linux-hardening - Re: [PATCH v3 03/10] gpiolib: implement low-level, shared GPIO support

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: <CAMRc=Me5qPS2PhLK5hpK8BbTS8b9q3T-+86mq6rVDpyKZZUfoA@mail.gmail.com>
Date: Wed, 29 Oct 2025 13:39:34 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Andy Shevchenko <andriy.shevchenko@...el.com>
Cc: Kees Cook <kees@...nel.org>, Mika Westerberg <westeri@...nel.org>, 
	Dmitry Torokhov <dmitry.torokhov@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, 
	Linus Walleij <linus.walleij@...aro.org>, Manivannan Sadhasivam <mani@...nel.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Saravana Kannan <saravanak@...gle.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Andy Shevchenko <andy@...nel.org>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
	Srinivas Kandagatla <srini@...nel.org>, Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, 
	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>, 
	Alexey Klimov <alexey.klimov@...aro.org>, linux-hardening@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-sound@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v3 03/10] gpiolib: implement low-level, shared GPIO support

On Wed, Oct 29, 2025 at 12:45 PM Andy Shevchenko
<andriy.shevchenko@...el.com> wrote:
>
> On Wed, Oct 29, 2025 at 12:20:39PM +0100, Bartosz Golaszewski wrote:
> >
> > This module scans the device tree (for now only OF nodes are supported
> > but care is taken to make other fwnode implementations easy to
> > integrate) and determines which GPIO lines are shared by multiple users.
> > It stores that information in memory. When the GPIO chip exposing shared
> > lines is registered, the shared GPIO descriptors it exposes are marked
> > as shared and virtual "proxy" devices that mediate access to the shared
> > lines are created. When a consumer of a shared GPIO looks it up, its
> > fwnode lookup is redirected to a just-in-time machine lookup that points
> > to this proxy device.
> >
> > This code can be compiled out on platforms which don't use shared GPIOs.
>
> Besides strcmp_suffix() that already exists in OF core, there are also some
> existing pieces that seems being repeated here (again). Can we reduce amount
> of duplication?
>

I'm afraid you need to be more specific here.

> ...
>
> > +#if IS_ENABLED(CONFIG_OF)
> > +static int gpio_shared_of_traverse(struct device_node *curr)
> > +{
>
> I believe parts of this code may be resided somewhere in drivers/of/property.c
> or nearby as it has the similar parsing routines.
>

I don't think this is a good idea, I want to keep it within the
confines of drivers/gpio/ and the use-case is so specific, there's
really no point in putting parts of it under drivers/of/.

If I could only iterate over all properties of an fwnode, I'd have
skipped using OF-specific routines altogether.

Bart