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 static struct vm_area_struct* hugetlb_vma(unsigned long addr, struct mm_walk *walk) 131 { 132 struct vm_area_struct *vma; 133 134 /* We don't need vma lookup at all. */ 135 if (!walk->hugetlb_entry) 136 return NULL; 137 138 VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem)); 139 vma = find_vma(walk->mm, addr); 140 if (vma && vma->vm_start <= addr && is_vm_hugetlb_page(vma)) 141 return vma; 142 143 return NULL; 144 } 145 146 #else /* CONFIG_HUGETLB_PAGE */ 147 static struct vm_area_struct* hugetlb_vma(unsigned long addr, struct mm_walk *walk) 148 { 149 return NULL; 150 } 151 152 static int walk_hugetlb_range(struct vm_area_struct *vma, 153 unsigned long addr, unsigned long end, 154 struct mm_walk *walk) 155 { 156 return 0; 157 } 158 159 #endif /* CONFIG_HUGETLB_PAGE */ 160 161 162 163 /** 164 * walk_page_range - walk a memory map's page tables with a callback 165 * @addr: starting address 166 * @end: ending address 167 * @walk: set of callbacks to invoke for each level of the tree 168 * 169 * Recursively walk the page table for the memory area in a VMA, 170 * calling supplied callbacks. Callbacks are called in-order (first 171 * PGD, first PUD, first PMD, first PTE, second PTE... second PMD, 172 * etc.). If lower-level callbacks are omitted, walking depth is reduced. 173 * 174 * Each callback receives an entry pointer and the start and end of the 175 * associated range, and a copy of the original mm_walk for access to 176 * the ->private or ->mm fields. 177 * 178 * Usually no locks are taken, but splitting transparent huge page may 179 * take page table lock. And the bottom level iterator will map PTE 180 * directories from highmem if necessary. 181 * 182 * If any callback returns a non-zero value, the walk is aborted and 183 * the return value is propagated back to the caller. Otherwise 0 is returned. 184 * 185 * walk->mm->mmap_sem must be held for at least read if walk->hugetlb_entry 186 * is !NULL. 187 */ 188 int walk_page_range(unsigned long addr, unsigned long end, 189 struct mm_walk *walk) 190 { 191 pgd_t *pgd; 192 unsigned long next; 193 int err = 0; 194 195 if (addr >= end) 196 return err; 197 198 if (!walk->mm) 199 return -EINVAL; 200 201 pgd = pgd_offset(walk->mm, addr); 202 do { 203 struct vm_area_struct *vma; 204 205 next = pgd_addr_end(addr, end); 206 207 /* 208 * handle hugetlb vma individually because pagetable walk for 209 * the hugetlb page is dependent on the architecture and 210 * we can't handled it in the same manner as non-huge pages. 211 */ 212 vma = hugetlb_vma(addr, walk); 213 if (vma) { 214 if (vma->vm_end < next) 215 next = vma->vm_end; 216 /* 217 * Hugepage is very tightly coupled with vma, so 218 * walk through hugetlb entries within a given vma. 219 */ 220 err = walk_hugetlb_range(vma, addr, next, walk); 221 if (err) 222 break; 223 pgd = pgd_offset(walk->mm, next); 224 continue; 225 } 226 227 if (pgd_none_or_clear_bad(pgd)) { 228 if (walk->pte_hole) 229 err = walk->pte_hole(addr, next, walk); 230 if (err) 231 break; 232 pgd++; 233 continue; 234 } 235 if (walk->pgd_entry) 236 err = walk->pgd_entry(pgd, addr, next, walk); 237 if (!err && 238 (walk->pud_entry || walk->pmd_entry || walk->pte_entry)) 239 err = walk_pud_range(pgd, addr, next, walk); 240 if (err) 241 break; 242 pgd++; 243 } while (addr = next, addr != end); 244 245 return err; 246 } 247