x86: pass in cpu number to switch_to_new_gdt()

Impact: cleanup, prepare for xen boot fix.

Xen needs to call this function very early to setup the GDT and
per-cpu segments.  Remove the call to smp_processor_id() and just
pass in the cpu number.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

arch/x86/include/asm/processor.h

@@ -768,7 +768,7 @@ extern int sysenter_setup(void);
 extern struct desc_ptr		early_gdt_descr;
 
 extern void cpu_set_gdt(int);
-extern void switch_to_new_gdt(void);
+extern void switch_to_new_gdt(int);
 extern void cpu_init(void);
 
 static inline unsigned long get_debugctlmsr(void)

arch/x86/kernel/cpu/common.c

@@ -255,10 +255,9 @@ __u32 cleared_cpu_caps[NCAPINTS] __cpuinitdata;
 
 /* Current gdt points %fs at the "master" per-cpu area: after this,
  * it's on the real one. */
-void switch_to_new_gdt(void)
+void switch_to_new_gdt(int cpu)
 {
 	struct desc_ptr gdt_descr;
-	int cpu = smp_processor_id();
 
 	gdt_descr.address = (long)get_cpu_gdt_table(cpu);
 	gdt_descr.size = GDT_SIZE - 1;
@@ -993,7 +992,7 @@ void __cpuinit cpu_init(void)
 	 * and set up the GDT descriptor:
 	 */
 
-	switch_to_new_gdt();
+	switch_to_new_gdt(cpu);
 	loadsegment(fs, 0);
 
 	load_idt((const struct desc_ptr *)&idt_descr);
@@ -1098,7 +1097,7 @@ void __cpuinit cpu_init(void)
 		clear_in_cr4(X86_CR4_VME|X86_CR4_PVI|X86_CR4_TSD|X86_CR4_DE);
 
 	load_idt(&idt_descr);
-	switch_to_new_gdt();
+	switch_to_new_gdt(cpu);
 
 	/*
 	 * Set up and load the per-CPU TSS and LDT

arch/x86/kernel/setup_percpu.c

@@ -122,7 +122,7 @@ void __init setup_per_cpu_areas(void)
 		 * area.  Reload any changed state for the boot CPU.
 		 */
 		if (cpu == boot_cpu_id)
-			switch_to_new_gdt();
+			switch_to_new_gdt(cpu);
 
 		DBG("PERCPU: cpu %4d %p\n", cpu, ptr);
 	}

arch/x86/kernel/smpboot.c

@@ -1185,7 +1185,7 @@ out:
 void __init native_smp_prepare_boot_cpu(void)
 {
 	int me = smp_processor_id();
-	switch_to_new_gdt();
+	switch_to_new_gdt(me);
 	/* already set me in cpu_online_mask in boot_cpu_init() */
 	cpumask_set_cpu(me, cpu_callout_mask);
 	per_cpu(cpu_state, me) = CPU_ONLINE;

arch/x86/mach-voyager/voyager_smp.c

@@ -1746,12 +1746,13 @@ static void __init voyager_smp_prepare_cpus(unsigned int max_cpus)
 
 static void __cpuinit voyager_smp_prepare_boot_cpu(void)
 {
-	switch_to_new_gdt();
+	int cpu = smp_processor_id();
+	switch_to_new_gdt(cpu);
 
-	cpu_set(smp_processor_id(), cpu_online_map);
-	cpu_set(smp_processor_id(), cpu_callout_map);
-	cpu_set(smp_processor_id(), cpu_possible_map);
-	cpu_set(smp_processor_id(), cpu_present_map);
+	cpu_set(cpu, cpu_online_map);
+	cpu_set(cpu, cpu_callout_map);
+	cpu_set(cpu, cpu_possible_map);
+	cpu_set(cpu, cpu_present_map);
 }
 
 static int __cpuinit voyager_cpu_up(unsigned int cpu)