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 --- include/asm-generic/export.h | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'include/asm-generic/export.h') diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h index 4d73e6e3c66c..294d6ae785d4 100644 --- a/include/asm-generic/export.h +++ b/include/asm-generic/export.h @@ -59,16 +59,19 @@ __kcrctab_\name: .endm #undef __put -#if defined(__KSYM_DEPS__) - -#define __EXPORT_SYMBOL(sym, val, sec) === __KSYM_##sym === - -#elif defined(CONFIG_TRIM_UNUSED_KSYMS) +#if defined(CONFIG_TRIM_UNUSED_KSYMS) #include #include +.macro __ksym_marker sym + .section ".discard.ksym","a" +__ksym_marker_\sym: + .previous +.endm + #define __EXPORT_SYMBOL(sym, val, sec) \ + __ksym_marker sym; \ __cond_export_sym(sym, val, sec, __is_defined(__KSYM_##sym)) #define __cond_export_sym(sym, val, sec, conf) \ ___cond_export_sym(sym, val, sec, conf) -- cgit v1.2.3