generic: fix broken ARM gc sections patch

Upstream version of ARM gc sections skip eeping some section. It was
reported some kernel load hang hence restore what we original did and
introduce a new patch that add the additional entry on top of the
upstream version.

Fixes: #18500
Fixes: 7843f21c5120 ("generic: replace ARM gc sections patch with upstream version")
Tested-by: Stefan Kalscheuer <[email protected]> (Turris Omnia)
Link: https://github.com/openwrt/openwrt/pull/18503
Signed-off-by: Christian Marangi <[email protected]>

target/linux/generic/pending-6.6/200-ARM-9404-1-arm32-fix-boot-hang-with-HAVE_LD_DEAD_COD.patch

@@ -0,0 +1,79 @@
+From cf3d39cfd29ab7bcbd6aa79d4a2f132817969e3d Mon Sep 17 00:00:00 2001
+From: Christian Marangi <[email protected]>
+Date: Tue, 15 Apr 2025 23:16:40 +0200
+Subject: [PATCH] ARM: 9404/1: arm32: fix boot hang with
+ HAVE_LD_DEAD_CODE_DATA_ELIMINATION
+
+It was reported that some SoC (mvebu based for example) hang on kernel
+loading. A variant of the feature was present in OpenWrt from long ago
+and adding the additional entry with KEEP, fix the problem.
+
+Fixes: ed0f94102251 ("ARM: 9404/1: arm32: enable HAVE_LD_DEAD_CODE_DATA_ELIMINATION")
+Signed-off-by: Christian Marangi <[email protected]>
+---
+ arch/arm/include/asm/vmlinux.lds.h | 10 +++++-----
+ arch/arm/kernel/vmlinux.lds.S      |  4 ++--
+ 2 files changed, 7 insertions(+), 7 deletions(-)
+
+--- a/arch/arm/include/asm/vmlinux.lds.h
++++ b/arch/arm/include/asm/vmlinux.lds.h
+@@ -48,7 +48,7 @@
+ #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);				\
+--- a/arch/arm/kernel/vmlinux.lds.S
++++ b/arch/arm/kernel/vmlinux.lds.S
+@@ -104,13 +104,13 @@ SECTIONS
+ 	}
+ 	.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