From 5bb60ea611db1e04814426ed4bd1c95d1487678e Mon Sep 17 00:00:00 2001
From: Christophe Leroy <christophe.leroy@csgroup.eu>
Date: Thu, 18 Nov 2021 10:39:53 +0100
Subject: powerpc/32: Fix hardlockup on vmap stack overflow
Since the commit c118c7303ad5 ("powerpc/32: Fix vmap stack - Do not
activate MMU before reading task struct") a vmap stack overflow
results in a hard lockup. This is because emergency_ctx is still
addressed with its virtual address allthough data MMU is not active
anymore at that time.
Fix it by using a physical address instead.
Fixes: c118c7303ad5 ("powerpc/32: Fix vmap stack - Do not activate MMU before reading task struct")
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/ce30364fb7ccda489272af4a1612b6aa147e1d23.1637227521.git.christophe.leroy@csgroup.eu
---
arch/powerpc/kernel/head_32.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
(limited to 'arch/powerpc')
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index 6b1ec9e3541b..349c4a820231 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -202,11 +202,11 @@ vmap_stack_overflow:
mfspr r1, SPRN_SPRG_THREAD
lwz r1, TASK_CPU - THREAD(r1)
slwi r1, r1, 3
- addis r1, r1, emergency_ctx@ha
+ addis r1, r1, emergency_ctx-PAGE_OFFSET@ha
#else
- lis r1, emergency_ctx@ha
+ lis r1, emergency_ctx-PAGE_OFFSET@ha
#endif
- lwz r1, emergency_ctx@l(r1)
+ lwz r1, emergency_ctx-PAGE_OFFSET@l(r1)
addi r1, r1, THREAD_SIZE - INT_FRAME_SIZE
EXCEPTION_PROLOG_2 0 vmap_stack_overflow
prepare_transfer_to_handler
--
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