openwrt/target/linux/generic/hack-5.4/220-arm-gc_sections.patch
Rui Salvaterra 023a1366ee kernel/generic: fix the arm gc-sections patch
Latest binutils (2.37) exposed a long-standing bug. The kernel linking stage
would break at the SORTTAB step, due to the exception table having been
previously purged from vmlinux, as its section wasn't marked as unconditionally
kept. Fix thusly.

Additionally, the "#define ARM_MMU_DISCARD(x) KEEP(x)" change is bogus. It
would only apply to !CONFIG_MMU devices (which we don't support in OpenWrt), and
it would even break the build if referenced. Drop it.

While at it, rename the patch in order to make it obvious that it's
arm-specific.

Signed-off-by: Rui Salvaterra <rsalvaterra@gmail.com>
[Add same changes for kernel 5.4 too]
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
2021-07-25 13:52:34 +02:00

139 lines
3.9 KiB
Diff

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>
---
Makefile | 10 +++----
arch/arm/Kconfig | 1 +
arch/arm/boot/compressed/Makefile | 1 +
arch/arm/kernel/vmlinux.lds.S | 26 ++++++++--------
arch/mips/Kconfig | 1 +
arch/mips/kernel/vmlinux.lds.S | 4 +--
include/asm-generic/vmlinux.lds.h | 63 ++++++++++++++++++++-------------------
7 files changed, 55 insertions(+), 51 deletions(-)
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -111,6 +111,7 @@ config ARM
select HAVE_UID16
select HAVE_VIRT_CPU_ACCOUNTING_GEN
select IRQ_FORCED_THREADING
+ 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
@@ -106,6 +106,7 @@ ifeq ($(CONFIG_FUNCTION_TRACER),y)
ORIG_CFLAGS := $(KBUILD_CFLAGS)
KBUILD_CFLAGS = $(subst -pg, , $(ORIG_CFLAGS))
endif
+KBUILD_CFLAGS_KERNEL := $(patsubst -f%-sections,,$(KBUILD_CFLAGS_KERNEL))
# -fstack-protector-strong triggers protection checks in this code,
# but it is being used too early to link to meaningful stack_chk logic.
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -73,7 +73,7 @@ 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 = .;
}
@@ -100,24 +100,24 @@ 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/kernel/vmlinux.lds.h
+++ b/arch/arm/kernel/vmlinux.lds.h
@@ -28,7 +28,7 @@
#define PROC_INFO \
. = ALIGN(4); \
__proc_info_begin = .; \
- *(.proc.info.init) \
+ KEEP(*(.proc.info.init)) \
__proc_info_end = .;
#define HYPERVISOR_TEXT \
@@ -39,11 +39,11 @@
#define IDMAP_TEXT \
ALIGN_FUNCTION(); \
__idmap_text_start = .; \
- *(.idmap.text) \
+ KEEP(*(.idmap.text)) \
__idmap_text_end = .; \
. = ALIGN(PAGE_SIZE); \
__hyp_idmap_text_start = .; \
- *(.hyp.idmap.text) \
+ KEEP(*(.hyp.idmap.text)) \
__hyp_idmap_text_end = .;
#define ARM_DISCARD \
@@ -86,12 +86,12 @@
. = 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 = .; \
}
@@ -102,14 +102,14 @@
#define ARM_VECTORS \
__vectors_start = .; \
.vectors 0xffff0000 : AT(__vectors_start) { \
- *(.vectors) \
+ KEEP(*(.vectors)) \
} \
. = __vectors_start + SIZEOF(.vectors); \
__vectors_end = .; \
\
__stubs_start = .; \
.stubs ADDR(.vectors) + 0x1000 : AT(__stubs_start) { \
- *(.stubs) \
+ KEEP(*(.stubs)) \
} \
. = __stubs_start + SIZEOF(.stubs); \
__stubs_end = .; \