2023-07-10 05:04:37

by Huacai Chen

Subject: [PATCH] LoongArch: Fix module relocation error with binutils 2.41

Binutils 2.41 enable linker relaxation by default, but kernel module
loader doesn't support that, so disable it. Otherwise we get such an
error when loading modules: "Unknown relocation type 102".

Signed-off-by: Huacai Chen <[email protected]>
---
arch/loongarch/Makefile | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
index 09ba338a64de..7466d3b15db8 100644
--- a/arch/loongarch/Makefile
+++ b/arch/loongarch/Makefile
@@ -68,6 +68,8 @@ LDFLAGS_vmlinux += -static -n -nostdlib
ifdef CONFIG_AS_HAS_EXPLICIT_RELOCS
cflags-y += $(call cc-option,-mexplicit-relocs)
KBUILD_CFLAGS_KERNEL += $(call cc-option,-mdirect-extern-access)
+KBUILD_AFLAGS_MODULE += $(call cc-option,-mno-relax) $(call cc-option,-Wa$(comma)-mno-relax)
+KBUILD_CFLAGS_MODULE += $(call cc-option,-mno-relax) $(call cc-option,-Wa$(comma)-mno-relax)
else
cflags-y += $(call cc-option,-mno-explicit-relocs)
KBUILD_AFLAGS_KERNEL += -Wa,-mla-global-with-pcrel
--
2.39.3

2023-07-10 05:04:50

by WANG Xuerui

Subject: Re: [PATCH] LoongArch: Fix module relocation error with binutils 2.41

On 2023/7/10 12:29, Huacai Chen wrote:
> Binutils 2.41 enable linker relaxation by default, but kernel module

"enables" / "will enable"

> loader doesn't support that, so disable it. Otherwise we get such an
> error when loading modules: "Unknown relocation type 102".

IMO it could be better to also justify the disabling (instead of adding
proper support): linker relaxation is relatively large complexity that
may or may not bring a similar gain, and we don't really want to include
this linker pass in the kernel.

>
> Signed-off-by: Huacai Chen <[email protected]>
> ---
> arch/loongarch/Makefile | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
> index 09ba338a64de..7466d3b15db8 100644
> --- a/arch/loongarch/Makefile
> +++ b/arch/loongarch/Makefile
> @@ -68,6 +68,8 @@ LDFLAGS_vmlinux += -static -n -nostdlib
> ifdef CONFIG_AS_HAS_EXPLICIT_RELOCS
> cflags-y += $(call cc-option,-mexplicit-relocs)
> KBUILD_CFLAGS_KERNEL += $(call cc-option,-mdirect-extern-access)
> +KBUILD_AFLAGS_MODULE += $(call cc-option,-mno-relax) $(call cc-option,-Wa$(comma)-mno-relax)
> +KBUILD_CFLAGS_MODULE += $(call cc-option,-mno-relax) $(call cc-option,-Wa$(comma)-mno-relax)
> else
> cflags-y += $(call cc-option,-mno-explicit-relocs)
> KBUILD_AFLAGS_KERNEL += -Wa,-mla-global-with-pcrel

The code changes are good. With the commit message improved:

Reviewed-by: WANG Xuerui <[email protected]>

--
WANG "xen0n" Xuerui

Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/

2023-07-10 05:32:03

by Huacai Chen

Subject: Re: [PATCH] LoongArch: Fix module relocation error with binutils 2.41

On Mon, Jul 10, 2023 at 12:45 PM WANG Xuerui <[email protected]> wrote:
>
> On 2023/7/10 12:29, Huacai Chen wrote:
> > Binutils 2.41 enable linker relaxation by default, but kernel module
>
> "enables" / "will enable"
>
> > loader doesn't support that, so disable it. Otherwise we get such an
> > error when loading modules: "Unknown relocation type 102".
>
> IMO it could be better to also justify the disabling (instead of adding
> proper support): linker relaxation is relatively large complexity that
> may or may not bring a similar gain, and we don't really want to include
> this linker pass in the kernel.
OK, thanks.

Huacai
>
> >
> > Signed-off-by: Huacai Chen <[email protected]>
> > ---
> > arch/loongarch/Makefile | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
> > index 09ba338a64de..7466d3b15db8 100644
> > --- a/arch/loongarch/Makefile
> > +++ b/arch/loongarch/Makefile
> > @@ -68,6 +68,8 @@ LDFLAGS_vmlinux += -static -n -nostdlib
> > ifdef CONFIG_AS_HAS_EXPLICIT_RELOCS
> > cflags-y += $(call cc-option,-mexplicit-relocs)
> > KBUILD_CFLAGS_KERNEL += $(call cc-option,-mdirect-extern-access)
> > +KBUILD_AFLAGS_MODULE += $(call cc-option,-mno-relax) $(call cc-option,-Wa$(comma)-mno-relax)
> > +KBUILD_CFLAGS_MODULE += $(call cc-option,-mno-relax) $(call cc-option,-Wa$(comma)-mno-relax)
> > else
> > cflags-y += $(call cc-option,-mno-explicit-relocs)
> > KBUILD_AFLAGS_KERNEL += -Wa,-mla-global-with-pcrel
>
> The code changes are good. With the commit message improved:
>
> Reviewed-by: WANG Xuerui <[email protected]>
>
> --
> WANG "xen0n" Xuerui
>
> Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/
>
>