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) || !walk->vma) { 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_trans_unstable(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->pmd_entry || walk->pte_entry) 90 err = walk_pmd_range(pud, addr, next, walk); 91 if (err) 92 break; 93 } while (pud++, addr = next, addr != end); 94 95 return err; 96 } 97 98 static int walk_pgd_range(unsigned long addr, unsigned long end, 99 struct mm_walk *walk) 100 { 101 pgd_t *pgd; 102 unsigned long next; 103 int err = 0; 104 105 pgd = pgd_offset(walk->mm, addr); 106 do { 107 next = pgd_addr_end(addr, end); 108 if (pgd_none_or_clear_bad(pgd)) { 109 if (walk->pte_hole) 110 err = walk->pte_hole(addr, next, walk); 111 if (err) 112 break; 113 continue; 114 } 115 if (walk->pmd_entry || walk->pte_entry) 116 err = walk_pud_range(pgd, addr, next, walk); 117 if (err) 118 break; 119 } while (pgd++, addr = next, addr != end); 120 121 return err; 122 } 123 124 #ifdef CONFIG_HUGETLB_PAGE 125 static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr, 126 unsigned long end) 127 { 128 unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h); 129 return boundary < end ? boundary : end; 130 } 131 132 static int walk_hugetlb_range(unsigned long addr, unsigned long end, 133 struct mm_walk *walk) 134 { 135 struct vm_area_struct *vma = walk->vma; 136 struct hstate *h = hstate_vma(vma); 137 unsigned long next; 138 unsigned long hmask = huge_page_mask(h); 139 pte_t *pte; 140 int err = 0; 141 142 do { 143 next = hugetlb_entry_end(h, addr, end); 144 pte = huge_pte_offset(walk->mm, addr & hmask); 145 if (pte && walk->hugetlb_entry) 146 err = walk->hugetlb_entry(pte, hmask, addr, next, walk); 147 if (err) 148 break; 149 } while (addr = next, addr != end); 150 151 return err; 152 } 153 154 #else /* CONFIG_HUGETLB_PAGE */ 155 static int walk_hugetlb_range(unsigned long addr, unsigned long end, 156 struct mm_walk *walk) 157 { 158 return 0; 159 } 160 161 #endif /* CONFIG_HUGETLB_PAGE */ 162 163 /* 164 * Decide whether we really walk over the current vma on [@start, @end) 165 * or skip it via the returned value. Return 0 if we do walk over the 166 * current vma, and return 1 if we skip the vma. Negative values means 167 * error, where we abort the current walk. 168 */ 169 static int walk_page_test(unsigned long start, unsigned long end, 170 struct mm_walk *walk) 171 { 172 struct vm_area_struct *vma = walk->vma; 173 174 if (walk->test_walk) 175 return walk->test_walk(start, end, walk); 176 177 /* 178 * vma(VM_PFNMAP) doesn't have any valid struct pages behind VM_PFNMAP 179 * range, so we don't walk over it as we do for normal vmas. However, 180 * Some callers are interested in handling hole range and they don't 181 * want to just ignore any single address range. Such users certainly 182 * define their ->pte_hole() callbacks, so let's delegate them to handle 183 * vma(VM_PFNMAP). 184 */ 185 if (vma->vm_flags & VM_PFNMAP) { 186 int err = 1; 187 if (walk->pte_hole) 188 err = walk->pte_hole(start, end, walk); 189 return err ? err : 1; 190 } 191 return 0; 192 } 193 194 static int __walk_page_range(unsigned long start, unsigned long end, 195 struct mm_walk *walk) 196 { 197 int err = 0; 198 struct vm_area_struct *vma = walk->vma; 199 200 if (vma && is_vm_hugetlb_page(vma)) { 201 if (walk->hugetlb_entry) 202 err = walk_hugetlb_range(start, end, walk); 203 } else 204 err = walk_pgd_range(start, end, walk); 205 206 return err; 207 } 208 209 /** 210 * walk_page_range - walk page table with caller specific callbacks 211 * 212 * Recursively walk the page table tree of the process represented by @walk->mm 213 * within the virtual address range [@start, @end). During walking, we can do 214 * some caller-specific works for each entry, by setting up pmd_entry(), 215 * pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these 216 * callbacks, the associated entries/pages are just ignored. 217 * The return values of these callbacks are commonly defined like below: 218 * - 0 : succeeded to handle the current entry, and if you don't reach the 219 * end address yet, continue to walk. 220 * - >0 : succeeded to handle the current entry, and return to the caller 221 * with caller specific value. 222 * - <0 : failed to handle the current entry, and return to the caller 223 * with error code. 224 * 225 * Before starting to walk page table, some callers want to check whether 226 * they really want to walk over the current vma, typically by checking 227 * its vm_flags. walk_page_test() and @walk->test_walk() are used for this 228 * purpose. 229 * 230 * struct mm_walk keeps current values of some common data like vma and pmd, 231 * which are useful for the access from callbacks. If you want to pass some 232 * caller-specific data to callbacks, @walk->private should be helpful. 233 * 234 * Locking: 235 * Callers of walk_page_range() and walk_page_vma() should hold 236 * @walk->mm->mmap_sem, because these function traverse vma list and/or 237 * access to vma's data. 238 */ 239 int walk_page_range(unsigned long start, unsigned long end, 240 struct mm_walk *walk) 241 { 242 int err = 0; 243 unsigned long next; 244 struct vm_area_struct *vma; 245 246 if (start >= end) 247 return -EINVAL; 248 249 if (!walk->mm) 250 return -EINVAL; 251 252 VM_BUG_ON_MM(!rwsem_is_locked(&walk->mm->mmap_sem), walk->mm); 253 254 vma = find_vma(walk->mm, start); 255 do { 256 if (!vma) { /* after the last vma */ 257 walk->vma = NULL; 258 next = end; 259 } else if (start < vma->vm_start) { /* outside vma */ 260 walk->vma = NULL; 261 next = min(end, vma->vm_start); 262 } else { /* inside vma */ 263 walk->vma = vma; 264 next = min(end, vma->vm_end); 265 vma = vma->vm_next; 266 267 err = walk_page_test(start, next, walk); 268 if (err > 0) { 269 /* 270 * positive return values are purely for 271 * controlling the pagewalk, so should never 272 * be passed to the callers. 273 */ 274 err = 0; 275 continue; 276 } 277 if (err < 0) 278 break; 279 } 280 if (walk->vma || walk->pte_hole) 281 err = __walk_page_range(start, next, walk); 282 if (err) 283 break; 284 } while (start = next, start < end); 285 return err; 286 } 287 288 int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk) 289 { 290 int err; 291 292 if (!walk->mm) 293 return -EINVAL; 294 295 VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem)); 296 VM_BUG_ON(!vma); 297 walk->vma = vma; 298 err = walk_page_test(vma->vm_start, vma->vm_end, walk); 299 if (err > 0) 300 return 0; 301 if (err < 0) 302 return err; 303 return __walk_page_range(vma->vm_start, vma->vm_end, walk); 304 } 305