[PATCH] powerpc/32s: Fix RTAS machine check with VMAP stack - again

[Christophe Leroy]

When it is not a RTAS machine check, don't trash r1
because it is needed by prolog 1.

Fixes: 9c7422b92cb2 ("powerpc/32s: Fix RTAS machine check with VMAP stack")
Cc: stable at vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy at csgroup.eu>
---
Sorry Michael for this last minute fix of the fix.

 arch/powerpc/kernel/head_book3s_32.S | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
index fbc48a500846..858fbc8b19f3 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -265,12 +265,14 @@ MachineCheck:
 	mfspr	r1, SPRN_SPRG_THREAD
 	lwz	r1, RTAS_SP(r1)
 	cmpwi	cr1, r1, 0
+	bne	cr1, 7f
+	mfspr	r1, SPRN_SPRG_SCRATCH2
 #else
 	mfspr	r11, SPRN_SPRG_THREAD
 	lwz	r11, RTAS_SP(r11)
 	cmpwi	cr1, r11, 0
-#endif
 	bne	cr1, 7f
+#endif
 #endif /* CONFIG_PPC_CHRP */
 	EXCEPTION_PROLOG_1 for_rtas=1
 7:	EXCEPTION_PROLOG_2
-- 
2.25.0