[PATCH] [EXPERIMENTAL, v2] enable thin archives and --gc-sections on ARM
From: Arnd Bergmann <arnd@arndb.de>
Date: 2017-03-15 16:52:11
I'm still build testing with an experimental change to enable
thin architeves and --gc-sections on ARM, which should bring
multiple benefits
- improve build times
- allow 'allyesconfig' to succeed without exceeding the
section size when linking drivers/built-in.o
- reduce the kernel image size
However, I have now run into a build error binutils commit
f02cb05 ("Always descend into output section statements in
lang_do_assignments") in binutils-2.28 and later:
no __ex_table in file: vmlinux
Any idea what's going wrong here?
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Alan Modra <redacted>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
arch/arm/Kconfig | 2 ++
arch/arm/kernel/Makefile | 3 +++
arch/arm/kernel/vmlinux-xip.lds.S | 32 +++++++++++++++++++++-----------
arch/arm/kernel/vmlinux.lds.S | 22 ++++++++++++++++------
4 files changed, 42 insertions(+), 17 deletions(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 27e738b82e45..333a1f685abb 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig@@ -89,6 +89,7 @@ config ARM select HAVE_UID16 select HAVE_VIRT_CPU_ACCOUNTING_GEN select IRQ_FORCED_THREADING + select LD_DEAD_CODE_DATA_ELIMINATION select MODULES_USE_ELF_REL select NO_BOOTMEM select OF_EARLY_FLATTREE if OF
@@ -98,6 +99,7 @@ config ARM select PERF_USE_VMALLOC select RTC_LIB select SYS_SUPPORTS_APM_EMULATION + select THIN_ARCHIVES # Above selects are sorted alphabetically; please add new ones # according to that. Thanks. help
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index d1b06cd79b23..469b78f5f529 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile@@ -13,6 +13,9 @@ endif CFLAGS_REMOVE_return_address.o = -pg +ccflags-y += -fno-function-sections -fno-data-sections +subdir-ccflags-y += -fno-function-sections -fno-data-sections + # Object file lists. obj-y := elf.o entry-common.o irq.o opcodes.o \
diff --git a/arch/arm/kernel/vmlinux-xip.lds.S b/arch/arm/kernel/vmlinux-xip.lds.S
index 2e5b5f0dbadf..bf900f5421a1 100644
--- a/arch/arm/kernel/vmlinux-xip.lds.S
+++ b/arch/arm/kernel/vmlinux-xip.lds.S@@ -18,17 +18,17 @@ #define PROC_INFO \ . = ALIGN(4); \ VMLINUX_SYMBOL(__proc_info_begin) = .; \ - *(.proc.info.init) \ + KEEP(*(.proc.info.init)) \ VMLINUX_SYMBOL(__proc_info_end) = .; #define IDMAP_TEXT \ ALIGN_FUNCTION(); \ VMLINUX_SYMBOL(__idmap_text_start) = .; \ - *(.idmap.text) \ + KEEP(*(.idmap.text)) \ VMLINUX_SYMBOL(__idmap_text_end) = .; \ . = ALIGN(PAGE_SIZE); \ VMLINUX_SYMBOL(__hyp_idmap_text_start) = .; \ - *(.hyp.idmap.text) \ + KEEP(*(.hyp.idmap.text)) \ VMLINUX_SYMBOL(__hyp_idmap_text_end) = .; #ifdef CONFIG_HOTPLUG_CPU
@@ -48,6 +48,16 @@ #define ARM_EXIT_DISCARD(x) x #endif +#undef TEXT_TEXT +#define TEXT_TEXT \ + ALIGN_FUNCTION(); \ + *(.text.hot .text.hot.*) \ + *(.text.unlikely .text.unlikely.*) \ + *(.text .text.*) \ + *(.ref.text) \ + MEM_KEEP(init.text) \ + MEM_KEEP(exit.text) \ + OUTPUT_ARCH(arm) ENTRY(stext)
@@ -121,7 +131,7 @@ SECTIONS __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) { __start___ex_table = .; #ifdef CONFIG_MMU - *(__ex_table) + KEEP(*(__ex_table)) #endif __stop___ex_table = .; }
@@ -133,12 +143,12 @@ SECTIONS . = 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 = .; } #endif
@@ -153,7 +163,7 @@ SECTIONS */ __vectors_start = .; .vectors 0xffff0000 : AT(__vectors_start) { - *(.vectors) + KEEP(*(.vectors)) } . = __vectors_start + SIZEOF(.vectors); __vectors_end = .;
@@ -176,24 +186,24 @@ 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 = .; } .init.data : {
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 30f04ce52dde..5f2c8c90beac 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S@@ -17,7 +17,7 @@ #define PROC_INFO \ . = ALIGN(4); \ VMLINUX_SYMBOL(__proc_info_begin) = .; \ - *(.proc.info.init) \ + KEEP(*(.proc.info.init)) \ VMLINUX_SYMBOL(__proc_info_end) = .; #define HYPERVISOR_TEXT \
@@ -35,6 +35,16 @@ *(.hyp.idmap.text) \ VMLINUX_SYMBOL(__hyp_idmap_text_end) = .; +#undef TEXT_TEXT +#define TEXT_TEXT \ + ALIGN_FUNCTION(); \ + *(.text.hot .text.hot.*) \ + *(.text.unlikely .text.unlikely.*) \ + *(.text .text.*) \ + *(.ref.text) \ + MEM_KEEP(init.text) \ + MEM_KEEP(exit.text) \ + #ifdef CONFIG_HOTPLUG_CPU #define ARM_CPU_DISCARD(x) #define ARM_CPU_KEEP(x) x
@@ -170,7 +180,7 @@ SECTIONS */ __vectors_start = .; .vectors 0xffff0000 : AT(__vectors_start) { - *(.vectors) + KEEP(*(.vectors)) } . = __vectors_start + SIZEOF(.vectors); __vectors_end = .;
@@ -193,24 +203,24 @@ 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 = .; } .init.data : {
--
2.9.0