124 lines
3.3 KiB
Diff
124 lines
3.3 KiB
Diff
From e3d8676f5722b7622685581e06e8f53e6138e3ab Mon Sep 17 00:00:00 2001
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From: Felix Fietkau <nbd@nbd.name>
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Date: Sat, 15 Jul 2017 23:42:36 +0200
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Subject: use -ffunction-sections, -fdata-sections and --gc-sections
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In combination with kernel symbol export stripping this significantly reduces
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the kernel image size. Used on both ARM and MIPS architectures.
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Signed-off-by: Felix Fietkau <nbd@nbd.name>
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Signed-off-by: Jonas Gorski <jogo@openwrt.org>
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Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
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---
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--- a/arch/arm/Kconfig
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+++ b/arch/arm/Kconfig
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@@ -117,6 +117,7 @@ config ARM
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select HAVE_UID16
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select HAVE_VIRT_CPU_ACCOUNTING_GEN
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select IRQ_FORCED_THREADING
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+ select HAVE_LD_DEAD_CODE_DATA_ELIMINATION
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select MODULES_USE_ELF_REL
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select NEED_DMA_MAP_STATE
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select OF_EARLY_FLATTREE if OF
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--- a/arch/arm/boot/compressed/Makefile
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+++ b/arch/arm/boot/compressed/Makefile
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@@ -92,6 +92,7 @@ endif
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ifeq ($(CONFIG_USE_OF),y)
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OBJS += $(libfdt_objs) fdt_check_mem_start.o
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endif
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+KBUILD_CFLAGS_KERNEL := $(patsubst -f%-sections,,$(KBUILD_CFLAGS_KERNEL))
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# -fstack-protector-strong triggers protection checks in this code,
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# but it is being used too early to link to meaningful stack_chk logic.
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--- a/arch/arm/kernel/vmlinux.lds.S
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+++ b/arch/arm/kernel/vmlinux.lds.S
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@@ -75,7 +75,7 @@ SECTIONS
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. = ALIGN(4);
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__ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
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__start___ex_table = .;
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- ARM_MMU_KEEP(*(__ex_table))
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+ KEEP(*(__ex_table))
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__stop___ex_table = .;
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}
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@@ -100,24 +100,24 @@ SECTIONS
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}
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.init.arch.info : {
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__arch_info_begin = .;
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- *(.arch.info.init)
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+ KEEP(*(.arch.info.init))
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__arch_info_end = .;
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}
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.init.tagtable : {
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__tagtable_begin = .;
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- *(.taglist.init)
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+ KEEP(*(.taglist.init))
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__tagtable_end = .;
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}
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#ifdef CONFIG_SMP_ON_UP
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.init.smpalt : {
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__smpalt_begin = .;
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- *(.alt.smp.init)
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+ KEEP(*(.alt.smp.init))
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__smpalt_end = .;
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}
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#endif
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.init.pv_table : {
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__pv_table_begin = .;
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- *(.pv_table)
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+ KEEP(*(.pv_table))
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__pv_table_end = .;
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}
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--- a/arch/arm/include/asm/vmlinux.lds.h
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+++ b/arch/arm/include/asm/vmlinux.lds.h
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@@ -42,13 +42,13 @@
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#define PROC_INFO \
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. = ALIGN(4); \
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__proc_info_begin = .; \
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- *(.proc.info.init) \
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+ KEEP(*(.proc.info.init)) \
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__proc_info_end = .;
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#define IDMAP_TEXT \
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ALIGN_FUNCTION(); \
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__idmap_text_start = .; \
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- *(.idmap.text) \
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+ KEEP(*(.idmap.text)) \
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__idmap_text_end = .; \
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#define ARM_DISCARD \
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@@ -109,12 +109,12 @@
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. = ALIGN(8); \
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.ARM.unwind_idx : { \
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__start_unwind_idx = .; \
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- *(.ARM.exidx*) \
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+ KEEP(*(.ARM.exidx*)) \
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__stop_unwind_idx = .; \
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} \
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.ARM.unwind_tab : { \
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__start_unwind_tab = .; \
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- *(.ARM.extab*) \
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+ KEEP(*(.ARM.extab*)) \
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__stop_unwind_tab = .; \
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}
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@@ -126,7 +126,7 @@
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__vectors_lma = .; \
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OVERLAY 0xffff0000 : NOCROSSREFS AT(__vectors_lma) { \
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.vectors { \
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- *(.vectors) \
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+ KEEP(*(.vectors)) \
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} \
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.vectors.bhb.loop8 { \
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*(.vectors.bhb.loop8) \
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@@ -144,7 +144,7 @@
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\
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__stubs_lma = .; \
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.stubs ADDR(.vectors) + 0x1000 : AT(__stubs_lma) { \
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- *(.stubs) \
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+ KEEP(*(.stubs)) \
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} \
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ARM_LMA(__stubs, .stubs); \
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. = __stubs_lma + SIZEOF(.stubs); \
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