arm64: Execute DSB during thread switching for TLB/cache maintenance

The DSB following TLB or cache maintenance ops must be run on the same
CPU. With kernel preemption enabled or for user-space cache maintenance
this may not be the case. This patch adds an explicit DSB in the
__switch_to() function.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index c2cc2493481b..116a60abe86f 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -313,6 +313,12 @@ struct task_struct *__switch_to(struct task_struct *prev,
         hw_breakpoint_thread_switch(next);
         contextidr_thread_switch(next);
 
+        /*
+         * Complete any pending TLB or cache maintenance on this CPU in case
+         * the thread migrates to a different CPU.
+         */
+        dsb();
+
         /* the actual thread switch */
         last = cpu_switch_to(prev, next);