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From: Geert Uytterhoeven <geert+renesas@glider.be>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Gilad Ben-Yossef <gilad@benyossef.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S . Miller" <davem@davemloft.net>,
	"Rafael J . Wysocki" <rafael@kernel.org>
Cc: Rob Clark <robdclark@gmail.com>, Sean Paul <sean@poorly.run>,
	Felipe Balbi <balbi@kernel.org>,
	Alan Stern <stern@rowland.harvard.edu>,
	Thierry Reding <thierry.reding@gmail.com>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Mathias Nyman <mathias.nyman@intel.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Chunfeng Yun <chunfeng.yun@mediatek.com>, Bin Liu <b-liu@ti.com>,
	linux-crypto@vger.kernel.org, linux-pm@vger.kernel.org,
	linux-renesas-soc@vger.kernel.org, linux-usb@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH 0/2] Fix debugfs register access while suspended
Date: Fri, 24 Jan 2020 14:29:55 +0100
Message-ID: <20200124132957.15769-1-geert+renesas@glider.be> (raw)

	Hi all,

While comparing register values read from debugfs files under
/sys/kernel/debug/ccree/, I noticed some oddities.
Apparently there is no guarantee these registers are read from the
device while it is resumed.  This may lead to bogus values, or crashes
and lock-ups.

This patch series:
  1. Allows debugfs_create_regset32() to be used for devices whose
     registers must be accessed when resumed,
  2. Fixes the CCREE driver to make use of this.

I have identified several other drivers that may be affected (i.e.
using debugfs_create_regset32() and pm_runtime_*()):
  - drivers/gpu/drm/msm/disp/dpu1
  - drivers/usb/dwc3
  - drivers/usb/host/ehci-omap.c
  - drivers/usb/host/ehci-tegra.c
  - drivers/usb/host/ohci-platform.c
  - drivers/usb/host/xhci.c
  - drivers/usb/host/xhci-dbgcap.c
  - drivers/usb/host/xhci-histb.c
  - drivers/usb/host/xhci-hub.c
  - drivers/usb/host/xhci-mtk.c
  - drivers/usb/host/xhci-pci.c
  - drivers/usb/host/xhci-plat.c
  - drivers/usb/host/xhci-tegra.c
  - drivers/usb/mtu3
  - drivers/usb/musb

Some of these call pm_runtime_forbid(), but given the comment "users
should enable runtime pm using power/control in sysfs", this can be
overridden from userspace, so these are unsafe, too?

Thanks for your comments!

Geert Uytterhoeven (2):
  debugfs: regset32: Add Runtime PM support
  crypto: ccree - fix debugfs register access while suspended

 drivers/crypto/ccree/cc_debugfs.c | 2 ++
 fs/debugfs/file.c                 | 8 ++++++++
 include/linux/debugfs.h           | 1 +
 3 files changed, 11 insertions(+)

-- 
2.17.1

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds

             reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-24 13:29 Geert Uytterhoeven [this message]
2020-01-24 13:29 ` [PATCH 1/2] debugfs: regset32: Add Runtime PM support Geert Uytterhoeven
2020-01-31 10:13   ` Rafael J. Wysocki
2020-02-10 19:01   ` Greg Kroah-Hartman
2020-01-24 13:29 ` [PATCH 2/2] crypto: ccree - fix debugfs register access while suspended Geert Uytterhoeven
2020-01-26 13:32   ` Gilad Ben-Yossef
2020-01-31 10:11   ` Rafael J. Wysocki
2020-01-24 16:24 ` [PATCH 0/2] Fix " Niklas Söderlund

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