+
+/* Make sure %gs is initialized properly in idle threads */
+struct pt_regs * __devinit idle_regs(struct pt_regs *regs)
+{
+ memset(regs, 0, sizeof(struct pt_regs));
+ regs->xgs = __KERNEL_PDA;
+ return regs;
+}
+
+static __cpuinit int alloc_gdt(int cpu)
+{
+ struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
+ struct desc_struct *gdt;
+ struct i386_pda *pda;
+
+ gdt = (struct desc_struct *)cpu_gdt_descr->address;
+ pda = cpu_pda(cpu);
+
+ /*
+ * This is a horrible hack to allocate the GDT. The problem
+ * is that cpu_init() is called really early for the boot CPU
+ * (and hence needs bootmem) but much later for the secondary
+ * CPUs, when bootmem will have gone away
+ */
+ if (NODE_DATA(0)->bdata->node_bootmem_map) {
+ BUG_ON(gdt != NULL || pda != NULL);
+
+ gdt = alloc_bootmem_pages(PAGE_SIZE);
+ pda = alloc_bootmem(sizeof(*pda));
+ /* alloc_bootmem(_pages) panics on failure, so no check */
+
+ memset(gdt, 0, PAGE_SIZE);
+ memset(pda, 0, sizeof(*pda));
+ } else {
+ /* GDT and PDA might already have been allocated if
+ this is a CPU hotplug re-insertion. */
+ if (gdt == NULL)
+ gdt = (struct desc_struct *)get_zeroed_page(GFP_KERNEL);
+
+ if (pda == NULL)
+ pda = kmalloc_node(sizeof(*pda), GFP_KERNEL, cpu_to_node(cpu));
+
+ if (unlikely(!gdt || !pda)) {
+ free_pages((unsigned long)gdt, 0);
+ kfree(pda);
+ return 0;
+ }
+ }
+
+ cpu_gdt_descr->address = (unsigned long)gdt;
+ cpu_pda(cpu) = pda;
+
+ return 1;
+}
+
+/* Initial PDA used by boot CPU */
+struct i386_pda boot_pda = {
+ ._pda = &boot_pda,
+ .cpu_number = 0,
+ .pcurrent = &init_task,
+};
+
+static inline void set_kernel_gs(void)
+{
+ /* Set %gs for this CPU's PDA. Memory clobber is to create a
+ barrier with respect to any PDA operations, so the compiler
+ doesn't move any before here. */
+ asm volatile ("mov %0, %%gs" : : "r" (__KERNEL_PDA) : "memory");
+}
+
+/* Initialize the CPU's GDT and PDA. The boot CPU does this for
+ itself, but secondaries find this done for them. */
+__cpuinit int init_gdt(int cpu, struct task_struct *idle)
+{
+ struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
+ struct desc_struct *gdt;
+ struct i386_pda *pda;
+
+ /* For non-boot CPUs, the GDT and PDA should already have been
+ allocated. */
+ if (!alloc_gdt(cpu)) {
+ printk(KERN_CRIT "CPU%d failed to allocate GDT or PDA\n", cpu);
+ return 0;
+ }
+
+ gdt = (struct desc_struct *)cpu_gdt_descr->address;
+ pda = cpu_pda(cpu);
+
+ BUG_ON(gdt == NULL || pda == NULL);
+
+ /*
+ * Initialize the per-CPU GDT with the boot GDT,
+ * and set up the GDT descriptor:
+ */
+ memcpy(gdt, cpu_gdt_table, GDT_SIZE);
+ cpu_gdt_descr->size = GDT_SIZE - 1;
+
+ pack_descriptor((u32 *)&gdt[GDT_ENTRY_PDA].a,
+ (u32 *)&gdt[GDT_ENTRY_PDA].b,
+ (unsigned long)pda, sizeof(*pda) - 1,
+ 0x80 | DESCTYPE_S | 0x2, 0); /* present read-write data segment */
+
+ memset(pda, 0, sizeof(*pda));
+ pda->_pda = pda;
+ pda->cpu_number = cpu;
+ pda->pcurrent = idle;
+
+ return 1;
+}
+
+void __cpuinit cpu_set_gdt(int cpu)
+{
+ struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
+
+ /* Reinit these anyway, even if they've already been done (on
+ the boot CPU, this will transition from the boot gdt+pda to
+ the real ones). */
+ load_gdt(cpu_gdt_descr);
+ set_kernel_gs();
+}
+
+/* Common CPU init for both boot and secondary CPUs */
+static void __cpuinit _cpu_init(int cpu, struct task_struct *curr)