linux/arch/x86/kernel/cpu/common.c
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   1#include <linux/bootmem.h>
   2#include <linux/linkage.h>
   3#include <linux/bitops.h>
   4#include <linux/kernel.h>
   5#include <linux/module.h>
   6#include <linux/percpu.h>
   7#include <linux/string.h>
   8#include <linux/delay.h>
   9#include <linux/sched.h>
  10#include <linux/init.h>
  11#include <linux/kgdb.h>
  12#include <linux/smp.h>
  13#include <linux/io.h>
  14
  15#include <asm/stackprotector.h>
  16#include <asm/perf_event.h>
  17#include <asm/mmu_context.h>
  18#include <asm/archrandom.h>
  19#include <asm/hypervisor.h>
  20#include <asm/processor.h>
  21#include <asm/sections.h>
  22#include <linux/topology.h>
  23#include <linux/cpumask.h>
  24#include <asm/pgtable.h>
  25#include <linux/atomic.h>
  26#include <asm/proto.h>
  27#include <asm/setup.h>
  28#include <asm/apic.h>
  29#include <asm/desc.h>
  30#include <asm/i387.h>
  31#include <asm/mtrr.h>
  32#include <linux/numa.h>
  33#include <asm/asm.h>
  34#include <asm/cpu.h>
  35#include <asm/mce.h>
  36#include <asm/msr.h>
  37#include <asm/pat.h>
  38
  39#ifdef CONFIG_X86_LOCAL_APIC
  40#include <asm/uv/uv.h>
  41#endif
  42
  43#include "cpu.h"
  44
  45/* all of these masks are initialized in setup_cpu_local_masks() */
  46cpumask_var_t cpu_initialized_mask;
  47cpumask_var_t cpu_callout_mask;
  48cpumask_var_t cpu_callin_mask;
  49
  50/* representing cpus for which sibling maps can be computed */
  51cpumask_var_t cpu_sibling_setup_mask;
  52
  53/* correctly size the local cpu masks */
  54void __init setup_cpu_local_masks(void)
  55{
  56        alloc_bootmem_cpumask_var(&cpu_initialized_mask);
  57        alloc_bootmem_cpumask_var(&cpu_callin_mask);
  58        alloc_bootmem_cpumask_var(&cpu_callout_mask);
  59        alloc_bootmem_cpumask_var(&cpu_sibling_setup_mask);
  60}
  61
  62static void __cpuinit default_init(struct cpuinfo_x86 *c)
  63{
  64#ifdef CONFIG_X86_64
  65        cpu_detect_cache_sizes(c);
  66#else
  67        /* Not much we can do here... */
  68        /* Check if at least it has cpuid */
  69        if (c->cpuid_level == -1) {
  70                /* No cpuid. It must be an ancient CPU */
  71                if (c->x86 == 4)
  72                        strcpy(c->x86_model_id, "486");
  73                else if (c->x86 == 3)
  74                        strcpy(c->x86_model_id, "386");
  75        }
  76#endif
  77}
  78
  79static const struct cpu_dev __cpuinitconst default_cpu = {
  80        .c_init         = default_init,
  81        .c_vendor       = "Unknown",
  82        .c_x86_vendor   = X86_VENDOR_UNKNOWN,
  83};
  84
  85static const struct cpu_dev *this_cpu __cpuinitdata = &default_cpu;
  86
  87DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = {
  88#ifdef CONFIG_X86_64
  89        /*
  90         * We need valid kernel segments for data and code in long mode too
  91         * IRET will check the segment types  kkeil 2000/10/28
  92         * Also sysret mandates a special GDT layout
  93         *
  94         * TLS descriptors are currently at a different place compared to i386.
  95         * Hopefully nobody expects them at a fixed place (Wine?)
  96         */
  97        [GDT_ENTRY_KERNEL32_CS]         = GDT_ENTRY_INIT(0xc09b, 0, 0xfffff),
  98        [GDT_ENTRY_KERNEL_CS]           = GDT_ENTRY_INIT(0xa09b, 0, 0xfffff),
  99        [GDT_ENTRY_KERNEL_DS]           = GDT_ENTRY_INIT(0xc093, 0, 0xfffff),
 100        [GDT_ENTRY_DEFAULT_USER32_CS]   = GDT_ENTRY_INIT(0xc0fb, 0, 0xfffff),
 101        [GDT_ENTRY_DEFAULT_USER_DS]     = GDT_ENTRY_INIT(0xc0f3, 0, 0xfffff),
 102        [GDT_ENTRY_DEFAULT_USER_CS]     = GDT_ENTRY_INIT(0xa0fb, 0, 0xfffff),
 103#else
 104        [GDT_ENTRY_KERNEL_CS]           = GDT_ENTRY_INIT(0xc09a, 0, 0xfffff),
 105        [GDT_ENTRY_KERNEL_DS]           = GDT_ENTRY_INIT(0xc092, 0, 0xfffff),
 106        [GDT_ENTRY_DEFAULT_USER_CS]     = GDT_ENTRY_INIT(0xc0fa, 0, 0xfffff),
 107        [GDT_ENTRY_DEFAULT_USER_DS]     = GDT_ENTRY_INIT(0xc0f2, 0, 0xfffff),
 108        /*
 109         * Segments used for calling PnP BIOS have byte granularity.
 110         * They code segments and data segments have fixed 64k limits,
 111         * the transfer segment sizes are set at run time.
 112         */
 113        /* 32-bit code */
 114        [GDT_ENTRY_PNPBIOS_CS32]        = GDT_ENTRY_INIT(0x409a, 0, 0xffff),
 115        /* 16-bit code */
 116        [GDT_ENTRY_PNPBIOS_CS16]        = GDT_ENTRY_INIT(0x009a, 0, 0xffff),
 117        /* 16-bit data */
 118        [GDT_ENTRY_PNPBIOS_DS]          = GDT_ENTRY_INIT(0x0092, 0, 0xffff),
 119        /* 16-bit data */
 120        [GDT_ENTRY_PNPBIOS_TS1]         = GDT_ENTRY_INIT(0x0092, 0, 0),
 121        /* 16-bit data */
 122        [GDT_ENTRY_PNPBIOS_TS2]         = GDT_ENTRY_INIT(0x0092, 0, 0),
 123        /*
 124         * The APM segments have byte granularity and their bases
 125         * are set at run time.  All have 64k limits.
 126         */
 127        /* 32-bit code */
 128        [GDT_ENTRY_APMBIOS_BASE]        = GDT_ENTRY_INIT(0x409a, 0, 0xffff),
 129        /* 16-bit code */
 130        [GDT_ENTRY_APMBIOS_BASE+1]      = GDT_ENTRY_INIT(0x009a, 0, 0xffff),
 131        /* data */
 132        [GDT_ENTRY_APMBIOS_BASE+2]      = GDT_ENTRY_INIT(0x4092, 0, 0xffff),
 133
 134        [GDT_ENTRY_ESPFIX_SS]           = GDT_ENTRY_INIT(0xc092, 0, 0xfffff),
 135        [GDT_ENTRY_PERCPU]              = GDT_ENTRY_INIT(0xc092, 0, 0xfffff),
 136        GDT_STACK_CANARY_INIT
 137#endif
 138} };
 139EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);
 140
 141static int __init x86_xsave_setup(char *s)
 142{
 143        setup_clear_cpu_cap(X86_FEATURE_XSAVE);
 144        setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
 145        return 1;
 146}
 147__setup("noxsave", x86_xsave_setup);
 148
 149static int __init x86_xsaveopt_setup(char *s)
 150{
 151        setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
 152        return 1;
 153}
 154__setup("noxsaveopt", x86_xsaveopt_setup);
 155
 156#ifdef CONFIG_X86_32
 157static int cachesize_override __cpuinitdata = -1;
 158static int disable_x86_serial_nr __cpuinitdata = 1;
 159
 160static int __init cachesize_setup(char *str)
 161{
 162        get_option(&str, &cachesize_override);
 163        return 1;
 164}
 165__setup("cachesize=", cachesize_setup);
 166
 167static int __init x86_fxsr_setup(char *s)
 168{
 169        setup_clear_cpu_cap(X86_FEATURE_FXSR);
 170        setup_clear_cpu_cap(X86_FEATURE_XMM);
 171        return 1;
 172}
 173__setup("nofxsr", x86_fxsr_setup);
 174
 175static int __init x86_sep_setup(char *s)
 176{
 177        setup_clear_cpu_cap(X86_FEATURE_SEP);
 178        return 1;
 179}
 180__setup("nosep", x86_sep_setup);
 181
 182/* Standard macro to see if a specific flag is changeable */
 183static inline int flag_is_changeable_p(u32 flag)
 184{
 185        u32 f1, f2;
 186
 187        /*
 188         * Cyrix and IDT cpus allow disabling of CPUID
 189         * so the code below may return different results
 190         * when it is executed before and after enabling
 191         * the CPUID. Add "volatile" to not allow gcc to
 192         * optimize the subsequent calls to this function.
 193         */
 194        asm volatile ("pushfl           \n\t"
 195                      "pushfl           \n\t"
 196                      "popl %0          \n\t"
 197                      "movl %0, %1      \n\t"
 198                      "xorl %2, %0      \n\t"
 199                      "pushl %0         \n\t"
 200                      "popfl            \n\t"
 201                      "pushfl           \n\t"
 202                      "popl %0          \n\t"
 203                      "popfl            \n\t"
 204
 205                      : "=&r" (f1), "=&r" (f2)
 206                      : "ir" (flag));
 207
 208        return ((f1^f2) & flag) != 0;
 209}
 210
 211/* Probe for the CPUID instruction */
 212static int __cpuinit have_cpuid_p(void)
 213{
 214        return flag_is_changeable_p(X86_EFLAGS_ID);
 215}
 216
 217static void __cpuinit squash_the_stupid_serial_number(struct cpuinfo_x86 *c)
 218{
 219        unsigned long lo, hi;
 220
 221        if (!cpu_has(c, X86_FEATURE_PN) || !disable_x86_serial_nr)
 222                return;
 223
 224        /* Disable processor serial number: */
 225
 226        rdmsr(MSR_IA32_BBL_CR_CTL, lo, hi);
 227        lo |= 0x200000;
 228        wrmsr(MSR_IA32_BBL_CR_CTL, lo, hi);
 229
 230        printk(KERN_NOTICE "CPU serial number disabled.\n");
 231        clear_cpu_cap(c, X86_FEATURE_PN);
 232
 233        /* Disabling the serial number may affect the cpuid level */
 234        c->cpuid_level = cpuid_eax(0);
 235}
 236
 237static int __init x86_serial_nr_setup(char *s)
 238{
 239        disable_x86_serial_nr = 0;
 240        return 1;
 241}
 242__setup("serialnumber", x86_serial_nr_setup);
 243#else
 244static inline int flag_is_changeable_p(u32 flag)
 245{
 246        return 1;
 247}
 248/* Probe for the CPUID instruction */
 249static inline int have_cpuid_p(void)
 250{
 251        return 1;
 252}
 253static inline void squash_the_stupid_serial_number(struct cpuinfo_x86 *c)
 254{
 255}
 256#endif
 257
 258static int disable_smep __cpuinitdata;
 259static __init int setup_disable_smep(char *arg)
 260{
 261        disable_smep = 1;
 262        return 1;
 263}
 264__setup("nosmep", setup_disable_smep);
 265
 266static __cpuinit void setup_smep(struct cpuinfo_x86 *c)
 267{
 268        if (cpu_has(c, X86_FEATURE_SMEP)) {
 269                if (unlikely(disable_smep)) {
 270                        setup_clear_cpu_cap(X86_FEATURE_SMEP);
 271                        clear_in_cr4(X86_CR4_SMEP);
 272                } else
 273                        set_in_cr4(X86_CR4_SMEP);
 274        }
 275}
 276
 277/*
 278 * Some CPU features depend on higher CPUID levels, which may not always
 279 * be available due to CPUID level capping or broken virtualization
 280 * software.  Add those features to this table to auto-disable them.
 281 */
 282struct cpuid_dependent_feature {
 283        u32 feature;
 284        u32 level;
 285};
 286
 287static const struct cpuid_dependent_feature __cpuinitconst
 288cpuid_dependent_features[] = {
 289        { X86_FEATURE_MWAIT,            0x00000005 },
 290        { X86_FEATURE_DCA,              0x00000009 },
 291        { X86_FEATURE_XSAVE,            0x0000000d },
 292        { 0, 0 }
 293};
 294
 295static void __cpuinit filter_cpuid_features(struct cpuinfo_x86 *c, bool warn)
 296{
 297        const struct cpuid_dependent_feature *df;
 298
 299        for (df = cpuid_dependent_features; df->feature; df++) {
 300
 301                if (!cpu_has(c, df->feature))
 302                        continue;
 303                /*
 304                 * Note: cpuid_level is set to -1 if unavailable, but
 305                 * extended_extended_level is set to 0 if unavailable
 306                 * and the legitimate extended levels are all negative
 307                 * when signed; hence the weird messing around with
 308                 * signs here...
 309                 */
 310                if (!((s32)df->level < 0 ?
 311                     (u32)df->level > (u32)c->extended_cpuid_level :
 312                     (s32)df->level > (s32)c->cpuid_level))
 313                        continue;
 314
 315                clear_cpu_cap(c, df->feature);
 316                if (!warn)
 317                        continue;
 318
 319                printk(KERN_WARNING
 320                       "CPU: CPU feature %s disabled, no CPUID level 0x%x\n",
 321                                x86_cap_flags[df->feature], df->level);
 322        }
 323}
 324
 325/*
 326 * Naming convention should be: <Name> [(<Codename>)]
 327 * This table only is used unless init_<vendor>() below doesn't set it;
 328 * in particular, if CPUID levels 0x80000002..4 are supported, this
 329 * isn't used
 330 */
 331
 332/* Look up CPU names by table lookup. */
 333static const char *__cpuinit table_lookup_model(struct cpuinfo_x86 *c)
 334{
 335        const struct cpu_model_info *info;
 336
 337        if (c->x86_model >= 16)
 338                return NULL;    /* Range check */
 339
 340        if (!this_cpu)
 341                return NULL;
 342
 343        info = this_cpu->c_models;
 344
 345        while (info && info->family) {
 346                if (info->family == c->x86)
 347                        return info->model_names[c->x86_model];
 348                info++;
 349        }
 350        return NULL;            /* Not found */
 351}
 352
 353__u32 cpu_caps_cleared[NCAPINTS] __cpuinitdata;
 354__u32 cpu_caps_set[NCAPINTS] __cpuinitdata;
 355
 356void load_percpu_segment(int cpu)
 357{
 358#ifdef CONFIG_X86_32
 359        loadsegment(fs, __KERNEL_PERCPU);
 360#else
 361        loadsegment(gs, 0);
 362        wrmsrl(MSR_GS_BASE, (unsigned long)per_cpu(irq_stack_union.gs_base, cpu));
 363#endif
 364        load_stack_canary_segment();
 365}
 366
 367/*
 368 * Current gdt points %fs at the "master" per-cpu area: after this,
 369 * it's on the real one.
 370 */
 371void switch_to_new_gdt(int cpu)
 372{
 373        struct desc_ptr gdt_descr;
 374
 375        gdt_descr.address = (long)get_cpu_gdt_table(cpu);
 376        gdt_descr.size = GDT_SIZE - 1;
 377        load_gdt(&gdt_descr);
 378        /* Reload the per-cpu base */
 379
 380        load_percpu_segment(cpu);
 381}
 382
 383static const struct cpu_dev *__cpuinitdata cpu_devs[X86_VENDOR_NUM] = {};
 384
 385static void __cpuinit get_model_name(struct cpuinfo_x86 *c)
 386{
 387        unsigned int *v;
 388        char *p, *q;
 389
 390        if (c->extended_cpuid_level < 0x80000004)
 391                return;
 392
 393        v = (unsigned int *)c->x86_model_id;
 394        cpuid(0x80000002, &v[0], &v[1], &v[2], &v[3]);
 395        cpuid(0x80000003, &v[4], &v[5], &v[6], &v[7]);
 396        cpuid(0x80000004, &v[8], &v[9], &v[10], &v[11]);
 397        c->x86_model_id[48] = 0;
 398
 399        /*
 400         * Intel chips right-justify this string for some dumb reason;
 401         * undo that brain damage:
 402         */
 403        p = q = &c->x86_model_id[0];
 404        while (*p == ' ')
 405                p++;
 406        if (p != q) {
 407                while (*p)
 408                        *q++ = *p++;
 409                while (q <= &c->x86_model_id[48])
 410                        *q++ = '\0';    /* Zero-pad the rest */
 411        }
 412}
 413
 414void __cpuinit cpu_detect_cache_sizes(struct cpuinfo_x86 *c)
 415{
 416        unsigned int n, dummy, ebx, ecx, edx, l2size;
 417
 418        n = c->extended_cpuid_level;
 419
 420        if (n >= 0x80000005) {
 421                cpuid(0x80000005, &dummy, &ebx, &ecx, &edx);
 422                c->x86_cache_size = (ecx>>24) + (edx>>24);
 423#ifdef CONFIG_X86_64
 424                /* On K8 L1 TLB is inclusive, so don't count it */
 425                c->x86_tlbsize = 0;
 426#endif
 427        }
 428
 429        if (n < 0x80000006)     /* Some chips just has a large L1. */
 430                return;
 431
 432        cpuid(0x80000006, &dummy, &ebx, &ecx, &edx);
 433        l2size = ecx >> 16;
 434
 435#ifdef CONFIG_X86_64
 436        c->x86_tlbsize += ((ebx >> 16) & 0xfff) + (ebx & 0xfff);
 437#else
 438        /* do processor-specific cache resizing */
 439        if (this_cpu->c_size_cache)
 440                l2size = this_cpu->c_size_cache(c, l2size);
 441
 442        /* Allow user to override all this if necessary. */
 443        if (cachesize_override != -1)
 444                l2size = cachesize_override;
 445
 446        if (l2size == 0)
 447                return;         /* Again, no L2 cache is possible */
 448#endif
 449
 450        c->x86_cache_size = l2size;
 451}
 452
 453void __cpuinit detect_ht(struct cpuinfo_x86 *c)
 454{
 455#ifdef CONFIG_X86_HT
 456        u32 eax, ebx, ecx, edx;
 457        int index_msb, core_bits;
 458        static bool printed;
 459
 460        if (!cpu_has(c, X86_FEATURE_HT))
 461                return;
 462
 463        if (cpu_has(c, X86_FEATURE_CMP_LEGACY))
 464                goto out;
 465
 466        if (cpu_has(c, X86_FEATURE_XTOPOLOGY))
 467                return;
 468
 469        cpuid(1, &eax, &ebx, &ecx, &edx);
 470
 471        smp_num_siblings = (ebx & 0xff0000) >> 16;
 472
 473        if (smp_num_siblings == 1) {
 474                printk_once(KERN_INFO "CPU0: Hyper-Threading is disabled\n");
 475                goto out;
 476        }
 477
 478        if (smp_num_siblings <= 1)
 479                goto out;
 480
 481        index_msb = get_count_order(smp_num_siblings);
 482        c->phys_proc_id = apic->phys_pkg_id(c->initial_apicid, index_msb);
 483
 484        smp_num_siblings = smp_num_siblings / c->x86_max_cores;
 485
 486        index_msb = get_count_order(smp_num_siblings);
 487
 488        core_bits = get_count_order(c->x86_max_cores);
 489
 490        c->cpu_core_id = apic->phys_pkg_id(c->initial_apicid, index_msb) &
 491                                       ((1 << core_bits) - 1);
 492
 493out:
 494        if (!printed && (c->x86_max_cores * smp_num_siblings) > 1) {
 495                printk(KERN_INFO  "CPU: Physical Processor ID: %d\n",
 496                       c->phys_proc_id);
 497                printk(KERN_INFO  "CPU: Processor Core ID: %d\n",
 498                       c->cpu_core_id);
 499                printed = 1;
 500        }
 501#endif
 502}
 503
 504static void __cpuinit get_cpu_vendor(struct cpuinfo_x86 *c)
 505{
 506        char *v = c->x86_vendor_id;
 507        int i;
 508
 509        for (i = 0; i < X86_VENDOR_NUM; i++) {
 510                if (!cpu_devs[i])
 511                        break;
 512
 513                if (!strcmp(v, cpu_devs[i]->c_ident[0]) ||
 514                    (cpu_devs[i]->c_ident[1] &&
 515                     !strcmp(v, cpu_devs[i]->c_ident[1]))) {
 516
 517                        this_cpu = cpu_devs[i];
 518                        c->x86_vendor = this_cpu->c_x86_vendor;
 519                        return;
 520                }
 521        }
 522
 523        printk_once(KERN_ERR
 524                        "CPU: vendor_id '%s' unknown, using generic init.\n" \
 525                        "CPU: Your system may be unstable.\n", v);
 526
 527        c->x86_vendor = X86_VENDOR_UNKNOWN;
 528        this_cpu = &default_cpu;
 529}
 530
 531void __cpuinit cpu_detect(struct cpuinfo_x86 *c)
 532{
 533        /* Get vendor name */
 534        cpuid(0x00000000, (unsigned int *)&c->cpuid_level,
 535              (unsigned int *)&c->x86_vendor_id[0],
 536              (unsigned int *)&c->x86_vendor_id[8],
 537              (unsigned int *)&c->x86_vendor_id[4]);
 538
 539        c->x86 = 4;
 540        /* Intel-defined flags: level 0x00000001 */
 541        if (c->cpuid_level >= 0x00000001) {
 542                u32 junk, tfms, cap0, misc;
 543
 544                cpuid(0x00000001, &tfms, &misc, &junk, &cap0);
 545                c->x86 = (tfms >> 8) & 0xf;
 546                c->x86_model = (tfms >> 4) & 0xf;
 547                c->x86_mask = tfms & 0xf;
 548
 549                if (c->x86 == 0xf)
 550                        c->x86 += (tfms >> 20) & 0xff;
 551                if (c->x86 >= 0x6)
 552                        c->x86_model += ((tfms >> 16) & 0xf) << 4;
 553
 554                if (cap0 & (1<<19)) {
 555                        c->x86_clflush_size = ((misc >> 8) & 0xff) * 8;
 556                        c->x86_cache_alignment = c->x86_clflush_size;
 557                }
 558        }
 559}
 560
 561void __cpuinit get_cpu_cap(struct cpuinfo_x86 *c)
 562{
 563        u32 tfms, xlvl;
 564        u32 ebx;
 565
 566        /* Intel-defined flags: level 0x00000001 */
 567        if (c->cpuid_level >= 0x00000001) {
 568                u32 capability, excap;
 569
 570                cpuid(0x00000001, &tfms, &ebx, &excap, &capability);
 571                c->x86_capability[0] = capability;
 572                c->x86_capability[4] = excap;
 573        }
 574
 575        /* Additional Intel-defined flags: level 0x00000007 */
 576        if (c->cpuid_level >= 0x00000007) {
 577                u32 eax, ebx, ecx, edx;
 578
 579                cpuid_count(0x00000007, 0, &eax, &ebx, &ecx, &edx);
 580
 581                c->x86_capability[9] = ebx;
 582        }
 583
 584        /* AMD-defined flags: level 0x80000001 */
 585        xlvl = cpuid_eax(0x80000000);
 586        c->extended_cpuid_level = xlvl;
 587
 588        if ((xlvl & 0xffff0000) == 0x80000000) {
 589                if (xlvl >= 0x80000001) {
 590                        c->x86_capability[1] = cpuid_edx(0x80000001);
 591                        c->x86_capability[6] = cpuid_ecx(0x80000001);
 592                }
 593        }
 594
 595        if (c->extended_cpuid_level >= 0x80000008) {
 596                u32 eax = cpuid_eax(0x80000008);
 597
 598                c->x86_virt_bits = (eax >> 8) & 0xff;
 599                c->x86_phys_bits = eax & 0xff;
 600        }
 601#ifdef CONFIG_X86_32
 602        else if (cpu_has(c, X86_FEATURE_PAE) || cpu_has(c, X86_FEATURE_PSE36))
 603                c->x86_phys_bits = 36;
 604#endif
 605
 606        if (c->extended_cpuid_level >= 0x80000007)
 607                c->x86_power = cpuid_edx(0x80000007);
 608
 609        init_scattered_cpuid_features(c);
 610}
 611
 612static void __cpuinit identify_cpu_without_cpuid(struct cpuinfo_x86 *c)
 613{
 614#ifdef CONFIG_X86_32
 615        int i;
 616
 617        /*
 618         * First of all, decide if this is a 486 or higher
 619         * It's a 486 if we can modify the AC flag
 620         */
 621        if (flag_is_changeable_p(X86_EFLAGS_AC))
 622                c->x86 = 4;
 623        else
 624                c->x86 = 3;
 625
 626        for (i = 0; i < X86_VENDOR_NUM; i++)
 627                if (cpu_devs[i] && cpu_devs[i]->c_identify) {
 628                        c->x86_vendor_id[0] = 0;
 629                        cpu_devs[i]->c_identify(c);
 630                        if (c->x86_vendor_id[0]) {
 631                                get_cpu_vendor(c);
 632                                break;
 633                        }
 634                }
 635#endif
 636}
 637
 638/*
 639 * Do minimum CPU detection early.
 640 * Fields really needed: vendor, cpuid_level, family, model, mask,
 641 * cache alignment.
 642 * The others are not touched to avoid unwanted side effects.
 643 *
 644 * WARNING: this function is only called on the BP.  Don't add code here
 645 * that is supposed to run on all CPUs.
 646 */
 647static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 648{
 649#ifdef CONFIG_X86_64
 650        c->x86_clflush_size = 64;
 651        c->x86_phys_bits = 36;
 652        c->x86_virt_bits = 48;
 653#else
 654        c->x86_clflush_size = 32;
 655        c->x86_phys_bits = 32;
 656        c->x86_virt_bits = 32;
 657#endif
 658        c->x86_cache_alignment = c->x86_clflush_size;
 659
 660        memset(&c->x86_capability, 0, sizeof c->x86_capability);
 661        c->extended_cpuid_level = 0;
 662
 663        if (!have_cpuid_p())
 664                identify_cpu_without_cpuid(c);
 665
 666        /* cyrix could have cpuid enabled via c_identify()*/
 667        if (!have_cpuid_p())
 668                return;
 669
 670        cpu_detect(c);
 671
 672        get_cpu_vendor(c);
 673
 674        get_cpu_cap(c);
 675
 676        if (this_cpu->c_early_init)
 677                this_cpu->c_early_init(c);
 678
 679        c->cpu_index = 0;
 680        filter_cpuid_features(c, false);
 681
 682        setup_smep(c);
 683
 684        if (this_cpu->c_bsp_init)
 685                this_cpu->c_bsp_init(c);
 686}
 687
 688void __init early_cpu_init(void)
 689{
 690        const struct cpu_dev *const *cdev;
 691        int count = 0;
 692
 693#ifdef CONFIG_PROCESSOR_SELECT
 694        printk(KERN_INFO "KERNEL supported cpus:\n");
 695#endif
 696
 697        for (cdev = __x86_cpu_dev_start; cdev < __x86_cpu_dev_end; cdev++) {
 698                const struct cpu_dev *cpudev = *cdev;
 699
 700                if (count >= X86_VENDOR_NUM)
 701                        break;
 702                cpu_devs[count] = cpudev;
 703                count++;
 704
 705#ifdef CONFIG_PROCESSOR_SELECT
 706                {
 707                        unsigned int j;
 708
 709                        for (j = 0; j < 2; j++) {
 710                                if (!cpudev->c_ident[j])
 711                                        continue;
 712                                printk(KERN_INFO "  %s %s\n", cpudev->c_vendor,
 713                                        cpudev->c_ident[j]);
 714                        }
 715                }
 716#endif
 717        }
 718        early_identify_cpu(&boot_cpu_data);
 719}
 720
 721/*
 722 * The NOPL instruction is supposed to exist on all CPUs of family >= 6;
 723 * unfortunately, that's not true in practice because of early VIA
 724 * chips and (more importantly) broken virtualizers that are not easy
 725 * to detect. In the latter case it doesn't even *fail* reliably, so
 726 * probing for it doesn't even work. Disable it completely on 32-bit
 727 * unless we can find a reliable way to detect all the broken cases.
 728 * Enable it explicitly on 64-bit for non-constant inputs of cpu_has().
 729 */
 730static void __cpuinit detect_nopl(struct cpuinfo_x86 *c)
 731{
 732#ifdef CONFIG_X86_32
 733        clear_cpu_cap(c, X86_FEATURE_NOPL);
 734#else
 735        set_cpu_cap(c, X86_FEATURE_NOPL);
 736#endif
 737}
 738
 739static void __cpuinit generic_identify(struct cpuinfo_x86 *c)
 740{
 741        c->extended_cpuid_level = 0;
 742
 743        if (!have_cpuid_p())
 744                identify_cpu_without_cpuid(c);
 745
 746        /* cyrix could have cpuid enabled via c_identify()*/
 747        if (!have_cpuid_p())
 748                return;
 749
 750        cpu_detect(c);
 751
 752        get_cpu_vendor(c);
 753
 754        get_cpu_cap(c);
 755
 756        if (c->cpuid_level >= 0x00000001) {
 757                c->initial_apicid = (cpuid_ebx(1) >> 24) & 0xFF;
 758#ifdef CONFIG_X86_32
 759# ifdef CONFIG_X86_HT
 760                c->apicid = apic->phys_pkg_id(c->initial_apicid, 0);
 761# else
 762                c->apicid = c->initial_apicid;
 763# endif
 764#endif
 765                c->phys_proc_id = c->initial_apicid;
 766        }
 767
 768        setup_smep(c);
 769
 770        get_model_name(c); /* Default name */
 771
 772        detect_nopl(c);
 773}
 774
 775/*
 776 * This does the hard work of actually picking apart the CPU stuff...
 777 */
 778static void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
 779{
 780        int i;
 781
 782        c->loops_per_jiffy = loops_per_jiffy;
 783        c->x86_cache_size = -1;
 784        c->x86_vendor = X86_VENDOR_UNKNOWN;
 785        c->x86_model = c->x86_mask = 0; /* So far unknown... */
 786        c->x86_vendor_id[0] = '\0'; /* Unset */
 787        c->x86_model_id[0] = '\0';  /* Unset */
 788        c->x86_max_cores = 1;
 789        c->x86_coreid_bits = 0;
 790#ifdef CONFIG_X86_64
 791        c->x86_clflush_size = 64;
 792        c->x86_phys_bits = 36;
 793        c->x86_virt_bits = 48;
 794#else
 795        c->cpuid_level = -1;    /* CPUID not detected */
 796        c->x86_clflush_size = 32;
 797        c->x86_phys_bits = 32;
 798        c->x86_virt_bits = 32;
 799#endif
 800        c->x86_cache_alignment = c->x86_clflush_size;
 801        memset(&c->x86_capability, 0, sizeof c->x86_capability);
 802
 803        generic_identify(c);
 804
 805        if (this_cpu->c_identify)
 806                this_cpu->c_identify(c);
 807
 808        /* Clear/Set all flags overriden by options, after probe */
 809        for (i = 0; i < NCAPINTS; i++) {
 810                c->x86_capability[i] &= ~cpu_caps_cleared[i];
 811                c->x86_capability[i] |= cpu_caps_set[i];
 812        }
 813
 814#ifdef CONFIG_X86_64
 815        c->apicid = apic->phys_pkg_id(c->initial_apicid, 0);
 816#endif
 817
 818        /*
 819         * Vendor-specific initialization.  In this section we
 820         * canonicalize the feature flags, meaning if there are
 821         * features a certain CPU supports which CPUID doesn't
 822         * tell us, CPUID claiming incorrect flags, or other bugs,
 823         * we handle them here.
 824         *
 825         * At the end of this section, c->x86_capability better
 826         * indicate the features this CPU genuinely supports!
 827         */
 828        if (this_cpu->c_init)
 829                this_cpu->c_init(c);
 830
 831        /* Disable the PN if appropriate */
 832        squash_the_stupid_serial_number(c);
 833
 834        /*
 835         * The vendor-specific functions might have changed features.
 836         * Now we do "generic changes."
 837         */
 838
 839        /* Filter out anything that depends on CPUID levels we don't have */
 840        filter_cpuid_features(c, true);
 841
 842        /* If the model name is still unset, do table lookup. */
 843        if (!c->x86_model_id[0]) {
 844                const char *p;
 845                p = table_lookup_model(c);
 846                if (p)
 847                        strcpy(c->x86_model_id, p);
 848                else
 849                        /* Last resort... */
 850                        sprintf(c->x86_model_id, "%02x/%02x",
 851                                c->x86, c->x86_model);
 852        }
 853
 854#ifdef CONFIG_X86_64
 855        detect_ht(c);
 856#endif
 857
 858        init_hypervisor(c);
 859        x86_init_rdrand(c);
 860
 861        /*
 862         * Clear/Set all flags overriden by options, need do it
 863         * before following smp all cpus cap AND.
 864         */
 865        for (i = 0; i < NCAPINTS; i++) {
 866                c->x86_capability[i] &= ~cpu_caps_cleared[i];
 867                c->x86_capability[i] |= cpu_caps_set[i];
 868        }
 869
 870        /*
 871         * On SMP, boot_cpu_data holds the common feature set between
 872         * all CPUs; so make sure that we indicate which features are
 873         * common between the CPUs.  The first time this routine gets
 874         * executed, c == &boot_cpu_data.
 875         */
 876        if (c != &boot_cpu_data) {
 877                /* AND the already accumulated flags with these */
 878                for (i = 0; i < NCAPINTS; i++)
 879                        boot_cpu_data.x86_capability[i] &= c->x86_capability[i];
 880        }
 881
 882        /* Init Machine Check Exception if available. */
 883        mcheck_cpu_init(c);
 884
 885        select_idle_routine(c);
 886
 887#ifdef CONFIG_NUMA
 888        numa_add_cpu(smp_processor_id());
 889#endif
 890}
 891
 892#ifdef CONFIG_X86_64
 893static void vgetcpu_set_mode(void)
 894{
 895        if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP))
 896                vgetcpu_mode = VGETCPU_RDTSCP;
 897        else
 898                vgetcpu_mode = VGETCPU_LSL;
 899}
 900#endif
 901
 902void __init identify_boot_cpu(void)
 903{
 904        identify_cpu(&boot_cpu_data);
 905        init_amd_e400_c1e_mask();
 906#ifdef CONFIG_X86_32
 907        sysenter_setup();
 908        enable_sep_cpu();
 909#else
 910        vgetcpu_set_mode();
 911#endif
 912}
 913
 914void __cpuinit identify_secondary_cpu(struct cpuinfo_x86 *c)
 915{
 916        BUG_ON(c == &boot_cpu_data);
 917        identify_cpu(c);
 918#ifdef CONFIG_X86_32
 919        enable_sep_cpu();
 920#endif
 921        mtrr_ap_init();
 922}
 923
 924struct msr_range {
 925        unsigned        min;
 926        unsigned        max;
 927};
 928
 929static const struct msr_range msr_range_array[] __cpuinitconst = {
 930        { 0x00000000, 0x00000418},
 931        { 0xc0000000, 0xc000040b},
 932        { 0xc0010000, 0xc0010142},
 933        { 0xc0011000, 0xc001103b},
 934};
 935
 936static void __cpuinit print_cpu_msr(void)
 937{
 938        unsigned index_min, index_max;
 939        unsigned index;
 940        u64 val;
 941        int i;
 942
 943        for (i = 0; i < ARRAY_SIZE(msr_range_array); i++) {
 944                index_min = msr_range_array[i].min;
 945                index_max = msr_range_array[i].max;
 946
 947                for (index = index_min; index < index_max; index++) {
 948                        if (rdmsrl_amd_safe(index, &val))
 949                                continue;
 950                        printk(KERN_INFO " MSR%08x: %016llx\n", index, val);
 951                }
 952        }
 953}
 954
 955static int show_msr __cpuinitdata;
 956
 957static __init int setup_show_msr(char *arg)
 958{
 959        int num;
 960
 961        get_option(&arg, &num);
 962
 963        if (num > 0)
 964                show_msr = num;
 965        return 1;
 966}
 967__setup("show_msr=", setup_show_msr);
 968
 969static __init int setup_noclflush(char *arg)
 970{
 971        setup_clear_cpu_cap(X86_FEATURE_CLFLSH);
 972        return 1;
 973}
 974__setup("noclflush", setup_noclflush);
 975
 976void __cpuinit print_cpu_info(struct cpuinfo_x86 *c)
 977{
 978        const char *vendor = NULL;
 979
 980        if (c->x86_vendor < X86_VENDOR_NUM) {
 981                vendor = this_cpu->c_vendor;
 982        } else {
 983                if (c->cpuid_level >= 0)
 984                        vendor = c->x86_vendor_id;
 985        }
 986
 987        if (vendor && !strstr(c->x86_model_id, vendor))
 988                printk(KERN_CONT "%s ", vendor);
 989
 990        if (c->x86_model_id[0])
 991                printk(KERN_CONT "%s", c->x86_model_id);
 992        else
 993                printk(KERN_CONT "%d86", c->x86);
 994
 995        if (c->x86_mask || c->cpuid_level >= 0)
 996                printk(KERN_CONT " stepping %02x\n", c->x86_mask);
 997        else
 998                printk(KERN_CONT "\n");
 999
1000#ifdef CONFIG_SMP
1001        if (c->cpu_index < show_msr)
1002                print_cpu_msr();
1003#else
1004        if (show_msr)
1005                print_cpu_msr();
1006#endif
1007}
1008
1009static __init int setup_disablecpuid(char *arg)
1010{
1011        int bit;
1012
1013        if (get_option(&arg, &bit) && bit < NCAPINTS*32)
1014                setup_clear_cpu_cap(bit);
1015        else
1016                return 0;
1017
1018        return 1;
1019}
1020__setup("clearcpuid=", setup_disablecpuid);
1021
1022#ifdef CONFIG_X86_64
1023struct desc_ptr idt_descr = { NR_VECTORS * 16 - 1, (unsigned long) idt_table };
1024struct desc_ptr nmi_idt_descr = { NR_VECTORS * 16 - 1,
1025                                    (unsigned long) nmi_idt_table };
1026
1027DEFINE_PER_CPU_FIRST(union irq_stack_union,
1028                     irq_stack_union) __aligned(PAGE_SIZE);
1029
1030/*
1031 * The following four percpu variables are hot.  Align current_task to
1032 * cacheline size such that all four fall in the same cacheline.
1033 */
1034DEFINE_PER_CPU(struct task_struct *, current_task) ____cacheline_aligned =
1035        &init_task;
1036EXPORT_PER_CPU_SYMBOL(current_task);
1037
1038DEFINE_PER_CPU(unsigned long, kernel_stack) =
1039        (unsigned long)&init_thread_union - KERNEL_STACK_OFFSET + THREAD_SIZE;
1040EXPORT_PER_CPU_SYMBOL(kernel_stack);
1041
1042DEFINE_PER_CPU(char *, irq_stack_ptr) =
1043        init_per_cpu_var(irq_stack_union.irq_stack) + IRQ_STACK_SIZE - 64;
1044
1045DEFINE_PER_CPU(unsigned int, irq_count) = -1;
1046
1047DEFINE_PER_CPU(struct task_struct *, fpu_owner_task);
1048EXPORT_PER_CPU_SYMBOL(fpu_owner_task);
1049
1050/*
1051 * Special IST stacks which the CPU switches to when it calls
1052 * an IST-marked descriptor entry. Up to 7 stacks (hardware
1053 * limit), all of them are 4K, except the debug stack which
1054 * is 8K.
1055 */
1056static const unsigned int exception_stack_sizes[N_EXCEPTION_STACKS] = {
1057          [0 ... N_EXCEPTION_STACKS - 1]        = EXCEPTION_STKSZ,
1058          [DEBUG_STACK - 1]                     = DEBUG_STKSZ
1059};
1060
1061static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks
1062        [(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ]);
1063
1064/* May not be marked __init: used by software suspend */
1065void syscall_init(void)
1066{
1067        /*
1068         * LSTAR and STAR live in a bit strange symbiosis.
1069         * They both write to the same internal register. STAR allows to
1070         * set CS/DS but only a 32bit target. LSTAR sets the 64bit rip.
1071         */
1072        wrmsrl(MSR_STAR,  ((u64)__USER32_CS)<<48  | ((u64)__KERNEL_CS)<<32);
1073        wrmsrl(MSR_LSTAR, system_call);
1074        wrmsrl(MSR_CSTAR, ignore_sysret);
1075
1076#ifdef CONFIG_IA32_EMULATION
1077        syscall32_cpu_init();
1078#endif
1079
1080        /* Flags to clear on syscall */
1081        wrmsrl(MSR_SYSCALL_MASK,
1082               X86_EFLAGS_TF|X86_EFLAGS_DF|X86_EFLAGS_IF|X86_EFLAGS_IOPL);
1083}
1084
1085unsigned long kernel_eflags;
1086
1087/*
1088 * Copies of the original ist values from the tss are only accessed during
1089 * debugging, no special alignment required.
1090 */
1091DEFINE_PER_CPU(struct orig_ist, orig_ist);
1092
1093static DEFINE_PER_CPU(unsigned long, debug_stack_addr);
1094DEFINE_PER_CPU(int, debug_stack_usage);
1095
1096int is_debug_stack(unsigned long addr)
1097{
1098        return __get_cpu_var(debug_stack_usage) ||
1099                (addr <= __get_cpu_var(debug_stack_addr) &&
1100                 addr > (__get_cpu_var(debug_stack_addr) - DEBUG_STKSZ));
1101}
1102
1103void debug_stack_set_zero(void)
1104{
1105        load_idt((const struct desc_ptr *)&nmi_idt_descr);
1106}
1107
1108void debug_stack_reset(void)
1109{
1110        load_idt((const struct desc_ptr *)&idt_descr);
1111}
1112
1113#else   /* CONFIG_X86_64 */
1114
1115DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
1116EXPORT_PER_CPU_SYMBOL(current_task);
1117DEFINE_PER_CPU(struct task_struct *, fpu_owner_task);
1118EXPORT_PER_CPU_SYMBOL(fpu_owner_task);
1119
1120#ifdef CONFIG_CC_STACKPROTECTOR
1121DEFINE_PER_CPU_ALIGNED(struct stack_canary, stack_canary);
1122#endif
1123
1124/* Make sure %fs and %gs are initialized properly in idle threads */
1125struct pt_regs * __cpuinit idle_regs(struct pt_regs *regs)
1126{
1127        memset(regs, 0, sizeof(struct pt_regs));
1128        regs->fs = __KERNEL_PERCPU;
1129        regs->gs = __KERNEL_STACK_CANARY;
1130
1131        return regs;
1132}
1133#endif  /* CONFIG_X86_64 */
1134
1135/*
1136 * Clear all 6 debug registers:
1137 */
1138static void clear_all_debug_regs(void)
1139{
1140        int i;
1141
1142        for (i = 0; i < 8; i++) {
1143                /* Ignore db4, db5 */
1144                if ((i == 4) || (i == 5))
1145                        continue;
1146
1147                set_debugreg(0, i);
1148        }
1149}
1150
1151#ifdef CONFIG_KGDB
1152/*
1153 * Restore debug regs if using kgdbwait and you have a kernel debugger
1154 * connection established.
1155 */
1156static void dbg_restore_debug_regs(void)
1157{
1158        if (unlikely(kgdb_connected && arch_kgdb_ops.correct_hw_break))
1159                arch_kgdb_ops.correct_hw_break();
1160}
1161#else /* ! CONFIG_KGDB */
1162#define dbg_restore_debug_regs()
1163#endif /* ! CONFIG_KGDB */
1164
1165/*
1166 * Prints an error where the NUMA and configured core-number mismatch and the
1167 * platform didn't override this to fix it up
1168 */
1169void __cpuinit x86_default_fixup_cpu_id(struct cpuinfo_x86 *c, int node)
1170{
1171        pr_err("NUMA core number %d differs from configured core number %d\n", node, c->phys_proc_id);
1172}
1173
1174/*
1175 * cpu_init() initializes state that is per-CPU. Some data is already
1176 * initialized (naturally) in the bootstrap process, such as the GDT
1177 * and IDT. We reload them nevertheless, this function acts as a
1178 * 'CPU state barrier', nothing should get across.
1179 * A lot of state is already set up in PDA init for 64 bit
1180 */
1181#ifdef CONFIG_X86_64
1182
1183void __cpuinit cpu_init(void)
1184{
1185        struct orig_ist *oist;
1186        struct task_struct *me;
1187        struct tss_struct *t;
1188        unsigned long v;
1189        int cpu;
1190        int i;
1191
1192        cpu = stack_smp_processor_id();
1193        t = &per_cpu(init_tss, cpu);
1194        oist = &per_cpu(orig_ist, cpu);
1195
1196#ifdef CONFIG_NUMA
1197        if (cpu != 0 && percpu_read(numa_node) == 0 &&
1198            early_cpu_to_node(cpu) != NUMA_NO_NODE)
1199                set_numa_node(early_cpu_to_node(cpu));
1200#endif
1201
1202        me = current;
1203
1204        if (cpumask_test_and_set_cpu(cpu, cpu_initialized_mask))
1205                panic("CPU#%d already initialized!\n", cpu);
1206
1207        pr_debug("Initializing CPU#%d\n", cpu);
1208
1209        clear_in_cr4(X86_CR4_VME|X86_CR4_PVI|X86_CR4_TSD|X86_CR4_DE);
1210
1211        /*
1212         * Initialize the per-CPU GDT with the boot GDT,
1213         * and set up the GDT descriptor:
1214         */
1215
1216        switch_to_new_gdt(cpu);
1217        loadsegment(fs, 0);
1218
1219        load_idt((const struct desc_ptr *)&idt_descr);
1220
1221        memset(me->thread.tls_array, 0, GDT_ENTRY_TLS_ENTRIES * 8);
1222        syscall_init();
1223
1224        wrmsrl(MSR_FS_BASE, 0);
1225        wrmsrl(MSR_KERNEL_GS_BASE, 0);
1226        barrier();
1227
1228        x86_configure_nx();
1229        if (cpu != 0)
1230                enable_x2apic();
1231
1232        /*
1233         * set up and load the per-CPU TSS
1234         */
1235        if (!oist->ist[0]) {
1236                char *estacks = per_cpu(exception_stacks, cpu);
1237
1238                for (v = 0; v < N_EXCEPTION_STACKS; v++) {
1239                        estacks += exception_stack_sizes[v];
1240                        oist->ist[v] = t->x86_tss.ist[v] =
1241                                        (unsigned long)estacks;
1242                        if (v == DEBUG_STACK-1)
1243                                per_cpu(debug_stack_addr, cpu) = (unsigned long)estacks;
1244                }
1245        }
1246
1247        t->x86_tss.io_bitmap_base = offsetof(struct tss_struct, io_bitmap);
1248
1249        /*
1250         * <= is required because the CPU will access up to
1251         * 8 bits beyond the end of the IO permission bitmap.
1252         */
1253        for (i = 0; i <= IO_BITMAP_LONGS; i++)
1254                t->io_bitmap[i] = ~0UL;
1255
1256        atomic_inc(&init_mm.mm_count);
1257        me->active_mm = &init_mm;
1258        BUG_ON(me->mm);
1259        enter_lazy_tlb(&init_mm, me);
1260
1261        load_sp0(t, &current->thread);
1262        set_tss_desc(cpu, t);
1263        load_TR_desc();
1264        load_LDT(&init_mm.context);
1265
1266        clear_all_debug_regs();
1267        dbg_restore_debug_regs();
1268
1269        fpu_init();
1270        xsave_init();
1271
1272        raw_local_save_flags(kernel_eflags);
1273
1274        if (is_uv_system())
1275                uv_cpu_init();
1276}
1277
1278#else
1279
1280void __cpuinit cpu_init(void)
1281{
1282        int cpu = smp_processor_id();
1283        struct task_struct *curr = current;
1284        struct tss_struct *t = &per_cpu(init_tss, cpu);
1285        struct thread_struct *thread = &curr->thread;
1286
1287        if (cpumask_test_and_set_cpu(cpu, cpu_initialized_mask)) {
1288                printk(KERN_WARNING "CPU#%d already initialized!\n", cpu);
1289                for (;;)
1290                        local_irq_enable();
1291        }
1292
1293        printk(KERN_INFO "Initializing CPU#%d\n", cpu);
1294
1295        if (cpu_has_vme || cpu_has_tsc || cpu_has_de)
1296                clear_in_cr4(X86_CR4_VME|X86_CR4_PVI|X86_CR4_TSD|X86_CR4_DE);
1297
1298        load_idt(&idt_descr);
1299        switch_to_new_gdt(cpu);
1300
1301        /*
1302         * Set up and load the per-CPU TSS and LDT
1303         */
1304        atomic_inc(&init_mm.mm_count);
1305        curr->active_mm = &init_mm;
1306        BUG_ON(curr->mm);
1307        enter_lazy_tlb(&init_mm, curr);
1308
1309        load_sp0(t, thread);
1310        set_tss_desc(cpu, t);
1311        load_TR_desc();
1312        load_LDT(&init_mm.context);
1313
1314        t->x86_tss.io_bitmap_base = offsetof(struct tss_struct, io_bitmap);
1315
1316#ifdef CONFIG_DOUBLEFAULT
1317        /* Set up doublefault TSS pointer in the GDT */
1318        __set_tss_desc(cpu, GDT_ENTRY_DOUBLEFAULT_TSS, &doublefault_tss);
1319#endif
1320
1321        clear_all_debug_regs();
1322        dbg_restore_debug_regs();
1323
1324        fpu_init();
1325        xsave_init();
1326}
1327#endif
1328