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1da177e4 LT |
1 | /* |
2 | * IA-32 Huge TLB Page Support for Kernel. | |
3 | * | |
4 | * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com> | |
5 | */ | |
6 | ||
1da177e4 LT |
7 | #include <linux/init.h> |
8 | #include <linux/fs.h> | |
9 | #include <linux/mm.h> | |
10 | #include <linux/hugetlb.h> | |
11 | #include <linux/pagemap.h> | |
12 | #include <linux/smp_lock.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/err.h> | |
15 | #include <linux/sysctl.h> | |
16 | #include <asm/mman.h> | |
17 | #include <asm/tlb.h> | |
18 | #include <asm/tlbflush.h> | |
19 | ||
39dde65c KC |
20 | static unsigned long page_table_shareable(struct vm_area_struct *svma, |
21 | struct vm_area_struct *vma, | |
22 | unsigned long addr, pgoff_t idx) | |
23 | { | |
24 | unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) + | |
25 | svma->vm_start; | |
26 | unsigned long sbase = saddr & PUD_MASK; | |
27 | unsigned long s_end = sbase + PUD_SIZE; | |
28 | ||
29 | /* | |
30 | * match the virtual addresses, permission and the alignment of the | |
31 | * page table page. | |
32 | */ | |
33 | if (pmd_index(addr) != pmd_index(saddr) || | |
34 | vma->vm_flags != svma->vm_flags || | |
35 | sbase < svma->vm_start || svma->vm_end < s_end) | |
36 | return 0; | |
37 | ||
38 | return saddr; | |
39 | } | |
40 | ||
41 | static int vma_shareable(struct vm_area_struct *vma, unsigned long addr) | |
42 | { | |
43 | unsigned long base = addr & PUD_MASK; | |
44 | unsigned long end = base + PUD_SIZE; | |
45 | ||
46 | /* | |
47 | * check on proper vm_flags and page table alignment | |
48 | */ | |
49 | if (vma->vm_flags & VM_MAYSHARE && | |
50 | vma->vm_start <= base && end <= vma->vm_end) | |
51 | return 1; | |
52 | return 0; | |
53 | } | |
54 | ||
55 | /* | |
56 | * search for a shareable pmd page for hugetlb. | |
57 | */ | |
58 | static void huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud) | |
59 | { | |
60 | struct vm_area_struct *vma = find_vma(mm, addr); | |
61 | struct address_space *mapping = vma->vm_file->f_mapping; | |
62 | pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + | |
63 | vma->vm_pgoff; | |
64 | struct prio_tree_iter iter; | |
65 | struct vm_area_struct *svma; | |
66 | unsigned long saddr; | |
67 | pte_t *spte = NULL; | |
68 | ||
69 | if (!vma_shareable(vma, addr)) | |
70 | return; | |
71 | ||
72 | spin_lock(&mapping->i_mmap_lock); | |
73 | vma_prio_tree_foreach(svma, &iter, &mapping->i_mmap, idx, idx) { | |
74 | if (svma == vma) | |
75 | continue; | |
76 | ||
77 | saddr = page_table_shareable(svma, vma, addr, idx); | |
78 | if (saddr) { | |
79 | spte = huge_pte_offset(svma->vm_mm, saddr); | |
80 | if (spte) { | |
81 | get_page(virt_to_page(spte)); | |
82 | break; | |
83 | } | |
84 | } | |
85 | } | |
86 | ||
87 | if (!spte) | |
88 | goto out; | |
89 | ||
90 | spin_lock(&mm->page_table_lock); | |
91 | if (pud_none(*pud)) | |
92 | pud_populate(mm, pud, (unsigned long) spte & PAGE_MASK); | |
93 | else | |
94 | put_page(virt_to_page(spte)); | |
95 | spin_unlock(&mm->page_table_lock); | |
96 | out: | |
97 | spin_unlock(&mapping->i_mmap_lock); | |
98 | } | |
99 | ||
100 | /* | |
101 | * unmap huge page backed by shared pte. | |
102 | * | |
103 | * Hugetlb pte page is ref counted at the time of mapping. If pte is shared | |
104 | * indicated by page_count > 1, unmap is achieved by clearing pud and | |
105 | * decrementing the ref count. If count == 1, the pte page is not shared. | |
106 | * | |
107 | * called with vma->vm_mm->page_table_lock held. | |
108 | * | |
109 | * returns: 1 successfully unmapped a shared pte page | |
110 | * 0 the underlying pte page is not shared, or it is the last user | |
111 | */ | |
112 | int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep) | |
113 | { | |
114 | pgd_t *pgd = pgd_offset(mm, *addr); | |
115 | pud_t *pud = pud_offset(pgd, *addr); | |
116 | ||
117 | BUG_ON(page_count(virt_to_page(ptep)) == 0); | |
118 | if (page_count(virt_to_page(ptep)) == 1) | |
119 | return 0; | |
120 | ||
121 | pud_clear(pud); | |
122 | put_page(virt_to_page(ptep)); | |
123 | *addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE; | |
124 | return 1; | |
125 | } | |
126 | ||
63551ae0 | 127 | pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr) |
1da177e4 LT |
128 | { |
129 | pgd_t *pgd; | |
130 | pud_t *pud; | |
7bf07f3d | 131 | pte_t *pte = NULL; |
1da177e4 LT |
132 | |
133 | pgd = pgd_offset(mm, addr); | |
134 | pud = pud_alloc(mm, pgd, addr); | |
39dde65c KC |
135 | if (pud) { |
136 | if (pud_none(*pud)) | |
137 | huge_pmd_share(mm, addr, pud); | |
0e5c9f39 | 138 | pte = (pte_t *) pmd_alloc(mm, pud, addr); |
39dde65c | 139 | } |
0e5c9f39 | 140 | BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte)); |
7bf07f3d | 141 | |
7bf07f3d | 142 | return pte; |
1da177e4 LT |
143 | } |
144 | ||
63551ae0 | 145 | pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr) |
1da177e4 LT |
146 | { |
147 | pgd_t *pgd; | |
148 | pud_t *pud; | |
149 | pmd_t *pmd = NULL; | |
150 | ||
151 | pgd = pgd_offset(mm, addr); | |
02b0ccef AL |
152 | if (pgd_present(*pgd)) { |
153 | pud = pud_offset(pgd, addr); | |
154 | if (pud_present(*pud)) | |
155 | pmd = pmd_offset(pud, addr); | |
156 | } | |
1da177e4 LT |
157 | return (pte_t *) pmd; |
158 | } | |
159 | ||
1da177e4 LT |
160 | #if 0 /* This is just for testing */ |
161 | struct page * | |
162 | follow_huge_addr(struct mm_struct *mm, unsigned long address, int write) | |
163 | { | |
164 | unsigned long start = address; | |
165 | int length = 1; | |
166 | int nr; | |
167 | struct page *page; | |
168 | struct vm_area_struct *vma; | |
169 | ||
170 | vma = find_vma(mm, addr); | |
171 | if (!vma || !is_vm_hugetlb_page(vma)) | |
172 | return ERR_PTR(-EINVAL); | |
173 | ||
174 | pte = huge_pte_offset(mm, address); | |
175 | ||
176 | /* hugetlb should be locked, and hence, prefaulted */ | |
177 | WARN_ON(!pte || pte_none(*pte)); | |
178 | ||
179 | page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)]; | |
180 | ||
181 | WARN_ON(!PageCompound(page)); | |
182 | ||
183 | return page; | |
184 | } | |
185 | ||
186 | int pmd_huge(pmd_t pmd) | |
187 | { | |
188 | return 0; | |
189 | } | |
190 | ||
191 | struct page * | |
192 | follow_huge_pmd(struct mm_struct *mm, unsigned long address, | |
193 | pmd_t *pmd, int write) | |
194 | { | |
195 | return NULL; | |
196 | } | |
197 | ||
198 | #else | |
199 | ||
200 | struct page * | |
201 | follow_huge_addr(struct mm_struct *mm, unsigned long address, int write) | |
202 | { | |
203 | return ERR_PTR(-EINVAL); | |
204 | } | |
205 | ||
206 | int pmd_huge(pmd_t pmd) | |
207 | { | |
208 | return !!(pmd_val(pmd) & _PAGE_PSE); | |
209 | } | |
210 | ||
211 | struct page * | |
212 | follow_huge_pmd(struct mm_struct *mm, unsigned long address, | |
213 | pmd_t *pmd, int write) | |
214 | { | |
215 | struct page *page; | |
216 | ||
217 | page = pte_page(*(pte_t *)pmd); | |
218 | if (page) | |
219 | page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT); | |
220 | return page; | |
221 | } | |
222 | #endif | |
223 | ||
1da177e4 LT |
224 | /* x86_64 also uses this file */ |
225 | ||
226 | #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA | |
227 | static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file, | |
228 | unsigned long addr, unsigned long len, | |
229 | unsigned long pgoff, unsigned long flags) | |
230 | { | |
231 | struct mm_struct *mm = current->mm; | |
232 | struct vm_area_struct *vma; | |
233 | unsigned long start_addr; | |
234 | ||
1363c3cd WW |
235 | if (len > mm->cached_hole_size) { |
236 | start_addr = mm->free_area_cache; | |
237 | } else { | |
238 | start_addr = TASK_UNMAPPED_BASE; | |
239 | mm->cached_hole_size = 0; | |
240 | } | |
1da177e4 LT |
241 | |
242 | full_search: | |
243 | addr = ALIGN(start_addr, HPAGE_SIZE); | |
244 | ||
245 | for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { | |
246 | /* At this point: (!vma || addr < vma->vm_end). */ | |
247 | if (TASK_SIZE - len < addr) { | |
248 | /* | |
249 | * Start a new search - just in case we missed | |
250 | * some holes. | |
251 | */ | |
252 | if (start_addr != TASK_UNMAPPED_BASE) { | |
253 | start_addr = TASK_UNMAPPED_BASE; | |
1363c3cd | 254 | mm->cached_hole_size = 0; |
1da177e4 LT |
255 | goto full_search; |
256 | } | |
257 | return -ENOMEM; | |
258 | } | |
259 | if (!vma || addr + len <= vma->vm_start) { | |
260 | mm->free_area_cache = addr + len; | |
261 | return addr; | |
262 | } | |
1363c3cd WW |
263 | if (addr + mm->cached_hole_size < vma->vm_start) |
264 | mm->cached_hole_size = vma->vm_start - addr; | |
1da177e4 LT |
265 | addr = ALIGN(vma->vm_end, HPAGE_SIZE); |
266 | } | |
267 | } | |
268 | ||
269 | static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file, | |
270 | unsigned long addr0, unsigned long len, | |
271 | unsigned long pgoff, unsigned long flags) | |
272 | { | |
273 | struct mm_struct *mm = current->mm; | |
274 | struct vm_area_struct *vma, *prev_vma; | |
275 | unsigned long base = mm->mmap_base, addr = addr0; | |
1363c3cd | 276 | unsigned long largest_hole = mm->cached_hole_size; |
1da177e4 LT |
277 | int first_time = 1; |
278 | ||
279 | /* don't allow allocations above current base */ | |
280 | if (mm->free_area_cache > base) | |
281 | mm->free_area_cache = base; | |
282 | ||
1363c3cd WW |
283 | if (len <= largest_hole) { |
284 | largest_hole = 0; | |
285 | mm->free_area_cache = base; | |
286 | } | |
1da177e4 LT |
287 | try_again: |
288 | /* make sure it can fit in the remaining address space */ | |
289 | if (mm->free_area_cache < len) | |
290 | goto fail; | |
291 | ||
292 | /* either no address requested or cant fit in requested address hole */ | |
293 | addr = (mm->free_area_cache - len) & HPAGE_MASK; | |
294 | do { | |
295 | /* | |
296 | * Lookup failure means no vma is above this address, | |
297 | * i.e. return with success: | |
298 | */ | |
299 | if (!(vma = find_vma_prev(mm, addr, &prev_vma))) | |
300 | return addr; | |
301 | ||
302 | /* | |
303 | * new region fits between prev_vma->vm_end and | |
304 | * vma->vm_start, use it: | |
305 | */ | |
306 | if (addr + len <= vma->vm_start && | |
1363c3cd | 307 | (!prev_vma || (addr >= prev_vma->vm_end))) { |
1da177e4 | 308 | /* remember the address as a hint for next time */ |
1363c3cd WW |
309 | mm->cached_hole_size = largest_hole; |
310 | return (mm->free_area_cache = addr); | |
311 | } else { | |
1da177e4 | 312 | /* pull free_area_cache down to the first hole */ |
1363c3cd | 313 | if (mm->free_area_cache == vma->vm_end) { |
1da177e4 | 314 | mm->free_area_cache = vma->vm_start; |
1363c3cd WW |
315 | mm->cached_hole_size = largest_hole; |
316 | } | |
317 | } | |
318 | ||
319 | /* remember the largest hole we saw so far */ | |
320 | if (addr + largest_hole < vma->vm_start) | |
321 | largest_hole = vma->vm_start - addr; | |
1da177e4 LT |
322 | |
323 | /* try just below the current vma->vm_start */ | |
324 | addr = (vma->vm_start - len) & HPAGE_MASK; | |
325 | } while (len <= vma->vm_start); | |
326 | ||
327 | fail: | |
328 | /* | |
329 | * if hint left us with no space for the requested | |
330 | * mapping then try again: | |
331 | */ | |
332 | if (first_time) { | |
333 | mm->free_area_cache = base; | |
1363c3cd | 334 | largest_hole = 0; |
1da177e4 LT |
335 | first_time = 0; |
336 | goto try_again; | |
337 | } | |
338 | /* | |
339 | * A failed mmap() very likely causes application failure, | |
340 | * so fall back to the bottom-up function here. This scenario | |
341 | * can happen with large stack limits and large mmap() | |
342 | * allocations. | |
343 | */ | |
344 | mm->free_area_cache = TASK_UNMAPPED_BASE; | |
1363c3cd | 345 | mm->cached_hole_size = ~0UL; |
1da177e4 LT |
346 | addr = hugetlb_get_unmapped_area_bottomup(file, addr0, |
347 | len, pgoff, flags); | |
348 | ||
349 | /* | |
350 | * Restore the topdown base: | |
351 | */ | |
352 | mm->free_area_cache = base; | |
1363c3cd | 353 | mm->cached_hole_size = ~0UL; |
1da177e4 LT |
354 | |
355 | return addr; | |
356 | } | |
357 | ||
358 | unsigned long | |
359 | hugetlb_get_unmapped_area(struct file *file, unsigned long addr, | |
360 | unsigned long len, unsigned long pgoff, unsigned long flags) | |
361 | { | |
362 | struct mm_struct *mm = current->mm; | |
363 | struct vm_area_struct *vma; | |
364 | ||
365 | if (len & ~HPAGE_MASK) | |
366 | return -EINVAL; | |
367 | if (len > TASK_SIZE) | |
368 | return -ENOMEM; | |
369 | ||
370 | if (addr) { | |
371 | addr = ALIGN(addr, HPAGE_SIZE); | |
372 | vma = find_vma(mm, addr); | |
373 | if (TASK_SIZE - len >= addr && | |
374 | (!vma || addr + len <= vma->vm_start)) | |
375 | return addr; | |
376 | } | |
377 | if (mm->get_unmapped_area == arch_get_unmapped_area) | |
378 | return hugetlb_get_unmapped_area_bottomup(file, addr, len, | |
379 | pgoff, flags); | |
380 | else | |
381 | return hugetlb_get_unmapped_area_topdown(file, addr, len, | |
382 | pgoff, flags); | |
383 | } | |
384 | ||
385 | #endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/ | |
386 |