Re: [PATCH 1/7] powerpc/build: put sys_call_table in .data.rel.ro if RELOCATABLE

["Nicholas Piggin" <npiggin@gmail.com>]

On Thu Sep 15, 2022 at 10:51 PM AEST, Michael Ellerman wrote:
> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> > Le 14/09/2022 à 17:47, Nicholas Piggin a écrit :
> >> Const function pointers live in .data.rel.ro rather than .rodata because
> >> they must be relocated. This change prevents powerpc/32 from generating
> >> R_PPC_UADDR32 relocations (which are not handled). The sys_call_table is
> >> moved to writeable memory, but a later change will move it back.
> >
> > Aren't you missing commit c7acee3d2f12 ("powerpc: align syscall table 
> > for ppc32") ?
>
> That's in fixes. I'll sort it out when I apply this, or when I merge
> fixes into next.

Yeah that explains the relocations I was seeing, I should have dug
further into that, so they're really unrelated to this patch.

> > I can't see any R_PPC_UADDR32 relocations generated by ppc4xx_defconfig 
> > + CONFIG_RELOCATABLE unless I revert that commit.
>
> Presumably this change accidentally aligns the syscall table.
>
> >> After this patch, 44x_defconfig + CONFIG_RELOCATABLE boots to busybox.
>  
> So that's probably just because of the alignment too.
>
> I think this patch should go after .data.rel.ro is made read only.

Yeah that should be fine.

Thanks,
Nick