--- /dev/null
+From ed0f941022515ff40473ea5335769a5dc2524a3f Mon Sep 17 00:00:00 2001
+From: Yuntao Liu <liuyuntao12@huawei.com>
+Date: Mon, 3 Jun 2024 16:37:50 +0100
+Subject: [PATCH] ARM: 9404/1: arm32: enable HAVE_LD_DEAD_CODE_DATA_ELIMINATION
+
+The current arm32 architecture does not yet support the
+HAVE_LD_DEAD_CODE_DATA_ELIMINATION feature. arm32 is widely used in
+embedded scenarios, and enabling this feature would be beneficial for
+reducing the size of the kernel image.
+
+In order to make this work, we keep the necessary tables by annotating
+them with KEEP, also it requires further changes to linker script to KEEP
+some tables and wildcard compiler generated sections into the right place.
+When using ld.lld for linking, KEEP is not recognized within the OVERLAY
+command, and Ard proposed a concise method to solve this problem.
+
+It boots normally with defconfig, vexpress_defconfig and tinyconfig.
+
+The size comparison of zImage is as follows:
+defconfig vexpress_defconfig tinyconfig
+5137712 5138024 424192 no dce
+5032560 4997824 298384 dce
+2.0% 2.7% 29.7% shrink
+
+When using smaller config file, there is a significant reduction in the
+size of the zImage.
+
+We also tested this patch on a commercially available single-board
+computer, and the comparison is as follows:
+a15eb_config
+2161384 no dce
+2092240 dce
+3.2% shrink
+
+The zImage size has been reduced by approximately 3.2%, which is 70KB on
+2.1M.
+
+Signed-off-by: Yuntao Liu <liuyuntao12@huawei.com>
+Tested-by: Arnd Bergmann <arnd@arndb.de>
+Reviewed-by: Arnd Bergmann <arnd@arndb.de>
+Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
+Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
+---
+ arch/arm/Kconfig | 1 +
+ arch/arm/boot/compressed/vmlinux.lds.S | 2 +-
+ arch/arm/include/asm/vmlinux.lds.h | 2 +-
+ arch/arm/kernel/entry-armv.S | 3 +++
+ arch/arm/kernel/vmlinux-xip.lds.S | 4 ++--
+ arch/arm/kernel/vmlinux.lds.S | 6 +++---
+ drivers/firmware/efi/libstub/Makefile | 4 ++++
+ 7 files changed, 15 insertions(+), 7 deletions(-)
+
+--- a/arch/arm/Kconfig
++++ b/arch/arm/Kconfig
+@@ -111,6 +111,7 @@ config ARM
+ select HAVE_KERNEL_XZ
+ select HAVE_KPROBES if !XIP_KERNEL && !CPU_ENDIAN_BE32 && !CPU_V7M
+ select HAVE_KRETPROBES if HAVE_KPROBES
++ select HAVE_LD_DEAD_CODE_DATA_ELIMINATION
+ select HAVE_MOD_ARCH_SPECIFIC
+ select HAVE_NMI
+ select HAVE_OPTPROBES if !THUMB2_KERNEL
+--- a/arch/arm/boot/compressed/vmlinux.lds.S
++++ b/arch/arm/boot/compressed/vmlinux.lds.S
+@@ -125,7 +125,7 @@ SECTIONS
+
+ . = BSS_START;
+ __bss_start = .;
+- .bss : { *(.bss) }
++ .bss : { *(.bss .bss.*) }
+ _end = .;
+
+ . = ALIGN(8); /* the stack must be 64-bit aligned */
+--- a/arch/arm/include/asm/vmlinux.lds.h
++++ b/arch/arm/include/asm/vmlinux.lds.h
+@@ -42,7 +42,7 @@
+ #define PROC_INFO \
+ . = ALIGN(4); \
+ __proc_info_begin = .; \
+- *(.proc.info.init) \
++ KEEP(*(.proc.info.init)) \
+ __proc_info_end = .;
+
+ #define IDMAP_TEXT \
+--- a/arch/arm/kernel/entry-armv.S
++++ b/arch/arm/kernel/entry-armv.S
+@@ -1073,6 +1073,7 @@ vector_addrexcptn:
+ .globl vector_fiq
+
+ .section .vectors, "ax", %progbits
++ .reloc .text, R_ARM_NONE, .
+ W(b) vector_rst
+ W(b) vector_und
+ ARM( .reloc ., R_ARM_LDR_PC_G0, .L__vector_swi )
+@@ -1086,6 +1087,7 @@ THUMB( .reloc ., R_ARM_THM_PC12, .L__vec
+
+ #ifdef CONFIG_HARDEN_BRANCH_HISTORY
+ .section .vectors.bhb.loop8, "ax", %progbits
++ .reloc .text, R_ARM_NONE, .
+ W(b) vector_rst
+ W(b) vector_bhb_loop8_und
+ ARM( .reloc ., R_ARM_LDR_PC_G0, .L__vector_bhb_loop8_swi )
+@@ -1098,6 +1100,7 @@ THUMB( .reloc ., R_ARM_THM_PC12, .L__vec
+ W(b) vector_bhb_loop8_fiq
+
+ .section .vectors.bhb.bpiall, "ax", %progbits
++ .reloc .text, R_ARM_NONE, .
+ W(b) vector_rst
+ W(b) vector_bhb_bpiall_und
+ ARM( .reloc ., R_ARM_LDR_PC_G0, .L__vector_bhb_bpiall_swi )
+--- a/arch/arm/kernel/vmlinux-xip.lds.S
++++ b/arch/arm/kernel/vmlinux-xip.lds.S
+@@ -63,7 +63,7 @@ SECTIONS
+ . = ALIGN(4);
+ __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
+ __start___ex_table = .;
+- ARM_MMU_KEEP(*(__ex_table))
++ ARM_MMU_KEEP(KEEP(*(__ex_table)))
+ __stop___ex_table = .;
+ }
+
+@@ -83,7 +83,7 @@ SECTIONS
+ }
+ .init.arch.info : {
+ __arch_info_begin = .;
+- *(.arch.info.init)
++ KEEP(*(.arch.info.init))
+ __arch_info_end = .;
+ }
+ .init.tagtable : {
+--- a/arch/arm/kernel/vmlinux.lds.S
++++ b/arch/arm/kernel/vmlinux.lds.S
+@@ -74,7 +74,7 @@ SECTIONS
+ . = ALIGN(4);
+ __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
+ __start___ex_table = .;
+- ARM_MMU_KEEP(*(__ex_table))
++ ARM_MMU_KEEP(KEEP(*(__ex_table)))
+ __stop___ex_table = .;
+ }
+
+@@ -99,7 +99,7 @@ SECTIONS
+ }
+ .init.arch.info : {
+ __arch_info_begin = .;
+- *(.arch.info.init)
++ KEEP(*(.arch.info.init))
+ __arch_info_end = .;
+ }
+ .init.tagtable : {
+@@ -116,7 +116,7 @@ SECTIONS
+ #endif
+ .init.pv_table : {
+ __pv_table_begin = .;
+- *(.pv_table)
++ KEEP(*(.pv_table))
+ __pv_table_end = .;
+ }
+
+--- a/drivers/firmware/efi/libstub/Makefile
++++ b/drivers/firmware/efi/libstub/Makefile
+@@ -67,6 +67,10 @@ OBJECT_FILES_NON_STANDARD := y
+ # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
+ KCOV_INSTRUMENT := n
+
++# The .data section would be renamed to .data.efistub, therefore, remove
++# `-fdata-sections` flag from KBUILD_CFLAGS_KERNEL
++KBUILD_CFLAGS_KERNEL := $(filter-out -fdata-sections, $(KBUILD_CFLAGS_KERNEL))
++
+ lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \
+ file.o mem.o random.o randomalloc.o pci.o \
+ skip_spaces.o lib-cmdline.o lib-ctype.o \
+++ /dev/null
-From e3d8676f5722b7622685581e06e8f53e6138e3ab Mon Sep 17 00:00:00 2001
-From: Felix Fietkau <nbd@nbd.name>
-Date: Sat, 15 Jul 2017 23:42:36 +0200
-Subject: use -ffunction-sections, -fdata-sections and --gc-sections
-
-In combination with kernel symbol export stripping this significantly reduces
-the kernel image size. Used on both ARM and MIPS architectures.
-
-Signed-off-by: Felix Fietkau <nbd@nbd.name>
-Signed-off-by: Jonas Gorski <jogo@openwrt.org>
-Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
----
---- a/arch/arm/Kconfig
-+++ b/arch/arm/Kconfig
-@@ -128,6 +128,7 @@ config ARM
- select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
- select IRQ_FORCED_THREADING
- select LOCK_MM_AND_FIND_VMA
-+ select HAVE_LD_DEAD_CODE_DATA_ELIMINATION
- select MODULES_USE_ELF_REL
- select NEED_DMA_MAP_STATE
- select OF_EARLY_FLATTREE if OF
---- a/arch/arm/boot/compressed/Makefile
-+++ b/arch/arm/boot/compressed/Makefile
-@@ -92,6 +92,7 @@ endif
- ifeq ($(CONFIG_USE_OF),y)
- OBJS += $(libfdt_objs) fdt_check_mem_start.o
- endif
-+KBUILD_CFLAGS_KERNEL := $(patsubst -f%-sections,,$(KBUILD_CFLAGS_KERNEL))
-
- OBJS += lib1funcs.o ashldi3.o bswapsdi2.o
-
---- a/arch/arm/kernel/vmlinux.lds.S
-+++ b/arch/arm/kernel/vmlinux.lds.S
-@@ -74,7 +74,7 @@ SECTIONS
- . = ALIGN(4);
- __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
- __start___ex_table = .;
-- ARM_MMU_KEEP(*(__ex_table))
-+ KEEP(*(__ex_table))
- __stop___ex_table = .;
- }
-
-@@ -99,24 +99,24 @@ SECTIONS
- }
- .init.arch.info : {
- __arch_info_begin = .;
-- *(.arch.info.init)
-+ KEEP(*(.arch.info.init))
- __arch_info_end = .;
- }
- .init.tagtable : {
- __tagtable_begin = .;
-- *(.taglist.init)
-+ KEEP(*(.taglist.init))
- __tagtable_end = .;
- }
- #ifdef CONFIG_SMP_ON_UP
- .init.smpalt : {
- __smpalt_begin = .;
-- *(.alt.smp.init)
-+ KEEP(*(.alt.smp.init))
- __smpalt_end = .;
- }
- #endif
- .init.pv_table : {
- __pv_table_begin = .;
-- *(.pv_table)
-+ KEEP(*(.pv_table))
- __pv_table_end = .;
- }
-
---- a/arch/arm/include/asm/vmlinux.lds.h
-+++ b/arch/arm/include/asm/vmlinux.lds.h
-@@ -42,13 +42,13 @@
- #define PROC_INFO \
- . = ALIGN(4); \
- __proc_info_begin = .; \
-- *(.proc.info.init) \
-+ KEEP(*(.proc.info.init)) \
- __proc_info_end = .;
-
- #define IDMAP_TEXT \
- ALIGN_FUNCTION(); \
- __idmap_text_start = .; \
-- *(.idmap.text) \
-+ KEEP(*(.idmap.text)) \
- __idmap_text_end = .; \
-
- #define ARM_DISCARD \
-@@ -108,12 +108,12 @@
- . = ALIGN(8); \
- .ARM.unwind_idx : { \
- __start_unwind_idx = .; \
-- *(.ARM.exidx*) \
-+ KEEP(*(.ARM.exidx*)) \
- __stop_unwind_idx = .; \
- } \
- .ARM.unwind_tab : { \
- __start_unwind_tab = .; \
-- *(.ARM.extab*) \
-+ KEEP(*(.ARM.extab*)) \
- __stop_unwind_tab = .; \
- }
-
-@@ -125,7 +125,7 @@
- __vectors_lma = .; \
- OVERLAY 0xffff0000 : NOCROSSREFS AT(__vectors_lma) { \
- .vectors { \
-- *(.vectors) \
-+ KEEP(*(.vectors)) \
- } \
- .vectors.bhb.loop8 { \
- *(.vectors.bhb.loop8) \
-@@ -143,7 +143,7 @@
- \
- __stubs_lma = .; \
- .stubs ADDR(.vectors) + 0x1000 : AT(__stubs_lma) { \
-- *(.stubs) \
-+ KEEP(*(.stubs)) \
- } \
- ARM_LMA(__stubs, .stubs); \
- . = __stubs_lma + SIZEOF(.stubs); \
projects / thirdparty / openwrt.git / commitdiff
