MIPS: Malta: Fix crash in SMP kernel on non-CMP systems.

Since 6be63bbbdab66b9185dc6f67c8b1bacb6f37f946 (lmo) rsp.
af3a1f6f4813907e143f87030cde67a9971db533 (kernel.org) the Malta code does
no longer probe for presence of GCMP if CMP is not configured.  This means
that the variable gcmp_present well be left at its default value of -1
which normally is meant to indicate that GCMP has not yet been mmapped.
This non-zero value is now interpreted as GCMP being present resulting
in a write attempt to a GCMP register resulting in a crash.

Reported and a build fix on top of my fix by Rob Landley <rob@landley.net>.

Reported-by: Rob Landley <rob@landley.net>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/2413/

1 files changed, 38 insertions, 3 deletions

diff --git a/arch/mips/include/asm/smp-ops.h b/arch/mips/include/asm/smp-ops.h
index 9e09af34c8a8..48b03fff31e5 100644
--- a/arch/mips/include/asm/smp-ops.h
+++ b/arch/mips/include/asm/smp-ops.h
@@ -56,8 +56,43 @@ static inline void register_smp_ops(struct plat_smp_ops *ops)
 
 #endif /* !CONFIG_SMP */
 
-extern struct plat_smp_ops up_smp_ops;
-extern struct plat_smp_ops cmp_smp_ops;
-extern struct plat_smp_ops vsmp_smp_ops;
+static inline int register_up_smp_ops(void)
+{
+#ifdef CONFIG_SMP_UP
+	extern struct plat_smp_ops up_smp_ops;
+
+	register_smp_ops(&up_smp_ops);
+
+	return 0;
+#else
+	return -ENODEV;
+#endif
+}
+
+static inline int register_cmp_smp_ops(void)
+{
+#ifdef CONFIG_MIPS_CMP
+	extern struct plat_smp_ops cmp_smp_ops;
+
+	register_smp_ops(&cmp_smp_ops);
+
+	return 0;
+#else
+	return -ENODEV;
+#endif
+}
+
+static inline int register_vsmp_smp_ops(void)
+{
+#ifdef CONFIG_MIPS_MT_SMP
+	extern struct plat_smp_ops vsmp_smp_ops;
+
+	register_smp_ops(&vsmp_smp_ops);
+
+	return 0;
+#else
+	return -ENODEV;
+#endif
+}
 
 #endif /* __ASM_SMP_OPS_H */