This is a note to let you know that I've just added the patch titled
firmware/psci: Don't register with debugfs if PSCI isn't available
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
firmware-psci-don-t-register-with-debugfs-if-psci-isn-t-available.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From cef139299fd86098c6e3dbd389d1d0b2462d7710 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <maz@xxxxxxxxxx>
Date: Thu, 5 Jan 2023 09:08:34 +0000
Subject: firmware/psci: Don't register with debugfs if PSCI isn't available
From: Marc Zyngier <maz@xxxxxxxxxx>
commit cef139299fd86098c6e3dbd389d1d0b2462d7710 upstream.
Contrary to popular belief, PSCI is not a universal property of an
ARM/arm64 system. There is a garden variety of systems out there
that don't (or even cannot) implement it.
I'm the first one deplore such a situation, but hey...
On such systems, a "cat /sys/kernel/debug/psci" results in
fireworks, as no invocation callback is registered.
Check for the invoke_psci_fn and psci_ops.get_version pointers
before registering with the debugfs subsystem, avoiding the
issue altogether.
Fixes: 3137f2e60098 ("firmware/psci: Add debugfs support to ease debugging")
Reported-by: Hector Martin <marcan@xxxxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx>
Reviewed-by: Hector Martin <marcan@xxxxxxxxx>
Acked-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Link: https://lore.kernel.org/r/20230105090834.630238-1-maz@xxxxxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/firmware/psci/psci.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
index e7bcfca4159f..447ee4ea5c90 100644
--- a/drivers/firmware/psci/psci.c
+++ b/drivers/firmware/psci/psci.c
@@ -440,6 +440,9 @@ static const struct file_operations psci_debugfs_ops = {
static int __init psci_debugfs_init(void)
{
+ if (!invoke_psci_fn || !psci_ops.get_version)
+ return 0;
+
return PTR_ERR_OR_ZERO(debugfs_create_file("psci", 0444, NULL, NULL,
&psci_debugfs_ops));
}
--
2.39.0
Patches currently in stable-queue which might be from maz@xxxxxxxxxx are
queue-6.1/firmware-psci-fix-mem_protect_range-function-numbers.patch
queue-6.1/kvm-arm64-fix-s1ptw-handling-on-ro-memslots.patch
queue-6.1/firmware-psci-don-t-register-with-debugfs-if-psci-isn-t-available.patch
