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, the KEEP keyword is not recognized within
the OVERLAY command, 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 <[email protected]>
Tested-by: Arnd Bergmann <[email protected]>
Reviewed-by: Arnd Bergmann <[email protected]>
---
v3:
- A better way to KEEP .vectors section for ld.lld linking.
v2:
- Support config XIP_KERNEL.
- Support LLVM compilation.
- https://lore.kernel.org/all/[email protected]/
v1: https://lore.kernel.org/all/[email protected]/
---
arch/arm/Kconfig | 1 +
arch/arm/boot/compressed/vmlinux.lds.S | 6 +++++-
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 +++---
6 files changed, 15 insertions(+), 7 deletions(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index b14aed3a17ab..45f25f6e7a62 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -114,6 +114,7 @@ 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
diff --git a/arch/arm/boot/compressed/vmlinux.lds.S b/arch/arm/boot/compressed/vmlinux.lds.S
index 3fcb3e62dc56..affd30714f01 100644
--- a/arch/arm/boot/compressed/vmlinux.lds.S
+++ b/arch/arm/boot/compressed/vmlinux.lds.S
@@ -89,7 +89,11 @@ SECTIONS
* The EFI stub always executes from RAM, and runs strictly before the
* decompressor, so we can make an exception for its r/w data, and keep it
*/
+#ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
+ *(.data.* .bss.*)
+#else
*(.data.efistub .bss.efistub)
+#endif
__pecoff_data_end = .;
/*
@@ -125,7 +129,7 @@ SECTIONS
. = BSS_START;
__bss_start = .;
- .bss : { *(.bss) }
+ .bss : { *(.bss .bss.*) }
_end = .;
. = ALIGN(8); /* the stack must be 64-bit aligned */
diff --git a/arch/arm/include/asm/vmlinux.lds.h b/arch/arm/include/asm/vmlinux.lds.h
index 4c8632d5c432..d60f6e83a9f7 100644
--- 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 \
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 6150a716828c..f01d23a220e6 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -1065,6 +1065,7 @@ 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 )
@@ -1078,6 +1079,7 @@ THUMB( .reloc ., R_ARM_THM_PC12, .L__vector_swi )
#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 )
@@ -1090,6 +1092,7 @@ THUMB( .reloc ., R_ARM_THM_PC12, .L__vector_bhb_loop8_swi )
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 )
diff --git a/arch/arm/kernel/vmlinux-xip.lds.S b/arch/arm/kernel/vmlinux-xip.lds.S
index c16d196b5aad..5eddb75a7174 100644
--- 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 : {
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index bd9127c4b451..de373c6c2ae8 100644
--- 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 = .;
}
--
2.34.1
On Fri, 15 Mar 2024 at 07:37, Yuntao Liu <[email protected]> wrote:
>
> 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, the KEEP keyword is not recognized within
> the OVERLAY command, 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 <[email protected]>
> Tested-by: Arnd Bergmann <[email protected]>
> Reviewed-by: Arnd Bergmann <[email protected]>
> ---
> v3:
> - A better way to KEEP .vectors section for ld.lld linking.
>
> v2:
> - Support config XIP_KERNEL.
> - Support LLVM compilation.
> - https://lore.kernel.org/all/[email protected]/
>
> v1: https://lore.kernel.org/all/[email protected]/
> ---
> arch/arm/Kconfig | 1 +
> arch/arm/boot/compressed/vmlinux.lds.S | 6 +++++-
> 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 +++---
> 6 files changed, 15 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index b14aed3a17ab..45f25f6e7a62 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -114,6 +114,7 @@ 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
> diff --git a/arch/arm/boot/compressed/vmlinux.lds.S b/arch/arm/boot/compressed/vmlinux.lds.S
> index 3fcb3e62dc56..affd30714f01 100644
> --- a/arch/arm/boot/compressed/vmlinux.lds.S
> +++ b/arch/arm/boot/compressed/vmlinux.lds.S
> @@ -89,7 +89,11 @@ SECTIONS
> * The EFI stub always executes from RAM, and runs strictly before the
> * decompressor, so we can make an exception for its r/w data, and keep it
> */
> +#ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
> + *(.data.* .bss.*)
> +#else
> *(.data.efistub .bss.efistub)
> +#endif
> __pecoff_data_end = .;
>
This is still not right.
Can you just add -fno-data-sections to cflags-$(CONFIG_ARM) in
drivers/firmware/efi/libstub/Makefile?
> /*
> @@ -125,7 +129,7 @@ SECTIONS
>
> . = BSS_START;
> __bss_start = .;
> - .bss : { *(.bss) }
> + .bss : { *(.bss .bss.*) }
> _end = .;
>
> . = ALIGN(8); /* the stack must be 64-bit aligned */
> diff --git a/arch/arm/include/asm/vmlinux.lds.h b/arch/arm/include/asm/vmlinux.lds.h
> index 4c8632d5c432..d60f6e83a9f7 100644
> --- 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 \
> diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
> index 6150a716828c..f01d23a220e6 100644
> --- a/arch/arm/kernel/entry-armv.S
> +++ b/arch/arm/kernel/entry-armv.S
> @@ -1065,6 +1065,7 @@ 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 )
> @@ -1078,6 +1079,7 @@ THUMB( .reloc ., R_ARM_THM_PC12, .L__vector_swi )
>
> #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 )
> @@ -1090,6 +1092,7 @@ THUMB( .reloc ., R_ARM_THM_PC12, .L__vector_bhb_loop8_swi )
> 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 )
> diff --git a/arch/arm/kernel/vmlinux-xip.lds.S b/arch/arm/kernel/vmlinux-xip.lds.S
> index c16d196b5aad..5eddb75a7174 100644
> --- 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 : {
> diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
> index bd9127c4b451..de373c6c2ae8 100644
> --- 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 = .;
> }
>
> --
> 2.34.1
>
On 2024/3/15 16:06, Ard Biesheuvel wrote:
> On Fri, 15 Mar 2024 at 07:37, Yuntao Liu <[email protected]> wrote:
>>
>> 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, the KEEP keyword is not recognized within
>> the OVERLAY command, 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 <[email protected]>
>> Tested-by: Arnd Bergmann <[email protected]>
>> Reviewed-by: Arnd Bergmann <[email protected]>
>> ---
>> v3:
>> - A better way to KEEP .vectors section for ld.lld linking.
>>
>> v2:
>> - Support config XIP_KERNEL.
>> - Support LLVM compilation.
>> - https://lore.kernel.org/all/[email protected]/
>>
>> v1: https://lore.kernel.org/all/[email protected]/
>> ---
>> arch/arm/Kconfig | 1 +
>> arch/arm/boot/compressed/vmlinux.lds.S | 6 +++++-
>> 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 +++---
>> 6 files changed, 15 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
>> index b14aed3a17ab..45f25f6e7a62 100644
>> --- a/arch/arm/Kconfig
>> +++ b/arch/arm/Kconfig
>> @@ -114,6 +114,7 @@ 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
>> diff --git a/arch/arm/boot/compressed/vmlinux.lds.S b/arch/arm/boot/compressed/vmlinux.lds.S
>> index 3fcb3e62dc56..affd30714f01 100644
>> --- a/arch/arm/boot/compressed/vmlinux.lds.S
>> +++ b/arch/arm/boot/compressed/vmlinux.lds.S
>> @@ -89,7 +89,11 @@ SECTIONS
>> * The EFI stub always executes from RAM, and runs strictly before the
>> * decompressor, so we can make an exception for its r/w data, and keep it
>> */
>> +#ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
>> + *(.data.* .bss.*)
>> +#else
>> *(.data.efistub .bss.efistub)
>> +#endif
>> __pecoff_data_end = .;
>>
>
> This is still not right.
>
> Can you just add -fno-data-sections to cflags-$(CONFIG_ARM) in
> drivers/firmware/efi/libstub/Makefile?
>
I rebuild kernel in such way:
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -28,6 +28,7 @@ cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN
-DEFI_HAVE_STRNLEN \
-DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
-DEFI_HAVE_STRCMP -fno-builtin -fpic \
$(call cc-option,-mno-single-pic-base)
+cflags-$(CONFIG_ARM) += -fno-data-sections
cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
cflags-$(CONFIG_LOONGARCH) += -fpi
but I am still encountering this error:
arm-linux-gnueabi-ld: warning: orphan section `.data.efi_loglevel' from
`drivers/firmware/efi/libstub/printk.stub.o' being placed in section
`.data.efi_loglevel'
arm-linux-gnueabi-ld: warning: orphan section `.data.screen_info_guid'
from `drivers/firmware/efi/libstub/screen_info.stub.o' being placed in
section `.data.screen_info_guid'
arm-linux-gnueabi-ld: warning: orphan section `.data.cpu_state_guid'
from `drivers/firmware/efi/libstub/arm32-stub.stub.o' being placed in
section `.data.cpu_state_guid'
arm-linux-gnueabi-ld: warning: orphan section `.data.efi_nokaslr' from
`drivers/firmware/efi/libstub/efi-stub-helper.stub.o' being placed in
section `.data.efi_nokaslr'
arm-linux-gnueabi-ld: error: zImage file size is incorrect
I am puzzled because I could not find any option named
-fno-data-sections for GCC.
On Fri, 15 Mar 2024 at 11:23, liuyuntao (F) <[email protected]> wrote:
>
>
>
> On 2024/3/15 16:06, Ard Biesheuvel wrote:
> > On Fri, 15 Mar 2024 at 07:37, Yuntao Liu <[email protected]> wrote:
> >>
> >> 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, the KEEP keyword is not recognized within
> >> the OVERLAY command, 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 <[email protected]>
> >> Tested-by: Arnd Bergmann <[email protected]>
> >> Reviewed-by: Arnd Bergmann <[email protected]>
> >> ---
> >> v3:
> >> - A better way to KEEP .vectors section for ld.lld linking.
> >>
> >> v2:
> >> - Support config XIP_KERNEL.
> >> - Support LLVM compilation.
> >> - https://lore.kernel.org/all/[email protected]/
> >>
> >> v1: https://lore.kernel.org/all/[email protected]/
> >> ---
> >> arch/arm/Kconfig | 1 +
> >> arch/arm/boot/compressed/vmlinux.lds.S | 6 +++++-
> >> 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 +++---
> >> 6 files changed, 15 insertions(+), 7 deletions(-)
> >>
> >> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> >> index b14aed3a17ab..45f25f6e7a62 100644
> >> --- a/arch/arm/Kconfig
> >> +++ b/arch/arm/Kconfig
> >> @@ -114,6 +114,7 @@ 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
> >> diff --git a/arch/arm/boot/compressed/vmlinux.lds.S b/arch/arm/boot/compressed/vmlinux.lds.S
> >> index 3fcb3e62dc56..affd30714f01 100644
> >> --- a/arch/arm/boot/compressed/vmlinux.lds.S
> >> +++ b/arch/arm/boot/compressed/vmlinux.lds.S
> >> @@ -89,7 +89,11 @@ SECTIONS
> >> * The EFI stub always executes from RAM, and runs strictly before the
> >> * decompressor, so we can make an exception for its r/w data, and keep it
> >> */
> >> +#ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
> >> + *(.data.* .bss.*)
> >> +#else
> >> *(.data.efistub .bss.efistub)
> >> +#endif
> >> __pecoff_data_end = .;
> >>
> >
> > This is still not right.
> >
> > Can you just add -fno-data-sections to cflags-$(CONFIG_ARM) in
> > drivers/firmware/efi/libstub/Makefile?
> >
>
> I rebuild kernel in such way:
> --- a/drivers/firmware/efi/libstub/Makefile
> +++ b/drivers/firmware/efi/libstub/Makefile
> @@ -28,6 +28,7 @@ cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN
> -DEFI_HAVE_STRNLEN \
> -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
> -DEFI_HAVE_STRCMP -fno-builtin -fpic \
> $(call cc-option,-mno-single-pic-base)
> +cflags-$(CONFIG_ARM) += -fno-data-sections
> cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
> cflags-$(CONFIG_LOONGARCH) += -fpi
> but I am still encountering this error:
> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_loglevel' from
> `drivers/firmware/efi/libstub/printk.stub.o' being placed in section
> `.data.efi_loglevel'
> arm-linux-gnueabi-ld: warning: orphan section `.data.screen_info_guid'
> from `drivers/firmware/efi/libstub/screen_info.stub.o' being placed in
> section `.data.screen_info_guid'
> arm-linux-gnueabi-ld: warning: orphan section `.data.cpu_state_guid'
> from `drivers/firmware/efi/libstub/arm32-stub.stub.o' being placed in
> section `.data.cpu_state_guid'
> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_nokaslr' from
> `drivers/firmware/efi/libstub/efi-stub-helper.stub.o' being placed in
> section `.data.efi_nokaslr'
> arm-linux-gnueabi-ld: error: zImage file size is incorrect
>
> I am puzzled because I could not find any option named
> -fno-data-sections for GCC.
>
How about
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -28,6 +28,7 @@
-DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
-DEFI_HAVE_STRCMP -fno-builtin -fpic \
$(call cc-option,-mno-single-pic-base)
+cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(CFLAGS-y))
cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
cflags-$(CONFIG_LOONGARCH) += -fpie
On 2024/3/15 18:46, Ard Biesheuvel wrote:
> On Fri, 15 Mar 2024 at 11:23, liuyuntao (F) <[email protected]> wrote:
>>
>>
>>
>> On 2024/3/15 16:06, Ard Biesheuvel wrote:
>>> On Fri, 15 Mar 2024 at 07:37, Yuntao Liu <[email protected]> wrote:
>>>>
>>>> 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, the KEEP keyword is not recognized within
>>>> the OVERLAY command, 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 <[email protected]>
>>>> Tested-by: Arnd Bergmann <[email protected]>
>>>> Reviewed-by: Arnd Bergmann <[email protected]>
>>>> ---
>>>> v3:
>>>> - A better way to KEEP .vectors section for ld.lld linking.
>>>>
>>>> v2:
>>>> - Support config XIP_KERNEL.
>>>> - Support LLVM compilation.
>>>> - https://lore.kernel.org/all/[email protected]/
>>>>
>>>> v1: https://lore.kernel.org/all/[email protected]/
>>>> ---
>>>> arch/arm/Kconfig | 1 +
>>>> arch/arm/boot/compressed/vmlinux.lds.S | 6 +++++-
>>>> 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 +++---
>>>> 6 files changed, 15 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
>>>> index b14aed3a17ab..45f25f6e7a62 100644
>>>> --- a/arch/arm/Kconfig
>>>> +++ b/arch/arm/Kconfig
>>>> @@ -114,6 +114,7 @@ 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
>>>> diff --git a/arch/arm/boot/compressed/vmlinux.lds.S b/arch/arm/boot/compressed/vmlinux.lds.S
>>>> index 3fcb3e62dc56..affd30714f01 100644
>>>> --- a/arch/arm/boot/compressed/vmlinux.lds.S
>>>> +++ b/arch/arm/boot/compressed/vmlinux.lds.S
>>>> @@ -89,7 +89,11 @@ SECTIONS
>>>> * The EFI stub always executes from RAM, and runs strictly before the
>>>> * decompressor, so we can make an exception for its r/w data, and keep it
>>>> */
>>>> +#ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
>>>> + *(.data.* .bss.*)
>>>> +#else
>>>> *(.data.efistub .bss.efistub)
>>>> +#endif
>>>> __pecoff_data_end = .;
>>>>
>>>
>>> This is still not right.
>>>
>>> Can you just add -fno-data-sections to cflags-$(CONFIG_ARM) in
>>> drivers/firmware/efi/libstub/Makefile?
>>>
>>
>> I rebuild kernel in such way:
>> --- a/drivers/firmware/efi/libstub/Makefile
>> +++ b/drivers/firmware/efi/libstub/Makefile
>> @@ -28,6 +28,7 @@ cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN
>> -DEFI_HAVE_STRNLEN \
>> -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
>> -DEFI_HAVE_STRCMP -fno-builtin -fpic \
>> $(call cc-option,-mno-single-pic-base)
>> +cflags-$(CONFIG_ARM) += -fno-data-sections
>> cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
>> cflags-$(CONFIG_LOONGARCH) += -fpi
>> but I am still encountering this error:
>> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_loglevel' from
>> `drivers/firmware/efi/libstub/printk.stub.o' being placed in section
>> `.data.efi_loglevel'
>> arm-linux-gnueabi-ld: warning: orphan section `.data.screen_info_guid'
>> from `drivers/firmware/efi/libstub/screen_info.stub.o' being placed in
>> section `.data.screen_info_guid'
>> arm-linux-gnueabi-ld: warning: orphan section `.data.cpu_state_guid'
>> from `drivers/firmware/efi/libstub/arm32-stub.stub.o' being placed in
>> section `.data.cpu_state_guid'
>> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_nokaslr' from
>> `drivers/firmware/efi/libstub/efi-stub-helper.stub.o' being placed in
>> section `.data.efi_nokaslr'
>> arm-linux-gnueabi-ld: error: zImage file size is incorrect
>>
>> I am puzzled because I could not find any option named
>> -fno-data-sections for GCC.
>>
>
> How about
>
> --- a/drivers/firmware/efi/libstub/Makefile
> +++ b/drivers/firmware/efi/libstub/Makefile
> @@ -28,6 +28,7 @@
> -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
> -DEFI_HAVE_STRCMP -fno-builtin -fpic \
> $(call cc-option,-mno-single-pic-base)
> +cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(CFLAGS-y))
> cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
> cflags-$(CONFIG_LOONGARCH) += -fpie
Another error:
cannot initialize array of ‘short unsigned int’ from a string literal
with type array of ‘unsigned int’
17 | static const efi_char16_t shim_MokSBState_name[] = L"MokSBStateRT";
I checked the cflags-y variable, and the -fshort-wchar option does
exist.cflags-y = -std=gnu11 -fshort-wchar -funsigned-char -fno-common
-fno-PIE -fno-strict-aliasing ...
On Fri, Mar 15, 2024, at 12:48, liuyuntao (F) wrote:
> On 2024/3/15 18:46, Ard Biesheuvel wrote:
>> @@ -28,6 +28,7 @@
>> -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
>> -DEFI_HAVE_STRCMP -fno-builtin -fpic \
>> $(call cc-option,-mno-single-pic-base)
>> +cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(CFLAGS-y))
>> cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
>> cflags-$(CONFIG_LOONGARCH) += -fpie
>
> Another error:
> cannot initialize array of ‘short unsigned int’ from a string literal
> with type array of ‘unsigned int’
> 17 | static const efi_char16_t shim_MokSBState_name[] = L"MokSBStateRT";
The line sets cflags-y to an empty string.
It probably should have been
cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(cflags-y))
(small cflags instead of CFLAGS).
Arnd
On 2024/3/15 19:51, Arnd Bergmann wrote:
> On Fri, Mar 15, 2024, at 12:48, liuyuntao (F) wrote:
>> On 2024/3/15 18:46, Ard Biesheuvel wrote:
>>> @@ -28,6 +28,7 @@
>>> -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
>>> -DEFI_HAVE_STRCMP -fno-builtin -fpic \
>>> $(call cc-option,-mno-single-pic-base)
>>> +cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(CFLAGS-y))
>>> cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
>>> cflags-$(CONFIG_LOONGARCH) += -fpie
>>
>> Another error:
>> cannot initialize array of ‘short unsigned int’ from a string literal
>> with type array of ‘unsigned int’
>> 17 | static const efi_char16_t shim_MokSBState_name[] = L"MokSBStateRT";
>
> The line sets cflags-y to an empty string.
>
> It probably should have been
>
> cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(cflags-y))
>
> (small cflags instead of CFLAGS).
>
> Arnd
Oh, my mistake, after fixed this bug, still this error:
> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_loglevel' from `drivers/firmware/efi/libstub/printk.stub.o' being placed in section `.data.efi_loglevel'
> arm-linux-gnueabi-ld: warning: orphan section `.data.screen_info_guid' from `drivers/firmware/efi/libstub/screen_info.stub.o' being placed in section `.data.screen_info_guid'
> arm-linux-gnueabi-ld: warning: orphan section `.data.cpu_state_guid' from `drivers/firmware/efi/libstub/arm32-stub.stub.o' being placed in section `.data.cpu_state_guid'
> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_nokaslr' from `drivers/firmware/efi/libstub/efi-stub-helper.stub.o' being placed in section `.data.efi_nokaslr'
The -fdata-sections option is present in the KBUILD_CFLAGS_KERNEL
variable; altering cflags-y only affect the KBUILD_CFLAGS variable.
It seems that the -fdata-sections option needs to be removed from the
KBUILD_CFLAGS_KERNEL variable.
> ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
> KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections
> KBUILD_RUSTFLAGS_KERNEL += -Zfunction-sections=y
> LDFLAGS_vmlinux += --gc-sections
> endif
On 2024/3/15 20:13, Ard Biesheuvel wrote:
> On Fri, 15 Mar 2024 at 13:10, liuyuntao (F) <[email protected]> wrote:
>>
>>
>>
>> On 2024/3/15 19:51, Arnd Bergmann wrote:
>>> On Fri, Mar 15, 2024, at 12:48, liuyuntao (F) wrote:
>>>> On 2024/3/15 18:46, Ard Biesheuvel wrote:
>>>>> @@ -28,6 +28,7 @@
>>>>> -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
>>>>> -DEFI_HAVE_STRCMP -fno-builtin -fpic \
>>>>> $(call cc-option,-mno-single-pic-base)
>>>>> +cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(CFLAGS-y))
>>>>> cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
>>>>> cflags-$(CONFIG_LOONGARCH) += -fpie
>>>>
>>>> Another error:
>>>> cannot initialize array of ‘short unsigned int’ from a string literal
>>>> with type array of ‘unsigned int’
>>>> 17 | static const efi_char16_t shim_MokSBState_name[] = L"MokSBStateRT";
>>>
>>> The line sets cflags-y to an empty string.
>>>
>>> It probably should have been
>>>
>>> cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(cflags-y))
>>>
>>> (small cflags instead of CFLAGS).
>>>
>
> Oops indeed.
>
>> Oh, my mistake, after fixed this bug, still this error:
>>> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_loglevel' from `drivers/firmware/efi/libstub/printk.stub.o' being placed in section `.data.efi_loglevel'
>>> arm-linux-gnueabi-ld: warning: orphan section `.data.screen_info_guid' from `drivers/firmware/efi/libstub/screen_info.stub.o' being placed in section `.data.screen_info_guid'
>>> arm-linux-gnueabi-ld: warning: orphan section `.data.cpu_state_guid' from `drivers/firmware/efi/libstub/arm32-stub.stub.o' being placed in section `.data.cpu_state_guid'
>>> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_nokaslr' from `drivers/firmware/efi/libstub/efi-stub-helper.stub.o' being placed in section `.data.efi_nokaslr'
>>
>> The -fdata-sections option is present in the KBUILD_CFLAGS_KERNEL
>> variable; altering cflags-y only affect the KBUILD_CFLAGS variable.
>> It seems that the -fdata-sections option needs to be removed from the
>> KBUILD_CFLAGS_KERNEL variable.
>
> Indeed.
>
> So
>
> KBUILD_CFLAGS_KERNEL := $(filter-out -fdata-sections,$(KBUILD_CFLAGS_KERNEL))
>
> (assuming I got it right this time without build testing)
Um, it not worked,too, same error.
> --- a/drivers/firmware/efi/libstub/Makefile
> +++ b/drivers/firmware/efi/libstub/Makefile
> @@ -28,6 +28,7 @@ cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \
> -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
> -DEFI_HAVE_STRCMP -fno-builtin -fpic \
> $(call cc-option,-mno-single-pic-base)
> +KBUILD_CFLAGS_KERNE := $(filter-out -fdata-sections, $(KBUILD_CFLAGS_KERNE))
> cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
> cflags-$(CONFIG_LOONGARCH) += -fpie
On Fri, 15 Mar 2024 at 13:10, liuyuntao (F) <[email protected]> wrote:
>
>
>
> On 2024/3/15 19:51, Arnd Bergmann wrote:
> > On Fri, Mar 15, 2024, at 12:48, liuyuntao (F) wrote:
> >> On 2024/3/15 18:46, Ard Biesheuvel wrote:
> >>> @@ -28,6 +28,7 @@
> >>> -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
> >>> -DEFI_HAVE_STRCMP -fno-builtin -fpic \
> >>> $(call cc-option,-mno-single-pic-base)
> >>> +cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(CFLAGS-y))
> >>> cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
> >>> cflags-$(CONFIG_LOONGARCH) += -fpie
> >>
> >> Another error:
> >> cannot initialize array of ‘short unsigned int’ from a string literal
> >> with type array of ‘unsigned int’
> >> 17 | static const efi_char16_t shim_MokSBState_name[] = L"MokSBStateRT";
> >
> > The line sets cflags-y to an empty string.
> >
> > It probably should have been
> >
> > cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(cflags-y))
> >
> > (small cflags instead of CFLAGS).
> >
Oops indeed.
> Oh, my mistake, after fixed this bug, still this error:
> > arm-linux-gnueabi-ld: warning: orphan section `.data.efi_loglevel' from `drivers/firmware/efi/libstub/printk.stub.o' being placed in section `.data.efi_loglevel'
> > arm-linux-gnueabi-ld: warning: orphan section `.data.screen_info_guid' from `drivers/firmware/efi/libstub/screen_info.stub.o' being placed in section `.data.screen_info_guid'
> > arm-linux-gnueabi-ld: warning: orphan section `.data.cpu_state_guid' from `drivers/firmware/efi/libstub/arm32-stub.stub.o' being placed in section `.data.cpu_state_guid'
> > arm-linux-gnueabi-ld: warning: orphan section `.data.efi_nokaslr' from `drivers/firmware/efi/libstub/efi-stub-helper.stub.o' being placed in section `.data.efi_nokaslr'
>
> The -fdata-sections option is present in the KBUILD_CFLAGS_KERNEL
> variable; altering cflags-y only affect the KBUILD_CFLAGS variable.
> It seems that the -fdata-sections option needs to be removed from the
> KBUILD_CFLAGS_KERNEL variable.
Indeed.
So
KBUILD_CFLAGS_KERNEL := $(filter-out -fdata-sections,$(KBUILD_CFLAGS_KERNEL))
(assuming I got it right this time without build testing)
On Fri, 15 Mar 2024 at 13:22, liuyuntao (F) <[email protected]> wrote:
>
>
>
> On 2024/3/15 20:13, Ard Biesheuvel wrote:
> > On Fri, 15 Mar 2024 at 13:10, liuyuntao (F) <[email protected]> wrote:
> >>
> >>
> >>
> >> On 2024/3/15 19:51, Arnd Bergmann wrote:
> >>> On Fri, Mar 15, 2024, at 12:48, liuyuntao (F) wrote:
> >>>> On 2024/3/15 18:46, Ard Biesheuvel wrote:
> >>>>> @@ -28,6 +28,7 @@
> >>>>> -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
> >>>>> -DEFI_HAVE_STRCMP -fno-builtin -fpic \
> >>>>> $(call cc-option,-mno-single-pic-base)
> >>>>> +cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(CFLAGS-y))
> >>>>> cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
> >>>>> cflags-$(CONFIG_LOONGARCH) += -fpie
> >>>>
> >>>> Another error:
> >>>> cannot initialize array of ‘short unsigned int’ from a string literal
> >>>> with type array of ‘unsigned int’
> >>>> 17 | static const efi_char16_t shim_MokSBState_name[] = L"MokSBStateRT";
> >>>
> >>> The line sets cflags-y to an empty string.
> >>>
> >>> It probably should have been
> >>>
> >>> cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(cflags-y))
> >>>
> >>> (small cflags instead of CFLAGS).
> >>>
> >
> > Oops indeed.
> >
> >> Oh, my mistake, after fixed this bug, still this error:
> >>> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_loglevel' from `drivers/firmware/efi/libstub/printk.stub.o' being placed in section `.data.efi_loglevel'
> >>> arm-linux-gnueabi-ld: warning: orphan section `.data.screen_info_guid' from `drivers/firmware/efi/libstub/screen_info.stub.o' being placed in section `.data.screen_info_guid'
> >>> arm-linux-gnueabi-ld: warning: orphan section `.data.cpu_state_guid' from `drivers/firmware/efi/libstub/arm32-stub.stub.o' being placed in section `.data.cpu_state_guid'
> >>> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_nokaslr' from `drivers/firmware/efi/libstub/efi-stub-helper.stub.o' being placed in section `.data.efi_nokaslr'
> >>
> >> The -fdata-sections option is present in the KBUILD_CFLAGS_KERNEL
> >> variable; altering cflags-y only affect the KBUILD_CFLAGS variable.
> >> It seems that the -fdata-sections option needs to be removed from the
> >> KBUILD_CFLAGS_KERNEL variable.
> >
> > Indeed.
> >
> > So
> >
> > KBUILD_CFLAGS_KERNEL := $(filter-out -fdata-sections,$(KBUILD_CFLAGS_KERNEL))
> >
> > (assuming I got it right this time without build testing)
>
> Um, it not worked,too, same error.
Aren't you missing a 'L' ?
> > --- a/drivers/firmware/efi/libstub/Makefile
> > +++ b/drivers/firmware/efi/libstub/Makefile
> > @@ -28,6 +28,7 @@ cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \
> > -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
> >
> > ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
> > KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections
> > KBUILD_RUSTFLAGS_KERNEL += -Zfunction-sections=y
> > LDFLAGS_vmlinux += --gc-sections
> > endif
>
> -DEFI_HAVE_STRCMP -fno-builtin -fpic \
> > $(call cc-option,-mno-single-pic-base)
> > +KBUILD_CFLAGS_KERNE := $(filter-out -fdata-sections, $(KBUILD_CFLAGS_KERNE))
> > cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
> > cflags-$(CONFIG_LOONGARCH) += -fpie
>
>
On 2024/3/15 20:46, Ard Biesheuvel wrote:
> On Fri, 15 Mar 2024 at 13:22, liuyuntao (F) <[email protected]> wrote:
>>
>>
>>
>> On 2024/3/15 20:13, Ard Biesheuvel wrote:
>>> On Fri, 15 Mar 2024 at 13:10, liuyuntao (F) <[email protected]> wrote:
>>>>
>>>>
>>>>
>>>> On 2024/3/15 19:51, Arnd Bergmann wrote:
>>>>> On Fri, Mar 15, 2024, at 12:48, liuyuntao (F) wrote:
>>>>>> On 2024/3/15 18:46, Ard Biesheuvel wrote:
>>>>>>> @@ -28,6 +28,7 @@
>>>>>>> -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
>>>>>>> -DEFI_HAVE_STRCMP -fno-builtin -fpic \
>>>>>>> $(call cc-option,-mno-single-pic-base)
>>>>>>> +cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(CFLAGS-y))
>>>>>>> cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
>>>>>>> cflags-$(CONFIG_LOONGARCH) += -fpie
>>>>>>
>>>>>> Another error:
>>>>>> cannot initialize array of ‘short unsigned int’ from a string literal
>>>>>> with type array of ‘unsigned int’
>>>>>> 17 | static const efi_char16_t shim_MokSBState_name[] = L"MokSBStateRT";
>>>>>
>>>>> The line sets cflags-y to an empty string.
>>>>>
>>>>> It probably should have been
>>>>>
>>>>> cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(cflags-y))
>>>>>
>>>>> (small cflags instead of CFLAGS).
>>>>>
>>>
>>> Oops indeed.
>>>
>>>> Oh, my mistake, after fixed this bug, still this error:
>>>>> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_loglevel' from `drivers/firmware/efi/libstub/printk.stub.o' being placed in section `.data.efi_loglevel'
>>>>> arm-linux-gnueabi-ld: warning: orphan section `.data.screen_info_guid' from `drivers/firmware/efi/libstub/screen_info.stub.o' being placed in section `.data.screen_info_guid'
>>>>> arm-linux-gnueabi-ld: warning: orphan section `.data.cpu_state_guid' from `drivers/firmware/efi/libstub/arm32-stub.stub.o' being placed in section `.data.cpu_state_guid'
>>>>> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_nokaslr' from `drivers/firmware/efi/libstub/efi-stub-helper.stub.o' being placed in section `.data.efi_nokaslr'
>>>>
>>>> The -fdata-sections option is present in the KBUILD_CFLAGS_KERNEL
>>>> variable; altering cflags-y only affect the KBUILD_CFLAGS variable.
>>>> It seems that the -fdata-sections option needs to be removed from the
>>>> KBUILD_CFLAGS_KERNEL variable.
>>>
>>> Indeed.
>>>
>>> So
>>>
>>> KBUILD_CFLAGS_KERNEL := $(filter-out -fdata-sections,$(KBUILD_CFLAGS_KERNEL))
>>>
>>> (assuming I got it right this time without build testing)
>>
>> Um, it not worked,too, same error.
>
> Aren't you missing a 'L' ?
>
>>> --- a/drivers/firmware/efi/libstub/Makefile
>>> +++ b/drivers/firmware/efi/libstub/Makefile
>>> @@ -28,6 +28,7 @@ cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \
>>> -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
>>>
>
>>> ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
>>> KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections
>>> KBUILD_RUSTFLAGS_KERNEL += -Zfunction-sections=y
>>> LDFLAGS_vmlinux += --gc-sections
>>> endif
>>
>> -DEFI_HAVE_STRCMP -fno-builtin -fpic \
>>> $(call cc-option,-mno-single-pic-base)
>>> +KBUILD_CFLAGS_KERNE := $(filter-out -fdata-sections, $(KBUILD_CFLAGS_KERNE))
>>> cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
>>> cflags-$(CONFIG_LOONGARCH) += -fpie
>>
>>
Sorry, I was too careless.
How about reset KBUILD_CFLAGS_KERNEL?
> +# KBUILD_CFLAGS_KERNEL is is set by CONFIG_LD_DEAD_CODE_DATA_ELIMINATION,
> +# not need here, just reset it.
> +KBUILD_CFLAGS_KERNEL :=
> +
> # non-x86 reuses KBUILD_CFLAGS, x86 does not
> cflags-y := $(KBUILD_CFLAGS)
On Fri, 15 Mar 2024 at 13:52, liuyuntao (F) <[email protected]> wrote:
>
>
>
> On 2024/3/15 20:46, Ard Biesheuvel wrote:
> > On Fri, 15 Mar 2024 at 13:22, liuyuntao (F) <[email protected]> wrote:
> >>
> >>
> >>
> >> On 2024/3/15 20:13, Ard Biesheuvel wrote:
> >>> On Fri, 15 Mar 2024 at 13:10, liuyuntao (F) <[email protected]> wrote:
> >>>>
> >>>>
> >>>>
> >>>> On 2024/3/15 19:51, Arnd Bergmann wrote:
> >>>>> On Fri, Mar 15, 2024, at 12:48, liuyuntao (F) wrote:
> >>>>>> On 2024/3/15 18:46, Ard Biesheuvel wrote:
> >>>>>>> @@ -28,6 +28,7 @@
> >>>>>>> -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
> >>>>>>> -DEFI_HAVE_STRCMP -fno-builtin -fpic \
> >>>>>>> $(call cc-option,-mno-single-pic-base)
> >>>>>>> +cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(CFLAGS-y))
> >>>>>>> cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
> >>>>>>> cflags-$(CONFIG_LOONGARCH) += -fpie
> >>>>>>
> >>>>>> Another error:
> >>>>>> cannot initialize array of ‘short unsigned int’ from a string literal
> >>>>>> with type array of ‘unsigned int’
> >>>>>> 17 | static const efi_char16_t shim_MokSBState_name[] = L"MokSBStateRT";
> >>>>>
> >>>>> The line sets cflags-y to an empty string.
> >>>>>
> >>>>> It probably should have been
> >>>>>
> >>>>> cflags-$(CONFIG_ARM) := $(filter-out -fdata-sections, $(cflags-y))
> >>>>>
> >>>>> (small cflags instead of CFLAGS).
> >>>>>
> >>>
> >>> Oops indeed.
> >>>
> >>>> Oh, my mistake, after fixed this bug, still this error:
> >>>>> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_loglevel' from `drivers/firmware/efi/libstub/printk.stub.o' being placed in section `data.efi_loglevel'
> >>>>> arm-linux-gnueabi-ld: warning: orphan section `.data.screen_info_guid' from `drivers/firmware/efi/libstub/screen_info.stub.o' being placed in section `.data.screen_info_guid'
> >>>>> arm-linux-gnueabi-ld: warning: orphan section `.data.cpu_state_guid' from `drivers/firmware/efi/libstub/arm32-stub.stub.o' being placed in section `.data.cpu_state_guid'
> >>>>> arm-linux-gnueabi-ld: warning: orphan section `.data.efi_nokaslr' from `drivers/firmware/efi/libstub/efi-stub-helper.stub.o' being placed in section `.data.efi_nokaslr'
> >>>>
> >>>> The -fdata-sections option is present in the KBUILD_CFLAGS_KERNEL
> >>>> variable; altering cflags-y only affect the KBUILD_CFLAGS variable.
> >>>> It seems that the -fdata-sections option needs to be removed from the
> >>>> KBUILD_CFLAGS_KERNEL variable.
> >>>
> >>> Indeed.
> >>>
> >>> So
> >>>
> >>> KBUILD_CFLAGS_KERNEL := $(filter-out -fdata-sections,$(KBUILD_CFLAGS_KERNEL))
> >>>
> >>> (assuming I got it right this time without build testing)
> >>
> >> Um, it not worked,too, same error.
> >
> > Aren't you missing a 'L' ?
> >
> >>> --- a/drivers/firmware/efi/libstub/Makefile
> >>> +++ b/drivers/firmware/efi/libstub/Makefile
> >>> @@ -28,6 +28,7 @@ cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \
> >>> -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \
> >>>
> >
> >>> ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
> >>> KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections
> >>> KBUILD_RUSTFLAGS_KERNEL += -Zfunction-sections=y
> >>> LDFLAGS_vmlinux += --gc-sections
> >>> endif
> >>
> >> -DEFI_HAVE_STRCMP -fno-builtin -fpic \
> >>> $(call cc-option,-mno-single-pic-base)
> >>> +KBUILD_CFLAGS_KERNE := $(filter-out -fdata-sections, $(KBUILD_CFLAGS_KERNE))
> >>> cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax
> >>> cflags-$(CONFIG_LOONGARCH) += -fpie
> >>
> >>
> Sorry, I was too careless.
> How about reset KBUILD_CFLAGS_KERNEL?
>
No, that is not the solution.
Either avoid setting -fdata-sections altogether, or filter it out.
> > +# KBUILD_CFLAGS_KERNEL is is set by CONFIG_LD_DEAD_CODE_DATA_ELIMINATION,
> > +# not need here, just reset it.
> > +KBUILD_CFLAGS_KERNEL :=
> > +
> > # non-x86 reuses KBUILD_CFLAGS, x86 does not
> > cflags-y := $(KBUILD_CFLAGS)
>