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arm64: core: force data synchronization between context switch

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This patch fixes memory corruption that can happen when running in
multi-thread and multi-core environment with heavy scheduling stress.

In SMP configuration, we must ensure that all thread's context is
stored before writing the switch_handle flag. Otherwise some of the
thread context writes could be delayed after another CPU begins to
schedule this thread which could lead to memory corruptions.

Signed-off-by: Sylvain Chouleur <schouleur@snapchat.com>
This commit is contained in:
Sylvain Chouleur 2025-05-14 09:22:21 +02:00 • committed by Benjamin Cabé
commit a8b3238437
1 changed files with 7 additions and 0 deletions
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7
arch/arm64/core/switch.S
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@ -74,6 +74,13 @@ SECTION_FUNC(TEXT, z_arm64_context_switch)
ldp x0, x1, [sp], #16
#endif
#ifdef CONFIG_SMP
/* Write barrier: ensure all preceding writes are executed
* before writing the switch handle
*/
dmb sy
#endif
/* save old thread into switch handle which is required by
* z_sched_switch_spin()
*/