Messages in this thread | | | From | Geert Uytterhoeven <> | Subject | [PATCH 0/2] Fix debugfs register access while suspended | Date | Fri, 24 Jan 2020 14:29:55 +0100 |
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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
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