s390/numa: always use logical cpu and core ids

The toptree algorithm uses the physical core ids to create a mapping
between cores and nodes (to_node_id array within emu_cores structure).
The core ids are used as an index into an array which size depends on
CONFIG_NR_CPUS. If the physical core ids are larger, this will result
in out-of-bounds write accesses.

Generate logical core ids instead to avoid this.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/smp.h

@@ -69,6 +69,12 @@ static inline void smp_stop_cpu(void)
 	}
 }
 
+/* Return thread 0 CPU number as base CPU */
+static inline int smp_get_base_cpu(int cpu)
+{
+	return cpu - (cpu % (smp_cpu_mtid + 1));
+}
+
 #ifdef CONFIG_HOTPLUG_CPU
 extern int smp_rescan_cpus(void);
 extern void __noreturn cpu_die(void);