From b14784e7883390c20ed3ff904892255404a5914b Mon Sep 17 00:00:00 2001 From: Felix Fietkau Date: Fri, 7 Jul 2017 17:05:53 +0200 Subject: add an optional config option for stripping all unnecessary symbol exports from the kernel image lede-commit: bb5a40c64b7c4f4848509fa0a6625055fc9e66cc Signed-off-by: Felix Fietkau --- include/asm-generic/vmlinux.lds.h | 18 +++++++++++++++--- include/linux/export.h | 9 ++++++++- scripts/Makefile.build | 2 +- 3 files changed, 24 insertions(+), 5 deletions(-) --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -54,6 +54,16 @@ #define LOAD_OFFSET 0 #endif +#ifndef SYMTAB_KEEP +#define SYMTAB_KEEP KEEP(*(SORT(___ksymtab+*))) +#define SYMTAB_KEEP_GPL KEEP(*(SORT(___ksymtab_gpl+*))) +#endif + +#ifndef SYMTAB_DISCARD +#define SYMTAB_DISCARD +#define SYMTAB_DISCARD_GPL +#endif + #include /* Align . to a 8 byte boundary equals to maximum function alignment. */ @@ -342,14 +352,14 @@ /* Kernel symbol table: Normal symbols */ \ __ksymtab : AT(ADDR(__ksymtab) - LOAD_OFFSET) { \ VMLINUX_SYMBOL(__start___ksymtab) = .; \ - KEEP(*(SORT(___ksymtab+*))) \ + SYMTAB_KEEP \ VMLINUX_SYMBOL(__stop___ksymtab) = .; \ } \ \ /* Kernel symbol table: GPL-only symbols */ \ __ksymtab_gpl : AT(ADDR(__ksymtab_gpl) - LOAD_OFFSET) { \ VMLINUX_SYMBOL(__start___ksymtab_gpl) = .; \ - KEEP(*(SORT(___ksymtab_gpl+*))) \ + SYMTAB_KEEP_GPL \ VMLINUX_SYMBOL(__stop___ksymtab_gpl) = .; \ } \ \ @@ -411,7 +421,7 @@ \ /* Kernel symbol table: strings */ \ __ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) { \ - *(__ksymtab_strings) \ + *(__ksymtab_strings+*) \ } \ \ /* __*init sections */ \ @@ -804,6 +814,8 @@ EXIT_TEXT \ EXIT_DATA \ EXIT_CALL \ + SYMTAB_DISCARD \ + SYMTAB_DISCARD_GPL \ *(.discard) \ *(.discard.*) \ } --- a/include/linux/export.h +++ b/include/linux/export.h @@ -60,12 +60,19 @@ extern struct module __this_module; #define __CRC_SYMBOL(sym, sec) #endif +#ifdef MODULE +#define __EXPORT_SUFFIX(sym) +#else +#define __EXPORT_SUFFIX(sym) "+" #sym +#endif + /* For every exported symbol, place a struct in the __ksymtab section */ #define ___EXPORT_SYMBOL(sym, sec) \ extern typeof(sym) sym; \ __CRC_SYMBOL(sym, sec) \ static const char __kstrtab_##sym[] \ - __attribute__((section("__ksymtab_strings"), aligned(1))) \ + __attribute__((section("__ksymtab_strings" \ + __EXPORT_SUFFIX(sym)), aligned(1))) \ = VMLINUX_SYMBOL_STR(sym); \ static const struct kernel_symbol __ksymtab_##sym \ __used \ --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -435,7 +435,7 @@ targets += $(extra-y) $(MAKECMDGOALS) $( # Linker scripts preprocessor (.lds.S -> .lds) # --------------------------------------------------------------------------- quiet_cmd_cpp_lds_S = LDS $@ - cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \ + cmd_cpp_lds_S = $(CPP) $(EXTRA_LDSFLAGS) $(cpp_flags) -P -U$(ARCH) \ -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $< $(obj)/%.lds: $(src)/%.lds.S FORCE