Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/shaggy...

[mirror_ubuntu-artful-kernel.git] / arch / x86 / kernel / cpu / common.c

#include <linux/bootmem.h>
#include <linux/linkage.h>
#include <linux/bitops.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/kgdb.h>
#include <linux/smp.h>
#include <linux/io.h>

#include <asm/stackprotector.h>
#include <asm/mmu_context.h>
#include <asm/hypervisor.h>
#include <asm/processor.h>
#include <asm/sections.h>
#include <asm/topology.h>
#include <asm/cpumask.h>
#include <asm/pgtable.h>
#include <asm/atomic.h>
#include <asm/proto.h>
#include <asm/setup.h>
#include <asm/apic.h>
#include <asm/desc.h>
#include <asm/i387.h>
#include <asm/mtrr.h>
#include <asm/numa.h>
#include <asm/asm.h>
#include <asm/cpu.h>
#include <asm/mce.h>
#include <asm/msr.h>
#include <asm/pat.h>
#include <asm/smp.h>

#ifdef CONFIG_X86_LOCAL_APIC
#include <asm/uv/uv.h>
#endif

#include "cpu.h"

/* all of these masks are initialized in setup_cpu_local_masks() */
cpumask_var_t cpu_initialized_mask;
cpumask_var_t cpu_callout_mask;
cpumask_var_t cpu_callin_mask;

/* representing cpus for which sibling maps can be computed */
cpumask_var_t cpu_sibling_setup_mask;

/* correctly size the local cpu masks */
void __init setup_cpu_local_masks(void)
{
        alloc_bootmem_cpumask_var(&cpu_initialized_mask);
        alloc_bootmem_cpumask_var(&cpu_callin_mask);
        alloc_bootmem_cpumask_var(&cpu_callout_mask);
        alloc_bootmem_cpumask_var(&cpu_sibling_setup_mask);
}

static const struct cpu_dev *this_cpu __cpuinitdata;

DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = {
#ifdef CONFIG_X86_64
        /*
         * 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
         *
         * TLS descriptors are currently at a different place compared to i386.
         * Hopefully nobody expects them at a fixed place (Wine?)
         */
        [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 } } },
#else
        [GDT_ENTRY_KERNEL_CS]           = { { { 0x0000ffff, 0x00cf9a00 } } },
        [GDT_ENTRY_KERNEL_DS]           = { { { 0x0000ffff, 0x00cf9200 } } },
        [GDT_ENTRY_DEFAULT_USER_CS]     = { { { 0x0000ffff, 0x00cffa00 } } },
        [GDT_ENTRY_DEFAULT_USER_DS]     = { { { 0x0000ffff, 0x00cff200 } } },
        /*
         * Segments used for calling PnP BIOS have byte granularity.
         * They code segments and data segments have fixed 64k limits,
         * the transfer segment sizes are set at run time.
         */
        /* 32-bit code */
        [GDT_ENTRY_PNPBIOS_CS32]        = { { { 0x0000ffff, 0x00409a00 } } },
        /* 16-bit code */
        [GDT_ENTRY_PNPBIOS_CS16]        = { { { 0x0000ffff, 0x00009a00 } } },
        /* 16-bit data */
        [GDT_ENTRY_PNPBIOS_DS]          = { { { 0x0000ffff, 0x00009200 } } },
        /* 16-bit data */
        [GDT_ENTRY_PNPBIOS_TS1]         = { { { 0x00000000, 0x00009200 } } },
        /* 16-bit data */
        [GDT_ENTRY_PNPBIOS_TS2]         = { { { 0x00000000, 0x00009200 } } },
        /*
         * The APM segments have byte granularity and their bases
         * are set at run time.  All have 64k limits.
         */
        /* 32-bit code */
        [GDT_ENTRY_APMBIOS_BASE]        = { { { 0x0000ffff, 0x00409a00 } } },
        /* 16-bit code */
        [GDT_ENTRY_APMBIOS_BASE+1]      = { { { 0x0000ffff, 0x00009a00 } } },
        /* data */
        [GDT_ENTRY_APMBIOS_BASE+2]      = { { { 0x0000ffff, 0x00409200 } } },

        [GDT_ENTRY_ESPFIX_SS]           = { { { 0x00000000, 0x00c09200 } } },
        [GDT_ENTRY_PERCPU]              = { { { 0x0000ffff, 0x00cf9200 } } },
        GDT_STACK_CANARY_INIT
#endif
} };
EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);

static int __init x86_xsave_setup(char *s)
{
        setup_clear_cpu_cap(X86_FEATURE_XSAVE);
        return 1;
}
__setup("noxsave", x86_xsave_setup);

#ifdef CONFIG_X86_32
static int cachesize_override __cpuinitdata = -1;
static int disable_x86_serial_nr __cpuinitdata = 1;

static int __init cachesize_setup(char *str)
{
        get_option(&str, &cachesize_override);
        return 1;
}
__setup("cachesize=", cachesize_setup);

static int __init x86_fxsr_setup(char *s)
{
        setup_clear_cpu_cap(X86_FEATURE_FXSR);
        setup_clear_cpu_cap(X86_FEATURE_XMM);
        return 1;
}
__setup("nofxsr", x86_fxsr_setup);

static int __init x86_sep_setup(char *s)
{
        setup_clear_cpu_cap(X86_FEATURE_SEP);
        return 1;
}
__setup("nosep", x86_sep_setup);

/* Standard macro to see if a specific flag is changeable */
static inline int flag_is_changeable_p(u32 flag)
{
        u32 f1, f2;

        /*
         * Cyrix and IDT cpus allow disabling of CPUID
         * so the code below may return different results
         * when it is executed before and after enabling
         * the CPUID. Add "volatile" to not allow gcc to
         * optimize the subsequent calls to this function.
         */
        asm volatile ("pushfl           \n\t"
                      "pushfl           \n\t"
                      "popl %0          \n\t"
                      "movl %0, %1      \n\t"
                      "xorl %2, %0      \n\t"
                      "pushl %0         \n\t"
                      "popfl            \n\t"
                      "pushfl           \n\t"
                      "popl %0          \n\t"
                      "popfl            \n\t"

                      : "=&r" (f1), "=&r" (f2)
                      : "ir" (flag));

        return ((f1^f2) & flag) != 0;
}

/* Probe for the CPUID instruction */
static int __cpuinit have_cpuid_p(void)
{
        return flag_is_changeable_p(X86_EFLAGS_ID);
}

static void __cpuinit squash_the_stupid_serial_number(struct cpuinfo_x86 *c)
{
        unsigned long lo, hi;

        if (!cpu_has(c, X86_FEATURE_PN) || !disable_x86_serial_nr)
                return;

        /* Disable processor serial number: */

        rdmsr(MSR_IA32_BBL_CR_CTL, lo, hi);
        lo |= 0x200000;
        wrmsr(MSR_IA32_BBL_CR_CTL, lo, hi);

        printk(KERN_NOTICE "CPU serial number disabled.\n");
        clear_cpu_cap(c, X86_FEATURE_PN);

        /* Disabling the serial number may affect the cpuid level */
        c->cpuid_level = cpuid_eax(0);
}

static int __init x86_serial_nr_setup(char *s)
{
        disable_x86_serial_nr = 0;
        return 1;
}
__setup("serialnumber", x86_serial_nr_setup);
#else
static inline int flag_is_changeable_p(u32 flag)
{
        return 1;
}
/* Probe for the CPUID instruction */
static inline int have_cpuid_p(void)
{
        return 1;
}
static inline void squash_the_stupid_serial_number(struct cpuinfo_x86 *c)
{
}
#endif

/*
 * Some CPU features depend on higher CPUID levels, which may not always
 * be available due to CPUID level capping or broken virtualization
 * software.  Add those features to this table to auto-disable them.
 */
struct cpuid_dependent_feature {
        u32 feature;
        u32 level;
};

static const struct cpuid_dependent_feature __cpuinitconst
cpuid_dependent_features[] = {
        { X86_FEATURE_MWAIT,            0x00000005 },
        { X86_FEATURE_DCA,              0x00000009 },
        { X86_FEATURE_XSAVE,            0x0000000d },
        { 0, 0 }
};

static void __cpuinit filter_cpuid_features(struct cpuinfo_x86 *c, bool warn)
{
        const struct cpuid_dependent_feature *df;

        for (df = cpuid_dependent_features; df->feature; df++) {

                if (!cpu_has(c, df->feature))
                        continue;
                /*
                 * Note: cpuid_level is set to -1 if unavailable, but
                 * extended_extended_level is set to 0 if unavailable
                 * and the legitimate extended levels are all negative
                 * when signed; hence the weird messing around with
                 * signs here...
                 */
                if (!((s32)df->level < 0 ?
                     (u32)df->level > (u32)c->extended_cpuid_level :
                     (s32)df->level > (s32)c->cpuid_level))
                        continue;

                clear_cpu_cap(c, df->feature);
                if (!warn)
                        continue;

                printk(KERN_WARNING
                       "CPU: CPU feature %s disabled, no CPUID level 0x%x\n",
                                x86_cap_flags[df->feature], df->level);
        }
}

/*
 * Naming convention should be: <Name> [(<Codename>)]
 * This table only is used unless init_<vendor>() below doesn't set it;
 * in particular, if CPUID levels 0x80000002..4 are supported, this
 * isn't used
 */

/* Look up CPU names by table lookup. */
static const char *__cpuinit table_lookup_model(struct cpuinfo_x86 *c)
{
        const struct cpu_model_info *info;

        if (c->x86_model >= 16)
                return NULL;    /* Range check */

        if (!this_cpu)
                return NULL;

        info = this_cpu->c_models;

        while (info && info->family) {
                if (info->family == c->x86)
                        return info->model_names[c->x86_model];
                info++;
        }
        return NULL;            /* Not found */
}

__u32 cpu_caps_cleared[NCAPINTS] __cpuinitdata;
__u32 cpu_caps_set[NCAPINTS] __cpuinitdata;

void load_percpu_segment(int cpu)
{
#ifdef CONFIG_X86_32
        loadsegment(fs, __KERNEL_PERCPU);
#else
        loadsegment(gs, 0);
        wrmsrl(MSR_GS_BASE, (unsigned long)per_cpu(irq_stack_union.gs_base, cpu));
#endif
        load_stack_canary_segment();
}

/*
 * Current gdt points %fs at the "master" per-cpu area: after this,
 * it's on the real one.
 */
void switch_to_new_gdt(int cpu)
{
        struct desc_ptr gdt_descr;

        gdt_descr.address = (long)get_cpu_gdt_table(cpu);
        gdt_descr.size = GDT_SIZE - 1;
        load_gdt(&gdt_descr);
        /* Reload the per-cpu base */

        load_percpu_segment(cpu);
}

static const struct cpu_dev *__cpuinitdata cpu_devs[X86_VENDOR_NUM] = {};

static void __cpuinit default_init(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_X86_64
        display_cacheinfo(c);
#else
        /* Not much we can do here... */
        /* Check if at least it has cpuid */
        if (c->cpuid_level == -1) {
                /* No cpuid. It must be an ancient CPU */
                if (c->x86 == 4)
                        strcpy(c->x86_model_id, "486");
                else if (c->x86 == 3)
                        strcpy(c->x86_model_id, "386");
        }
#endif
}

static const struct cpu_dev __cpuinitconst default_cpu = {
        .c_init = default_init,
        .c_vendor = "Unknown",
        .c_x86_vendor = X86_VENDOR_UNKNOWN,
};

static void __cpuinit get_model_name(struct cpuinfo_x86 *c)
{
        unsigned int *v;
        char *p, *q;

        if (c->extended_cpuid_level < 0x80000004)
                return;

        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;

        /*
         * Intel chips right-justify this string for some dumb reason;
         * undo that brain damage:
         */
        p = q = &c->x86_model_id[0];
        while (*p == ' ')
                p++;
        if (p != q) {
                while (*p)
                        *q++ = *p++;
                while (q <= &c->x86_model_id[48])
                        *q++ = '\0';    /* Zero-pad the rest */
        }
}

void __cpuinit display_cacheinfo(struct cpuinfo_x86 *c)
{
        unsigned int n, dummy, ebx, ecx, edx, l2size;

        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);
#ifdef CONFIG_X86_64
                /* On K8 L1 TLB is inclusive, so don't count it */
                c->x86_tlbsize = 0;
#endif
        }

        if (n < 0x80000006)     /* Some chips just has a large L1. */
                return;

        cpuid(0x80000006, &dummy, &ebx, &ecx, &edx);
        l2size = ecx >> 16;

#ifdef CONFIG_X86_64
        c->x86_tlbsize += ((ebx >> 16) & 0xfff) + (ebx & 0xfff);
#else
        /* do processor-specific cache resizing */
        if (this_cpu->c_size_cache)
                l2size = this_cpu->c_size_cache(c, l2size);

        /* Allow user to override all this if necessary. */
        if (cachesize_override != -1)
                l2size = cachesize_override;

        if (l2size == 0)
                return;         /* Again, no L2 cache is possible */
#endif

        c->x86_cache_size = l2size;

        printk(KERN_INFO "CPU: L2 Cache: %dK (%d bytes/line)\n",
                        l2size, ecx & 0xFF);
}

void __cpuinit detect_ht(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_X86_HT
        u32 eax, ebx, ecx, edx;
        int index_msb, core_bits;

        if (!cpu_has(c, X86_FEATURE_HT))
                return;

        if (cpu_has(c, X86_FEATURE_CMP_LEGACY))
                goto out;

        if (cpu_has(c, X86_FEATURE_XTOPOLOGY))
                return;

        cpuid(1, &eax, &ebx, &ecx, &edx);

        smp_num_siblings = (ebx & 0xff0000) >> 16;

        if (smp_num_siblings == 1) {
                printk(KERN_INFO  "CPU: Hyper-Threading is disabled\n");
                goto out;
        }

        if (smp_num_siblings <= 1)
                goto out;

        if (smp_num_siblings > nr_cpu_ids) {
                pr_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 = apic->phys_pkg_id(c->initial_apicid, 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 = apic->phys_pkg_id(c->initial_apicid, 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;
        static int printed;
        int i;

        for (i = 0; i < X86_VENDOR_NUM; i++) {
                if (!cpu_devs[i])
                        break;

                if (!strcmp(v, cpu_devs[i]->c_ident[0]) ||
                    (cpu_devs[i]->c_ident[1] &&
                     !strcmp(v, cpu_devs[i]->c_ident[1]))) {

                        this_cpu = cpu_devs[i];
                        c->x86_vendor = this_cpu->c_x86_vendor;
                        return;
                }
        }

        if (!printed) {
                printed++;
                printk(KERN_ERR
                    "CPU: vendor_id '%s' unknown, using generic init.\n", v);

                printk(KERN_ERR "CPU: Your system may be unstable.\n");
        }

        c->x86_vendor = X86_VENDOR_UNKNOWN;
        this_cpu = &default_cpu;
}

void __cpuinit cpu_detect(struct cpuinfo_x86 *c)
{
        /* 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]);

        c->x86 = 4;
        /* Intel-defined flags: level 0x00000001 */
        if (c->cpuid_level >= 0x00000001) {
                u32 junk, tfms, cap0, misc;

                cpuid(0x00000001, &tfms, &misc, &junk, &cap0);
                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 (cap0 & (1<<19)) {
                        c->x86_clflush_size = ((misc >> 8) & 0xff) * 8;
                        c->x86_cache_alignment = c->x86_clflush_size;
                }
        }
}

static void __cpuinit get_cpu_cap(struct cpuinfo_x86 *c)
{
        u32 tfms, xlvl;
        u32 ebx;

        /* Intel-defined flags: level 0x00000001 */
        if (c->cpuid_level >= 0x00000001) {
                u32 capability, excap;

                cpuid(0x00000001, &tfms, &ebx, &excap, &capability);
                c->x86_capability[0] = capability;
                c->x86_capability[4] = excap;
        }

        /* 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 (c->extended_cpuid_level >= 0x80000008) {
                u32 eax = cpuid_eax(0x80000008);

                c->x86_virt_bits = (eax >> 8) & 0xff;
                c->x86_phys_bits = eax & 0xff;
        }
#ifdef CONFIG_X86_32
        else if (cpu_has(c, X86_FEATURE_PAE) || cpu_has(c, X86_FEATURE_PSE36))
                c->x86_phys_bits = 36;
#endif

        if (c->extended_cpuid_level >= 0x80000007)
                c->x86_power = cpuid_edx(0x80000007);

}

static void __cpuinit identify_cpu_without_cpuid(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_X86_32
        int i;

        /*
         * First of all, decide if this is a 486 or higher
         * It's a 486 if we can modify the AC flag
         */
        if (flag_is_changeable_p(X86_EFLAGS_AC))
                c->x86 = 4;
        else
                c->x86 = 3;

        for (i = 0; i < X86_VENDOR_NUM; i++)
                if (cpu_devs[i] && cpu_devs[i]->c_identify) {
                        c->x86_vendor_id[0] = 0;
                        cpu_devs[i]->c_identify(c);
                        if (c->x86_vendor_id[0]) {
                                get_cpu_vendor(c);
                                break;
                        }
                }
#endif
}

/*
 * Do minimum CPU detection early.
 * Fields really needed: vendor, cpuid_level, family, model, mask,
 * cache alignment.
 * The others are not touched to avoid unwanted side effects.
 *
 * WARNING: this function is only called on the BP.  Don't add code here
 * that is supposed to run on all CPUs.
 */
static void __init early_identify_cpu(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_X86_64
        c->x86_clflush_size = 64;
        c->x86_phys_bits = 36;
        c->x86_virt_bits = 48;
#else
        c->x86_clflush_size = 32;
        c->x86_phys_bits = 32;
        c->x86_virt_bits = 32;
#endif
        c->x86_cache_alignment = c->x86_clflush_size;

        memset(&c->x86_capability, 0, sizeof c->x86_capability);
        c->extended_cpuid_level = 0;

        if (!have_cpuid_p())
                identify_cpu_without_cpuid(c);

        /* cyrix could have cpuid enabled via c_identify()*/
        if (!have_cpuid_p())
                return;

        cpu_detect(c);

        get_cpu_vendor(c);

        get_cpu_cap(c);

        if (this_cpu->c_early_init)
                this_cpu->c_early_init(c);

#ifdef CONFIG_SMP
        c->cpu_index = boot_cpu_id;
#endif
        filter_cpuid_features(c, false);
}

void __init early_cpu_init(void)
{
        const struct cpu_dev *const *cdev;
        int count = 0;

        printk(KERN_INFO "KERNEL supported cpus:\n");
        for (cdev = __x86_cpu_dev_start; cdev < __x86_cpu_dev_end; cdev++) {
                const struct cpu_dev *cpudev = *cdev;
                unsigned int j;

                if (count >= X86_VENDOR_NUM)
                        break;
                cpu_devs[count] = cpudev;
                count++;

                for (j = 0; j < 2; j++) {
                        if (!cpudev->c_ident[j])
                                continue;
                        printk(KERN_INFO "  %s %s\n", cpudev->c_vendor,
                                cpudev->c_ident[j]);
                }
        }

        early_identify_cpu(&boot_cpu_data);
}

/*
 * The NOPL instruction is supposed to exist on all CPUs with
 * family >= 6; unfortunately, that's not true in practice because
 * of early VIA chips and (more importantly) broken virtualizers that
 * are not easy to detect.  In the latter case it doesn't even *fail*
 * reliably, so probing for it doesn't even work.  Disable it completely
 * unless we can find a reliable way to detect all the broken cases.
 */
static void __cpuinit detect_nopl(struct cpuinfo_x86 *c)
{
        clear_cpu_cap(c, X86_FEATURE_NOPL);
}

static void __cpuinit generic_identify(struct cpuinfo_x86 *c)
{
        c->extended_cpuid_level = 0;

        if (!have_cpuid_p())
                identify_cpu_without_cpuid(c);

        /* cyrix could have cpuid enabled via c_identify()*/
        if (!have_cpuid_p())
                return;

        cpu_detect(c);

        get_cpu_vendor(c);

        get_cpu_cap(c);

        if (c->cpuid_level >= 0x00000001) {
                c->initial_apicid = (cpuid_ebx(1) >> 24) & 0xFF;
#ifdef CONFIG_X86_32
# ifdef CONFIG_X86_HT
                c->apicid = apic->phys_pkg_id(c->initial_apicid, 0);
# else
                c->apicid = c->initial_apicid;
# endif
#endif

#ifdef CONFIG_X86_HT
                c->phys_proc_id = c->initial_apicid;
#endif
        }

        get_model_name(c); /* Default name */

        init_scattered_cpuid_features(c);
        detect_nopl(c);
}

/*
 * This does the hard work of actually picking apart the CPU stuff...
 */
static void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
{
        int i;

        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_max_cores = 1;
        c->x86_coreid_bits = 0;
#ifdef CONFIG_X86_64
        c->x86_clflush_size = 64;
        c->x86_phys_bits = 36;
        c->x86_virt_bits = 48;
#else
        c->cpuid_level = -1;    /* CPUID not detected */
        c->x86_clflush_size = 32;
        c->x86_phys_bits = 32;
        c->x86_virt_bits = 32;
#endif
        c->x86_cache_alignment = c->x86_clflush_size;
        memset(&c->x86_capability, 0, sizeof c->x86_capability);

        generic_identify(c);

        if (this_cpu->c_identify)
                this_cpu->c_identify(c);

        /* Clear/Set all flags overriden by options, after probe */
        for (i = 0; i < NCAPINTS; i++) {
                c->x86_capability[i] &= ~cpu_caps_cleared[i];
                c->x86_capability[i] |= cpu_caps_set[i];
        }

#ifdef CONFIG_X86_64
        c->apicid = apic->phys_pkg_id(c->initial_apicid, 0);
#endif

        /*
         * 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);

        /* Disable the PN if appropriate */
        squash_the_stupid_serial_number(c);

        /*
         * The vendor-specific functions might have changed features.
         * Now we do "generic changes."
         */

        /* Filter out anything that depends on CPUID levels we don't have */
        filter_cpuid_features(c, true);

        /* If the model name is still unset, do table lookup. */
        if (!c->x86_model_id[0]) {
                const char *p;
                p = table_lookup_model(c);
                if (p)
                        strcpy(c->x86_model_id, p);
                else
                        /* Last resort... */
                        sprintf(c->x86_model_id, "%02x/%02x",
                                c->x86, c->x86_model);
        }

#ifdef CONFIG_X86_64
        detect_ht(c);
#endif

        init_hypervisor(c);

        /*
         * Clear/Set all flags overriden by options, need do it
         * before following smp all cpus cap AND.
         */
        for (i = 0; i < NCAPINTS; i++) {
                c->x86_capability[i] &= ~cpu_caps_cleared[i];
                c->x86_capability[i] |= cpu_caps_set[i];
        }

        /*
         * 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];
        }

#ifdef CONFIG_X86_MCE
        /* Init Machine Check Exception if available. */
        mcheck_init(c);
#endif

        select_idle_routine(c);

#if defined(CONFIG_NUMA) && defined(CONFIG_X86_64)
        numa_add_cpu(smp_processor_id());
#endif
}

#ifdef CONFIG_X86_64
static void vgetcpu_set_mode(void)
{
        if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP))
                vgetcpu_mode = VGETCPU_RDTSCP;
        else
                vgetcpu_mode = VGETCPU_LSL;
}
#endif

void __init identify_boot_cpu(void)
{
        identify_cpu(&boot_cpu_data);
        init_c1e_mask();
#ifdef CONFIG_X86_32
        sysenter_setup();
        enable_sep_cpu();
#else
        vgetcpu_set_mode();
#endif
}

void __cpuinit identify_secondary_cpu(struct cpuinfo_x86 *c)
{
        BUG_ON(c == &boot_cpu_data);
        identify_cpu(c);
#ifdef CONFIG_X86_32
        enable_sep_cpu();
#endif
        mtrr_ap_init();
}

struct msr_range {
        unsigned        min;
        unsigned        max;
};

static const struct msr_range msr_range_array[] __cpuinitconst = {
        { 0x00000000, 0x00000418},
        { 0xc0000000, 0xc000040b},
        { 0xc0010000, 0xc0010142},
        { 0xc0011000, 0xc001103b},
};

static void __cpuinit print_cpu_msr(void)
{
        unsigned index_min, index_max;
        unsigned index;
        u64 val;
        int i;

        for (i = 0; i < ARRAY_SIZE(msr_range_array); i++) {
                index_min = msr_range_array[i].min;
                index_max = msr_range_array[i].max;

                for (index = index_min; index < index_max; index++) {
                        if (rdmsrl_amd_safe(index, &val))
                                continue;
                        printk(KERN_INFO " MSR%08x: %016llx\n", index, val);
                }
        }
}

static int show_msr __cpuinitdata;

static __init int setup_show_msr(char *arg)
{
        int num;

        get_option(&arg, &num);

        if (num > 0)
                show_msr = num;
        return 1;
}
__setup("show_msr=", setup_show_msr);

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)
{
        const char *vendor = NULL;

        if (c->x86_vendor < X86_VENDOR_NUM) {
                vendor = this_cpu->c_vendor;
        } else {
                if (c->cpuid_level >= 0)
                        vendor = c->x86_vendor_id;
        }

        if (vendor && !strstr(c->x86_model_id, vendor))
                printk(KERN_CONT "%s ", vendor);

        if (c->x86_model_id[0])
                printk(KERN_CONT "%s", c->x86_model_id);
        else
                printk(KERN_CONT "%d86", c->x86);

        if (c->x86_mask || c->cpuid_level >= 0)
                printk(KERN_CONT " stepping %02x\n", c->x86_mask);
        else
                printk(KERN_CONT "\n");

#ifdef CONFIG_SMP
        if (c->cpu_index < show_msr)
                print_cpu_msr();
#else
        if (show_msr)
                print_cpu_msr();
#endif
}

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);

#ifdef CONFIG_X86_64
struct desc_ptr idt_descr = { 256 * 16 - 1, (unsigned long) idt_table };

DEFINE_PER_CPU_FIRST(union irq_stack_union,
                     irq_stack_union) __aligned(PAGE_SIZE);

DEFINE_PER_CPU(char *, irq_stack_ptr) =
        init_per_cpu_var(irq_stack_union.irq_stack) + IRQ_STACK_SIZE - 64;

DEFINE_PER_CPU(unsigned long, kernel_stack) =
        (unsigned long)&init_thread_union - KERNEL_STACK_OFFSET + THREAD_SIZE;
EXPORT_PER_CPU_SYMBOL(kernel_stack);

DEFINE_PER_CPU(unsigned int, irq_count) = -1;

/*
 * Special IST stacks which the CPU switches to when it calls
 * an IST-marked descriptor entry. Up to 7 stacks (hardware
 * limit), all of them are 4K, except the debug stack which
 * is 8K.
 */
static const unsigned int exception_stack_sizes[N_EXCEPTION_STACKS] = {
          [0 ... N_EXCEPTION_STACKS - 1]        = EXCEPTION_STKSZ,
          [DEBUG_STACK - 1]                     = DEBUG_STKSZ
};

static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks
        [(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ])
        __aligned(PAGE_SIZE);

/* 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);
}

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);

#else   /* CONFIG_X86_64 */

#ifdef CONFIG_CC_STACKPROTECTOR
DEFINE_PER_CPU(unsigned long, stack_canary);
#endif

/* Make sure %fs and %gs are initialized properly in idle threads */
struct pt_regs * __cpuinit idle_regs(struct pt_regs *regs)
{
        memset(regs, 0, sizeof(struct pt_regs));
        regs->fs = __KERNEL_PERCPU;
        regs->gs = __KERNEL_STACK_CANARY;

        return regs;
}
#endif  /* CONFIG_X86_64 */

/*
 * Clear all 6 debug registers:
 */
static void clear_all_debug_regs(void)
{
        int i;

        for (i = 0; i < 8; i++) {
                /* Ignore db4, db5 */
                if ((i == 4) || (i == 5))
                        continue;

                set_debugreg(0, i);
        }
}

/*
 * 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 for 64 bit
 */
#ifdef CONFIG_X86_64

void __cpuinit cpu_init(void)
{
        struct orig_ist *orig_ist;
        struct task_struct *me;
        struct tss_struct *t;
        unsigned long v;
        int cpu;
        int i;

        cpu = stack_smp_processor_id();
        t = &per_cpu(init_tss, cpu);
        orig_ist = &per_cpu(orig_ist, cpu);

#ifdef CONFIG_NUMA
        if (cpu != 0 && percpu_read(node_number) == 0 &&
            cpu_to_node(cpu) != NUMA_NO_NODE)
                percpu_write(node_number, cpu_to_node(cpu));
#endif

        me = current;

        if (cpumask_test_and_set_cpu(cpu, cpu_initialized_mask))
                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(cpu);
        loadsegment(fs, 0);

        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();
        if (cpu != 0)
                enable_x2apic();

        /*
         * set up and load the per-CPU TSS
         */
        if (!orig_ist->ist[0]) {
                char *estacks = per_cpu(exception_stacks, cpu);

                for (v = 0; v < N_EXCEPTION_STACKS; v++) {
                        estacks += exception_stack_sizes[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;
        BUG_ON(me->mm);
        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_debug_regs();

        fpu_init();

        raw_local_save_flags(kernel_eflags);

        if (is_uv_system())
                uv_cpu_init();
}

#else

void __cpuinit cpu_init(void)
{
        int cpu = smp_processor_id();
        struct task_struct *curr = current;
        struct tss_struct *t = &per_cpu(init_tss, cpu);
        struct thread_struct *thread = &curr->thread;

        if (cpumask_test_and_set_cpu(cpu, cpu_initialized_mask)) {
                printk(KERN_WARNING "CPU#%d already initialized!\n", cpu);
                for (;;)
                        local_irq_enable();
        }

        printk(KERN_INFO "Initializing CPU#%d\n", cpu);

        if (cpu_has_vme || cpu_has_tsc || cpu_has_de)
                clear_in_cr4(X86_CR4_VME|X86_CR4_PVI|X86_CR4_TSD|X86_CR4_DE);

        load_idt(&idt_descr);
        switch_to_new_gdt(cpu);

        /*
         * Set up and load the per-CPU TSS and LDT
         */
        atomic_inc(&init_mm.mm_count);
        curr->active_mm = &init_mm;
        BUG_ON(curr->mm);
        enter_lazy_tlb(&init_mm, curr);

        load_sp0(t, thread);
        set_tss_desc(cpu, t);
        load_TR_desc();
        load_LDT(&init_mm.context);

        t->x86_tss.io_bitmap_base = offsetof(struct tss_struct, io_bitmap);

#ifdef CONFIG_DOUBLEFAULT
        /* Set up doublefault TSS pointer in the GDT */
        __set_tss_desc(cpu, GDT_ENTRY_DOUBLEFAULT_TSS, &doublefault_tss);
#endif

        clear_all_debug_regs();

        /*
         * Force FPU initialization:
         */
        if (cpu_has_xsave)
                current_thread_info()->status = TS_XSAVE;
        else
                current_thread_info()->status = 0;
        clear_used_math();
        mxcsr_feature_mask_init();

        /*
         * Boot processor to setup the FP and extended state context info.
         */
        if (smp_processor_id() == boot_cpu_id)
                init_thread_xstate();

        xsave_init();
}
#endif