linux-kernel - Re: [PATCH] riscv: Check that vdso does not contain any dynamic relocations

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Message-ID: <7fac15fb-83e0-4711-91a0-db0cb616c2c9@ghiti.fr>
Date: Thu, 4 Jul 2024 13:16:25 +0200
From: Alexandre Ghiti <alex@...ti.fr>
To: Björn Töpel <bjorn@...nel.org>,
 Alexandre Ghiti <alexghiti@...osinc.com>,
 Vladimir Isaev <vladimir.isaev@...tacore.com>,
 Roman Artemev <roman.artemev@...tacore.com>, Guo Ren <guoren@...nel.org>,
 Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt
 <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
 linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] riscv: Check that vdso does not contain any dynamic
 relocations

Hi Björn,

On 03/07/2024 14:41, Björn Töpel wrote:
> Hey Alex,
>
> Alexandre Ghiti <alexghiti@...osinc.com> writes:
>
>> Like other architectures, use the common cmd_vdso_check to make sure of
>> that.
>>
>> Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
> Looking in PW, this fails on rv32? Is that a false negative?

I had missed that, thanks.

So it's not a false positive, the check this patch adds actually reveals 
an issue: gcc seems to be smart enough to insert a memset() in 
riscv_vdso_get_cpus(). And this call to memset() inserts a relocation. 
Weirdly, only on rv32.

I managed to fix this by adding:

ccflags-y += -fno-tree-loop-distribute-patterns

I'll send this fix soon.

Thanks,

>
> Other than that,
> Reviewed-by: Björn Töpel <bjorn@...osinc.com>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

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