openwrt/scripts/strip-kmod.sh
Felix Fietkau 3bbb927728 build: Allow kernel modules to set build ID debug symbol
This change adds support for specifying a build ID for kernel modules.
This is done by setting PKG_BUILD_ID to a hexadecimal string, which will
then be passed to the kernel linker. In addition, when this flag is set,
the build ID debug symbol (.note.gnu.build-id) will not be stripped from
the kernel module. This symbol is exported in sysfs by the kernel (if
the kernel is compiled with CONFIG_KALLSYMS) and so can be used to
uniquely identify a version of a kernel module in a running kernel. This
is useful for keeping track of different versions of a module when doing
experiments and development.

Modules that specify the build ID will be ~100 bytes larger (depending
on the length of the build ID specified). There is no size difference
for kernel modules that do not set this variable.

Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>

SVN-Revision: 47290
2015-10-30 15:20:12 +00:00

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#!/usr/bin/env bash
[ -n "$CROSS" ] || {
echo "The variable CROSS must be set to point to the cross-compiler prefix"
exit 1
}
MODULE="$1"
[ "$#" -ne 1 ] && {
echo "Usage: $0 <module>"
exit 1
}
ARGS=
if [ -n "$KEEP_SYMBOLS" ]; then
ARGS="-X --strip-debug"
else
ARGS="-x -G __this_module --strip-unneeded"
fi
if [ -z "$KEEP_BUILD_ID" ]; then
ARGS="$ARGS -R .note.gnu.build-id"
fi
${CROSS}objcopy \
-R .comment \
-R .pdr \
-R .mdebug.abi32 \
-R .gnu.attributes \
-R .reginfo \
$ARGS \
"$MODULE" "$MODULE.tmp"
[ -n "$NO_RENAME" ] && {
mv "${MODULE}.tmp" "$MODULE"
exit 0
}
${CROSS}nm "$MODULE.tmp" | awk '
BEGIN {
n = 0
}
$3 && $2 ~ /[brtd]/ && $3 !~ /\$LC/ && !def[$3] {
print "--redefine-sym "$3"=_"n;
n = n + 1
def[$3] = 1
}
' > "$MODULE.tmp1"
${CROSS}objcopy `cat ${MODULE}.tmp1` ${MODULE}.tmp ${MODULE}.out
mv "${MODULE}.out" "${MODULE}"
rm -f "${MODULE}".t*