From efe9711214e6138a5a2a46ca4068bfce50c03444 Mon Sep 17 00:00:00 2001 From: Neal Liu Date: Mon, 27 Jul 2020 11:25:46 +0800 Subject: cpuidle: change enter_s2idle() prototype Control Flow Integrity(CFI) is a security mechanism that disallows changes to the original control flow graph of a compiled binary, making it significantly harder to perform such attacks. init_state_node() assign same function callback to different function pointer declarations. static int init_state_node(struct cpuidle_state *idle_state, const struct of_device_id *matches, struct device_node *state_node) { ... idle_state->enter = match_id->data; ... idle_state->enter_s2idle = match_id->data; } Function declarations: struct cpuidle_state { ... int (*enter) (struct cpuidle_device *dev, struct cpuidle_driver *drv, int index); void (*enter_s2idle) (struct cpuidle_device *dev, struct cpuidle_driver *drv, int index); }; In this case, either enter() or enter_s2idle() would cause CFI check failed since they use same callee. Align function prototype of enter() since it needs return value for some use cases. The return value of enter_s2idle() is no need currently. Signed-off-by: Neal Liu Reviewed-by: Sami Tolvanen Signed-off-by: Rafael J. Wysocki --- include/linux/cpuidle.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'include') diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h index ec2ef63771f0..b65909ae4e20 100644 --- a/include/linux/cpuidle.h +++ b/include/linux/cpuidle.h @@ -65,10 +65,13 @@ struct cpuidle_state { * CPUs execute ->enter_s2idle with the local tick or entire timekeeping * suspended, so it must not re-enable interrupts at any point (even * temporarily) or attempt to change states of clock event devices. + * + * This callback may point to the same function as ->enter if all of + * the above requirements are met by it. */ - void (*enter_s2idle) (struct cpuidle_device *dev, - struct cpuidle_driver *drv, - int index); + int (*enter_s2idle)(struct cpuidle_device *dev, + struct cpuidle_driver *drv, + int index); }; /* Idle State Flags */ -- cgit v1.2.3