linux-kernel - Re: [PATCH v5 2/2] powerpc/64: Add module check for ELF ABI version

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Message-Id: <CO6202HG8VAN.1ROEE25G4KDK2@bobo>
Date:   Mon, 07 Nov 2022 22:14:16 +1000
From:   "Nicholas Piggin" <npiggin@...il.com>
To:     "Christophe Leroy" <christophe.leroy@...roup.eu>,
        "linux-modules@...r.kernel.org" <linux-modules@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Michael Ellerman" <mpe@...erman.id.au>,
        "Jessica Yu" <jeyu@...nel.org>,
        "Luis Chamberlain" <mcgrof@...nel.org>
Subject: Re: [PATCH v5 2/2] powerpc/64: Add module check for ELF ABI version

On Thu Nov 3, 2022 at 6:35 PM AEST, Christophe Leroy wrote:
>
>
> Le 31/10/2022 à 13:07, Nicholas Piggin a écrit :
> > Override the generic module ELF check to provide a check for the ELF ABI
> > version. This becomes important if we allow big-endian ELF ABI V2 builds
> > but it doesn't hurt to check now.
> > 
> > Cc: Jessica Yu <jeyu@...nel.org>
> > Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
> > [np: split patch, added changelog, adjust to Jessica's proposal]
> > Signed-off-by: Nicholas Piggin <npiggin@...il.com>
> > ---
> >   arch/powerpc/kernel/module.c | 17 +++++++++++++++++
> >   1 file changed, 17 insertions(+)
> > 
> > diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c
> > index f6d6ae0a1692..d46bf9bfda26 100644
> > --- a/arch/powerpc/kernel/module.c
> > +++ b/arch/powerpc/kernel/module.c
> > @@ -19,6 +19,23 @@
> >   
> >   static LIST_HEAD(module_bug_list);
> >   
> > +#ifdef CONFIG_PPC64
>
> Can it go in arch/powerpc/kernel/module_64.c instead ?
>
> > +bool module_elf_check_arch(Elf_Ehdr *hdr)
> > +{
> > +	unsigned long abi_level = hdr->e_flags & 0x3;
> > +
> > +	if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) {
> > +		if (abi_level != 2)
> > +			return false;
> > +	} else {
> > +		if (abi_level >= 2)
> > +			return false;
> > +	}
> > +
> > +	return true;
>
> Can be simpler:
>
> 	if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2))
> 		return abi_level == 2;
> 	else
> 		return abi_level < 2;

Yes I think both of those can be done. Good suggestions.

Thanks,
Nick