On Wed, Sep 04, 2024 at 11:22:54AM +0100, Will Deacon wrote:

On Tue, Sep 03, 2024 at 03:54:13PM +0100, Joey Gouly wrote:

quoted

commit 3141fb86bee8d48ae47cab1594dad54f974a8899
Author: Joey Gouly [off-list ref]
Date:   Tue Sep 3 15:47:26 2024 +0100

    fixup! arm64: context switch POR_EL0 register

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index a3a61ecdb165..c224b0955f1a 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c

@@ -515,11 +515,8 @@ static void permission_overlay_switch(struct task_struct *next)
                return;

        current->thread.por_el0 = read_sysreg_s(SYS_POR_EL0);
-       if (current->thread.por_el0 != next->thread.por_el0) {
+       if (current->thread.por_el0 != next->thread.por_el0)
                write_sysreg_s(next->thread.por_el0, SYS_POR_EL0);
-               /* ISB required for kernel uaccess routines when chaning POR_EL0 */
-               isb();
-       }
 }

What about the one in flush_poe()? I'm inclined to drop that as well.

Yes, that's a similar thing.

-- 
Catalin