linux-kernel - [PATCH 0/4] Add tooling to disable debugfs on OMAP based systems

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Message-ID: <20251129142042.344359-1-richard@nod.at>
Date: Sat, 29 Nov 2025 15:20:38 +0100
From: Richard Weinberger <richard@....at>
To: linux-kernel@...r.kernel.org
Cc: linux-omap@...r.kernel.org,
	devicetree@...r.kernel.org,
	arnd@...db.de,
	lee@...nel.org,
	dakr@...nel.org,
	rafael@...nel.org,
	gregkh@...uxfoundation.org,
	broonie@...nel.org,
	tony@...mide.com,
	rogerq@...nel.org,
	khilman@...libre.com,
	andreas@...nade.info,
	aaro.koskinen@....fi,
	conor+dt@...nel.org,
	krzk+dt@...nel.org,
	robh@...nel.org,
	Richard Weinberger <richard@....at>
Subject: [PATCH 0/4] Add tooling to disable debugfs on OMAP based systems

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.

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.

Richard Weinberger (4):
  dt-bindings: Document new common property: has-inaccessible-regs
  regmap: Allow disabling debugfs via regmap_config
  syscon: Wire up has-inaccessible-regs
  arm: dts: omap: Mark various register maps as dangerous

 .../devicetree/bindings/common-properties.txt        | 12 ++++++++++++
 arch/arm/boot/dts/ti/omap/dra7-l4.dtsi               |  4 ++++
 arch/arm/boot/dts/ti/omap/dra7.dtsi                  |  1 +
 arch/arm/boot/dts/ti/omap/dra74x.dtsi                |  1 +
 drivers/base/regmap/regmap.c                         |  2 ++
 drivers/mfd/syscon.c                                 | 10 ++++++++++
 include/linux/regmap.h                               |  3 +++
 7 files changed, 33 insertions(+)

-- 
2.51.0