Commit a6aaeb84 authored by Masahiro Yamada's avatar Masahiro Yamada
Browse files

kbuild: fix UNUSED_KSYMS_WHITELIST for Clang LTO 



Commit fbe078d3 ("kbuild: lto: add a default list of used symbols")
does not work as expected if the .config file has already specified
CONFIG_UNUSED_KSYMS_WHITELIST="my/own/white/list" before enabling
CONFIG_LTO_CLANG.

So, the user-supplied whitelist and LTO-specific white list must be
independent of each other.

I refactored the shell script so CONFIG_MODVERSIONS and CONFIG_CLANG_LTO
handle whitelists in the same way.

Fixes: fbe078d3 ("kbuild: lto: add a default list of used symbols")
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
Tested-by: default avatarSedat Dilek <sedat.dilek@gmail.com>
parent da83616b

init/Kconfig

+0 −1
Original line number Diff line number Diff line
@@ -2283,7 +2283,6 @@ config TRIM_UNUSED_KSYMS 
config UNUSED_KSYMS_WHITELIST

	string "Whitelist of symbols to keep in ksymtab"

	depends on TRIM_UNUSED_KSYMS

	default "scripts/lto-used-symbollist.txt" if LTO_CLANG

	help

	  By default, all unused exported symbols will be un-exported from the

	  build when TRIM_UNUSED_KSYMS is selected.

scripts/gen_autoksyms.sh

+26 −9
Original line number Diff line number Diff line
@@ -19,7 +19,26 @@ esac 
# We need access to CONFIG_ symbols

. include/config/auto.conf



ksym_wl=/dev/null

needed_symbols=



# Special case for modversions (see modpost.c)

if [ -n "$CONFIG_MODVERSIONS" ]; then

	needed_symbols="$needed_symbols module_layout"

fi



# With CONFIG_LTO_CLANG, LLVM bitcode has not yet been compiled into a binary

# when the .mod files are generated, which means they don't yet contain

# references to certain symbols that will be present in the final binaries.

if [ -n "$CONFIG_LTO_CLANG" ]; then

	# intrinsic functions

	needed_symbols="$needed_symbols memcpy memmove memset"

	# ftrace

	needed_symbols="$needed_symbols _mcount"

	# stack protector symbols

	needed_symbols="$needed_symbols __stack_chk_fail __stack_chk_guard"

fi



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="$CONFIG_UNUSED_KSYMS_WHITELIST"
@@ -40,16 +59,14 @@ cat > "$output_file" << EOT 
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" |



{

	sed 's/ko$/mod/' $modlist | xargs -n1 sed -n -e '2p'

	echo "$needed_symbols"

	[ -n "$ksym_wl" ] && cat "$ksym_wl"

} | sed -e 's/ /\n/g' | sed -n -e '/^$/!p' |

# 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

scripts/lto-used-symbollist.txt

deleted100644 → 0
+0 −6
Original line number Diff line number Diff line 
memcpy

memmove

memset

_mcount

__stack_chk_fail

__stack_chk_guard