[PATCH] ARM: Link with '-z norelro'

[Nick Desaulniers]

On Mon, Nov 9, 2020 at 5:56 PM Nathan Chancellor
<natechancellor at gmail.com> wrote:
>
> When linking a multi_v7_defconfig + CONFIG_KASAN=y kernel with
> LD=ld.lld, the following error occurs:
>
> $ make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- LLVM=1 zImage
> ld.lld: error: section: .exit.data is not contiguous with other relro sections
>
> LLD defaults to '-z relro', which is unneeded for the kernel because
> program headers are not used nor is there any position independent code
> generation or linking for ARM. Add '-z norelro' to LDFLAGS_vmlinux to
> avoid this error.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/1189
> Signed-off-by: Nathan Chancellor <natechancellor at gmail.com>

Reviewed-by: Nick Desaulniers <ndesaulniers at google.com>
Tested-by: Nick Desaulniers <ndesaulniers at google.com>

Thanks for the patch!
See also: https://lore.kernel.org/linux-arm-kernel/20201016175339.2429280-1-ndesaulniers@google.com/
where we just did the same thing for aarch64.

> ---
>  arch/arm/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/Makefile b/arch/arm/Makefile
> index 4d76eab2b22d..3c0a64cefe52 100644
> --- a/arch/arm/Makefile
> +++ b/arch/arm/Makefile
> @@ -10,7 +10,7 @@
>  #
>  # Copyright (C) 1995-2001 by Russell King
>
> -LDFLAGS_vmlinux        := --no-undefined -X --pic-veneer
> +LDFLAGS_vmlinux        := --no-undefined -X --pic-veneer -z norelro
>  ifeq ($(CONFIG_CPU_ENDIAN_BE8),y)
>  LDFLAGS_vmlinux        += --be8
>  KBUILD_LDFLAGS_MODULE  += --be8
>
> base-commit: a0796429c6abecf8afaeb65b1db286af1fb579d1
> --
> 2.29.2


-- 
Thanks,
~Nick Desaulniers