Re: [PATCH 0/4] Add tooling to disable debugfs on OMAP based systems

[Andreas Kemnade]

On Sat, 29 Nov 2025 15:20:38 +0100
Richard Weinberger <richard@xxxxxx> wrote:

> It came to my attention that commands such as `grep -r / -e ...` can cause
> crashes on an AM572x based system.
> An investigation found that reading from various files in /sys/kernel/debug/regmap
> causes imprecise async data aborts.
> 
> One of these register maps is the CTRL_MODULE_CORE register map at 0x4A002000.
> It contains various registers marked as reserved, but the manual indicates
> that read access is still allowed.
> On said system, reading from most registers seems to work, but for some
> an async data abort happens. So it's not entirely clear what registers are safe
> and which are not.
> 
it is usually not about individual registers, but about accessing 
unpowered devices/modules,

so it is probably more the logic like:

if (pm_runtime_is_suspended(regmap->device))
	-EACCESS;

Try to play around with on >power/control in sysfs.

> So, add tooling to allow disabling debugfs access to such dangerous registers.
> Splitting the register map definitions in the device tree seemed less practical to
> me since it would unnecessarily make the device trees more complicated.
> 
So is it really a description of the hardware? Maybe there are some special
cases, too.

Regards,
Andreas