hugetlbpage.c 9.59 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
/*
 * IA-32 Huge TLB Page Support for Kernel.
 *
 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
 */

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/sysctl.h>
#include <asm/mman.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
18
#include <asm/pgalloc.h>
Linus Torvalds's avatar
Linus Torvalds committed
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
static unsigned long page_table_shareable(struct vm_area_struct *svma,
				struct vm_area_struct *vma,
				unsigned long addr, pgoff_t idx)
{
	unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
				svma->vm_start;
	unsigned long sbase = saddr & PUD_MASK;
	unsigned long s_end = sbase + PUD_SIZE;

	/*
	 * match the virtual addresses, permission and the alignment of the
	 * page table page.
	 */
	if (pmd_index(addr) != pmd_index(saddr) ||
	    vma->vm_flags != svma->vm_flags ||
	    sbase < svma->vm_start || svma->vm_end < s_end)
		return 0;

	return saddr;
}

static int vma_shareable(struct vm_area_struct *vma, unsigned long addr)
{
	unsigned long base = addr & PUD_MASK;
	unsigned long end = base + PUD_SIZE;

	/*
	 * check on proper vm_flags and page table alignment
	 */
	if (vma->vm_flags & VM_MAYSHARE &&
	    vma->vm_start <= base && end <= vma->vm_end)
		return 1;
	return 0;
}

/*
 * search for a shareable pmd page for hugetlb.
 */
static void huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
{
	struct vm_area_struct *vma = find_vma(mm, addr);
	struct address_space *mapping = vma->vm_file->f_mapping;
	pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
			vma->vm_pgoff;
	struct prio_tree_iter iter;
	struct vm_area_struct *svma;
	unsigned long saddr;
	pte_t *spte = NULL;

	if (!vma_shareable(vma, addr))
		return;

	spin_lock(&mapping->i_mmap_lock);
	vma_prio_tree_foreach(svma, &iter, &mapping->i_mmap, idx, idx) {
		if (svma == vma)
			continue;

		saddr = page_table_shareable(svma, vma, addr, idx);
		if (saddr) {
			spte = huge_pte_offset(svma->vm_mm, saddr);
			if (spte) {
				get_page(virt_to_page(spte));
				break;
			}
		}
	}

	if (!spte)
		goto out;

	spin_lock(&mm->page_table_lock);
	if (pud_none(*pud))
92
		pud_populate(mm, pud, (pmd_t *)((unsigned long)spte & PAGE_MASK));
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
	else
		put_page(virt_to_page(spte));
	spin_unlock(&mm->page_table_lock);
out:
	spin_unlock(&mapping->i_mmap_lock);
}

/*
 * unmap huge page backed by shared pte.
 *
 * Hugetlb pte page is ref counted at the time of mapping.  If pte is shared
 * indicated by page_count > 1, unmap is achieved by clearing pud and
 * decrementing the ref count. If count == 1, the pte page is not shared.
 *
 * called with vma->vm_mm->page_table_lock held.
 *
 * returns: 1 successfully unmapped a shared pte page
 *	    0 the underlying pte page is not shared, or it is the last user
 */
int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
{
	pgd_t *pgd = pgd_offset(mm, *addr);
	pud_t *pud = pud_offset(pgd, *addr);

	BUG_ON(page_count(virt_to_page(ptep)) == 0);
	if (page_count(virt_to_page(ptep)) == 1)
		return 0;

	pud_clear(pud);
	put_page(virt_to_page(ptep));
	*addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
	return 1;
}

127
128
pte_t *huge_pte_alloc(struct mm_struct *mm,
			unsigned long addr, unsigned long sz)
Linus Torvalds's avatar
Linus Torvalds committed
129
130
131
{
	pgd_t *pgd;
	pud_t *pud;
132
	pte_t *pte = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
133
134
135

	pgd = pgd_offset(mm, addr);
	pud = pud_alloc(mm, pgd, addr);
136
137
138
	if (pud) {
		if (pud_none(*pud))
			huge_pmd_share(mm, addr, pud);
139
		pte = (pte_t *) pmd_alloc(mm, pud, addr);
140
	}
141
	BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));
142
143

	return pte;
Linus Torvalds's avatar
Linus Torvalds committed
144
145
}

David Gibson's avatar
David Gibson committed
146
pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
Linus Torvalds's avatar
Linus Torvalds committed
147
148
149
150
151
152
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd = NULL;

	pgd = pgd_offset(mm, addr);
153
154
155
156
157
	if (pgd_present(*pgd)) {
		pud = pud_offset(pgd, addr);
		if (pud_present(*pud))
			pmd = pmd_offset(pud, addr);
	}
Linus Torvalds's avatar
Linus Torvalds committed
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
	return (pte_t *) pmd;
}

#if 0	/* This is just for testing */
struct page *
follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
{
	unsigned long start = address;
	int length = 1;
	int nr;
	struct page *page;
	struct vm_area_struct *vma;

	vma = find_vma(mm, addr);
	if (!vma || !is_vm_hugetlb_page(vma))
		return ERR_PTR(-EINVAL);

	pte = huge_pte_offset(mm, address);

	/* hugetlb should be locked, and hence, prefaulted */
	WARN_ON(!pte || pte_none(*pte));

	page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];

182
	WARN_ON(!PageHead(page));
Linus Torvalds's avatar
Linus Torvalds committed
183
184
185
186
187
188
189
190
191

	return page;
}

int pmd_huge(pmd_t pmd)
{
	return 0;
}

Andi Kleen's avatar
Andi Kleen committed
192
193
194
195
196
int pud_huge(pud_t pud)
{
	return 0;
}

Linus Torvalds's avatar
Linus Torvalds committed
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
struct page *
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
		pmd_t *pmd, int write)
{
	return NULL;
}

#else

struct page *
follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
{
	return ERR_PTR(-EINVAL);
}

int pmd_huge(pmd_t pmd)
{
	return !!(pmd_val(pmd) & _PAGE_PSE);
}

Andi Kleen's avatar
Andi Kleen committed
217
218
219
220
221
int pud_huge(pud_t pud)
{
	return 0;
}

Linus Torvalds's avatar
Linus Torvalds committed
222
223
224
225
226
227
228
229
struct page *
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
		pmd_t *pmd, int write)
{
	struct page *page;

	page = pte_page(*(pte_t *)pmd);
	if (page)
Andi Kleen's avatar
Andi Kleen committed
230
		page += ((address & ~PMD_MASK) >> PAGE_SHIFT);
Linus Torvalds's avatar
Linus Torvalds committed
231
232
	return page;
}
Andi Kleen's avatar
Andi Kleen committed
233
234
235
236
237
238
239
240
241
242
243
244
245

struct page *
follow_huge_pud(struct mm_struct *mm, unsigned long address,
		pud_t *pud, int write)
{
	struct page *page;

	page = pte_page(*(pte_t *)pud);
	if (page)
		page += ((address & ~PUD_MASK) >> PAGE_SHIFT);
	return page;
}

Linus Torvalds's avatar
Linus Torvalds committed
246
247
248
249
250
251
252
253
254
255
256
257
258
#endif

/* x86_64 also uses this file */

#ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
		unsigned long addr, unsigned long len,
		unsigned long pgoff, unsigned long flags)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	unsigned long start_addr;

259
260
261
262
263
264
	if (len > mm->cached_hole_size) {
	        start_addr = mm->free_area_cache;
	} else {
	        start_addr = TASK_UNMAPPED_BASE;
	        mm->cached_hole_size = 0;
	}
Linus Torvalds's avatar
Linus Torvalds committed
265
266
267
268
269
270
271
272
273
274
275
276
277

full_search:
	addr = ALIGN(start_addr, HPAGE_SIZE);

	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
		/* At this point:  (!vma || addr < vma->vm_end). */
		if (TASK_SIZE - len < addr) {
			/*
			 * Start a new search - just in case we missed
			 * some holes.
			 */
			if (start_addr != TASK_UNMAPPED_BASE) {
				start_addr = TASK_UNMAPPED_BASE;
278
				mm->cached_hole_size = 0;
Linus Torvalds's avatar
Linus Torvalds committed
279
280
281
282
283
284
285
286
				goto full_search;
			}
			return -ENOMEM;
		}
		if (!vma || addr + len <= vma->vm_start) {
			mm->free_area_cache = addr + len;
			return addr;
		}
287
288
		if (addr + mm->cached_hole_size < vma->vm_start)
		        mm->cached_hole_size = vma->vm_start - addr;
Linus Torvalds's avatar
Linus Torvalds committed
289
290
291
292
293
294
295
296
297
298
299
		addr = ALIGN(vma->vm_end, HPAGE_SIZE);
	}
}

static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
		unsigned long addr0, unsigned long len,
		unsigned long pgoff, unsigned long flags)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma, *prev_vma;
	unsigned long base = mm->mmap_base, addr = addr0;
300
	unsigned long largest_hole = mm->cached_hole_size;
Linus Torvalds's avatar
Linus Torvalds committed
301
302
303
304
305
306
	int first_time = 1;

	/* don't allow allocations above current base */
	if (mm->free_area_cache > base)
		mm->free_area_cache = base;

307
308
309
310
	if (len <= largest_hole) {
	        largest_hole = 0;
		mm->free_area_cache  = base;
	}
Linus Torvalds's avatar
Linus Torvalds committed
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
try_again:
	/* make sure it can fit in the remaining address space */
	if (mm->free_area_cache < len)
		goto fail;

	/* either no address requested or cant fit in requested address hole */
	addr = (mm->free_area_cache - len) & HPAGE_MASK;
	do {
		/*
		 * Lookup failure means no vma is above this address,
		 * i.e. return with success:
		 */
		if (!(vma = find_vma_prev(mm, addr, &prev_vma)))
			return addr;

		/*
		 * new region fits between prev_vma->vm_end and
		 * vma->vm_start, use it:
		 */
		if (addr + len <= vma->vm_start &&
331
		            (!prev_vma || (addr >= prev_vma->vm_end))) {
Linus Torvalds's avatar
Linus Torvalds committed
332
			/* remember the address as a hint for next time */
333
334
335
		        mm->cached_hole_size = largest_hole;
		        return (mm->free_area_cache = addr);
		} else {
Linus Torvalds's avatar
Linus Torvalds committed
336
			/* pull free_area_cache down to the first hole */
337
		        if (mm->free_area_cache == vma->vm_end) {
Linus Torvalds's avatar
Linus Torvalds committed
338
				mm->free_area_cache = vma->vm_start;
339
340
341
342
343
344
345
				mm->cached_hole_size = largest_hole;
			}
		}

		/* remember the largest hole we saw so far */
		if (addr + largest_hole < vma->vm_start)
		        largest_hole = vma->vm_start - addr;
Linus Torvalds's avatar
Linus Torvalds committed
346
347
348
349
350
351
352
353
354
355
356
357

		/* try just below the current vma->vm_start */
		addr = (vma->vm_start - len) & HPAGE_MASK;
	} while (len <= vma->vm_start);

fail:
	/*
	 * if hint left us with no space for the requested
	 * mapping then try again:
	 */
	if (first_time) {
		mm->free_area_cache = base;
358
		largest_hole = 0;
Linus Torvalds's avatar
Linus Torvalds committed
359
360
361
362
363
364
365
366
367
368
		first_time = 0;
		goto try_again;
	}
	/*
	 * A failed mmap() very likely causes application failure,
	 * so fall back to the bottom-up function here. This scenario
	 * can happen with large stack limits and large mmap()
	 * allocations.
	 */
	mm->free_area_cache = TASK_UNMAPPED_BASE;
369
	mm->cached_hole_size = ~0UL;
Linus Torvalds's avatar
Linus Torvalds committed
370
371
372
373
374
375
376
	addr = hugetlb_get_unmapped_area_bottomup(file, addr0,
			len, pgoff, flags);

	/*
	 * Restore the topdown base:
	 */
	mm->free_area_cache = base;
377
	mm->cached_hole_size = ~0UL;
Linus Torvalds's avatar
Linus Torvalds committed
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393

	return addr;
}

unsigned long
hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
		unsigned long len, unsigned long pgoff, unsigned long flags)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;

	if (len & ~HPAGE_MASK)
		return -EINVAL;
	if (len > TASK_SIZE)
		return -ENOMEM;

394
	if (flags & MAP_FIXED) {
395
		if (prepare_hugepage_range(file, addr, len))
396
397
398
399
			return -EINVAL;
		return addr;
	}

Linus Torvalds's avatar
Linus Torvalds committed
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
	if (addr) {
		addr = ALIGN(addr, HPAGE_SIZE);
		vma = find_vma(mm, addr);
		if (TASK_SIZE - len >= addr &&
		    (!vma || addr + len <= vma->vm_start))
			return addr;
	}
	if (mm->get_unmapped_area == arch_get_unmapped_area)
		return hugetlb_get_unmapped_area_bottomup(file, addr, len,
				pgoff, flags);
	else
		return hugetlb_get_unmapped_area_topdown(file, addr, len,
				pgoff, flags);
}

#endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/