generic: replace ARM gc sections patch with upstream version

Replace ARM gc sections patch with upstream version. It seems this
feature is finally supported upstream with some minor difference.

In theory the upstream version should cut even more stuff, this really
needs to be evaluated if it's OK also to handle regression with the
kernel 6.12 update.

Link: https://github.com/openwrt/openwrt/pull/18464
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

target/linux/generic/backport-6.6/200-v6.11-ARM-9404-1-arm32-enable-HAVE_LD_DEAD_CODE_DATA_ELIMI.patch

@@ -0,0 +1,172 @@
+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 \

target/linux/generic/hack-6.6/220-arm-gc_sections.patch

@@ -1,123 +0,0 @@
-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);				\