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firmware/psci: Don't register with debugfs if PSCI isn't available

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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: 3137f2e600 ("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>
Reviewed-by: Hector Martin <marcan@marcan.st>
Acked-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20230105090834.630238-1-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Marc Zyngier 2023-01-05 09:08:34 +00:00 committed by Will Deacon
parent f3dc61cde8
commit cef139299f
1 changed files with 3 additions and 0 deletions
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3
drivers/firmware/psci/psci.c
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@ -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));
}