]> git.openfabrics.org - ~shefty/rdma-dev.git/blob - arch/x86/mm/hugetlbpage.c
mm: use vm_unmapped_area() in hugetlbfs on i386 architecture
[~shefty/rdma-dev.git] / arch / x86 / mm / hugetlbpage.c
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/err.h>
13 #include <linux/sysctl.h>
14 #include <asm/mman.h>
15 #include <asm/tlb.h>
16 #include <asm/tlbflush.h>
17 #include <asm/pgalloc.h>
18
19 static 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         /* Allow segments to share if only one is marked locked */
29         unsigned long vm_flags = vma->vm_flags & ~VM_LOCKED;
30         unsigned long svm_flags = svma->vm_flags & ~VM_LOCKED;
31
32         /*
33          * match the virtual addresses, permission and the alignment of the
34          * page table page.
35          */
36         if (pmd_index(addr) != pmd_index(saddr) ||
37             vm_flags != svm_flags ||
38             sbase < svma->vm_start || svma->vm_end < s_end)
39                 return 0;
40
41         return saddr;
42 }
43
44 static int vma_shareable(struct vm_area_struct *vma, unsigned long addr)
45 {
46         unsigned long base = addr & PUD_MASK;
47         unsigned long end = base + PUD_SIZE;
48
49         /*
50          * check on proper vm_flags and page table alignment
51          */
52         if (vma->vm_flags & VM_MAYSHARE &&
53             vma->vm_start <= base && end <= vma->vm_end)
54                 return 1;
55         return 0;
56 }
57
58 /*
59  * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
60  * and returns the corresponding pte. While this is not necessary for the
61  * !shared pmd case because we can allocate the pmd later as well, it makes the
62  * code much cleaner. pmd allocation is essential for the shared case because
63  * pud has to be populated inside the same i_mmap_mutex section - otherwise
64  * racing tasks could either miss the sharing (see huge_pte_offset) or select a
65  * bad pmd for sharing.
66  */
67 static pte_t *
68 huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
69 {
70         struct vm_area_struct *vma = find_vma(mm, addr);
71         struct address_space *mapping = vma->vm_file->f_mapping;
72         pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
73                         vma->vm_pgoff;
74         struct vm_area_struct *svma;
75         unsigned long saddr;
76         pte_t *spte = NULL;
77         pte_t *pte;
78
79         if (!vma_shareable(vma, addr))
80                 return (pte_t *)pmd_alloc(mm, pud, addr);
81
82         mutex_lock(&mapping->i_mmap_mutex);
83         vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) {
84                 if (svma == vma)
85                         continue;
86
87                 saddr = page_table_shareable(svma, vma, addr, idx);
88                 if (saddr) {
89                         spte = huge_pte_offset(svma->vm_mm, saddr);
90                         if (spte) {
91                                 get_page(virt_to_page(spte));
92                                 break;
93                         }
94                 }
95         }
96
97         if (!spte)
98                 goto out;
99
100         spin_lock(&mm->page_table_lock);
101         if (pud_none(*pud))
102                 pud_populate(mm, pud, (pmd_t *)((unsigned long)spte & PAGE_MASK));
103         else
104                 put_page(virt_to_page(spte));
105         spin_unlock(&mm->page_table_lock);
106 out:
107         pte = (pte_t *)pmd_alloc(mm, pud, addr);
108         mutex_unlock(&mapping->i_mmap_mutex);
109         return pte;
110 }
111
112 /*
113  * unmap huge page backed by shared pte.
114  *
115  * Hugetlb pte page is ref counted at the time of mapping.  If pte is shared
116  * indicated by page_count > 1, unmap is achieved by clearing pud and
117  * decrementing the ref count. If count == 1, the pte page is not shared.
118  *
119  * called with vma->vm_mm->page_table_lock held.
120  *
121  * returns: 1 successfully unmapped a shared pte page
122  *          0 the underlying pte page is not shared, or it is the last user
123  */
124 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
125 {
126         pgd_t *pgd = pgd_offset(mm, *addr);
127         pud_t *pud = pud_offset(pgd, *addr);
128
129         BUG_ON(page_count(virt_to_page(ptep)) == 0);
130         if (page_count(virt_to_page(ptep)) == 1)
131                 return 0;
132
133         pud_clear(pud);
134         put_page(virt_to_page(ptep));
135         *addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
136         return 1;
137 }
138
139 pte_t *huge_pte_alloc(struct mm_struct *mm,
140                         unsigned long addr, unsigned long sz)
141 {
142         pgd_t *pgd;
143         pud_t *pud;
144         pte_t *pte = NULL;
145
146         pgd = pgd_offset(mm, addr);
147         pud = pud_alloc(mm, pgd, addr);
148         if (pud) {
149                 if (sz == PUD_SIZE) {
150                         pte = (pte_t *)pud;
151                 } else {
152                         BUG_ON(sz != PMD_SIZE);
153                         if (pud_none(*pud))
154                                 pte = huge_pmd_share(mm, addr, pud);
155                         else
156                                 pte = (pte_t *)pmd_alloc(mm, pud, addr);
157                 }
158         }
159         BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));
160
161         return pte;
162 }
163
164 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
165 {
166         pgd_t *pgd;
167         pud_t *pud;
168         pmd_t *pmd = NULL;
169
170         pgd = pgd_offset(mm, addr);
171         if (pgd_present(*pgd)) {
172                 pud = pud_offset(pgd, addr);
173                 if (pud_present(*pud)) {
174                         if (pud_large(*pud))
175                                 return (pte_t *)pud;
176                         pmd = pmd_offset(pud, addr);
177                 }
178         }
179         return (pte_t *) pmd;
180 }
181
182 #if 0   /* This is just for testing */
183 struct page *
184 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
185 {
186         unsigned long start = address;
187         int length = 1;
188         int nr;
189         struct page *page;
190         struct vm_area_struct *vma;
191
192         vma = find_vma(mm, addr);
193         if (!vma || !is_vm_hugetlb_page(vma))
194                 return ERR_PTR(-EINVAL);
195
196         pte = huge_pte_offset(mm, address);
197
198         /* hugetlb should be locked, and hence, prefaulted */
199         WARN_ON(!pte || pte_none(*pte));
200
201         page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
202
203         WARN_ON(!PageHead(page));
204
205         return page;
206 }
207
208 int pmd_huge(pmd_t pmd)
209 {
210         return 0;
211 }
212
213 int pud_huge(pud_t pud)
214 {
215         return 0;
216 }
217
218 struct page *
219 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
220                 pmd_t *pmd, int write)
221 {
222         return NULL;
223 }
224
225 #else
226
227 struct page *
228 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
229 {
230         return ERR_PTR(-EINVAL);
231 }
232
233 int pmd_huge(pmd_t pmd)
234 {
235         return !!(pmd_val(pmd) & _PAGE_PSE);
236 }
237
238 int pud_huge(pud_t pud)
239 {
240         return !!(pud_val(pud) & _PAGE_PSE);
241 }
242
243 struct page *
244 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
245                 pmd_t *pmd, int write)
246 {
247         struct page *page;
248
249         page = pte_page(*(pte_t *)pmd);
250         if (page)
251                 page += ((address & ~PMD_MASK) >> PAGE_SHIFT);
252         return page;
253 }
254
255 struct page *
256 follow_huge_pud(struct mm_struct *mm, unsigned long address,
257                 pud_t *pud, int write)
258 {
259         struct page *page;
260
261         page = pte_page(*(pte_t *)pud);
262         if (page)
263                 page += ((address & ~PUD_MASK) >> PAGE_SHIFT);
264         return page;
265 }
266
267 #endif
268
269 /* x86_64 also uses this file */
270
271 #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
272 static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
273                 unsigned long addr, unsigned long len,
274                 unsigned long pgoff, unsigned long flags)
275 {
276         struct hstate *h = hstate_file(file);
277         struct vm_unmapped_area_info info;
278
279         info.flags = 0;
280         info.length = len;
281         info.low_limit = TASK_UNMAPPED_BASE;
282         info.high_limit = TASK_SIZE;
283         info.align_mask = PAGE_MASK & ~huge_page_mask(h);
284         info.align_offset = 0;
285         return vm_unmapped_area(&info);
286 }
287
288 static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
289                 unsigned long addr0, unsigned long len,
290                 unsigned long pgoff, unsigned long flags)
291 {
292         struct hstate *h = hstate_file(file);
293         struct vm_unmapped_area_info info;
294         unsigned long addr;
295
296         info.flags = VM_UNMAPPED_AREA_TOPDOWN;
297         info.length = len;
298         info.low_limit = PAGE_SIZE;
299         info.high_limit = current->mm->mmap_base;
300         info.align_mask = PAGE_MASK & ~huge_page_mask(h);
301         info.align_offset = 0;
302         addr = vm_unmapped_area(&info);
303
304         /*
305          * A failed mmap() very likely causes application failure,
306          * so fall back to the bottom-up function here. This scenario
307          * can happen with large stack limits and large mmap()
308          * allocations.
309          */
310         if (addr & ~PAGE_MASK) {
311                 VM_BUG_ON(addr != -ENOMEM);
312                 info.flags = 0;
313                 info.low_limit = TASK_UNMAPPED_BASE;
314                 info.high_limit = TASK_SIZE;
315                 addr = vm_unmapped_area(&info);
316         }
317
318         return addr;
319 }
320
321 unsigned long
322 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
323                 unsigned long len, unsigned long pgoff, unsigned long flags)
324 {
325         struct hstate *h = hstate_file(file);
326         struct mm_struct *mm = current->mm;
327         struct vm_area_struct *vma;
328
329         if (len & ~huge_page_mask(h))
330                 return -EINVAL;
331         if (len > TASK_SIZE)
332                 return -ENOMEM;
333
334         if (flags & MAP_FIXED) {
335                 if (prepare_hugepage_range(file, addr, len))
336                         return -EINVAL;
337                 return addr;
338         }
339
340         if (addr) {
341                 addr = ALIGN(addr, huge_page_size(h));
342                 vma = find_vma(mm, addr);
343                 if (TASK_SIZE - len >= addr &&
344                     (!vma || addr + len <= vma->vm_start))
345                         return addr;
346         }
347         if (mm->get_unmapped_area == arch_get_unmapped_area)
348                 return hugetlb_get_unmapped_area_bottomup(file, addr, len,
349                                 pgoff, flags);
350         else
351                 return hugetlb_get_unmapped_area_topdown(file, addr, len,
352                                 pgoff, flags);
353 }
354
355 #endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/
356
357 #ifdef CONFIG_X86_64
358 static __init int setup_hugepagesz(char *opt)
359 {
360         unsigned long ps = memparse(opt, &opt);
361         if (ps == PMD_SIZE) {
362                 hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
363         } else if (ps == PUD_SIZE && cpu_has_gbpages) {
364                 hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
365         } else {
366                 printk(KERN_ERR "hugepagesz: Unsupported page size %lu M\n",
367                         ps >> 20);
368                 return 0;
369         }
370         return 1;
371 }
372 __setup("hugepagesz=", setup_hugepagesz);
373 #endif