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[RFC PATCH 4/4] LoongArch: Remove -fno-jump-tables for objtool

Tiezhu Yang posted 4 patches 1 year, 7 months ago
There is a newer version of this series
[RFC PATCH 4/4] LoongArch: Remove -fno-jump-tables for objtool
Posted by Tiezhu Yang 1 year, 7 months ago 
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 arch/loongarch/Kconfig  | 8 +++++++-
 arch/loongarch/Makefile | 6 ++----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index ddc042895d01..57f28450a2ed 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -143,7 +143,7 @@ config LOONGARCH
 	select HAVE_LIVEPATCH
 	select HAVE_MOD_ARCH_SPECIFIC
 	select HAVE_NMI
-	select HAVE_OBJTOOL if AS_HAS_EXPLICIT_RELOCS && AS_HAS_THIN_ADD_SUB && !CC_IS_CLANG
+	select HAVE_OBJTOOL if TOOLCHAIN_SUPPORTS_OBJTOOL && !CC_IS_CLANG
 	select HAVE_PCI
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_REGS
@@ -276,6 +276,12 @@ config AS_HAS_LBT_EXTENSION
 config AS_HAS_LVZ_EXTENSION
 	def_bool $(as-instr,hvcl 0)
 
+config CC_HAS_ANNOTATE_TABLEJUMP
+	def_bool $(cc-option,-mannotate-tablejump)
+
+config TOOLCHAIN_SUPPORTS_OBJTOOL
+	def_bool AS_HAS_EXPLICIT_RELOCS && AS_HAS_THIN_ADD_SUB && CC_HAS_ANNOTATE_TABLEJUMP
+
 menu "Kernel type and options"
 
 source "kernel/Kconfig.hz"
diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
index 8674e7e24c4a..186c75c80daa 100644
--- a/arch/loongarch/Makefile
+++ b/arch/loongarch/Makefile
@@ -99,10 +99,8 @@ KBUILD_AFLAGS			+= $(call cc-option,-mno-relax) $(call cc-option,-Wa$(comma)-mno
 KBUILD_CFLAGS			+= $(call cc-option,-mno-relax) $(call cc-option,-Wa$(comma)-mno-relax)
 KBUILD_AFLAGS			+= $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)-mthin-add-sub)
 KBUILD_CFLAGS			+= $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)-mthin-add-sub)
-
-ifdef CONFIG_OBJTOOL
-KBUILD_CFLAGS			+= -fno-jump-tables
-endif
+KBUILD_AFLAGS			+= $(call cc-option,-mannotate-tablejump) $(call cc-option,-Wa$(comma)-mannotate-tablejump)
+KBUILD_CFLAGS			+= $(call cc-option,-mannotate-tablejump) $(call cc-option,-Wa$(comma)-mannotate-tablejump)
 
 KBUILD_RUSTFLAGS		+= --target=loongarch64-unknown-none-softfloat
 KBUILD_RUSTFLAGS_MODULE		+= -Crelocation-model=pic
-- 
2.42.0
Re: [RFC PATCH 4/4] LoongArch: Remove -fno-jump-tables for objtool
Posted by Xi Ruoyao 1 year, 7 months ago 
On Fri, 2024-07-12 at 17:15 +0800, Tiezhu Yang wrote:
> -ifdef CONFIG_OBJTOOL
> -KBUILD_CFLAGS			+= -fno-jump-tables
> -endif
> +KBUILD_AFLAGS			+= $(call cc-option,-mannotate-tablejump) $(call cc-option,-Wa$(comma)-mannotate-tablejump)
> +KBUILD_CFLAGS			+= $(call cc-option,-mannotate-tablejump) $(call cc-option,-Wa$(comma)-mannotate-tablejump)

KBUILD_AFLAGS isn't needed, and $(call cc-option,-Wa$(comma)-mannotate-
tablejump) will always expand to nothing because the assembler does not
have -mannotate-tablejump.

The assembler never creates a jump table itself.

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University
Re: [RFC PATCH 4/4] LoongArch: Remove -fno-jump-tables for objtool
Posted by Xi Ruoyao 1 year, 7 months ago 
On Fri, 2024-07-12 at 17:49 +0800, Xi Ruoyao wrote:
> On Fri, 2024-07-12 at 17:15 +0800, Tiezhu Yang wrote:
> > -ifdef CONFIG_OBJTOOL
> > -KBUILD_CFLAGS			+= -fno-jump-tables
> > -endif
> > +KBUILD_AFLAGS			+= $(call cc-option,-mannotate-tablejump) $(call cc-option,-Wa$(comma)-mannotate-tablejump)
> > +KBUILD_CFLAGS			+= $(call cc-option,-mannotate-tablejump) $(call cc-option,-Wa$(comma)-mannotate-tablejump)
> 
> KBUILD_AFLAGS isn't needed, and $(call cc-option,-Wa$(comma)-mannotate-
> tablejump) will always expand to nothing because the assembler does not
> have -mannotate-tablejump.
> 
> The assembler never creates a jump table itself.

BTW have you discussed with Lulu about the -mannotate-tablejump patch? 
I guess maybe an intra-Loongson discussion would be helpful.

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University
Re: [RFC PATCH 4/4] LoongArch: Remove -fno-jump-tables for objtool
Posted by Tiezhu Yang 1 year, 6 months ago 
On 07/13/2024 05:10 PM, Xi Ruoyao wrote:
> On Fri, 2024-07-12 at 17:49 +0800, Xi Ruoyao wrote:
>> On Fri, 2024-07-12 at 17:15 +0800, Tiezhu Yang wrote:
>>> -ifdef CONFIG_OBJTOOL
>>> -KBUILD_CFLAGS			+= -fno-jump-tables
>>> -endif
>>> +KBUILD_AFLAGS			+= $(call cc-option,-mannotate-tablejump) $(call cc-option,-Wa$(comma)-mannotate-tablejump)
>>> +KBUILD_CFLAGS			+= $(call cc-option,-mannotate-tablejump) $(call cc-option,-Wa$(comma)-mannotate-tablejump)
>>
>> KBUILD_AFLAGS isn't needed, and $(call cc-option,-Wa$(comma)-mannotate-
>> tablejump) will always expand to nothing because the assembler does not
>> have -mannotate-tablejump.
>>
>> The assembler never creates a jump table itself.

Thanks, you are right, I will modify it in the formal v1 series.

> BTW have you discussed with Lulu about the -mannotate-tablejump patch?
> I guess maybe an intra-Loongson discussion would be helpful.

Yes, I have discussed with Loongson compiler team some days ago
and will discuss more to reach an agreement in the next few days.

Thanks,
Tiezhu
Re: [RFC PATCH 4/4] LoongArch: Remove -fno-jump-tables for objtool
Posted by Huacai Chen 1 year, 7 months ago 
Hi, Tiezhu,

On Fri, Jul 12, 2024 at 5:15 PM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
>  arch/loongarch/Kconfig  | 8 +++++++-
>  arch/loongarch/Makefile | 6 ++----
>  2 files changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index ddc042895d01..57f28450a2ed 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -143,7 +143,7 @@ config LOONGARCH
>         select HAVE_LIVEPATCH
>         select HAVE_MOD_ARCH_SPECIFIC
>         select HAVE_NMI
> -       select HAVE_OBJTOOL if AS_HAS_EXPLICIT_RELOCS && AS_HAS_THIN_ADD_SUB && !CC_IS_CLANG
> +       select HAVE_OBJTOOL if TOOLCHAIN_SUPPORTS_OBJTOOL && !CC_IS_CLANG
>         select HAVE_PCI
>         select HAVE_PERF_EVENTS
>         select HAVE_PERF_REGS
> @@ -276,6 +276,12 @@ config AS_HAS_LBT_EXTENSION
>  config AS_HAS_LVZ_EXTENSION
>         def_bool $(as-instr,hvcl 0)
>
> +config CC_HAS_ANNOTATE_TABLEJUMP
> +       def_bool $(cc-option,-mannotate-tablejump)
> +
> +config TOOLCHAIN_SUPPORTS_OBJTOOL
> +       def_bool AS_HAS_EXPLICIT_RELOCS && AS_HAS_THIN_ADD_SUB && CC_HAS_ANNOTATE_TABLEJUMP
Can AS_HAS_THIN_ADD_SUB be removed now?

Huacai

> +
>  menu "Kernel type and options"
>
>  source "kernel/Kconfig.hz"
> diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
> index 8674e7e24c4a..186c75c80daa 100644
> --- a/arch/loongarch/Makefile
> +++ b/arch/loongarch/Makefile
> @@ -99,10 +99,8 @@ KBUILD_AFLAGS                        += $(call cc-option,-mno-relax) $(call cc-option,-Wa$(comma)-mno
>  KBUILD_CFLAGS                  += $(call cc-option,-mno-relax) $(call cc-option,-Wa$(comma)-mno-relax)
>  KBUILD_AFLAGS                  += $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)-mthin-add-sub)
>  KBUILD_CFLAGS                  += $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)-mthin-add-sub)
> -
> -ifdef CONFIG_OBJTOOL
> -KBUILD_CFLAGS                  += -fno-jump-tables
> -endif
> +KBUILD_AFLAGS                  += $(call cc-option,-mannotate-tablejump) $(call cc-option,-Wa$(comma)-mannotate-tablejump)
> +KBUILD_CFLAGS                  += $(call cc-option,-mannotate-tablejump) $(call cc-option,-Wa$(comma)-mannotate-tablejump)
>
>  KBUILD_RUSTFLAGS               += --target=loongarch64-unknown-none-softfloat
>  KBUILD_RUSTFLAGS_MODULE                += -Crelocation-model=pic
> --
> 2.42.0
>
>
Re: [RFC PATCH 4/4] LoongArch: Remove -fno-jump-tables for objtool
Posted by Tiezhu Yang 1 year, 6 months ago 
On 07/12/2024 05:40 PM, Huacai Chen wrote:
> Hi, Tiezhu,
>
> On Fri, Jul 12, 2024 at 5:15 PM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>>
>> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
>> ---
>>  arch/loongarch/Kconfig  | 8 +++++++-
>>  arch/loongarch/Makefile | 6 ++----
>>  2 files changed, 9 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
>> index ddc042895d01..57f28450a2ed 100644
>> --- a/arch/loongarch/Kconfig
>> +++ b/arch/loongarch/Kconfig
>> @@ -143,7 +143,7 @@ config LOONGARCH
>>         select HAVE_LIVEPATCH
>>         select HAVE_MOD_ARCH_SPECIFIC
>>         select HAVE_NMI
>> -       select HAVE_OBJTOOL if AS_HAS_EXPLICIT_RELOCS && AS_HAS_THIN_ADD_SUB && !CC_IS_CLANG
>> +       select HAVE_OBJTOOL if TOOLCHAIN_SUPPORTS_OBJTOOL && !CC_IS_CLANG
>>         select HAVE_PCI
>>         select HAVE_PERF_EVENTS
>>         select HAVE_PERF_REGS
>> @@ -276,6 +276,12 @@ config AS_HAS_LBT_EXTENSION
>>  config AS_HAS_LVZ_EXTENSION
>>         def_bool $(as-instr,hvcl 0)
>>
>> +config CC_HAS_ANNOTATE_TABLEJUMP
>> +       def_bool $(cc-option,-mannotate-tablejump)
>> +
>> +config TOOLCHAIN_SUPPORTS_OBJTOOL
>> +       def_bool AS_HAS_EXPLICIT_RELOCS && AS_HAS_THIN_ADD_SUB && CC_HAS_ANNOTATE_TABLEJUMP
> Can AS_HAS_THIN_ADD_SUB be removed now?

If the following patch can be accepted, then objtool will not rely
on AS_HAS_THIN_ADD_SUB, I will try to send this patch again.

objtool: Add skipped member in struct reloc
https://lore.kernel.org/loongarch/1690272910-11869-6-git-send-email-yangtiezhu@loongson.cn/

Thanks,
Tiezhu

Patchew 2.1-devel-b67e4c2

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