linux/scripts/mod/Makefile
Jack Brennen 4074532758 modpost: Optimize symbol search from linear to binary search
Modify modpost to use binary search for converting addresses back
into symbol references.  Previously it used linear search.

This change saves a few seconds of wall time for defconfig builds,
but can save several minutes on allyesconfigs.

Before:
$ make LLVM=1 -j128 allyesconfig vmlinux -s KCFLAGS="-Wno-error"
$ time scripts/mod/modpost -M -m -a -N -o vmlinux.symvers vmlinux.o
198.38user 1.27system 3:19.71elapsed

After:
$ make LLVM=1 -j128 allyesconfig vmlinux -s KCFLAGS="-Wno-error"
$ time scripts/mod/modpost -M -m -a -N -o vmlinux.symvers vmlinux.o
11.91user 0.85system 0:12.78elapsed

Signed-off-by: Jack Brennen <jbrennen@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-10-03 20:25:59 +09:00

29 lines
892 B
Makefile

# SPDX-License-Identifier: GPL-2.0
OBJECT_FILES_NON_STANDARD := y
CFLAGS_REMOVE_empty.o += $(CC_FLAGS_LTO)
hostprogs-always-y += modpost mk_elfconfig
always-y += empty.o
modpost-objs := modpost.o file2alias.o sumversion.o symsearch.o
devicetable-offsets-file := devicetable-offsets.h
$(obj)/$(devicetable-offsets-file): $(obj)/devicetable-offsets.s FORCE
$(call filechk,offsets,__DEVICETABLE_OFFSETS_H__)
targets += $(devicetable-offsets-file) devicetable-offsets.s
# dependencies on generated files need to be listed explicitly
$(obj)/modpost.o $(obj)/file2alias.o $(obj)/sumversion.o $(obj)/symsearch.o: $(obj)/elfconfig.h
$(obj)/file2alias.o: $(obj)/$(devicetable-offsets-file)
quiet_cmd_elfconfig = MKELF $@
cmd_elfconfig = $(obj)/mk_elfconfig < $< > $@
$(obj)/elfconfig.h: $(obj)/empty.o $(obj)/mk_elfconfig FORCE
$(call if_changed,elfconfig)
targets += elfconfig.h