x86: unify setup_trampoline

setup_trampoline() looks very similar between architectures, and this
patch unifies them. The i386 version allocates bootmem memory, while
the x86_64 version uses a fixed address.

In this patch, we initialize the global trampoline_base to the x86_64 version,
and i386 allocation can later override it.
Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/smpboot.c

@@ -3,6 +3,7 @@
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/percpu.h>
+#include <linux/bootmem.h>
 
 #include <asm/nmi.h>
 #include <asm/irq.h>
@@ -38,6 +39,9 @@ EXPORT_PER_CPU_SYMBOL(cpu_core_map);
 DEFINE_PER_CPU_SHARED_ALIGNED(struct cpuinfo_x86, cpu_info);
 EXPORT_PER_CPU_SYMBOL(cpu_info);
 
+/* ready for x86_64, no harm for x86, since it will overwrite after alloc */
+unsigned char *trampoline_base = __va(SMP_TRAMPOLINE_BASE);
+
 /* representing cpus for which sibling maps can be computed */
 static cpumask_t cpu_sibling_setup_map;
 
@@ -117,6 +121,35 @@ cpumask_t cpu_coregroup_map(int cpu)
 		return c->llc_shared_map;
 }
 
+/*
+ * Currently trivial. Write the real->protected mode
+ * bootstrap into the page concerned. The caller
+ * has made sure it's suitably aligned.
+ */
+
+unsigned long __cpuinit setup_trampoline(void)
+{
+	memcpy(trampoline_base, trampoline_data,
+	       trampoline_end - trampoline_data);
+	return virt_to_phys(trampoline_base);
+}
+
+#ifdef CONFIG_X86_32
+/*
+ * We are called very early to get the low memory for the
+ * SMP bootup trampoline page.
+ */
+void __init smp_alloc_memory(void)
+{
+	trampoline_base = alloc_bootmem_low_pages(PAGE_SIZE);
+	/*
+	 * Has to be in very low memory so we can execute
+	 * real-mode AP code.
+	 */
+	if (__pa(trampoline_base) >= 0x9F000)
+		BUG();
+}
+#endif
 
 #ifdef CONFIG_HOTPLUG_CPU
 void remove_siblinginfo(int cpu)

arch/x86/kernel/smpboot_32.c

@@ -73,40 +73,11 @@ EXPORT_PER_CPU_SYMBOL(x86_cpu_to_apicid);
 
 u8 apicid_2_node[MAX_APICID];
 
-static unsigned char *trampoline_base;
-
 static void map_cpu_to_logical_apicid(void);
 
 /* State of each CPU. */
 DEFINE_PER_CPU(int, cpu_state) = { 0 };
 
-/*
- * Currently trivial. Write the real->protected mode
- * bootstrap into the page concerned. The caller
- * has made sure it's suitably aligned.
- */
-
-static unsigned long __cpuinit setup_trampoline(void)
-{
-	memcpy(trampoline_base, trampoline_data, trampoline_end - trampoline_data);
-	return virt_to_phys(trampoline_base);
-}
-
-/*
- * We are called very early to get the low memory for the
- * SMP bootup trampoline page.
- */
-void __init smp_alloc_memory(void)
-{
-	trampoline_base = alloc_bootmem_low_pages(PAGE_SIZE);
-	/*
-	 * Has to be in very low memory so we can execute
-	 * real-mode AP code.
-	 */
-	if (__pa(trampoline_base) >= 0x9F000)
-		BUG();
-}
-
 /*
  * The bootstrap kernel entry code has set these up. Save them for
  * a given CPU

arch/x86/kernel/smpboot_64.c

@@ -85,20 +85,6 @@ struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ;
 #define set_idle_for_cpu(x,p)   (idle_thread_array[(x)] = (p))
 #endif
 
-
-/*
- * Currently trivial. Write the real->protected mode
- * bootstrap into the page concerned. The caller
- * has made sure it's suitably aligned.
- */
-
-static unsigned long __cpuinit setup_trampoline(void)
-{
-	void *tramp = __va(SMP_TRAMPOLINE_BASE); 
-	memcpy(tramp, trampoline_data, trampoline_end - trampoline_data);
-	return virt_to_phys(tramp);
-}
-
 /*
  * The bootstrap kernel entry code has set these up. Save them for
  * a given CPU

include/asm-x86/smp.h

@@ -14,6 +14,7 @@ extern unsigned int num_processors;
  */
 extern const unsigned char trampoline_data [];
 extern const unsigned char trampoline_end  [];
+extern unsigned char *trampoline_base;
 
 struct smp_ops {
 	void (*smp_prepare_boot_cpu)(void);
@@ -81,6 +82,9 @@ extern void __cpu_die(unsigned int cpu);
 
 extern unsigned disabled_cpus;
 extern void prefill_possible_map(void);
+
+#define SMP_TRAMPOLINE_BASE 0x6000
+extern unsigned long setup_trampoline(void);
 #endif
 
 #ifdef CONFIG_X86_32

include/asm-x86/smp_64.h

@@ -40,8 +40,6 @@ static inline int cpu_present_to_apicid(int mps_cpu)
 
 #ifdef CONFIG_SMP
 
-#define SMP_TRAMPOLINE_BASE 0x6000
-
 #define raw_smp_processor_id()	read_pda(cpunumber)
 #define cpu_physical_id(cpu)	per_cpu(x86_cpu_to_apicid, cpu)