1 files changed, 681 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/common_64.c b/arch/x86/kernel/cpu/common_64.c
new file mode 100644
index 000000000000..7b8cc72feb40
--- /dev/null
+++ b/arch/x86/kernel/cpu/common_64.c
@@ -0,0 +1,681 @@
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/bootmem.h>
+#include <linux/bitops.h>
+#include <linux/module.h>
+#include <linux/kgdb.h>
+#include <linux/topology.h>
+#include <linux/string.h>
+#include <linux/delay.h>
+#include <linux/smp.h>
+#include <linux/module.h>
+#include <linux/percpu.h>
+#include <asm/processor.h>
+#include <asm/i387.h>
+#include <asm/msr.h>
+#include <asm/io.h>
+#include <asm/mmu_context.h>
+#include <asm/mtrr.h>
+#include <asm/mce.h>
+#include <asm/pat.h>
+#include <asm/numa.h>
+#ifdef CONFIG_X86_LOCAL_APIC
+#include <asm/mpspec.h>
+#include <asm/apic.h>
+#include <mach_apic.h>
+#endif
+#include <asm/pda.h>
+#include <asm/pgtable.h>
+#include <asm/processor.h>
+#include <asm/desc.h>
+#include <asm/atomic.h>
+#include <asm/proto.h>
+#include <asm/sections.h>
+#include <asm/setup.h>
+#include <asm/genapic.h>
+
+#include "cpu.h"
+
+/* We need valid kernel segments for data and code in long mode too
+ * IRET will check the segment types  kkeil 2000/10/28
+ * Also sysret mandates a special GDT layout
+ */
+/* The TLS descriptors are currently at a different place compared to i386.
+   Hopefully nobody expects them at a fixed place (Wine?) */
+DEFINE_PER_CPU(struct gdt_page, gdt_page) = { .gdt = {
+        [GDT_ENTRY_KERNEL32_CS] = { { { 0x0000ffff, 0x00cf9b00 } } },
+        [GDT_ENTRY_KERNEL_CS] = { { { 0x0000ffff, 0x00af9b00 } } },
+        [GDT_ENTRY_KERNEL_DS] = { { { 0x0000ffff, 0x00cf9300 } } },
+        [GDT_ENTRY_DEFAULT_USER32_CS] = { { { 0x0000ffff, 0x00cffb00 } } },
+        [GDT_ENTRY_DEFAULT_USER_DS] = { { { 0x0000ffff, 0x00cff300 } } },
+        [GDT_ENTRY_DEFAULT_USER_CS] = { { { 0x0000ffff, 0x00affb00 } } },
+} };
+EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);
+
+__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)
+{
+        struct desc_ptr gdt_descr;
+
+        gdt_descr.address = (long)get_cpu_gdt_table(smp_processor_id());
+        gdt_descr.size = GDT_SIZE - 1;
+        load_gdt(&gdt_descr);
+}
+
+struct cpu_dev *cpu_devs[X86_VENDOR_NUM] = {};
+
+static void __cpuinit default_init(struct cpuinfo_x86 *c)
+{
+        display_cacheinfo(c);
+}
+
+static struct cpu_dev __cpuinitdata default_cpu = {
+        .c_init = default_init,
+        .c_vendor = "Unknown",
+};
+static struct cpu_dev *this_cpu __cpuinitdata = &default_cpu;
+
+int __cpuinit get_model_name(struct cpuinfo_x86 *c)
+{
+        unsigned int *v;
+
+        if (c->extended_cpuid_level < 0x80000004)
+                return 0;
+
+        v = (unsigned int *) c->x86_model_id;
+        cpuid(0x80000002, &v[0], &v[1], &v[2], &v[3]);
+        cpuid(0x80000003, &v[4], &v[5], &v[6], &v[7]);
+        cpuid(0x80000004, &v[8], &v[9], &v[10], &v[11]);
+        c->x86_model_id[48] = 0;
+        return 1;
+}
+
+
+void __cpuinit display_cacheinfo(struct cpuinfo_x86 *c)
+{
+        unsigned int n, dummy, ebx, ecx, edx;
+
+        n = c->extended_cpuid_level;
+
+        if (n >= 0x80000005) {
+                cpuid(0x80000005, &dummy, &ebx, &ecx, &edx);
+                printk(KERN_INFO "CPU: L1 I Cache: %dK (%d bytes/line), "
+                       "D cache %dK (%d bytes/line)\n",
+                       edx>>24, edx&0xFF, ecx>>24, ecx&0xFF);
+                c->x86_cache_size = (ecx>>24) + (edx>>24);
+                /* On K8 L1 TLB is inclusive, so don't count it */
+                c->x86_tlbsize = 0;
+        }
+
+        if (n >= 0x80000006) {
+                cpuid(0x80000006, &dummy, &ebx, &ecx, &edx);
+                ecx = cpuid_ecx(0x80000006);
+                c->x86_cache_size = ecx >> 16;
+                c->x86_tlbsize += ((ebx >> 16) & 0xfff) + (ebx & 0xfff);
+
+                printk(KERN_INFO "CPU: L2 Cache: %dK (%d bytes/line)\n",
+                c->x86_cache_size, ecx & 0xFF);
+        }
+}
+
+void __cpuinit detect_ht(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_SMP
+        u32 eax, ebx, ecx, edx;
+        int index_msb, core_bits;
+
+        cpuid(1, &eax, &ebx, &ecx, &edx);
+
+
+        if (!cpu_has(c, X86_FEATURE_HT))
+                return;
+        if (cpu_has(c, X86_FEATURE_CMP_LEGACY))
+                goto out;
+
+        smp_num_siblings = (ebx & 0xff0000) >> 16;
+
+        if (smp_num_siblings == 1) {
+                printk(KERN_INFO  "CPU: Hyper-Threading is disabled\n");
+        } else if (smp_num_siblings > 1) {
+
+                if (smp_num_siblings > NR_CPUS) {
+                        printk(KERN_WARNING "CPU: Unsupported number of "
+                               "siblings %d", smp_num_siblings);
+                        smp_num_siblings = 1;
+                        return;
+                }
+
+                index_msb = get_count_order(smp_num_siblings);
+                c->phys_proc_id = phys_pkg_id(index_msb);
+
+                smp_num_siblings = smp_num_siblings / c->x86_max_cores;
+
+                index_msb = get_count_order(smp_num_siblings);
+
+                core_bits = get_count_order(c->x86_max_cores);
+
+                c->cpu_core_id = phys_pkg_id(index_msb) &
+                                               ((1 << core_bits) - 1);
+        }
+out:
+        if ((c->x86_max_cores * smp_num_siblings) > 1) {
+                printk(KERN_INFO  "CPU: Physical Processor ID: %d\n",
+                       c->phys_proc_id);
+                printk(KERN_INFO  "CPU: Processor Core ID: %d\n",
+                       c->cpu_core_id);
+        }
+
+#endif
+}
+
+static void __cpuinit get_cpu_vendor(struct cpuinfo_x86 *c)
+{
+        char *v = c->x86_vendor_id;
+        int i;
+        static int printed;
+
+        for (i = 0; i < X86_VENDOR_NUM; i++) {
+                if (cpu_devs[i]) {
+                        if (!strcmp(v, cpu_devs[i]->c_ident[0]) ||
+                            (cpu_devs[i]->c_ident[1] &&
+                            !strcmp(v, cpu_devs[i]->c_ident[1]))) {
+                                c->x86_vendor = i;
+                                this_cpu = cpu_devs[i];
+                                return;
+                        }
+                }
+        }
+        if (!printed) {
+                printed++;
+                printk(KERN_ERR "CPU: Vendor unknown, using generic init.\n");
+                printk(KERN_ERR "CPU: Your system may be unstable.\n");
+        }
+        c->x86_vendor = X86_VENDOR_UNKNOWN;
+}
+
+static void __init early_cpu_support_print(void)
+{
+        int i,j;
+        struct cpu_dev *cpu_devx;
+
+        printk("KERNEL supported cpus:\n");
+        for (i = 0; i < X86_VENDOR_NUM; i++) {
+                cpu_devx = cpu_devs[i];
+                if (!cpu_devx)
+                        continue;
+                for (j = 0; j < 2; j++) {
+                        if (!cpu_devx->c_ident[j])
+                                continue;
+                        printk("  %s %s\n", cpu_devx->c_vendor,
+                                cpu_devx->c_ident[j]);
+                }
+        }
+}
+
+static void __cpuinit early_identify_cpu(struct cpuinfo_x86 *c);
+
+void __init early_cpu_init(void)
+{
+        struct cpu_vendor_dev *cvdev;
+
+        for (cvdev = __x86cpuvendor_start ;
+             cvdev < __x86cpuvendor_end   ;
+             cvdev++)
+                cpu_devs[cvdev->vendor] = cvdev->cpu_dev;
+        early_cpu_support_print();
+        early_identify_cpu(&boot_cpu_data);
+}
+
+/* Do some early cpuid on the boot CPU to get some parameter that are
+   needed before check_bugs. Everything advanced is in identify_cpu
+   below. */
+static void __cpuinit early_identify_cpu(struct cpuinfo_x86 *c)
+{
+        u32 tfms, xlvl;
+
+        c->loops_per_jiffy = loops_per_jiffy;
+        c->x86_cache_size = -1;
+        c->x86_vendor = X86_VENDOR_UNKNOWN;
+        c->x86_model = c->x86_mask = 0; /* So far unknown... */
+        c->x86_vendor_id[0] = '\0'; /* Unset */
+        c->x86_model_id[0] = '\0';  /* Unset */
+        c->x86_clflush_size = 64;
+        c->x86_cache_alignment = c->x86_clflush_size;
+        c->x86_max_cores = 1;
+        c->x86_coreid_bits = 0;
+        c->extended_cpuid_level = 0;
+        memset(&c->x86_capability, 0, sizeof c->x86_capability);
+
+        /* Get vendor name */
+        cpuid(0x00000000, (unsigned int *)&c->cpuid_level,
+              (unsigned int *)&c->x86_vendor_id[0],
+              (unsigned int *)&c->x86_vendor_id[8],
+              (unsigned int *)&c->x86_vendor_id[4]);
+
+        get_cpu_vendor(c);
+
+        /* Initialize the standard set of capabilities */
+        /* Note that the vendor-specific code below might override */
+
+        /* Intel-defined flags: level 0x00000001 */
+        if (c->cpuid_level >= 0x00000001) {
+                __u32 misc;
+                cpuid(0x00000001, &tfms, &misc, &c->x86_capability[4],
+                      &c->x86_capability[0]);
+                c->x86 = (tfms >> 8) & 0xf;
+                c->x86_model = (tfms >> 4) & 0xf;
+                c->x86_mask = tfms & 0xf;
+                if (c->x86 == 0xf)
+                        c->x86 += (tfms >> 20) & 0xff;
+                if (c->x86 >= 0x6)
+                        c->x86_model += ((tfms >> 16) & 0xF) << 4;
+                if (test_cpu_cap(c, X86_FEATURE_CLFLSH))
+                        c->x86_clflush_size = ((misc >> 8) & 0xff) * 8;
+        } else {
+                /* Have CPUID level 0 only - unheard of */
+                c->x86 = 4;
+        }
+
+        c->initial_apicid = (cpuid_ebx(1) >> 24) & 0xff;
+#ifdef CONFIG_SMP
+        c->phys_proc_id = c->initial_apicid;
+#endif
+        /* AMD-defined flags: level 0x80000001 */
+        xlvl = cpuid_eax(0x80000000);
+        c->extended_cpuid_level = xlvl;
+        if ((xlvl & 0xffff0000) == 0x80000000) {
+                if (xlvl >= 0x80000001) {
+                        c->x86_capability[1] = cpuid_edx(0x80000001);
+                        c->x86_capability[6] = cpuid_ecx(0x80000001);
+                }
+                if (xlvl >= 0x80000004)
+                        get_model_name(c); /* Default name */
+        }
+
+        /* Transmeta-defined flags: level 0x80860001 */
+        xlvl = cpuid_eax(0x80860000);
+        if ((xlvl & 0xffff0000) == 0x80860000) {
+                /* Don't set x86_cpuid_level here for now to not confuse. */
+                if (xlvl >= 0x80860001)
+                        c->x86_capability[2] = cpuid_edx(0x80860001);
+        }
+
+        c->extended_cpuid_level = cpuid_eax(0x80000000);
+        if (c->extended_cpuid_level >= 0x80000007)
+                c->x86_power = cpuid_edx(0x80000007);
+
+        if (c->extended_cpuid_level >= 0x80000008) {
+                u32 eax = cpuid_eax(0x80000008);
+
+                c->x86_virt_bits = (eax >> 8) & 0xff;
+                c->x86_phys_bits = eax & 0xff;
+        }
+
+        /* Assume all 64-bit CPUs support 32-bit syscall */
+        set_cpu_cap(c, X86_FEATURE_SYSCALL32);
+
+        if (c->x86_vendor != X86_VENDOR_UNKNOWN &&
+            cpu_devs[c->x86_vendor]->c_early_init)
+                cpu_devs[c->x86_vendor]->c_early_init(c);
+
+        validate_pat_support(c);
+
+        /* early_param could clear that, but recall get it set again */
+        if (disable_apic)
+                clear_cpu_cap(c, X86_FEATURE_APIC);
+}
+
+/*
+ * This does the hard work of actually picking apart the CPU stuff...
+ */
+static void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
+{
+        int i;
+
+        early_identify_cpu(c);
+
+        init_scattered_cpuid_features(c);
+
+        c->apicid = phys_pkg_id(0);
+
+        /*
+         * Vendor-specific initialization.  In this section we
+         * canonicalize the feature flags, meaning if there are
+         * features a certain CPU supports which CPUID doesn't
+         * tell us, CPUID claiming incorrect flags, or other bugs,
+         * we handle them here.
+         *
+         * At the end of this section, c->x86_capability better
+         * indicate the features this CPU genuinely supports!
+         */
+        if (this_cpu->c_init)
+                this_cpu->c_init(c);
+
+        detect_ht(c);
+
+        /*
+         * On SMP, boot_cpu_data holds the common feature set between
+         * all CPUs; so make sure that we indicate which features are
+         * common between the CPUs.  The first time this routine gets
+         * executed, c == &boot_cpu_data.
+         */
+        if (c != &boot_cpu_data) {
+                /* AND the already accumulated flags with these */
+                for (i = 0; i < NCAPINTS; i++)
+                        boot_cpu_data.x86_capability[i] &= c->x86_capability[i];
+        }
+
+        /* Clear all flags overriden by options */
+        for (i = 0; i < NCAPINTS; i++)
+                c->x86_capability[i] &= ~cleared_cpu_caps[i];
+
+#ifdef CONFIG_X86_MCE
+        mcheck_init(c);
+#endif
+        select_idle_routine(c);
+
+#ifdef CONFIG_NUMA
+        numa_add_cpu(smp_processor_id());
+#endif
+
+}
+
+void __cpuinit identify_boot_cpu(void)
+{
+        identify_cpu(&boot_cpu_data);
+}
+
+void __cpuinit identify_secondary_cpu(struct cpuinfo_x86 *c)
+{
+        BUG_ON(c == &boot_cpu_data);
+        identify_cpu(c);
+        mtrr_ap_init();
+}
+
+static __init int setup_noclflush(char *arg)
+{
+        setup_clear_cpu_cap(X86_FEATURE_CLFLSH);
+        return 1;
+}
+__setup("noclflush", setup_noclflush);
+
+void __cpuinit print_cpu_info(struct cpuinfo_x86 *c)
+{
+        if (c->x86_model_id[0])
+                printk(KERN_CONT "%s", c->x86_model_id);
+
+        if (c->x86_mask || c->cpuid_level >= 0)
+                printk(KERN_CONT " stepping %02x\n", c->x86_mask);
+        else
+                printk(KERN_CONT "\n");
+}
+
+static __init int setup_disablecpuid(char *arg)
+{
+        int bit;
+        if (get_option(&arg, &bit) && bit < NCAPINTS*32)
+                setup_clear_cpu_cap(bit);
+        else
+                return 0;
+        return 1;
+}
+__setup("clearcpuid=", setup_disablecpuid);
+
+cpumask_t cpu_initialized __cpuinitdata = CPU_MASK_NONE;
+
+struct x8664_pda **_cpu_pda __read_mostly;
+EXPORT_SYMBOL(_cpu_pda);
+
+struct desc_ptr idt_descr = { 256 * 16 - 1, (unsigned long) idt_table };
+
+char boot_cpu_stack[IRQSTACKSIZE] __page_aligned_bss;
+
+unsigned long __supported_pte_mask __read_mostly = ~0UL;
+EXPORT_SYMBOL_GPL(__supported_pte_mask);
+
+static int do_not_nx __cpuinitdata;
+
+/* noexec=on|off
+Control non executable mappings for 64bit processes.
+
+on      Enable(default)
+off     Disable
+*/
+static int __init nonx_setup(char *str)
+{
+        if (!str)
+                return -EINVAL;
+        if (!strncmp(str, "on", 2)) {
+                __supported_pte_mask |= _PAGE_NX;
+                do_not_nx = 0;
+        } else if (!strncmp(str, "off", 3)) {
+                do_not_nx = 1;
+                __supported_pte_mask &= ~_PAGE_NX;
+        }
+        return 0;
+}
+early_param("noexec", nonx_setup);
+
+int force_personality32;
+
+/* noexec32=on|off
+Control non executable heap for 32bit processes.
+To control the stack too use noexec=off
+
+on      PROT_READ does not imply PROT_EXEC for 32bit processes (default)
+off     PROT_READ implies PROT_EXEC
+*/
+static int __init nonx32_setup(char *str)
+{
+        if (!strcmp(str, "on"))
+                force_personality32 &= ~READ_IMPLIES_EXEC;
+        else if (!strcmp(str, "off"))
+                force_personality32 |= READ_IMPLIES_EXEC;
+        return 1;
+}
+__setup("noexec32=", nonx32_setup);
+
+void pda_init(int cpu)
+{
+        struct x8664_pda *pda = cpu_pda(cpu);
+
+        /* Setup up data that may be needed in __get_free_pages early */
+        loadsegment(fs, 0);
+        loadsegment(gs, 0);
+        /* Memory clobbers used to order PDA accessed */
+        mb();
+        wrmsrl(MSR_GS_BASE, pda);
+        mb();
+
+        pda->cpunumber = cpu;
+        pda->irqcount = -1;
+        pda->kernelstack = (unsigned long)stack_thread_info() -
+                                 PDA_STACKOFFSET + THREAD_SIZE;
+        pda->active_mm = &init_mm;
+        pda->mmu_state = 0;
+
+        if (cpu == 0) {
+                /* others are initialized in smpboot.c */
+                pda->pcurrent = &init_task;
+                pda->irqstackptr = boot_cpu_stack;
+        } else {
+                pda->irqstackptr = (char *)
+                        __get_free_pages(GFP_ATOMIC, IRQSTACK_ORDER);
+                if (!pda->irqstackptr)
+                        panic("cannot allocate irqstack for cpu %d", cpu);
+
+                if (pda->nodenumber == 0 && cpu_to_node(cpu) != NUMA_NO_NODE)
+                        pda->nodenumber = cpu_to_node(cpu);
+        }
+
+        pda->irqstackptr += IRQSTACKSIZE-64;
+}
+
+char boot_exception_stacks[(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ +
+                           DEBUG_STKSZ]
+__attribute__((section(".bss.page_aligned")));
+
+extern asmlinkage void ignore_sysret(void);
+
+/* May not be marked __init: used by software suspend */
+void syscall_init(void)
+{
+        /*
+         * LSTAR and STAR live in a bit strange symbiosis.
+         * They both write to the same internal register. STAR allows to
+         * set CS/DS but only a 32bit target. LSTAR sets the 64bit rip.
+         */
+        wrmsrl(MSR_STAR,  ((u64)__USER32_CS)<<48  | ((u64)__KERNEL_CS)<<32);
+        wrmsrl(MSR_LSTAR, system_call);
+        wrmsrl(MSR_CSTAR, ignore_sysret);
+
+#ifdef CONFIG_IA32_EMULATION
+        syscall32_cpu_init();
+#endif
+
+        /* Flags to clear on syscall */
+        wrmsrl(MSR_SYSCALL_MASK,
+               X86_EFLAGS_TF|X86_EFLAGS_DF|X86_EFLAGS_IF|X86_EFLAGS_IOPL);
+}
+
+void __cpuinit check_efer(void)
+{
+        unsigned long efer;
+
+        rdmsrl(MSR_EFER, efer);
+        if (!(efer & EFER_NX) || do_not_nx)
+                __supported_pte_mask &= ~_PAGE_NX;
+}
+
+unsigned long kernel_eflags;
+
+/*
+ * Copies of the original ist values from the tss are only accessed during
+ * debugging, no special alignment required.
+ */
+DEFINE_PER_CPU(struct orig_ist, orig_ist);
+
+/*
+ * cpu_init() initializes state that is per-CPU. Some data is already
+ * initialized (naturally) in the bootstrap process, such as the GDT
+ * and IDT. We reload them nevertheless, this function acts as a
+ * 'CPU state barrier', nothing should get across.
+ * A lot of state is already set up in PDA init.
+ */
+void __cpuinit cpu_init(void)
+{
+        int cpu = stack_smp_processor_id();
+        struct tss_struct *t = &per_cpu(init_tss, cpu);
+        struct orig_ist *orig_ist = &per_cpu(orig_ist, cpu);
+        unsigned long v;
+        char *estacks = NULL;
+        struct task_struct *me;
+        int i;
+
+        /* CPU 0 is initialised in head64.c */
+        if (cpu != 0)
+                pda_init(cpu);
+        else
+                estacks = boot_exception_stacks;
+
+        me = current;
+
+        if (cpu_test_and_set(cpu, cpu_initialized))
+                panic("CPU#%d already initialized!\n", cpu);
+
+        printk(KERN_INFO "Initializing CPU#%d\n", cpu);
+
+        clear_in_cr4(X86_CR4_VME|X86_CR4_PVI|X86_CR4_TSD|X86_CR4_DE);
+
+        /*
+         * Initialize the per-CPU GDT with the boot GDT,
+         * and set up the GDT descriptor:
+         */
+
+        switch_to_new_gdt();
+        load_idt((const struct desc_ptr *)&idt_descr);
+
+        memset(me->thread.tls_array, 0, GDT_ENTRY_TLS_ENTRIES * 8);
+        syscall_init();
+
+        wrmsrl(MSR_FS_BASE, 0);
+        wrmsrl(MSR_KERNEL_GS_BASE, 0);
+        barrier();
+
+        check_efer();
+
+        /*
+         * set up and load the per-CPU TSS
+         */
+        for (v = 0; v < N_EXCEPTION_STACKS; v++) {
+                static const unsigned int order[N_EXCEPTION_STACKS] = {
+                        [0 ... N_EXCEPTION_STACKS - 1] = EXCEPTION_STACK_ORDER,
+                        [DEBUG_STACK - 1] = DEBUG_STACK_ORDER
+                };
+                if (cpu) {
+                        estacks = (char *)__get_free_pages(GFP_ATOMIC, order[v]);
+                        if (!estacks)
+                                panic("Cannot allocate exception stack %ld %d\n",
+                                      v, cpu);
+                }
+                estacks += PAGE_SIZE << order[v];
+                orig_ist->ist[v] = t->x86_tss.ist[v] = (unsigned long)estacks;
+        }
+
+        t->x86_tss.io_bitmap_base = offsetof(struct tss_struct, io_bitmap);
+        /*
+         * <= is required because the CPU will access up to
+         * 8 bits beyond the end of the IO permission bitmap.
+         */
+        for (i = 0; i <= IO_BITMAP_LONGS; i++)
+                t->io_bitmap[i] = ~0UL;
+
+        atomic_inc(&init_mm.mm_count);
+        me->active_mm = &init_mm;
+        if (me->mm)
+                BUG();
+        enter_lazy_tlb(&init_mm, me);
+
+        load_sp0(t, &current->thread);
+        set_tss_desc(cpu, t);
+        load_TR_desc();
+        load_LDT(&init_mm.context);
+
+#ifdef CONFIG_KGDB
+        /*
+         * If the kgdb is connected no debug regs should be altered.  This
+         * is only applicable when KGDB and a KGDB I/O module are built
+         * into the kernel and you are using early debugging with
+         * kgdbwait. KGDB will control the kernel HW breakpoint registers.
+         */
+        if (kgdb_connected && arch_kgdb_ops.correct_hw_break)
+                arch_kgdb_ops.correct_hw_break();
+        else {
+#endif
+        /*
+         * Clear all 6 debug registers:
+         */
+
+        set_debugreg(0UL, 0);
+        set_debugreg(0UL, 1);
+        set_debugreg(0UL, 2);
+        set_debugreg(0UL, 3);
+        set_debugreg(0UL, 6);
+        set_debugreg(0UL, 7);
+#ifdef CONFIG_KGDB
+        /* If the kgdb is connected no debug regs should be altered. */
+        }
+#endif
+
+        fpu_init();
+
+        raw_local_save_flags(kernel_eflags);
+
+        if (is_uv_system())
+                uv_cpu_init();
+}