linux-stable/scripts/gen_autoksyms.sh
Masahiro Yamada 6ca89ac39e kbuild: fix CONFIG_TRIM_UNUSED_KSYMS build for ppc64
[ Upstream commit 29500f15b5 ]

Stephen Rothwell reported a build error on ppc64 when
CONFIG_TRIM_UNUSED_KSYMS is enabled.

Jessica Yu pointed out the cause of the error with the reference to the
ppc64 ELF ABI:
  "Symbol names with a dot (.) prefix are reserved for holding entry
   point addresses. The value of a symbol named ".FN", if it exists,
   is the entry point of the function "FN".

As it turned out, CONFIG_TRIM_UNUSED_KSYMS has never worked for ppc64,
but this issue has been unnoticed until recently because this option
depends on !UNUSED_SYMBOLS hence is disabled by all{mod,yes}config.
(Then, it was uncovered by another patch removing UNUSED_SYMBOLS.)

Removing the dot prefix in scripts/gen_autoksyms.sh fixes the issue.
Please note it must be done before 'sort -u' because modules have
both ._mcount and _mcount undefined when CONFIG_FUNCTION_TRACER=y.

Link: https://lore.kernel.org/lkml/20210209210843.3af66662@canb.auug.org.au/
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-02-26 10:13:01 +01:00

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#!/bin/sh
# SPDX-License-Identifier: GPL-2.0-only
# Create an autoksyms.h header file from the list of all module's needed symbols
# as recorded on the second line of *.mod files and the user-provided symbol
# whitelist.
set -e
output_file="$1"
# Use "make V=1" to debug this script.
case "$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: '$ksym_wl' whitelist file not found" >&2
exit 1
fi
fi
# Generate a new ksym list file with symbols needed by the current
# set of modules.
cat > "$output_file" << EOT
/*
* Automatically generated file; DO NOT EDIT.
*/
EOT
[ -f modules.order ] && modlist=modules.order || modlist=/dev/null
sed 's/ko$/mod/' $modlist |
xargs -n1 sed -n -e '2{s/ /\n/g;/^$/!p;}' -- |
cat - "$ksym_wl" |
# Remove the dot prefix for ppc64; symbol names with a dot (.) hold entry
# point addresses.
sed -e 's/^\.//' |
sort -u |
sed -e 's/\(.*\)/#define __KSYM_\1 1/' >> "$output_file"
# Special case for modversions (see modpost.c)
if [ -n "$CONFIG_MODVERSIONS" ]; then
echo "#define __KSYM_module_layout 1" >> "$output_file"
fi