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- From b14784e7883390c20ed3ff904892255404a5914b Mon Sep 17 00:00:00 2001
- From: Felix Fietkau <[email protected]>
- 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 <[email protected]>
- ---
- 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
- +
- /* Align . to a 8 byte boundary equals to maximum function alignment. */
- #define ALIGN_FUNCTION() . = ALIGN(8)
-
- @@ -372,14 +382,14 @@
- /* Kernel symbol table: Normal symbols */ \
- __ksymtab : AT(ADDR(__ksymtab) - LOAD_OFFSET) { \
- __start___ksymtab = .; \
- - KEEP(*(SORT(___ksymtab+*))) \
- + SYMTAB_KEEP \
- __stop___ksymtab = .; \
- } \
- \
- /* Kernel symbol table: GPL-only symbols */ \
- __ksymtab_gpl : AT(ADDR(__ksymtab_gpl) - LOAD_OFFSET) { \
- __start___ksymtab_gpl = .; \
- - KEEP(*(SORT(___ksymtab_gpl+*))) \
- + SYMTAB_KEEP_GPL \
- __stop___ksymtab_gpl = .; \
- } \
- \
- @@ -441,7 +451,7 @@
- \
- /* Kernel symbol table: strings */ \
- __ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) { \
- - *(__ksymtab_strings) \
- + *(__ksymtab_strings+*) \
- } \
- \
- /* __*init sections */ \
- @@ -841,6 +851,8 @@
- EXIT_TEXT \
- EXIT_DATA \
- EXIT_CALL \
- + SYMTAB_DISCARD \
- + SYMTAB_DISCARD_GPL \
- *(.discard) \
- *(.discard.*) \
- }
- --- a/include/linux/export.h
- +++ b/include/linux/export.h
- @@ -74,12 +74,19 @@ struct kernel_symbol {
- };
- #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"), used, aligned(1))) \
- + __attribute__((section("__ksymtab_strings" \
- + __EXPORT_SUFFIX(sym)), used, aligned(1))) \
- = #sym; \
- __KSYMTAB_ENTRY(sym, sec)
-
- --- a/scripts/Makefile.build
- +++ b/scripts/Makefile.build
- @@ -408,7 +408,7 @@ 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
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