Re: STRICT_KERNEL_RWX on PPC32 is broken on PowerMac G4

[Christophe LEROY]

Le 21/11/2017 Ã 03:28, Balbir Singh a ÃcritÂ:
> On Sun, Nov 19, 2017 at 1:36 AM, LEROY Christophe
> <christophe.leroy@xxxxxx> wrote:
> > Meelis Roos <mroos@xxxxxxxx> a Ãcrit :
> >
> > > > > > How early does it hang ? Any oops or trace ?
> > > > >
> > > > > Very early - instead oif kernel emssages, I see some repeated gibberish
> > > > > of some characteers, and the background turns white.
> > > > > I am booting from yaboot, background is normally black.
> > > >
> > > > Ok, could you try by replacing #ifdef CONFIG_STRICT_KERNEL_RWX by #if 0
> > > > in arch/powerpc/lib/code-patching.c
> > >
> > >
> > > With this change and CONFIG_STRICT_KERNEL_RWX=y, it still boots.
> > >
> > > BTW, I get these warnings (sorry for the word wrap from screen paste) -
> > > may they be related or rather not?
> > >
> > >    WRAP    arch/powerpc/boot/zImage.pmac
> > >    WRAP    arch/powerpc/boot/zImage.coff
> > >    WRAP    arch/powerpc/boot/zImage.miboot
> > > INFO: Uncompressed kernel (size 0x5d4c3c) overlaps the address of the
> > > wrapper(0x400000)
> > > INFO: Fixing the link_address of wrapper to (0x600000)
> >
> > Then i believe there is something wrong with commit
> > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?h=next-20171115&id=37bc3e5fd764fb258ff4fcbb90b6d1b67fb466c1
> >
> > Balbir, do you have any idea ?
>
> Hmm.. interesting, so nobats works, but code-patching has issues? Any
> chance you can boot with xmon=on on the command line
> when you drop into the xmon> prompt, type dl to get the kernel log.

I have the same issue with a 83xx board allthought it is booting well on 
my 8xx boards.

Indeed the issue is that patch_instruction() is called from 
early_init(), therefor all static data must be addressed using PTRRELOC()

I have submitted a fixup patch, can you review it ?
slab_is_available() cannot be called that early for the same reason but 
I believe it is not needed.

Christophe


> Balbir Singh.