linux-hardening - Re: [PATCH 01/28] mfd: Add Microchip ZL3073x support

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Message-ID: <CAHp75VcZrop0tvyX4Z-Gm3uOUKMbrAWxir2THuBqg8DfhN=hmQ@mail.gmail.com>
Date: Mon, 14 Apr 2025 16:58:28 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Ivan Vecera <ivecera@...hat.com>
Cc: Andy Shevchenko <andy@...nel.org>, netdev@...r.kernel.org, 
	Michal Schmidt <mschmidt@...hat.com>, Vadim Fedorenko <vadim.fedorenko@...ux.dev>, 
	Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>, Jiri Pirko <jiri@...nulli.us>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Prathosh Satish <Prathosh.Satish@...rochip.com>, Lee Jones <lee@...nel.org>, 
	Kees Cook <kees@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH 01/28] mfd: Add Microchip ZL3073x support

On Mon, Apr 14, 2025 at 2:40 PM Ivan Vecera <ivecera@...hat.com> wrote:
> On 14. 04. 25 8:36 dop., Andy Shevchenko wrote:

...

> >> What is wrong here?
> >>
> >> I have a device that uses 7-bit addresses and have 16 register pages.
> >> Each pages is from 0x00-0x7f and register 0x7f is used as page selector
> >> where bits 0-3 select the page.
> > The problem is that you overlap virtual page over the real one (the main one).
> >
> > The drivers you mentioned in v2 discussions most likely are also buggy.
> > As I implied in the above question the developers hardly get the regmap ranges
> > right. It took me quite a while to see the issue, so it's not particularly your
> > fault.

> thank you I see the point.
>
> Do you mean that the selector register should not be part of the range?

No.

> If so, does it mean that I have to specify a range for each page? Like this:

No.

Yes, tough thingy :-)

>         {
>                 /* Page 0 */
>                 .range_min      = 0x000,
>                 .range_max      = 0x07e,
>                 .selector_reg   = ZL3073x_PAGE_SEL,
>                 .selector_mask  = GENMASK(3, 0),
>                 .selector_shift = 0,
>                 .window_start   = 0,
>                 .window_len     = 0x7e,
>         },

Page 0 shouldn't exist in your case in the *virtual* ranges. And this
struct defines the *virtual* ranges.

>         {
>                 /* Page 1 */
>                 .range_min      = 0x080,
>                 .range_max      = 0x0fe,
>                 .selector_reg   = ZL3073x_PAGE_SEL,
>                 .selector_mask  = GENMASK(3, 0),
>                 .selector_shift = 0,
>                 .window_start   = 0,
>                 .window_len     = 0x7e,
>         },

-- 
With Best Regards,
Andy Shevchenko