linux-kernel - Re: [PATCH v2 00/18] clean up asm/uaccess.h, kill set

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Message-ID: <Yg8CjZwjWYIibrsd@zeniv-ca.linux.org.uk>
Date:   Fri, 18 Feb 2022 02:21:01 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
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Subject: Re: [PATCH v2 00/18] clean up asm/uaccess.h, kill set_fs for good

On Thu, Feb 17, 2022 at 08:49:59AM +0100, Arnd Bergmann wrote:

> Same here: architectures can already provide a __put_user_fn()
> and __get_user_fn(), to get the generic versions of the interface,
> but few architectures use that. You can actually get all the interfaces
> by just providing raw_copy_from_user() and raw_copy_to_user(),
> but the get_user/put_user versions you get from that are fairly
> inefficient.

FWIW, __{get,put}_user_{8,16,32,64} would probably make it easier to
unify.  That's where the really variable part tends to be, anyway.
IMO __get_user_fn() had been a mistake.

One thing I somewhat dislike about the series is the boilerplate in
asm/uaccess.h instances - #include <asm-generic/access-ok.h> in
a lot of them might make sense as a transitory state, but getting
stuck with those indefinitely...

	BTW, do we need user_addr_max() anymore?  The definition in
asm-generic/access-ok.h is the only one, so ifndef around it is pointless.