[PATCH v4 8/9] loongarch: avoid orphan input sections

[Ard Biesheuvel]

On Sun, 28 Aug 2022 at 05:31, Xi Ruoyao <xry111 at xry111.site> wrote:
>
> On Sat, 2022-08-27 at 15:27 +0200, Ard Biesheuvel wrote:
> > It does have a relation: the signing tool will complain because the
> > PE/COFF metadata goes out of sync, like so
> >
> >   SBSIGN  arch/loongarch/boot/vmlinux.efi.signed
> > warning: data remaining[20754944 vs 20755016]: gaps between PE/COFF
> > sections?
> >
> > This is because of the *(.rela.dyn) section created by the linker,
> > which is appended after the .data section, and so the PE/COFF .data
> > section size does not match the file size.
> >
> > *However*, you explained to me that vmlinux is not a PIC binary, and
> > the link should be non-PIE as well. So this looks like another
> > toolchain issue to me, that you may want to look into.
>
> In my builds:
>
> With Binutils 2.39 and GCC 12, vmlinux rela.dyn contains 48 zero bytes
> (or 3 R_LARCH_NONE relocations, which is defined "do thing" and is
> ignored by ld, ld.so, and kernel module loader).
>

But does the ELF psABI for LoongArch describe L_ARCH_NONE as a dynamic
relocation? .rela.dyn typically only contains relocations that are
specified as being suitable for runtime relocation.

> With Binutils trunk and GCC trunk, rela.dyn does not exist in
> vmlinux.(But for using the trunks of Binutils and GCC we'll need to
> either disable CONFIG_MODULES or apply [1].)
>

If this is going to land in v6.1 as well, I suggest to drop the patch
entirely. By the time this gets released, you can document which
minimal toolchain version is required for UEFI secure boot signed
kernels.

> [1]:https://lore.kernel.org/loongarch/20220827175436.156464-1-xry111@xry111.site/T/
>
> --
> Xi Ruoyao <xry111 at xry111.site>
> School of Aerospace Science and Technology, Xidian University