Re: mainline build failure of powerpc allmodconfig for prom_init_check

From: Segher Boessenkool <segher@kernel.crashing.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Sudip Mukherjee <sudipm.mukherjee@gmail.com>,
	Kees Cook <keescook@chromium.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Paul Mackerras <paulus@samba.org>,
	linux-hardening@vger.kernel.org,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: mainline build failure of powerpc allmodconfig for prom_init_check
Date: Mon, 18 Jul 2022 09:56:01 -0500	[thread overview]
Message-ID: <20220718145601.GE25951@gate.crashing.org> (raw)
In-Reply-To: <87k08bdqm1.fsf@mpe.ellerman.id.au>

On Mon, Jul 18, 2022 at 01:52:38PM +1000, Michael Ellerman wrote:
> Segher Boessenkool <segher@kernel.crashing.org> writes:
> > Can't we simply have a small simple implementation of these functions in
> > arch/powerpc/boot/?  This stuff is not performance-critical, and this is
> > not the first time we hit these problems.
> 
> prom_init.c isn't in arch/powerpc/boot :)

Ah duh :-)

> It's linked into the kernel proper, but we want it to behave like a
> pre-boot environment (because not all boot paths run it) which is why we
> restrict what symbols it can call.
> 
> We could have a prom_memset() etc. but we'd need to do some tricks to
> rewrite references to memset() to prom_memset() before linking.

You can do it in its linker script?

Segher