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

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Date:   Fri, 26 May 2023 18:38:14 +0200
From:   Alexandre Ghiti <alex@...ti.fr>
To:     Conor Dooley <conor@...nel.org>,
        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 26/05/2023 18:24, 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.

Damn, that's going to ruin my long week-end...Thanks though, I'll try to 
figure out what's going on, too bad I don't have any thead boards!

Thanks again,

Alex

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