linux-kernel - Re: [PATCH V2] LoongArch: Fix module relocation error with binutils 2.41

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Message-ID: <CAAhV-H6JTbuK+ypvrUi21KOYcTOWmTKbwxK_D8M5y9XaXfJK4A@mail.gmail.com>
Date:   Thu, 10 Aug 2023 11:34:29 +0800
From:   Huacai Chen <chenhuacai@...nel.org>
To:     Xi Ruoyao <xry111@...111.site>
Cc:     Huacai Chen <chenhuacai@...ngson.cn>,
        Arnd Bergmann <arnd@...db.de>, loongarch@...ts.linux.dev,
        linux-arch@...r.kernel.org, Xuefeng Li <lixuefeng@...ngson.cn>,
        Guo Ren <guoren@...nel.org>, Xuerui Wang <kernel@...0n.name>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        linux-kernel@...r.kernel.org, loongson-kernel@...ts.loongnix.cn,
        WANG Xuerui <git@...0n.name>, stable@...r.kernel.org
Subject: Re: [PATCH V2] LoongArch: Fix module relocation error with binutils 2.41

Hi, Ruoyao,

On Thu, Aug 10, 2023 at 11:21 AM Xi Ruoyao <xry111@...111.site> wrote:
>
> On Thu, 2023-08-10 at 11:20 +0800, Xi Ruoyao wrote:
> > Can we backport this patch into stable?  It fixes a build error with
> > binutils >= 2.41.
>
> Correction: not a build error, but all modules won't load if built with
> binutils >= 2.41 without the patch.
Generally we can backport, but I don't think there are users who use
the old kernels. :)

Huacai
>
> > On Mon, 2023-07-10 at 13:00 +0800, Huacai Chen wrote:
> > > Binutils 2.41 enables linker relaxation by default, but the kernel
> > > module loader doesn't support that, so just disable it. Otherwise we
> > > get such an error when loading modules:
> > >
> > > "Unknown relocation type 102"
> > >
> > > As an alternative, we could add linker relaxation support in the kernel
> > > module loader. But it 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.
> > >
> > > Reviewed-by: WANG Xuerui <git@...0n.name>
> > > Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
> > > ---
> > >  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
> >
>
> --
> Xi Ruoyao <xry111@...111.site>
> School of Aerospace Science and Technology, Xidian University