Re: [PATCH v2 4/8] KVM: arm64: Generate hyp relocation data

[Marc Zyngier]

Hi Guenter,

Thanks a lot for the heads up.

On 2021-01-29 21:43, Guenter Roeck wrote:
> Hi,
>
> On Tue, Jan 05, 2021 at 06:05:37PM +0000, David Brazdil wrote:
> > Add a post-processing step to compilation of KVM nVHE hyp code which
> > calls a custom host tool (gen-hyprel) on the partially linked object
> > file (hyp sections' names prefixed).
> >
> > The tool lists all R_AARCH64_ABS64 data relocations targeting hyp
> > sections and generates an assembly file that will form a new section
> > .hyp.reloc in the kernel binary. The new section contains an array of
> > 32-bit offsets to the positions targeted by these relocations.
> >
> > Since these addresses of those positions will not be determined until
> > linking of `vmlinux`, each 32-bit entry carries a R_AARCH64_PREL32
> > relocation with addend <section_base_sym> + <r_offset>. The linker of
> > `vmlinux` will therefore fill the slot accordingly.
> >
> > This relocation data will be used at runtime to convert the kernel VAs
> > at those positions to hyp VAs.
> >
> > Signed-off-by: David Brazdil <dbrazdil@xxxxxxxxxx>
>
> This patch results in the following error for me.
>
> error: arch/arm64/kvm/hyp/nvhe/kvm_nvhe.tmp.o: assertion
> elf.ehdr->e_ident[5] == 1 failed (lhs=2, rhs=1, line=250)
>
> The problem is seen when trying to build aarch64 images in big endian
> mode.

Ah, big-endian. of course, the ELF header is in native endianness,
and the sanity checks explode (still much better than generating crap).

I'll have a look shortly. It shouldn't too hard to fix, just a
bit invasive...

Thanks again,

        M.
--
Jazz is not dead. It just smells funny...