The following commit has been merged into the sched/urgent branch of tip:
Commit-ID: 45dfb89b8f96643268449c25d7025b17de46717c
Gitweb: https://git.kernel.org/tip/45dfb89b8f96643268449c25d7025b17de46717c
Author: Woody Lin <woodylin@xxxxxxxxxx>
AuthorDate: Tue, 12 Oct 2021 16:35:21 +08:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Mon, 18 Oct 2021 16:58:41 +02:00
sched/scs: Reset the shadow stack when idle_task_exit
There was a 'init_idle' that resets scs sp to base, but is removed by
f1a0a376ca0c. Without the resetting, the hot-plugging implemented by
cpu_psci_cpu_boot will use the previous scs sp as new base when starting
up a CPU core, so the usage on scs page is being stacked up until
overflow.
This only happens on idle task since __cpu_up is using idle task as the
main thread to start up a CPU core, so the overflow can be fixed by
resetting scs sp to base in 'idle_task_exit'.
Fixes: f1a0a376ca0c ("sched/core: Initialize the idle task with preemption disabled")
Signed-off-by: Woody Lin <woodylin@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Valentin Schneider <valentin.schneider@xxxxxxx>
Link: https://lore.kernel.org/r/20211012083521.973587-1-woodylin@xxxxxxxxxx
---
kernel/sched/core.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1bba412..f21714e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8795,6 +8795,7 @@ void idle_task_exit(void)
finish_arch_post_lock_switch();
}
+ scs_task_reset(current);
/* finish_cpu(), as ran on the BP, will clean up the active_mm state */
}
|