linux-kernel - Re: [PATCH -fixes] riscv: Fix relocatable kernels with early alternatives using -fno-pie

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Message-ID: <20230526-rockfish-moody-f6d3e71f9d24@spud>
Date:   Fri, 26 May 2023 17:35:10 +0100
From:   Conor Dooley <conor@...nel.org>
To:     Alexandre Ghiti <alexghiti@...osinc.com>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Andreas Schwab <schwab@...ux-m68k.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -fixes] riscv: Fix relocatable kernels with early
 alternatives using -fno-pie

On Fri, May 26, 2023 at 05:24:41PM +0100, Conor Dooley wrote:
> On Fri, May 26, 2023 at 05:46:30PM +0200, Alexandre Ghiti wrote:
> > Early alternatives are called with the mmu disabled, and then should not
> > access any global symbols through the GOT since it requires relocations,
> > relocations that we do before but *virtually*. So only use medany code
> > model for this early code.
> > 
> > Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
> > ---
> > 
> > Note that I'm not very happy with this fix, I think we need to put more
> > effort into "harmonizing" this very early code (ie before the mmu is
> > enabled) as it is spread between different locations and compiled
> > differently.
> 
> Totally & I'll happily spend the time trying to review that work.
> 
> > I'll work on that later, but for now, this fix does what is
> > needed to work (from my testing at least). Any Tested-by on the Unmatched
> > and T-head boards is welcome!
> 
> On 6.4-rc1 & v6.4-rc1 + this patch, with CONFIG_RELOCATABLE added to my
> config, my Nezha fails to boot. There is no output whatsoever from the
> kernel. Turning off CONFIG_RELOCATABLE boots again.

I don't know if this is better or worse news, but same thing happens on
an icicle kit. What systems, other than QEMU, has the relocatable
eries been tested with, btw?

Cheers,
Conor.

> 
> I didn't test on my unmatched.
> 
> Thanks,
> Conor.



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