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Subject[PATCH] xtensa: don't leave invalid TLB entry in fast_store_prohibited
When fast_store_prohibited needs to go to the C-level exception handler
it leaves TLB entry that caused page fault in the TLB. If the faulting
task gets switched to a different CPU and completes page table update
there the TLB entry will get out of sync with the page table which may
cause a livelock on access to that page.
Invalidate faulting TLB entry on a slow path exit from the

Signed-off-by: Max Filippov <>
arch/xtensa/kernel/entry.S | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index d703ed31254a..7852481d779c 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -1882,7 +1882,11 @@ ENTRY(fast_store_prohibited)
j 8b

2: /* If there was a problem, handle fault in C */
+ rsr a1, excvaddr
+ pdtlb a0, a1
+ bbci.l a0, DTLB_HIT_BIT, 1f
+ idtlb a0
rsr a3, depc # still holds a2
s32i a3, a2, PT_AREG2
mov a1, a2
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