On Thu, Jun 24, 2021 at 2:09 AM Jisheng Zhang
<Jisheng.Zhang@xxxxxxxxxxxxx> wrote:
>
> From: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
>
> commit 311bea3cb9ee20ef150ca76fc60a592bf6b159f5 upstream.
>
> With GNU binutils 2.35+, linking with BFD produces warnings for vmlinux:
> aarch64-linux-gnu-ld: warning: -z norelro ignored
>
> BFD can produce this warning when the target emulation mode does not
> support RELRO program headers, and -z relro or -z norelro is passed.
>
> Alan Modra clarifies:
> The default linker emulation for an aarch64-linux ld.bfd is
> -maarch64linux, the default for an aarch64-elf linker is
> -maarch64elf. They are not equivalent. If you choose -maarch64elf
> you get an emulation that doesn't support -z relro.
>
> The ARCH=arm64 kernel prefers -maarch64elf, but may fall back to
> -maarch64linux based on the toolchain configuration.
>
> LLD will always create RELRO program header regardless of target
> emulation.
>
> To avoid the above warning when linking with BFD, pass -z norelro only
> when linking with LLD or with -maarch64linux.
>
> Fixes: 3b92fa7485eb ("arm64: link with -z norelro thank you regardless of CONFIG_RELOCATABLE")
^ exists in 5.4 as 57a88e44b512
> Fixes: 3bbd3db86470 ("arm64: relocatable: fix inconsistencies in linker script and options")
^ landed in v5.0-rc1
> Cc: <stable@xxxxxxxxxxxxxxx> # 5.0.x-
> Reported-by: kernelci.org bot <bot@xxxxxxxxxxxx>
> Reported-by: Quentin Perret <qperret@xxxxxxxxxx>
> Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
> Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
> Cc: Alan Modra <amodra@xxxxxxxxx>
> Cc: Fāng-ruì Sòng <maskray@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/20201218002432.788499-1-ndesaulniers@xxxxxxxxxx
> Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> ---
> arch/arm64/Makefile | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
> index cd8f3cdabfd0..d227cf87c48f 100644
> --- a/arch/arm64/Makefile
> +++ b/arch/arm64/Makefile
> @@ -10,7 +10,7 @@
> #
> # Copyright (C) 1995-2001 by Russell King
>
> -LDFLAGS_vmlinux :=--no-undefined -X -z norelro
> +LDFLAGS_vmlinux :=--no-undefined -X
> CPPFLAGS_vmlinux.lds = -DTEXT_OFFSET=$(TEXT_OFFSET)
> GZFLAGS :=-9
>
> @@ -82,17 +82,21 @@ CHECKFLAGS += -D__AARCH64EB__
> AS += -EB
> # Prefer the baremetal ELF build target, but not all toolchains include
> # it so fall back to the standard linux version if needed.
> -KBUILD_LDFLAGS += -EB $(call ld-option, -maarch64elfb, -maarch64linuxb)
> +KBUILD_LDFLAGS += -EB $(call ld-option, -maarch64elfb, -maarch64linuxb -z norelro)
> UTS_MACHINE := aarch64_be
> else
> KBUILD_CPPFLAGS += -mlittle-endian
> CHECKFLAGS += -D__AARCH64EL__
> AS += -EL
> # Same as above, prefer ELF but fall back to linux target if needed.
> -KBUILD_LDFLAGS += -EL $(call ld-option, -maarch64elf, -maarch64linux)
> +KBUILD_LDFLAGS += -EL $(call ld-option, -maarch64elf, -maarch64linux -z norelro)
> UTS_MACHINE := aarch64
> endif
>
> +ifeq ($(CONFIG_LD_IS_LLD), y)
> +KBUILD_LDFLAGS += -z norelro
> +endif
^ ah but 5.4 doesn't have
commit b744b43f79cc ("kbuild: add CONFIG_LD_IS_LLD")
which landed in v5.8-rc1. So this patch will break LLD on 5.4. That
should be trivial to backport, but would you please send that first,
then this?
> +
> CHECKFLAGS += -D__aarch64__
>
> ifeq ($(CONFIG_ARM64_MODULE_PLTS),y)
> --
> 2.32.0
>
--
Thanks,
~Nick Desaulniers
