From cef139299fd86098c6e3dbd389d1d0b2462d7710 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 5 Jan 2023 09:08:34 +0000 Subject: [PATCH] firmware/psci: Don't register with debugfs if PSCI isn't available 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 Signed-off-by: Marc Zyngier Cc: Dmitry Baryshkov Cc: Mark Brown Cc: Ulf Hansson Cc: Arnd Bergmann Cc: Mark Rutland Cc: Lorenzo Pieralisi Reviewed-by: Hector Martin Acked-by: Dmitry Baryshkov Acked-by: Mark Rutland Link: https://lore.kernel.org/r/20230105090834.630238-1-maz@kernel.org Signed-off-by: Will Deacon --- 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)); }