aboutsummaryrefslogtreecommitdiffstats
path: root/arch/x86/mm/hugetlbpage.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/mm/hugetlbpage.c')
-rw-r--r--arch/x86/mm/hugetlbpage.c391
1 files changed, 391 insertions, 0 deletions
diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
new file mode 100644
index 000000000000..6c06d9c0488e
--- /dev/null
+++ b/arch/x86/mm/hugetlbpage.c
@@ -0,0 +1,391 @@
1/*
2 * IA-32 Huge TLB Page Support for Kernel.
3 *
4 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
5 */
6
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/slab.h>
13#include <linux/err.h>
14#include <linux/sysctl.h>
15#include <asm/mman.h>
16#include <asm/tlb.h>
17#include <asm/tlbflush.h>
18
19static unsigned long page_table_shareable(struct vm_area_struct *svma,
20 struct vm_area_struct *vma,
21 unsigned long addr, pgoff_t idx)
22{
23 unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
24 svma->vm_start;
25 unsigned long sbase = saddr & PUD_MASK;
26 unsigned long s_end = sbase + PUD_SIZE;
27
28 /*
29 * match the virtual addresses, permission and the alignment of the
30 * page table page.
31 */
32 if (pmd_index(addr) != pmd_index(saddr) ||
33 vma->vm_flags != svma->vm_flags ||
34 sbase < svma->vm_start || svma->vm_end < s_end)
35 return 0;
36
37 return saddr;
38}
39
40static int vma_shareable(struct vm_area_struct *vma, unsigned long addr)
41{
42 unsigned long base = addr & PUD_MASK;
43 unsigned long end = base + PUD_SIZE;
44
45 /*
46 * check on proper vm_flags and page table alignment
47 */
48 if (vma->vm_flags & VM_MAYSHARE &&
49 vma->vm_start <= base && end <= vma->vm_end)
50 return 1;
51 return 0;
52}
53
54/*
55 * search for a shareable pmd page for hugetlb.
56 */
57static void huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
58{
59 struct vm_area_struct *vma = find_vma(mm, addr);
60 struct address_space *mapping = vma->vm_file->f_mapping;
61 pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
62 vma->vm_pgoff;
63 struct prio_tree_iter iter;
64 struct vm_area_struct *svma;
65 unsigned long saddr;
66 pte_t *spte = NULL;
67
68 if (!vma_shareable(vma, addr))
69 return;
70
71 spin_lock(&mapping->i_mmap_lock);
72 vma_prio_tree_foreach(svma, &iter, &mapping->i_mmap, idx, idx) {
73 if (svma == vma)
74 continue;
75
76 saddr = page_table_shareable(svma, vma, addr, idx);
77 if (saddr) {
78 spte = huge_pte_offset(svma->vm_mm, saddr);
79 if (spte) {
80 get_page(virt_to_page(spte));
81 break;
82 }
83 }
84 }
85
86 if (!spte)
87 goto out;
88
89 spin_lock(&mm->page_table_lock);
90 if (pud_none(*pud))
91 pud_populate(mm, pud, (unsigned long) spte & PAGE_MASK);
92 else
93 put_page(virt_to_page(spte));
94 spin_unlock(&mm->page_table_lock);
95out:
96 spin_unlock(&mapping->i_mmap_lock);
97}
98
99/*
100 * unmap huge page backed by shared pte.
101 *
102 * Hugetlb pte page is ref counted at the time of mapping. If pte is shared
103 * indicated by page_count > 1, unmap is achieved by clearing pud and
104 * decrementing the ref count. If count == 1, the pte page is not shared.
105 *
106 * called with vma->vm_mm->page_table_lock held.
107 *
108 * returns: 1 successfully unmapped a shared pte page
109 * 0 the underlying pte page is not shared, or it is the last user
110 */
111int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
112{
113 pgd_t *pgd = pgd_offset(mm, *addr);
114 pud_t *pud = pud_offset(pgd, *addr);
115
116 BUG_ON(page_count(virt_to_page(ptep)) == 0);
117 if (page_count(virt_to_page(ptep)) == 1)
118 return 0;
119
120 pud_clear(pud);
121 put_page(virt_to_page(ptep));
122 *addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
123 return 1;
124}
125
126pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr)
127{
128 pgd_t *pgd;
129 pud_t *pud;
130 pte_t *pte = NULL;
131
132 pgd = pgd_offset(mm, addr);
133 pud = pud_alloc(mm, pgd, addr);
134 if (pud) {
135 if (pud_none(*pud))
136 huge_pmd_share(mm, addr, pud);
137 pte = (pte_t *) pmd_alloc(mm, pud, addr);
138 }
139 BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));
140
141 return pte;
142}
143
144pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
145{
146 pgd_t *pgd;
147 pud_t *pud;
148 pmd_t *pmd = NULL;
149
150 pgd = pgd_offset(mm, addr);
151 if (pgd_present(*pgd)) {
152 pud = pud_offset(pgd, addr);
153 if (pud_present(*pud))
154 pmd = pmd_offset(pud, addr);
155 }
156 return (pte_t *) pmd;
157}
158
159#if 0 /* This is just for testing */
160struct page *
161follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
162{
163 unsigned long start = address;
164 int length = 1;
165 int nr;
166 struct page *page;
167 struct vm_area_struct *vma;
168
169 vma = find_vma(mm, addr);
170 if (!vma || !is_vm_hugetlb_page(vma))
171 return ERR_PTR(-EINVAL);
172
173 pte = huge_pte_offset(mm, address);
174
175 /* hugetlb should be locked, and hence, prefaulted */
176 WARN_ON(!pte || pte_none(*pte));
177
178 page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
179
180 WARN_ON(!PageCompound(page));
181
182 return page;
183}
184
185int pmd_huge(pmd_t pmd)
186{
187 return 0;
188}
189
190struct page *
191follow_huge_pmd(struct mm_struct *mm, unsigned long address,
192 pmd_t *pmd, int write)
193{
194 return NULL;
195}
196
197#else
198
199struct page *
200follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
201{
202 return ERR_PTR(-EINVAL);
203}
204
205int pmd_huge(pmd_t pmd)
206{
207 return !!(pmd_val(pmd) & _PAGE_PSE);
208}
209
210struct page *
211follow_huge_pmd(struct mm_struct *mm, unsigned long address,
212 pmd_t *pmd, int write)
213{
214 struct page *page;
215
216 page = pte_page(*(pte_t *)pmd);
217 if (page)
218 page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT);
219 return page;
220}
221#endif
222
223/* x86_64 also uses this file */
224
225#ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
226static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
227 unsigned long addr, unsigned long len,
228 unsigned long pgoff, unsigned long flags)
229{
230 struct mm_struct *mm = current->mm;
231 struct vm_area_struct *vma;
232 unsigned long start_addr;
233
234 if (len > mm->cached_hole_size) {
235 start_addr = mm->free_area_cache;
236 } else {
237 start_addr = TASK_UNMAPPED_BASE;
238 mm->cached_hole_size = 0;
239 }
240
241full_search:
242 addr = ALIGN(start_addr, HPAGE_SIZE);
243
244 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
245 /* At this point: (!vma || addr < vma->vm_end). */
246 if (TASK_SIZE - len < addr) {
247 /*
248 * Start a new search - just in case we missed
249 * some holes.
250 */
251 if (start_addr != TASK_UNMAPPED_BASE) {
252 start_addr = TASK_UNMAPPED_BASE;
253 mm->cached_hole_size = 0;
254 goto full_search;
255 }
256 return -ENOMEM;
257 }
258 if (!vma || addr + len <= vma->vm_start) {
259 mm->free_area_cache = addr + len;
260 return addr;
261 }
262 if (addr + mm->cached_hole_size < vma->vm_start)
263 mm->cached_hole_size = vma->vm_start - addr;
264 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
265 }
266}
267
268static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
269 unsigned long addr0, unsigned long len,
270 unsigned long pgoff, unsigned long flags)
271{
272 struct mm_struct *mm = current->mm;
273 struct vm_area_struct *vma, *prev_vma;
274 unsigned long base = mm->mmap_base, addr = addr0;
275 unsigned long largest_hole = mm->cached_hole_size;
276 int first_time = 1;
277
278 /* don't allow allocations above current base */
279 if (mm->free_area_cache > base)
280 mm->free_area_cache = base;
281
282 if (len <= largest_hole) {
283 largest_hole = 0;
284 mm->free_area_cache = base;
285 }
286try_again:
287 /* make sure it can fit in the remaining address space */
288 if (mm->free_area_cache < len)
289 goto fail;
290
291 /* either no address requested or cant fit in requested address hole */
292 addr = (mm->free_area_cache - len) & HPAGE_MASK;
293 do {
294 /*
295 * Lookup failure means no vma is above this address,
296 * i.e. return with success:
297 */
298 if (!(vma = find_vma_prev(mm, addr, &prev_vma)))
299 return addr;
300
301 /*
302 * new region fits between prev_vma->vm_end and
303 * vma->vm_start, use it:
304 */
305 if (addr + len <= vma->vm_start &&
306 (!prev_vma || (addr >= prev_vma->vm_end))) {
307 /* remember the address as a hint for next time */
308 mm->cached_hole_size = largest_hole;
309 return (mm->free_area_cache = addr);
310 } else {
311 /* pull free_area_cache down to the first hole */
312 if (mm->free_area_cache == vma->vm_end) {
313 mm->free_area_cache = vma->vm_start;
314 mm->cached_hole_size = largest_hole;
315 }
316 }
317
318 /* remember the largest hole we saw so far */
319 if (addr + largest_hole < vma->vm_start)
320 largest_hole = vma->vm_start - addr;
321
322 /* try just below the current vma->vm_start */
323 addr = (vma->vm_start - len) & HPAGE_MASK;
324 } while (len <= vma->vm_start);
325
326fail:
327 /*
328 * if hint left us with no space for the requested
329 * mapping then try again:
330 */
331 if (first_time) {
332 mm->free_area_cache = base;
333 largest_hole = 0;
334 first_time = 0;
335 goto try_again;
336 }
337 /*
338 * A failed mmap() very likely causes application failure,
339 * so fall back to the bottom-up function here. This scenario
340 * can happen with large stack limits and large mmap()
341 * allocations.
342 */
343 mm->free_area_cache = TASK_UNMAPPED_BASE;
344 mm->cached_hole_size = ~0UL;
345 addr = hugetlb_get_unmapped_area_bottomup(file, addr0,
346 len, pgoff, flags);
347
348 /*
349 * Restore the topdown base:
350 */
351 mm->free_area_cache = base;
352 mm->cached_hole_size = ~0UL;
353
354 return addr;
355}
356
357unsigned long
358hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
359 unsigned long len, unsigned long pgoff, unsigned long flags)
360{
361 struct mm_struct *mm = current->mm;
362 struct vm_area_struct *vma;
363
364 if (len & ~HPAGE_MASK)
365 return -EINVAL;
366 if (len > TASK_SIZE)
367 return -ENOMEM;
368
369 if (flags & MAP_FIXED) {
370 if (prepare_hugepage_range(addr, len))
371 return -EINVAL;
372 return addr;
373 }
374
375 if (addr) {
376 addr = ALIGN(addr, HPAGE_SIZE);
377 vma = find_vma(mm, addr);
378 if (TASK_SIZE - len >= addr &&
379 (!vma || addr + len <= vma->vm_start))
380 return addr;
381 }
382 if (mm->get_unmapped_area == arch_get_unmapped_area)
383 return hugetlb_get_unmapped_area_bottomup(file, addr, len,
384 pgoff, flags);
385 else
386 return hugetlb_get_unmapped_area_topdown(file, addr, len,
387 pgoff, flags);
388}
389
390#endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/
391
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-30 13:32:12 -0500