summaryrefslogtreecommitdiff
path: root/arch/sparc/mm/tsb.c
blob: 0a04811f06b78ceb7851d70b56de63e4d40b6bf4 (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
/* arch/sparc64/mm/tsb.c
 *
 * Copyright (C) 2006, 2008 David S. Miller <davem@davemloft.net>
 */

#include <linux/kernel.h>
#include <linux/preempt.h>
#include <linux/slab.h>
#include <linux/mm_types.h>

#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/mmu_context.h>
#include <asm/setup.h>
#include <asm/tsb.h>
#include <asm/tlb.h>
#include <asm/oplib.h>

extern struct tsb swapper_tsb[KERNEL_TSB_NENTRIES];

static inline unsigned long tsb_hash(unsigned long vaddr, unsigned long hash_shift, unsigned long nentries)
{
	vaddr >>= hash_shift;
	return vaddr & (nentries - 1);
}

static inline int tag_compare(unsigned long tag, unsigned long vaddr)
{
	return (tag == (vaddr >> 22));
}

static void flush_tsb_kernel_range_scan(unsigned long start, unsigned long end)
{
	unsigned long idx;

	for (idx = 0; idx < KERNEL_TSB_NENTRIES; idx++) {
		struct tsb *ent = &swapper_tsb[idx];
		unsigned long match = idx << 13;

		match |= (ent->tag << 22);
		if (match >= start && match < end)
			ent->tag = (1UL << TSB_TAG_INVALID_BIT);
	}
}

/* TSB flushes need only occur on the processor initiating the address
 * space modification, not on each cpu the address space has run on.
 * Only the TLB flush needs that treatment.
 */

void flush_tsb_kernel_range(unsigned long start, unsigned long end)
{
	unsigned long v;

	if ((end - start) >> PAGE_SHIFT >= 2 * KERNEL_TSB_NENTRIES)
		return flush_tsb_kernel_range_scan(start, end);

	for (v = start; v < end; v += PAGE_SIZE) {
		unsigned long hash = tsb_hash(v, PAGE_SHIFT,
					      KERNEL_TSB_NENTRIES);
		struct tsb *ent = &swapper_tsb[hash];

		if (tag_compare(ent->tag, v))
			ent->tag = (1UL << TSB_TAG_INVALID_BIT);
	}
}

static void __flush_tsb_one_entry(unsigned long tsb, unsigned long v,
				  unsigned long hash_shift,
				  unsigned long nentries)
{
	unsigned long tag, ent, hash;

	v &= ~0x1UL;
	hash = tsb_hash(v, hash_shift, nentries);
	ent = tsb + (hash * sizeof(struct tsb));
	tag = (v >> 22UL);

	tsb_flush(ent, tag);
}

static void __flush_tsb_one(struct tlb_batch *tb, unsigned long hash_shift,
			    unsigned long tsb, unsigned long nentries)
{
	unsigned long i;

	for (i = 0; i < tb->tlb_nr; i++)
		__flush_tsb_one_entry(tsb, tb->vaddrs[i], hash_shift, nentries);
}

#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
static void __flush_huge_tsb_one_entry(unsigned long tsb, unsigned long v,
				       unsigned long hash_shift,
				       unsigned long nentries,
				       unsigned int hugepage_shift)
{
	unsigned int hpage_entries;
	unsigned int i;

	hpage_entries = 1 << (hugepage_shift - hash_shift);
	for (i = 0; i < hpage_entries; i++)
		__flush_tsb_one_entry(tsb, v + (i << hash_shift), hash_shift,
				      nentries);
}

static void __flush_huge_tsb_one(struct tlb_batch *tb, unsigned long hash_shift,
				 unsigned long tsb, unsigned long nentries,
				 unsigned int hugepage_shift)
{
	unsigned long i;

	for (i = 0; i < tb->tlb_nr; i++)
		__flush_huge_tsb_one_entry(tsb, tb->vaddrs[i], hash_shift,
					   nentries, hugepage_shift);
}
#endif

void flush_tsb_user(struct tlb_batch *tb)
{
	struct mm_struct *mm = tb->mm;
	unsigned long nentries, base, flags;

	spin_lock_irqsave(&mm->context.lock, flags);

	if (tb->hugepage_shift < HPAGE_SHIFT) {
		base = (unsigned long) mm->context.tsb_block[MM_TSB_BASE].tsb;
		nentries = mm->context.tsb_block[MM_TSB_BASE].tsb_nentries;
		if (tlb_type == cheetah_plus || tlb_type == hypervisor)
			base = __pa(base);
		if (tb->hugepage_shift == PAGE_SHIFT)
			__flush_tsb_one(tb, PAGE_SHIFT, base, nentries);
#if defined(CONFIG_HUGETLB_PAGE)
		else
			__flush_huge_tsb_one(tb, PAGE_SHIFT, base, nentries,
					     tb->hugepage_shift);
#endif
	}
#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
	else if (mm->context.tsb_block[MM_TSB_HUGE].tsb) {
		base = (unsigned long) mm->context.tsb_block[MM_TSB_HUGE].tsb;
		nentries = mm->context.tsb_block[MM_TSB_HUGE].tsb_nentries;
		if (tlb_type == cheetah_plus || tlb_type == hypervisor)
			base = __pa(base);
		__flush_huge_tsb_one(tb, REAL_HPAGE_SHIFT, base, nentries,
				     tb->hugepage_shift);
	}
#endif
	spin_unlock_irqrestore(&mm->context.lock, flags);
}

void flush_tsb_user_page(struct mm_struct *mm, unsigned long vaddr,
			 unsigned int hugepage_shift)
{
	unsigned long nentries, base, flags;

	spin_lock_irqsave(&mm->context.lock, flags);

	if (hugepage_shift < HPAGE_SHIFT) {
		base = (unsigned long) mm->context.tsb_block[MM_TSB_BASE].tsb;
		nentries = mm->context.tsb_block[MM_TSB_BASE].tsb_nentries;
		if (tlb_type == cheetah_plus || tlb_type == hypervisor)
			base = __pa(base);
		if (hugepage_shift == PAGE_SHIFT)
			__flush_tsb_one_entry(base, vaddr, PAGE_SHIFT,
					      nentries);
#if defined(CONFIG_HUGETLB_PAGE)
		else
			__flush_huge_tsb_one_entry(base, vaddr, PAGE_SHIFT,
						   nentries, hugepage_shift);
#endif
	}
#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
	else if (mm->context.tsb_block[MM_TSB_HUGE].tsb) {
		base = (unsigned long) mm->context.tsb_block[MM_TSB_HUGE].tsb;
		nentries = mm->context.tsb_block[MM_TSB_HUGE].tsb_nentries;
		if (tlb_type == cheetah_plus || tlb_type == hypervisor)
			base = __pa(base);
		__flush_huge_tsb_one_entry(base, vaddr, REAL_HPAGE_SHIFT,
					   nentries, hugepage_shift);
	}
#endif
	spin_unlock_irqrestore(&mm->context.lock, flags);
}

#define HV_PGSZ_IDX_BASE	HV_PGSZ_IDX_8K
#define HV_PGSZ_MASK_BASE	HV_PGSZ_MASK_8K

#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
#define HV_PGSZ_IDX_HUGE	HV_PGSZ_IDX_4MB
#define HV_PGSZ_MASK_HUGE	HV_PGSZ_MASK_4MB
#endif

static void setup_tsb_params(struct mm_struct *mm, unsigned long tsb_idx, unsigned long tsb_bytes)
{
	unsigned long tsb_reg, base, tsb_paddr;
	unsigned long page_sz, tte;

	mm->context.tsb_block[tsb_idx].tsb_nentries =
		tsb_bytes / sizeof(struct tsb);

	switch (tsb_idx) {
	case MM_TSB_BASE:
		base = TSBMAP_8K_BASE;
		break;
#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
	case MM_TSB_HUGE:
		base = TSBMAP_4M_BASE;
		break;
#endif
	default:
		BUG();
	}

	tte = pgprot_val(PAGE_KERNEL_LOCKED);
	tsb_paddr = __pa(mm->context.tsb_block[tsb_idx].tsb);
	BUG_ON(tsb_paddr & (tsb_bytes - 1UL));

	/* Use the smallest page size that can map the whole TSB
	 * in one TLB entry.
	 */
	switch (tsb_bytes) {
	case 8192 << 0:
		tsb_reg = 0x0UL;
#ifdef DCACHE_ALIASING_POSSIBLE
		base += (tsb_paddr & 8192);
#endif
		page_sz = 8192;
		break;

	case 8192 << 1:
		tsb_reg = 0x1UL;
		page_sz = 64 * 1024;
		break;

	case 8192 << 2:
		tsb_reg = 0x2UL;
		page_sz = 64 * 1024;
		break;

	case 8192 << 3:
		tsb_reg = 0x3UL;
		page_sz = 64 * 1024;
		break;

	case 8192 << 4:
		tsb_reg = 0x4UL;
		page_sz = 512 * 1024;
		break;

	case 8192 << 5:
		tsb_reg = 0x5UL;
		page_sz = 512 * 1024;
		break;

	case 8192 << 6:
		tsb_reg = 0x6UL;
		page_sz = 512 * 1024;
		break;

	case 8192 << 7:
		tsb_reg = 0x7UL;
		page_sz = 4 * 1024 * 1024;
		break;

	default:
		printk(KERN_ERR "TSB[%s:%d]: Impossible TSB size %lu, killing process.\n",
		       current->comm, current->pid, tsb_bytes);
		do_exit(SIGSEGV);
	}
	tte |= pte_sz_bits(page_sz);

	if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
		/* Physical mapping, no locked TLB entry for TSB.  */
		tsb_reg |= tsb_paddr;

		mm->context.tsb_block[tsb_idx].tsb_reg_val = tsb_reg;
		mm->context.tsb_block[tsb_idx].tsb_map_vaddr = 0;
		mm->context.tsb_block[tsb_idx].tsb_map_pte = 0;
	} else {
		tsb_reg |= base;
		tsb_reg |= (tsb_paddr & (page_sz - 1UL));
		tte |= (tsb_paddr & ~(page_sz - 1UL));

		mm->context.tsb_block[tsb_idx].tsb_reg_val = tsb_reg;
		mm->context.tsb_block[tsb_idx].tsb_map_vaddr = base;
		mm->context.tsb_block[tsb_idx].tsb_map_pte = tte;
	}

	/* Setup the Hypervisor TSB descriptor.  */
	if (tlb_type == hypervisor) {
		struct hv_tsb_descr *hp = &mm->context.tsb_descr[tsb_idx];

		switch (tsb_idx) {
		case MM_TSB_BASE:
			hp->pgsz_idx = HV_PGSZ_IDX_BASE;
			break;
#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
		case MM_TSB_HUGE:
			hp->pgsz_idx = HV_PGSZ_IDX_HUGE;
			break;
#endif
		default:
			BUG();
		}
		hp->assoc = 1;
		hp->num_ttes = tsb_bytes / 16;
		hp->ctx_idx = 0;
		switch (tsb_idx) {
		case MM_TSB_BASE:
			hp->pgsz_mask = HV_PGSZ_MASK_BASE;
			break;
#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
		case MM_TSB_HUGE:
			hp->pgsz_mask = HV_PGSZ_MASK_HUGE;
			break;
#endif
		default:
			BUG();
		}
		hp->tsb_base = tsb_paddr;
		hp->resv = 0;
	}
}

struct kmem_cache *pgtable_cache __read_mostly;

static struct kmem_cache *tsb_caches[8] __read_mostly;

static const char *tsb_cache_names[8] = {
	"tsb_8KB",
	"tsb_16KB",
	"tsb_32KB",
	"tsb_64KB",
	"tsb_128KB",
	"tsb_256KB",
	"tsb_512KB",
	"tsb_1MB",
};

void __init pgtable_cache_init(void)
{
	unsigned long i;

	pgtable_cache = kmem_cache_create("pgtable_cache",
					  PAGE_SIZE, PAGE_SIZE,
					  0,
					  _clear_page);
	if (!pgtable_cache) {
		prom_printf("pgtable_cache_init(): Could not create!\n");
		prom_halt();
	}

	for (i = 0; i < ARRAY_SIZE(tsb_cache_names); i++) {
		unsigned long size = 8192 << i;
		const char *name = tsb_cache_names[i];

		tsb_caches[i] = kmem_cache_create(name,
						  size, size,
						  0, NULL);
		if (!tsb_caches[i]) {
			prom_printf("Could not create %s cache\n", name);
			prom_halt();
		}
	}
}

int sysctl_tsb_ratio = -2;

static unsigned long tsb_size_to_rss_limit(unsigned long new_size)
{
	unsigned long num_ents = (new_size / sizeof(struct tsb));

	if (sysctl_tsb_ratio < 0)
		return num_ents - (num_ents >> -sysctl_tsb_ratio);
	else
		return num_ents + (num_ents >> sysctl_tsb_ratio);
}

/* When the RSS of an address space exceeds tsb_rss_limit for a TSB,
 * do_sparc64_fault() invokes this routine to try and grow it.
 *
 * When we reach the maximum TSB size supported, we stick ~0UL into
 * tsb_rss_limit for that TSB so the grow checks in do_sparc64_fault()
 * will not trigger any longer.
 *
 * The TSB can be anywhere from 8K to 1MB in size, in increasing powers
 * of two.  The TSB must be aligned to it's size, so f.e. a 512K TSB
 * must be 512K aligned.  It also must be physically contiguous, so we
 * cannot use vmalloc().
 *
 * The idea here is to grow the TSB when the RSS of the process approaches
 * the number of entries that the current TSB can hold at once.  Currently,
 * we trigger when the RSS hits 3/4 of the TSB capacity.
 */
void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long rss)
{
	unsigned long max_tsb_size = 1 * 1024 * 1024;
	unsigned long new_size, old_size, flags;
	struct tsb *old_tsb, *new_tsb;
	unsigned long new_cache_index, old_cache_index;
	unsigned long new_rss_limit;
	gfp_t gfp_flags;

	if (max_tsb_size > (PAGE_SIZE << MAX_ORDER))
		max_tsb_size = (PAGE_SIZE << MAX_ORDER);

	new_cache_index = 0;
	for (new_size = 8192; new_size < max_tsb_size; new_size <<= 1UL) {
		new_rss_limit = tsb_size_to_rss_limit(new_size);
		if (new_rss_limit > rss)
			break;
		new_cache_index++;
	}

	if (new_size == max_tsb_size)
		new_rss_limit = ~0UL;

retry_tsb_alloc:
	gfp_flags = GFP_KERNEL;
	if (new_size > (PAGE_SIZE * 2))
		gfp_flags |= __GFP_NOWARN | __GFP_NORETRY;

	new_tsb = kmem_cache_alloc_node(tsb_caches[new_cache_index],
					gfp_flags, numa_node_id());
	if (unlikely(!new_tsb)) {
		/* Not being able to fork due to a high-order TSB
		 * allocation failure is very bad behavior.  Just back
		 * down to a 0-order allocation and force no TSB
		 * growing for this address space.
		 */
		if (mm->context.tsb_block[tsb_index].tsb == NULL &&
		    new_cache_index > 0) {
			new_cache_index = 0;
			new_size = 8192;
			new_rss_limit = ~0UL;
			goto retry_tsb_alloc;
		}

		/* If we failed on a TSB grow, we are under serious
		 * memory pressure so don't try to grow any more.
		 */
		if (mm->context.tsb_block[tsb_index].tsb != NULL)
			mm->context.tsb_block[tsb_index].tsb_rss_limit = ~0UL;
		return;
	}

	/* Mark all tags as invalid.  */
	tsb_init(new_tsb, new_size);

	/* Ok, we are about to commit the changes.  If we are
	 * growing an existing TSB the locking is very tricky,
	 * so WATCH OUT!
	 *
	 * We have to hold mm->context.lock while committing to the
	 * new TSB, this synchronizes us with processors in
	 * flush_tsb_user() and switch_mm() for this address space.
	 *
	 * But even with that lock held, processors run asynchronously
	 * accessing the old TSB via TLB miss handling.  This is OK
	 * because those actions are just propagating state from the
	 * Linux page tables into the TSB, page table mappings are not
	 * being changed.  If a real fault occurs, the processor will
	 * synchronize with us when it hits flush_tsb_user(), this is
	 * also true for the case where vmscan is modifying the page
	 * tables.  The only thing we need to be careful with is to
	 * skip any locked TSB entries during copy_tsb().
	 *
	 * When we finish committing to the new TSB, we have to drop
	 * the lock and ask all other cpus running this address space
	 * to run tsb_context_switch() to see the new TSB table.
	 */
	spin_lock_irqsave(&mm->context.lock, flags);

	old_tsb = mm->context.tsb_block[tsb_index].tsb;
	old_cache_index =
		(mm->context.tsb_block[tsb_index].tsb_reg_val & 0x7UL);
	old_size = (mm->context.tsb_block[tsb_index].tsb_nentries *
		    sizeof(struct tsb));


	/* Handle multiple threads trying to grow the TSB at the same time.
	 * One will get in here first, and bump the size and the RSS limit.
	 * The others will get in here next and hit this check.
	 */
	if (unlikely(old_tsb &&
		     (rss < mm->context.tsb_block[tsb_index].tsb_rss_limit))) {
		spin_unlock_irqrestore(&mm->context.lock, flags);

		kmem_cache_free(tsb_caches[new_cache_index], new_tsb);
		return;
	}

	mm->context.tsb_block[tsb_index].tsb_rss_limit = new_rss_limit;

	if (old_tsb) {
		extern void copy_tsb(unsigned long old_tsb_base,
				     unsigned long old_tsb_size,
				     unsigned long new_tsb_base,
				     unsigned long new_tsb_size);
		unsigned long old_tsb_base = (unsigned long) old_tsb;
		unsigned long new_tsb_base = (unsigned long) new_tsb;

		if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
			old_tsb_base = __pa(old_tsb_base);
			new_tsb_base = __pa(new_tsb_base);
		}
		copy_tsb(old_tsb_base, old_size, new_tsb_base, new_size);
	}

	mm->context.tsb_block[tsb_index].tsb = new_tsb;
	setup_tsb_params(mm, tsb_index, new_size);

	spin_unlock_irqrestore(&mm->context.lock, flags);

	/* If old_tsb is NULL, we're being invoked for the first time
	 * from init_new_context().
	 */
	if (old_tsb) {
		/* Reload it on the local cpu.  */
		tsb_context_switch(mm);

		/* Now force other processors to do the same.  */
		preempt_disable();
		smp_tsb_sync(mm);
		preempt_enable();

		/* Now it is safe to free the old tsb.  */
		kmem_cache_free(tsb_caches[old_cache_index], old_tsb);
	}
}

int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
	unsigned long mm_rss = get_mm_rss(mm);
#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
	unsigned long saved_hugetlb_pte_count;
	unsigned long saved_thp_pte_count;
#endif
	unsigned int i;

	spin_lock_init(&mm->context.lock);

	mm->context.sparc64_ctx_val = 0UL;

#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
	/* We reset them to zero because the fork() page copying
	 * will re-increment the counters as the parent PTEs are
	 * copied into the child address space.
	 */
	saved_hugetlb_pte_count = mm->context.hugetlb_pte_count;
	saved_thp_pte_count = mm->context.thp_pte_count;
	mm->context.hugetlb_pte_count = 0;
	mm->context.thp_pte_count = 0;

	mm_rss -= saved_thp_pte_count * (HPAGE_SIZE / PAGE_SIZE);
#endif

	/* copy_mm() copies over the parent's mm_struct before calling
	 * us, so we need to zero out the TSB pointer or else tsb_grow()
	 * will be confused and think there is an older TSB to free up.
	 */
	for (i = 0; i < MM_NUM_TSBS; i++)
		mm->context.tsb_block[i].tsb = NULL;

	/* If this is fork, inherit the parent's TSB size.  We would
	 * grow it to that size on the first page fault anyways.
	 */
	tsb_grow(mm, MM_TSB_BASE, mm_rss);

#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
	if (unlikely(saved_hugetlb_pte_count + saved_thp_pte_count))
		tsb_grow(mm, MM_TSB_HUGE,
			 (saved_hugetlb_pte_count + saved_thp_pte_count) *
			 REAL_HPAGE_PER_HPAGE);
#endif

	if (unlikely(!mm->context.tsb_block[MM_TSB_BASE].tsb))
		return -ENOMEM;

	return 0;
}

static void tsb_destroy_one(struct tsb_config *tp)
{
	unsigned long cache_index;

	if (!tp->tsb)
		return;
	cache_index = tp->tsb_reg_val & 0x7UL;
	kmem_cache_free(tsb_caches[cache_index], tp->tsb);
	tp->tsb = NULL;
	tp->tsb_reg_val = 0UL;
}

void destroy_context(struct mm_struct *mm)
{
	unsigned long flags, i;

	for (i = 0; i < MM_NUM_TSBS; i++)
		tsb_destroy_one(&mm->context.tsb_block[i]);

	spin_lock_irqsave(&ctx_alloc_lock, flags);

	if (CTX_VALID(mm->context)) {
		unsigned long nr = CTX_NRBITS(mm->context);
		mmu_context_bmap[nr>>6] &= ~(1UL << (nr & 63));
	}

	spin_unlock_irqrestore(&ctx_alloc_lock, flags);
}