Commit 5bb60ea6 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/32: Fix hardlockup on vmap stack overflow 



Since the commit c118c730 ("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: c118c730 ("powerpc/32: Fix vmap stack - Do not activate MMU before reading task struct")
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/ce30364fb7ccda489272af4a1612b6aa147e1d23.1637227521.git.christophe.leroy@csgroup.eu
parent cf0b0e37

arch/powerpc/kernel/head_32.h

+3 −3
Original line number Diff line number Diff line
@@ -202,11 +202,11 @@ _ASM_NOKPROBE_SYMBOL(\name\()_virt) 
	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