Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc
[platform/adaptation/renesas_rcar/renesas_kernel.git] / mm / pagewalk.c
1 #include <linux/mm.h>
2 #include <linux/highmem.h>
3 #include <linux/sched.h>
4 #include <linux/hugetlb.h>
5
6 static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
7                           struct mm_walk *walk)
8 {
9         pte_t *pte;
10         int err = 0;
11
12         pte = pte_offset_map(pmd, addr);
13         for (;;) {
14                 err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
15                 if (err)
16                        break;
17                 addr += PAGE_SIZE;
18                 if (addr == end)
19                         break;
20                 pte++;
21         }
22
23         pte_unmap(pte);
24         return err;
25 }
26
27 static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
28                           struct mm_walk *walk)
29 {
30         pmd_t *pmd;
31         unsigned long next;
32         int err = 0;
33
34         pmd = pmd_offset(pud, addr);
35         do {
36 again:
37                 next = pmd_addr_end(addr, end);
38                 if (pmd_none(*pmd)) {
39                         if (walk->pte_hole)
40                                 err = walk->pte_hole(addr, next, walk);
41                         if (err)
42                                 break;
43                         continue;
44                 }
45                 /*
46                  * This implies that each ->pmd_entry() handler
47                  * needs to know about pmd_trans_huge() pmds
48                  */
49                 if (walk->pmd_entry)
50                         err = walk->pmd_entry(pmd, addr, next, walk);
51                 if (err)
52                         break;
53
54                 /*
55                  * Check this here so we only break down trans_huge
56                  * pages when we _need_ to
57                  */
58                 if (!walk->pte_entry)
59                         continue;
60
61                 split_huge_page_pmd_mm(walk->mm, addr, pmd);
62                 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
63                         goto again;
64                 err = walk_pte_range(pmd, addr, next, walk);
65                 if (err)
66                         break;
67         } while (pmd++, addr = next, addr != end);
68
69         return err;
70 }
71
72 static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
73                           struct mm_walk *walk)
74 {
75         pud_t *pud;
76         unsigned long next;
77         int err = 0;
78
79         pud = pud_offset(pgd, addr);
80         do {
81                 next = pud_addr_end(addr, end);
82                 if (pud_none_or_clear_bad(pud)) {
83                         if (walk->pte_hole)
84                                 err = walk->pte_hole(addr, next, walk);
85                         if (err)
86                                 break;
87                         continue;
88                 }
89                 if (walk->pud_entry)
90                         err = walk->pud_entry(pud, addr, next, walk);
91                 if (!err && (walk->pmd_entry || walk->pte_entry))
92                         err = walk_pmd_range(pud, addr, next, walk);
93                 if (err)
94                         break;
95         } while (pud++, addr = next, addr != end);
96
97         return err;
98 }
99
100 #ifdef CONFIG_HUGETLB_PAGE
101 static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
102                                        unsigned long end)
103 {
104         unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
105         return boundary < end ? boundary : end;
106 }
107
108 static int walk_hugetlb_range(struct vm_area_struct *vma,
109                               unsigned long addr, unsigned long end,
110                               struct mm_walk *walk)
111 {
112         struct hstate *h = hstate_vma(vma);
113         unsigned long next;
114         unsigned long hmask = huge_page_mask(h);
115         pte_t *pte;
116         int err = 0;
117
118         do {
119                 next = hugetlb_entry_end(h, addr, end);
120                 pte = huge_pte_offset(walk->mm, addr & hmask);
121                 if (pte && walk->hugetlb_entry)
122                         err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
123                 if (err)
124                         return err;
125         } while (addr = next, addr != end);
126
127         return 0;
128 }
129
130 #else /* CONFIG_HUGETLB_PAGE */
131 static int walk_hugetlb_range(struct vm_area_struct *vma,
132                               unsigned long addr, unsigned long end,
133                               struct mm_walk *walk)
134 {
135         return 0;
136 }
137
138 #endif /* CONFIG_HUGETLB_PAGE */
139
140
141
142 /**
143  * walk_page_range - walk a memory map's page tables with a callback
144  * @addr: starting address
145  * @end: ending address
146  * @walk: set of callbacks to invoke for each level of the tree
147  *
148  * Recursively walk the page table for the memory area in a VMA,
149  * calling supplied callbacks. Callbacks are called in-order (first
150  * PGD, first PUD, first PMD, first PTE, second PTE... second PMD,
151  * etc.). If lower-level callbacks are omitted, walking depth is reduced.
152  *
153  * Each callback receives an entry pointer and the start and end of the
154  * associated range, and a copy of the original mm_walk for access to
155  * the ->private or ->mm fields.
156  *
157  * Usually no locks are taken, but splitting transparent huge page may
158  * take page table lock. And the bottom level iterator will map PTE
159  * directories from highmem if necessary.
160  *
161  * If any callback returns a non-zero value, the walk is aborted and
162  * the return value is propagated back to the caller. Otherwise 0 is returned.
163  *
164  * walk->mm->mmap_sem must be held for at least read if walk->hugetlb_entry
165  * is !NULL.
166  */
167 int walk_page_range(unsigned long addr, unsigned long end,
168                     struct mm_walk *walk)
169 {
170         pgd_t *pgd;
171         unsigned long next;
172         int err = 0;
173
174         if (addr >= end)
175                 return err;
176
177         if (!walk->mm)
178                 return -EINVAL;
179
180         VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem));
181
182         pgd = pgd_offset(walk->mm, addr);
183         do {
184                 struct vm_area_struct *vma = NULL;
185
186                 next = pgd_addr_end(addr, end);
187
188                 /*
189                  * This function was not intended to be vma based.
190                  * But there are vma special cases to be handled:
191                  * - hugetlb vma's
192                  * - VM_PFNMAP vma's
193                  */
194                 vma = find_vma(walk->mm, addr);
195                 if (vma) {
196                         /*
197                          * There are no page structures backing a VM_PFNMAP
198                          * range, so do not allow split_huge_page_pmd().
199                          */
200                         if ((vma->vm_start <= addr) &&
201                             (vma->vm_flags & VM_PFNMAP)) {
202                                 next = vma->vm_end;
203                                 pgd = pgd_offset(walk->mm, next);
204                                 continue;
205                         }
206                         /*
207                          * Handle hugetlb vma individually because pagetable
208                          * walk for the hugetlb page is dependent on the
209                          * architecture and we can't handled it in the same
210                          * manner as non-huge pages.
211                          */
212                         if (walk->hugetlb_entry && (vma->vm_start <= addr) &&
213                             is_vm_hugetlb_page(vma)) {
214                                 if (vma->vm_end < next)
215                                         next = vma->vm_end;
216                                 /*
217                                  * Hugepage is very tightly coupled with vma,
218                                  * so walk through hugetlb entries within a
219                                  * given vma.
220                                  */
221                                 err = walk_hugetlb_range(vma, addr, next, walk);
222                                 if (err)
223                                         break;
224                                 pgd = pgd_offset(walk->mm, next);
225                                 continue;
226                         }
227                 }
228
229                 if (pgd_none_or_clear_bad(pgd)) {
230                         if (walk->pte_hole)
231                                 err = walk->pte_hole(addr, next, walk);
232                         if (err)
233                                 break;
234                         pgd++;
235                         continue;
236                 }
237                 if (walk->pgd_entry)
238                         err = walk->pgd_entry(pgd, addr, next, walk);
239                 if (!err &&
240                     (walk->pud_entry || walk->pmd_entry || walk->pte_entry))
241                         err = walk_pud_range(pgd, addr, next, walk);
242                 if (err)
243                         break;
244                 pgd++;
245         } while (addr = next, addr < end);
246
247         return err;
248 }