From bbda5ec671d3fe62faefa1cab7270aa586042a4b Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Fri, 30 Nov 2018 10:05:26 +0900 Subject: kbuild: simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS My main motivation of this commit is to clean up scripts/Kbuild.include and scripts/Makefile.build. Currently, CONFIG_TRIM_UNUSED_KSYMS works with a tricky gimmick; possibly exported symbols are detected by letting $(CPP) replace EXPORT_SYMBOL* with a special string '=== __KSYM_*===', which is post-processed by sed, and passed to fixdep. The extra preprocessing is costly, and hacking cmd_and_fixdep is ugly. I came up with a new way to find exported symbols; insert a dummy symbol __ksym_marker_* to each potentially exported symbol. Those dummy symbols are picked up by $(NM), post-processed by sed, then appended to .*.cmd files. I collected the post-process part to a new shell script scripts/gen_ksymdeps.sh for readability. The dummy symbols are put into the .discard.* section so that the linker script rips them off the final vmlinux or modules. A nice side-effect is building with CONFIG_TRIM_UNUSED_KSYMS will be much faster. Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Pitre --- scripts/Makefile.build | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'scripts/Makefile.build') diff --git a/scripts/Makefile.build b/scripts/Makefile.build index cdb25d163b42..23ebf2508234 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -254,9 +254,15 @@ objtool_dep = $(objtool_obj) \ $(wildcard include/config/orc/unwinder.h \ include/config/stack/validation.h) +ifdef CONFIG_TRIM_UNUSED_KSYMS +cmd_gen_ksymdeps = \ + $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd; +endif + define rule_cc_o_c $(call echo-cmd,checksrc) $(cmd_checksrc) \ $(call cmd_and_fixdep,cc_o_c) \ + $(cmd_gen_ksymdeps) \ $(cmd_checkdoc) \ $(call echo-cmd,objtool) $(cmd_objtool) \ $(cmd_modversions_c) \ @@ -265,6 +271,7 @@ endef define rule_as_o_S $(call cmd_and_fixdep,as_o_S) \ + $(cmd_gen_ksymdeps) \ $(call echo-cmd,objtool) $(cmd_objtool) \ $(cmd_modversions_S) endef -- cgit v1.2.3-55-g7522