aboutsummaryrefslogtreecommitdiff
path: root/arch/i386/kernel/cpu/common.c
blob: bbfc278dfa494c8096b13c219546078c6e495be0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
#include <linux/init.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/smp.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/bootmem.h>
#include <asm/semaphore.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/msr.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#ifdef CONFIG_X86_LOCAL_APIC
#include <asm/mpspec.h>
#include <asm/apic.h>
#include <mach_apic.h>
#endif

#include "cpu.h"

DEFINE_PER_CPU(struct Xgt_desc_struct, cpu_gdt_descr);
EXPORT_PER_CPU_SYMBOL(cpu_gdt_descr);

DEFINE_PER_CPU(unsigned char, cpu_16bit_stack[CPU_16BIT_STACK_SIZE]);
EXPORT_PER_CPU_SYMBOL(cpu_16bit_stack);

static int cachesize_override __cpuinitdata = -1;
static int disable_x86_fxsr __cpuinitdata;
static int disable_x86_serial_nr __cpuinitdata = 1;
static int disable_x86_sep __cpuinitdata;

struct cpu_dev * cpu_devs[X86_VENDOR_NUM] = {};

extern int disable_pse;

static void default_init(struct cpuinfo_x86 * c)
{
	/* 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");
	}
}

static struct cpu_dev default_cpu = {
	.c_init	= default_init,
	.c_vendor = "Unknown",
};
static struct cpu_dev * this_cpu = &default_cpu;

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

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

	if (cpuid_eax(0x80000000) < 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;

	/* 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 */
	}

	return 1;
}


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

	n = cpuid_eax(0x80000000);

	if (n >= 0x80000005) {
		cpuid(0x80000005, &dummy, &dummy, &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);	
	}

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

	ecx = cpuid_ecx(0x80000006);
	l2size = ecx >> 16;
	
	/* 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 */

	c->x86_cache_size = l2size;

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

/* 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 char __cpuinit *table_lookup_model(struct cpuinfo_x86 *c)
{
	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 */
}


static void __cpuinit get_cpu_vendor(struct cpuinfo_x86 *c, int early)
{
	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;
				if (!early)
					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;
	this_cpu = &default_cpu;
}


static int __init x86_fxsr_setup(char * s)
{
	disable_x86_fxsr = 1;
	return 1;
}
__setup("nofxsr", x86_fxsr_setup);


static int __init x86_sep_setup(char * s)
{
	disable_x86_sep = 1;
	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;

	asm("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);
}

/* 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_cpu_detect(void)
{
	struct cpuinfo_x86 *c = &boot_cpu_data;

	c->x86_cache_alignment = 32;

	if (!have_cpuid_p())
		return;

	/* Get vendor name */
	cpuid(0x00000000, &c->cpuid_level,
	      (int *)&c->x86_vendor_id[0],
	      (int *)&c->x86_vendor_id[8],
	      (int *)&c->x86_vendor_id[4]);

	get_cpu_vendor(c, 1);

	c->x86 = 4;
	if (c->cpuid_level >= 0x00000001) {
		u32 junk, tfms, cap0, misc;
		cpuid(0x00000001, &tfms, &misc, &junk, &cap0);
		c->x86 = (tfms >> 8) & 15;
		c->x86_model = (tfms >> 4) & 15;
		if (c->x86 == 0xf)
			c->x86 += (tfms >> 20) & 0xff;
		if (c->x86 >= 0x6)
			c->x86_model += ((tfms >> 16) & 0xF) << 4;
		c->x86_mask = tfms & 15;
		if (cap0 & (1<<19))
			c->x86_cache_alignment = ((misc >> 8) & 0xff) * 8;
	}
}

void __cpuinit generic_identify(struct cpuinfo_x86 * c)
{
	u32 tfms, xlvl;
	int junk;

	if (have_cpuid_p()) {
		/* Get vendor name */
		cpuid(0x00000000, &c->cpuid_level,
		      (int *)&c->x86_vendor_id[0],
		      (int *)&c->x86_vendor_id[8],
		      (int *)&c->x86_vendor_id[4]);
		
		get_cpu_vendor(c, 0);
		/* 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 capability, excap;
			cpuid(0x00000001, &tfms, &junk, &excap, &capability);
			c->x86_capability[0] = capability;
			c->x86_capability[4] = excap;
			c->x86 = (tfms >> 8) & 15;
			c->x86_model = (tfms >> 4) & 15;
			if (c->x86 == 0xf)
				c->x86 += (tfms >> 20) & 0xff;
			if (c->x86 >= 0x6)
				c->x86_model += ((tfms >> 16) & 0xF) << 4;
			c->x86_mask = tfms & 15;
		} else {
			/* Have CPUID level 0 only - unheard of */
			c->x86 = 4;
		}

		/* AMD-defined flags: level 0x80000001 */
		xlvl = cpuid_eax(0x80000000);
		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 */
		}
	}

	early_intel_workaround(c);

#ifdef CONFIG_X86_HT
	phys_proc_id[smp_processor_id()] = (cpuid_ebx(1) >> 24) & 0xff;
#endif
}

static void __cpuinit squash_the_stupid_serial_number(struct cpuinfo_x86 *c)
{
	if (cpu_has(c, X86_FEATURE_PN) && disable_x86_serial_nr ) {
		/* Disable processor serial number */
		unsigned long lo,hi;
		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_bit(X86_FEATURE_PN, c->x86_capability);

		/* 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);



/*
 * This does the hard work of actually picking apart the CPU stuff...
 */
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->cpuid_level = -1;	/* CPUID not detected */
	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;
	memset(&c->x86_capability, 0, sizeof c->x86_capability);

	if (!have_cpuid_p()) {
		/* 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;
	}

	generic_identify(c);

	printk(KERN_DEBUG "CPU: After generic identify, caps:");
	for (i = 0; i < NCAPINTS; i++)
		printk(" %08lx", c->x86_capability[i]);
	printk("\n");

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

		printk(KERN_DEBUG "CPU: After vendor identify, caps:");
		for (i = 0; i < NCAPINTS; i++)
			printk(" %08lx", c->x86_capability[i]);
		printk("\n");
	}

	/*
	 * 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."
	 */

	/* TSC disabled? */
	if ( tsc_disable )
		clear_bit(X86_FEATURE_TSC, c->x86_capability);

	/* FXSR disabled? */
	if (disable_x86_fxsr) {
		clear_bit(X86_FEATURE_FXSR, c->x86_capability);
		clear_bit(X86_FEATURE_XMM, c->x86_capability);
	}

	/* SEP disabled? */
	if (disable_x86_sep)
		clear_bit(X86_FEATURE_SEP, c->x86_capability);

	if (disable_pse)
		clear_bit(X86_FEATURE_PSE, c->x86_capability);

	/* If the model name is still unset, do table lookup. */
	if ( !c->x86_model_id[0] ) {
		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_vendor, c->x86_model);
	}

	/* Now the feature flags better reflect actual CPU features! */

	printk(KERN_DEBUG "CPU: After all inits, caps:");
	for (i = 0; i < NCAPINTS; i++)
		printk(" %08lx", c->x86_capability[i]);
	printk("\n");

	/*
	 * 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];
	}

	/* Init Machine Check Exception if available. */
	mcheck_init(c);

	if (c == &boot_cpu_data)
		sysenter_setup();
	enable_sep_cpu();

	if (c == &boot_cpu_data)
		mtrr_bp_init();
	else
		mtrr_ap_init();
}

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

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

	c->apicid = phys_pkg_id((ebx >> 24) & 0xFF, 0);

	if (!cpu_has(c, X86_FEATURE_HT) || cpu_has(c, X86_FEATURE_CMP_LEGACY))
		return;

	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 the siblings %d", smp_num_siblings);
			smp_num_siblings = 1;
			return;
		}

		index_msb = get_count_order(smp_num_siblings);
		phys_proc_id[cpu] = phys_pkg_id((ebx >> 24) & 0xFF, index_msb);

		printk(KERN_INFO  "CPU: Physical Processor ID: %d\n",
		       phys_proc_id[cpu]);

		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);

		cpu_core_id[cpu] = phys_pkg_id((ebx >> 24) & 0xFF, index_msb) &
					       ((1 << core_bits) - 1);

		if (c->x86_max_cores > 1)
			printk(KERN_INFO  "CPU: Processor Core ID: %d\n",
			       cpu_core_id[cpu]);
	}
}
#endif

void __cpuinit print_cpu_info(struct cpuinfo_x86 *c)
{
	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 && strncmp(c->x86_model_id, vendor, strlen(vendor)))
		printk("%s ", vendor);

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

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

cpumask_t cpu_initialized __cpuinitdata = CPU_MASK_NONE;

/* This is hacky. :)
 * We're emulating future behavior.
 * In the future, the cpu-specific init functions will be called implicitly
 * via the magic of initcalls.
 * They will insert themselves into the cpu_devs structure.
 * Then, when cpu_init() is called, we can just iterate over that array.
 */

extern int intel_cpu_init(void);
extern int cyrix_init_cpu(void);
extern int nsc_init_cpu(void);
extern int amd_init_cpu(void);
extern int centaur_init_cpu(void);
extern int transmeta_init_cpu(void);
extern int rise_init_cpu(void);
extern int nexgen_init_cpu(void);
extern int umc_init_cpu(void);

void __init early_cpu_init(void)
{
	intel_cpu_init();
	cyrix_init_cpu();
	nsc_init_cpu();
	amd_init_cpu();
	centaur_init_cpu();
	transmeta_init_cpu();
	rise_init_cpu();
	nexgen_init_cpu();
	umc_init_cpu();
	early_cpu_detect();

#ifdef CONFIG_DEBUG_PAGEALLOC
	/* pse is not compatible with on-the-fly unmapping,
	 * disable it even if the cpus claim to support it.
	 */
	clear_bit(X86_FEATURE_PSE, boot_cpu_data.x86_capability);
	disable_pse = 1;
#endif
}
/*
 * 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.
 */
void __cpuinit cpu_init(void)
{
	int cpu = smp_processor_id();
	struct tss_struct * t = &per_cpu(init_tss, cpu);
	struct thread_struct *thread = &current->thread;
	struct desc_struct *gdt;
	__u32 stk16_off = (__u32)&per_cpu(cpu_16bit_stack, cpu);
	struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);

	if (cpu_test_and_set(cpu, cpu_initialized)) {
		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);
	if (tsc_disable && cpu_has_tsc) {
		printk(KERN_NOTICE "Disabling TSC...\n");
		/**** FIX-HPA: DOES THIS REALLY BELONG HERE? ****/
		clear_bit(X86_FEATURE_TSC, boot_cpu_data.x86_capability);
		set_in_cr4(X86_CR4_TSD);
	}

	/*
	 * This is a horrible hack to allocate the GDT.  The problem
	 * is that cpu_init() is called really early for the boot CPU
	 * (and hence needs bootmem) but much later for the secondary
	 * CPUs, when bootmem will have gone away
	 */
	if (NODE_DATA(0)->bdata->node_bootmem_map) {
		gdt = (struct desc_struct *)alloc_bootmem_pages(PAGE_SIZE);
		/* alloc_bootmem_pages panics on failure, so no check */
		memset(gdt, 0, PAGE_SIZE);
	} else {
		gdt = (struct desc_struct *)get_zeroed_page(GFP_KERNEL);
		if (unlikely(!gdt)) {
			printk(KERN_CRIT "CPU%d failed to allocate GDT\n", cpu);
			for (;;)
				local_irq_enable();
		}
	}

	/*
	 * Initialize the per-CPU GDT with the boot GDT,
	 * and set up the GDT descriptor:
	 */
 	memcpy(gdt, cpu_gdt_table, GDT_SIZE);

	/* Set up GDT entry for 16bit stack */
 	*(__u64 *)(&gdt[GDT_ENTRY_ESPFIX_SS]) |=
		((((__u64)stk16_off) << 16) & 0x000000ffffff0000ULL) |
		((((__u64)stk16_off) << 32) & 0xff00000000000000ULL) |
		(CPU_16BIT_STACK_SIZE - 1);

	cpu_gdt_descr->size = GDT_SIZE - 1;
 	cpu_gdt_descr->address = (unsigned long)gdt;

	load_gdt(cpu_gdt_descr);
	load_idt(&idt_descr);

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

	load_esp0(t, thread);
	set_tss_desc(cpu,t);
	load_TR_desc();
	load_LDT(&init_mm.context);

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

	/* Clear %fs and %gs. */
	asm volatile ("xorl %eax, %eax; movl %eax, %fs; movl %eax, %gs");

	/* Clear all 6 debug registers: */
	set_debugreg(0, 0);
	set_debugreg(0, 1);
	set_debugreg(0, 2);
	set_debugreg(0, 3);
	set_debugreg(0, 6);
	set_debugreg(0, 7);

	/*
	 * Force FPU initialization:
	 */
	current_thread_info()->status = 0;
	clear_used_math();
	mxcsr_feature_mask_init();
}

#ifdef CONFIG_HOTPLUG_CPU
void __cpuinit cpu_uninit(void)
{
	int cpu = raw_smp_processor_id();
	cpu_clear(cpu, cpu_initialized);

	/* lazy TLB state */
	per_cpu(cpu_tlbstate, cpu).state = 0;
	per_cpu(cpu_tlbstate, cpu).active_mm = &init_mm;
}
#endif