Messages in this thread Patch in this message | | | Date | Thu, 5 Jan 2023 13:08:31 +0000 | From | Mark Rutland <> | Subject | Re: [PATCH] firmware/psci: Don't register with debugfs if PSCI isn't available |
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On Thu, Jan 05, 2023 at 09:08:34AM +0000, Marc Zyngier wrote: > 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@marcan.st> > Signed-off-by: Marc Zyngier <maz@kernel.org> > Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> > Cc: Mark Brown <broonie@kernel.org> > Cc: Ulf Hansson <ulf.hansson@linaro.org> > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Mark.
> --- > 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)); > } > -- > 2.34.1 >
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