyms_file"
|
|
|
|
# Special case for modversions (see modpost.c)
|
|
if [ -n "$CONFIG_MODVERSIONS" ]; then
|
|
echo "#define __KSYM_module_layout 1" >> "$new_ksyms_file"
|
|
fi
|
|
|
|
# Extract changes between old and new list and touch corresponding
|
|
# dependency files.
|
|
changed=$(
|
|
count=0
|
|
sort "$cur_ksyms_file" "$new_ksyms_file" | uniq -u |
|
|
sed -n 's/^#define __KSYM_\(.*\) 1/\1/p' | tr "A-Z_" "a-z/" |
|
|
while read sympath; do
|
|
if [ -z "$sympath" ]; then continue; fi
|
|
depfile="include/ksym/${sympath}.h"
|
|
mkdir -p "$(dirname "$depfile")"
|
|
touch "$depfile"
|
|
# Filesystems with coarse time precision may create timestamps
|
|
# equal to the one from a file that was very recently built and that
|
|
# needs to be rebuild. Let's guard against that by making sure our
|
|
# dep files are always newer than the first file we created here.
|
|
while [ ! "$depfile" -nt "$new_ksyms_file" ]; do
|
|
touch "$depfile"
|
|
done
|
|
echo $((count += 1))
|
|
done | tail -1 )
|
|
changed=${changed:-0}
|
|
|
|
if [ $changed -gt 0 ]; then
|
|
# Replace the old list with tne new one
|
|
old=$(grep -c "^#define __KSYM_" "$cur_ksyms_file" || true)
|
|
new=$(grep -c "^#define __KSYM_" "$new_ksyms_file" || true)
|
|
info "KSYMS" "symbols: before=$old, after=$new, changed=$changed"
|
|
info "UPD" "$cur_ksyms_file"
|
|
mv -f "$new_ksyms_file" "$cur_ksyms_file"
|
|
# Then trigger a rebuild of affected source files
|
|
exec $@
|
|
else
|
|
rm -f "$new_ksyms_file"
|
|
fi
|