This is backport for 5.10
(cherry picked from commit 98bf2d3f4970179c702ef64db658e0553bc6ef3a)
When we have VMAP stack, exception prolog 1 sets r1, not r11.
When it is not an RTAS machine check, don't trash r1 because it is
needed by prolog 1.
Fixes: da7bb43ab9da ("powerpc/32: Fix vmap stack - Properly set r1 before
activating MMU")
Cc: sta...@vger.kernel.org # v5.10+
Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
[mpe: Squash in fixup for RTAS machine check from Christophe]
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
Link:
https://lore.kernel.org/r/bc77d61d1c18940e456a2dee464f1e2eda65a3f0.1608621048.git.christophe.le...@csgroup.eu
---
arch/powerpc/kernel/head_book3s_32.S | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/powerpc/kernel/head_book3s_32.S
b/arch/powerpc/kernel/head_book3s_32.S
index a0dda2a1f2df..d66da35f2e8d 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -262,10 +262,19 @@ __secondary_hold_acknowledge:
MachineCheck:
EXCEPTION_PROLOG_0
#ifdef CONFIG_PPC_CHRP
+#ifdef CONFIG_VMAP_STACK
+ mr r11, r1
+ mfspr r1, SPRN_SPRG_THREAD
+ lwz r1, RTAS_SP(r1)
+ cmpwi cr1, r1, 0
+ bne cr1, 7f
+ mr r1, r11
+#else
mfspr r11, SPRN_SPRG_THREAD
lwz r11, RTAS_SP(r11)
cmpwi cr1, r11, 0
bne cr1, 7f
+#endif
#endif /* CONFIG_PPC_CHRP */
EXCEPTION_PROLOG_1 for_rtas=1
7: EXCEPTION_PROLOG_2
--
2.25.0
