From 2a26f4ee399db65ccd97465d57002339afe48572 Mon Sep 17 00:00:00 2001 From: Max Filippov Date: Sat, 23 Apr 2022 03:52:23 -0700 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 fast_store_prohibited. 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 d703ed3..7852481 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 +1: rsr a3, depc # still holds a2 s32i a3, a2, PT_AREG2 mov a1, a2 -- 2.7.4