From: "Clément Léger" <cleger@rivosinc.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Ben Dooks <ben.dooks@codethink.co.uk>,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
paul.walmsley@sifive.com, palmer@dabbelt.com,
aou@eecs.berkeley.edu
Subject: Re: [PATCH] riscv: fix __user annotation in traps_misaligned.c
Date: Fri, 24 Nov 2023 11:46:42 +0100 [thread overview]
Message-ID: <de9c1287-9be0-40bf-8dbd-717c56ea0d7e@rivosinc.com> (raw)
In-Reply-To: <ZWB+rPU4nm+Zxd7d@infradead.org>
On 24/11/2023 11:45, Christoph Hellwig wrote:
> On Fri, Nov 24, 2023 at 11:28:08AM +0100, Clément Léger wrote:
>> I sent a similar patch two days ago with the same modification. I'm not
>> sure to get it. Why is it better to pass the "unsigned long" type from
>> the caller ? I mean, the resulting code would look like this right ?
>
> Because you're legimitizing casting between address_space, which is a
> horrible idea. By casting either from the unsigned long you make it
> very clear that deep magic is coming in and you make an informed
> decisions based on the user_mode() predicate. Witht a blind cast
> to add/remove a __user you don't.
Makes sense indeed, thanks !
Clément
>
> I'm actually surprised sparse even allows __user casts without __force.
next prev parent reply other threads:[~2023-11-24 10:46 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-23 14:16 [PATCH] riscv: fix __user annotation in traps_misaligned.c Ben Dooks
2023-11-24 6:05 ` Christoph Hellwig
2023-11-24 10:28 ` Clément Léger
2023-11-24 10:45 ` Christoph Hellwig
2023-11-24 10:46 ` Clément Léger [this message]
2023-11-24 10:21 ` Clément Léger
2024-01-11 14:50 ` patchwork-bot+linux-riscv
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