mm/pgtable-generic.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  mm/pgtable-generic.c
   4  *
   5  *  Generic pgtable methods declared in linux/pgtable.h
   6  *
   7  *  Copyright (C) 2010  Linus Torvalds
   8  */
   9
  10 #include <linux/pagemap.h>
  11 #include <linux/hugetlb.h>
  12 #include <linux/pgtable.h>
  13 #include <linux/swap.h>
  14 #include <linux/swapops.h>
  15 #include <linux/mm_inline.h>
  16 #include <asm/pgalloc.h>
  17 #include <asm/tlb.h>
  18
  19 /*
  20  * If a p?d_bad entry is found while walking page tables, report
  21  * the error, before resetting entry to p?d_none.  Usually (but
  22  * very seldom) called out from the p?d_none_or_clear_bad macros.
  23  */
  24
  25 void pgd_clear_bad(pgd_t *pgd)
  26 {
  27         pgd_ERROR(*pgd);
  28         pgd_clear(pgd);
  29 }
  30
  31 #ifndef __PAGETABLE_P4D_FOLDED
  32 void p4d_clear_bad(p4d_t *p4d)
  33 {
  34         p4d_ERROR(*p4d);
  35         p4d_clear(p4d);
  36 }
  37 #endif
  38
  39 #ifndef __PAGETABLE_PUD_FOLDED
  40 void pud_clear_bad(pud_t *pud)
  41 {
  42         pud_ERROR(*pud);
  43         pud_clear(pud);
  44 }
  45 #endif
  46
  47 /*
  48  * Note that the pmd variant below can't be stub'ed out just as for p4d/pud
  49  * above. pmd folding is special and typically pmd_* macros refer to upper
  50  * level even when folded
  51  */
  52 void pmd_clear_bad(pmd_t *pmd)
  53 {
  54         pmd_ERROR(*pmd);
  55         pmd_clear(pmd);
  56 }
  57
  58 #ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
  59 /*
  60  * Only sets the access flags (dirty, accessed), as well as write
  61  * permission. Furthermore, we know it always gets set to a "more
  62  * permissive" setting, which allows most architectures to optimize
  63  * this. We return whether the PTE actually changed, which in turn
  64  * instructs the caller to do things like update__mmu_cache.  This
  65  * used to be done in the caller, but sparc needs minor faults to
  66  * force that call on sun4c so we changed this macro slightly
  67  */
  68 int ptep_set_access_flags(struct vm_area_struct *vma,
  69                           unsigned long address, pte_t *ptep,
  70                           pte_t entry, int dirty)
  71 {
  72         int changed = !pte_same(ptep_get(ptep), entry);
  73         if (changed) {
  74                 set_pte_at(vma->vm_mm, address, ptep, entry);
  75                 flush_tlb_fix_spurious_fault(vma, address, ptep);
  76         }
  77         return changed;
  78 }
  79 #endif
  80
  81 #ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
  82 int ptep_clear_flush_young(struct vm_area_struct *vma,
  83                            unsigned long address, pte_t *ptep)
  84 {
  85         int young;
  86         young = ptep_test_and_clear_young(vma, address, ptep);
  87         if (young)
  88                 flush_tlb_page(vma, address);
  89         return young;
  90 }
  91 #endif
  92
  93 #ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH
  94 pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address,
  95                        pte_t *ptep)
  96 {
  97         struct mm_struct *mm = (vma)->vm_mm;
  98         pte_t pte;
  99         pte = ptep_get_and_clear(mm, address, ptep);
 100         if (pte_accessible(mm, pte))
 101                 flush_tlb_page(vma, address);
 102         return pte;
 103 }
 104 #endif
 105
 106 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 107
 108 #ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
 109 int pmdp_set_access_flags(struct vm_area_struct *vma,
 110                           unsigned long address, pmd_t *pmdp,
 111                           pmd_t entry, int dirty)
 112 {
 113         int changed = !pmd_same(*pmdp, entry);
 114         VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 115         if (changed) {
 116                 set_pmd_at(vma->vm_mm, address, pmdp, entry);
 117                 flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
 118         }
 119         return changed;
 120 }
 121 #endif
 122
 123 #ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
 124 int pmdp_clear_flush_young(struct vm_area_struct *vma,
 125                            unsigned long address, pmd_t *pmdp)
 126 {
 127         int young;
 128         VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 129         young = pmdp_test_and_clear_young(vma, address, pmdp);
 130         if (young)
 131                 flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
 132         return young;
 133 }
 134 #endif
 135
 136 #ifndef __HAVE_ARCH_PMDP_HUGE_CLEAR_FLUSH
 137 pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
 138                             pmd_t *pmdp)
 139 {
 140         pmd_t pmd;
 141         VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 142         VM_BUG_ON(pmd_present(*pmdp) && !pmd_trans_huge(*pmdp) &&
 143                            !pmd_devmap(*pmdp));
 144         pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
 145         flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
 146         return pmd;
 147 }
 148
 149 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 150 pud_t pudp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
 151                             pud_t *pudp)
 152 {
 153         pud_t pud;
 154
 155         VM_BUG_ON(address & ~HPAGE_PUD_MASK);
 156         VM_BUG_ON(!pud_trans_huge(*pudp) && !pud_devmap(*pudp));
 157         pud = pudp_huge_get_and_clear(vma->vm_mm, address, pudp);
 158         flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
 159         return pud;
 160 }
 161 #endif
 162 #endif
 163
 164 #ifndef __HAVE_ARCH_PGTABLE_DEPOSIT
 165 void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
 166                                 pgtable_t pgtable)
 167 {
 168         assert_spin_locked(pmd_lockptr(mm, pmdp));
 169
 170         /* FIFO */
 171         if (!pmd_huge_pte(mm, pmdp))
 172                 INIT_LIST_HEAD(&pgtable->lru);
 173         else
 174                 list_add(&pgtable->lru, &pmd_huge_pte(mm, pmdp)->lru);
 175         pmd_huge_pte(mm, pmdp) = pgtable;
 176 }
 177 #endif
 178
 179 #ifndef __HAVE_ARCH_PGTABLE_WITHDRAW
 180 /* no "address" argument so destroys page coloring of some arch */
 181 pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
 182 {
 183         pgtable_t pgtable;
 184
 185         assert_spin_locked(pmd_lockptr(mm, pmdp));
 186
 187         /* FIFO */
 188         pgtable = pmd_huge_pte(mm, pmdp);
 189         pmd_huge_pte(mm, pmdp) = list_first_entry_or_null(&pgtable->lru,
 190                                                           struct page, lru);
 191         if (pmd_huge_pte(mm, pmdp))
 192                 list_del(&pgtable->lru);
 193         return pgtable;
 194 }
 195 #endif
 196
 197 #ifndef __HAVE_ARCH_PMDP_INVALIDATE
 198 pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
 199                      pmd_t *pmdp)
 200 {
 201         pmd_t old = pmdp_establish(vma, address, pmdp, pmd_mkinvalid(*pmdp));
 202         flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
 203         return old;
 204 }
 205 #endif
 206
 207 #ifndef __HAVE_ARCH_PMDP_INVALIDATE_AD
 208 pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma, unsigned long address,
 209                          pmd_t *pmdp)
 210 {
 211         return pmdp_invalidate(vma, address, pmdp);
 212 }
 213 #endif
 214
 215 #ifndef pmdp_collapse_flush
 216 pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
 217                           pmd_t *pmdp)
 218 {
 219         /*
 220          * pmd and hugepage pte format are same. So we could
 221          * use the same function.
 222          */
 223         pmd_t pmd;
 224
 225         VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 226         VM_BUG_ON(pmd_trans_huge(*pmdp));
 227         pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
 228
 229         /* collapse entails shooting down ptes not pmd */
 230         flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
 231         return pmd;
 232 }
 233 #endif
 234
 235 /* arch define pte_free_defer in asm/pgalloc.h for its own implementation */
 236 #ifndef pte_free_defer
 237 static void pte_free_now(struct rcu_head *head)
 238 {
 239         struct page *page;
 240
 241         page = container_of(head, struct page, rcu_head);
 242         pte_free(NULL /* mm not passed and not used */, (pgtable_t)page);
 243 }
 244
 245 void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable)
 246 {
 247         struct page *page;
 248
 249         page = pgtable;
 250         call_rcu(&page->rcu_head, pte_free_now);
 251 }
 252 #endif /* pte_free_defer */
 253 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 254
 255 #if defined(CONFIG_GUP_GET_PXX_LOW_HIGH) && \
 256         (defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RCU))
 257 /*
 258  * See the comment above ptep_get_lockless() in include/linux/pgtable.h:
 259  * the barriers in pmdp_get_lockless() cannot guarantee that the value in
 260  * pmd_high actually belongs with the value in pmd_low; but holding interrupts
 261  * off blocks the TLB flush between present updates, which guarantees that a
 262  * successful __pte_offset_map() points to a page from matched halves.
 263  */
 264 static unsigned long pmdp_get_lockless_start(void)
 265 {
 266         unsigned long irqflags;
 267
 268         local_irq_save(irqflags);
 269         return irqflags;
 270 }
 271 static void pmdp_get_lockless_end(unsigned long irqflags)
 272 {
 273         local_irq_restore(irqflags);
 274 }
 275 #else
 276 static unsigned long pmdp_get_lockless_start(void) { return 0; }
 277 static void pmdp_get_lockless_end(unsigned long irqflags) { }
 278 #endif
 279
 280 pte_t *__pte_offset_map(pmd_t *pmd, unsigned long addr, pmd_t *pmdvalp)
 281 {
 282         unsigned long irqflags;
 283         pmd_t pmdval;
 284
 285         rcu_read_lock();
 286         irqflags = pmdp_get_lockless_start();
 287         pmdval = pmdp_get_lockless(pmd);
 288         pmdp_get_lockless_end(irqflags);
 289
 290         if (pmdvalp)
 291                 *pmdvalp = pmdval;
 292         if (unlikely(pmd_none(pmdval) || is_pmd_migration_entry(pmdval)))
 293                 goto nomap;
 294         if (unlikely(pmd_trans_huge(pmdval) || pmd_devmap(pmdval)))
 295                 goto nomap;
 296         if (unlikely(pmd_bad(pmdval))) {
 297                 pmd_clear_bad(pmd);
 298                 goto nomap;
 299         }
 300         return __pte_map(&pmdval, addr);
 301 nomap:
 302         rcu_read_unlock();
 303         return NULL;
 304 }
 305
 306 pte_t *pte_offset_map_nolock(struct mm_struct *mm, pmd_t *pmd,
 307                              unsigned long addr, spinlock_t **ptlp)
 308 {
 309         pmd_t pmdval;
 310         pte_t *pte;
 311
 312         pte = __pte_offset_map(pmd, addr, &pmdval);
 313         if (likely(pte))
 314                 *ptlp = pte_lockptr(mm, &pmdval);
 315         return pte;
 316 }
 317
 318 pte_t *__pte_offset_map_lock(struct mm_struct *mm, pmd_t *pmd,
 319                              unsigned long addr, spinlock_t **ptlp)
 320 {
 321         spinlock_t *ptl;
 322         pmd_t pmdval;
 323         pte_t *pte;
 324 again:
 325         pte = __pte_offset_map(pmd, addr, &pmdval);
 326         if (unlikely(!pte))
 327                 return pte;
 328         ptl = pte_lockptr(mm, &pmdval);
 329         spin_lock(ptl);
 330         if (likely(pmd_same(pmdval, pmdp_get_lockless(pmd)))) {
 331                 *ptlp = ptl;
 332                 return pte;
 333         }
 334         pte_unmap_unlock(pte, ptl);
 335         goto again;
 336 }