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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
- @@ -81,6 +81,16 @@
- #define RO_EXCEPTION_TABLE
- #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)
-
- @@ -511,14 +521,14 @@
- /* 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 = .; \
- } \
- \
- @@ -538,7 +548,7 @@
- \
- /* Kernel symbol table: strings */ \
- __ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) { \
- - *(__ksymtab_strings) \
- + *(__ksymtab_strings+*) \
- } \
- \
- /* __*init sections */ \
- @@ -1042,6 +1052,8 @@
- #define COMMON_DISCARDS \
- SANITIZER_DISCARDS \
- PATCHABLE_DISCARDS \
- + SYMTAB_DISCARD \
- + SYMTAB_DISCARD_GPL \
- *(.discard) \
- *(.discard.*) \
- *(.modinfo) \
- --- a/include/linux/export.h
- +++ b/include/linux/export.h
- @@ -72,6 +72,12 @@ struct kernel_symbol {
-
- #else
-
- +#ifdef MODULE
- +#define __EXPORT_SUFFIX(sym)
- +#else
- +#define __EXPORT_SUFFIX(sym) "+" #sym
- +#endif
- +
- /*
- * For every exported symbol, do the following:
- *
- @@ -87,7 +93,7 @@ struct kernel_symbol {
- extern typeof(sym) sym; \
- extern const char __kstrtab_##sym[]; \
- extern const char __kstrtabns_##sym[]; \
- - asm(" .section \"__ksymtab_strings\",\"aMS\",%progbits,1 \n" \
- + asm(" .section \"__ksymtab_strings" __EXPORT_SUFFIX(sym) "\",\"aMS\",%progbits,1 \n" \
- "__kstrtab_" #sym ": \n" \
- " .asciz \"" #sym "\" \n" \
- "__kstrtabns_" #sym ": \n" \
- --- a/include/asm-generic/export.h
- +++ b/include/asm-generic/export.h
- @@ -31,6 +31,12 @@
- #endif
- .endm
-
- +#ifdef MODULE
- +#define __EXPORT_SUFFIX(name)
- +#else
- +#define __EXPORT_SUFFIX(name) + #name
- +#endif
- +
- /*
- * note on .section use: we specify progbits since usage of the "M" (SHF_MERGE)
- * section flag requires it. Use '%progbits' instead of '@progbits' since the
- @@ -44,7 +50,7 @@
- __ksymtab_\name:
- __put \val, __kstrtab_\name
- .previous
- - .section __ksymtab_strings,"aMS",%progbits,1
- + .section __ksymtab_strings __EXPORT_SUFFIX(name),"aMS",%progbits,1
- __kstrtab_\name:
- .asciz "\name"
- .previous
- --- a/scripts/Makefile.build
- +++ b/scripts/Makefile.build
- @@ -388,7 +388,7 @@ targets += $(real-dtb-y) $(lib-y) $(alwa
- # 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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