linux-kernel - Re: [PATCH v2 1/4] rust: io: Add big-endian read and write functions

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <45A7698F-6AE9-46DA-8CB2-9E09F7223229@collabora.com>
Date: Sun, 8 Feb 2026 14:17:36 -0300
From: Daniel Almeida <daniel.almeida@...labora.com>
To: Danilo Krummrich <dakr@...nel.org>
Cc: Gary Guo <gary@...yguo.net>,
 Link Mauve <linkmauve@...kmauve.fr>,
 rust-for-linux@...r.kernel.org,
 Madhavan Srinivasan <maddy@...ux.ibm.com>,
 Michael Ellerman <mpe@...erman.id.au>,
 Nicholas Piggin <npiggin@...il.com>,
 "Christophe Leroy (CS GROUP)" <chleroy@...nel.org>,
 Srinivas Kandagatla <srini@...nel.org>,
 Miguel Ojeda <ojeda@...nel.org>,
 Boqun Feng <boqun@...nel.org>,
 Björn Roy Baron <bjorn3_gh@...tonmail.com>,
 Benno Lossin <lossin@...nel.org>,
 Andreas Hindborg <a.hindborg@...nel.org>,
 Alice Ryhl <aliceryhl@...gle.com>,
 Trevor Gross <tmgross@...ch.edu>,
 Ard Biesheuvel <ardb@...nel.org>,
 "Martin K. Petersen" <martin.petersen@...cle.com>,
 Eric Biggers <ebiggers@...gle.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Lyude Paul <lyude@...hat.com>,
 Asahi Lina <lina+kernel@...hilina.net>,
 Viresh Kumar <viresh.kumar@...aro.org>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Tamir Duberstein <tamird@...nel.org>,
 FUJITA Tomonori <fujita.tomonori@...il.com>,
 linuxppc-dev@...ts.ozlabs.org,
 linux-kernel@...r.kernel.org,
 officialTechflashYT@...il.com,
 Ash Logan <ash@...quark.com>,
 Roberto Van Eeden <rw-r-r-0644@...tonmail.com>,
 Jonathan Neuschäfer <j.neuschaefer@....net>
Subject: Re: [PATCH v2 1/4] rust: io: Add big-endian read and write functions

> On 5 Feb 2026, at 19:43, Danilo Krummrich <dakr@...nel.org> wrote:
> 
> On Thu Feb 5, 2026 at 11:31 PM CET, Gary Guo wrote:
>> On Thu Feb 5, 2026 at 7:05 PM GMT, Danilo Krummrich wrote:
>>>  (1) Devices are either little-endian or big-endian. Hence, having to write
>>> 
>>> io.big_endian().write()
>>> 
>>>      is excessive, we always want big-endian for a big-endian device.
>> 
>> You don't need to always write this. You just need to do `big_endian()` once
>> when you obtain the io, and then keep using `BigEndian<Mmio>` instead of just
>> `Mmio`, and the rest of code is still `.write()`.
> 
> <snip>
> 
>>>  (2) It is error prone, if you forget to call big_endian() first, it is a bug.
>> 
>> Moot point when `big_endian()` is only done once.
> 
> Well, you need to do it at least once per driver entry point. For DRM IOCTLs for
> instance you also have to consider that it is always Devres<Mmio>.
> 

Well, this is also the case for relaxed(). I basically made peace with the fact that

let mmio = mmio.relaxed();
< use mmio >

is going to be a reality per driver entrypoint, unless I misunderstood?

— Daniel