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UPSTREAM: sched/scs: Reset the shadow stack when idle_task_exit

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Commit f1a0a376ca0c ("sched/core: Initialize the idle task with
preemption disabled") removed the init_idle() call from
idle_thread_get(). This was the sole call-path on hotplug that resets
the Shadow Call Stack (scs) Stack Pointer (sp).

Not resetting the scs-sp leads to scs overflow after enough hotplug
cycles. Therefore add an explicit scs_task_reset() to the hotplug code
to make sure the scs-sp does get reset on hotplug.

Fixes: f1a0a376ca0c ("sched/core: Initialize the idle task with preemption disabled")
Signed-off-by: Woody Lin <woodylin@google.com>
[peterz: Changelog]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lore.kernel.org/r/20211012083521.973587-1-woodylin@google.com
(cherry picked from commit 63acd42c0d4942f74710b11c38602fb14dea7320)
Bug: 201047587
Bug: 201771367
Change-Id: I9e48270f8d4c698c140cc3f427cadae636acb6d7
This commit is contained in:
Woody Lin
2021-10-12 16:35:21 +08:00
parent 74782dd0ce
commit ad8da78c87
1 changed files with 1 additions and 0 deletions
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kernel/sched/core.c
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@@ -6931,6 +6931,7 @@ void idle_task_exit(void)
finish_arch_post_lock_switch(); finish_arch_post_lock_switch();
} }
scs_task_reset(current);
/* finish_cpu(), as ran on the BP, will clean up the active_mm state */ /* finish_cpu(), as ran on the BP, will clean up the active_mm state */
} }