init: Get rid of x86isms

The UP local API support can be set up from an early initcall. No need
for horrible hackery in the init code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/20150115211703.827943883@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/Kconfig

@@ -855,6 +855,10 @@ config SCHED_MC
 
 source "kernel/Kconfig.preempt"
 
+config UP_LATE_INIT
+       def_bool y
+       depends on X86_UP_APIC
+
 config X86_UP_APIC
 	bool "Local APIC support on uniprocessors"
 	depends on X86_32 && !SMP && !X86_32_NON_STANDARD && !PCI_MSI

arch/x86/kernel/apic/apic.c

@@ -2267,6 +2267,13 @@ int __init APIC_init_uniprocessor(void)
 	return 0;
 }
 
+#ifdef CONFIG_UP_LATE_INIT
+void __init up_late_init(void)
+{
+	APIC_init_uniprocessor();
+}
+#endif
+
 /*
  * Power management
  */

include/linux/smp.h

@@ -151,6 +151,13 @@ smp_call_function_any(const struct cpumask *mask, smp_call_func_t func,
 static inline void kick_all_cpus_sync(void) {  }
 static inline void wake_up_all_idle_cpus(void) {  }
 
+#ifdef CONFIG_UP_LATE_INIT
+extern void __init up_late_init(void);
+static inline void smp_init(void) { up_late_init(); }
+#else
+static inline void smp_init(void) { }
+#endif
+
 #endif /* !SMP */
 
 /*

init/main.c

@@ -87,10 +87,6 @@
 #include <asm/sections.h>
 #include <asm/cacheflush.h>
 
-#ifdef CONFIG_X86_LOCAL_APIC
-#include <asm/smp.h>
-#endif
-
 static int kernel_init(void *);
 
 extern void init_IRQ(void);
@@ -351,15 +347,6 @@ __setup("rdinit=", rdinit_setup);
 
 #ifndef CONFIG_SMP
 static const unsigned int setup_max_cpus = NR_CPUS;
-#ifdef CONFIG_X86_LOCAL_APIC
-static void __init smp_init(void)
-{
-	APIC_init_uniprocessor();
-}
-#else
-#define smp_init()	do { } while (0)
-#endif
-
 static inline void setup_nr_cpu_ids(void) { }
 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 #endif