Re: [PATCH stable v5.4] arm64: link with -z norelro for LLD or aarch64-elf

[Jisheng Zhang <Jisheng.Zhang@synaptics.com>]

Hi Greg,

On Fri, 25 Jun 2021 12:09:33 +0200
Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:


> 
> On Thu, Jun 24, 2021 at 05:09:19PM +0800, Jisheng Zhang wrote:
> > From: Nick Desaulniers <ndesaulniers@google.com>
> >
> > 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 regardless of CONFIG_RELOCATABLE")
> > Fixes: 3bbd3db86470 ("arm64: relocatable: fix inconsistencies in linker script and options")
> > Cc: <stable@vger.kernel.org> # 5.0.x-
> > Reported-by: kernelci.org bot <bot@kernelci.org>
> > Reported-by: Quentin Perret <qperret@google.com>
> > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> > Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> > Acked-by: Ard Biesheuvel <ardb@kernel.org>
> > Cc: Alan Modra <amodra@gmail.com>
> > Cc: Fāng-ruì Sòng <maskray@google.com>

> > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> > ---
> >  arch/arm64/Makefile | 10 +++++++---
> >  1 file changed, 7 insertions(+), 3 deletions(-)  
> 
> Now queued up, thanks.
> 

I assume the two patches in v2 series are queued up. Nick pointed out
applying only this patch can break kernel building with lld.

Thanks