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

[Nathan Chancellor]

On Tue, Nov 10, 2020 at 10:49:32AM -0800, Nick Desaulniers wrote:
> On Mon, Nov 9, 2020 at 6:05 PM Nick Desaulniers <ndesaulniers at google.com> wrote:
> >
> > 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.
> 
> I was thinking more about this last night.  If we're going to be
> playing whack-a-mole for each architecture with this, would it be
> worthwhile for us to raise this up to the top level Makefile?

Sure, I can send a patch along tomorrow that adds '-z norelro' to
LDFLAGS_vmlinux in the top level Makefile.

Cheers,
Nathan