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ANDROID: adding __nocfi to cpuidle_enter_state

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Background:
  When CPU is going to idle state, it would inform RCU that
current CPU is entering idle through rcu_idle_enter(),
and RCU will ignore read-side critical sections of this CPU.
However, there is CFI check mechanism inside idle flow and
calls rcu_read_lock(), so "rcu_read_lock() used illegally while idle"
in rcu_read_lock() will be triggered because rcu_idle_enter()
was already called before.

  Beside, the pointer of rcu_dereference() might be invalid
due to the RCU read-side critical sections will be ignoring in
this going idle CPU, it might cause problems like:
access the wrong data/address, kernel exception...

Based on above description:
  We will add __nocfi to cpuidle_enter_state to avoid
“rcu_read_lock() used illegally while idle!”
and avoid the usage of invalid pointer of rcu_dereference()
in this situation.

Bug: 169017431
Change-Id: I8bbe25704e18cfde351a8f4277dd4b44b07421f5
Signed-off-by: rogercl.yang <rogercl.yang@mediatek.com>
Signed-off-by: Chun-Hung Wu <chun-hung.wu@mediatek.com>
This commit is contained in:
rogercl.yang
2020-09-23 11:32:32 +08:00
committed by Bruno Martins
parent 9bafb37470
commit b891b37591
1 changed files with 1 additions and 1 deletions
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2
drivers/cpuidle/cpuidle.c
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@@ -199,7 +199,7 @@ int cpuidle_enter_s2idle(struct cpuidle_driver *drv, struct cpuidle_device *dev)
* @drv: cpuidle driver for this cpu
* @index: index into the states table in @drv of the state to enter
*/
int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
int __nocfi cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
int index)
{
int entered_state;