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Diffstat (limited to '')
| -rw-r--r-- | mm/pgtable-generic.c | 380 |
1 files changed, 380 insertions, 0 deletions
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c new file mode 100644 index 0000000000..4fcd959dcc --- /dev/null +++ b/mm/pgtable-generic.c @@ -0,0 +1,380 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * mm/pgtable-generic.c + * + * Generic pgtable methods declared in linux/pgtable.h + * + * Copyright (C) 2010 Linus Torvalds + */ + +#include <linux/pagemap.h> +#include <linux/hugetlb.h> +#include <linux/pgtable.h> +#include <linux/swap.h> +#include <linux/swapops.h> +#include <linux/mm_inline.h> +#include <asm/pgalloc.h> +#include <asm/tlb.h> + +/* + * If a p?d_bad entry is found while walking page tables, report + * the error, before resetting entry to p?d_none. Usually (but + * very seldom) called out from the p?d_none_or_clear_bad macros. + */ + +void pgd_clear_bad(pgd_t *pgd) +{ + pgd_ERROR(*pgd); + pgd_clear(pgd); +} + +#ifndef __PAGETABLE_P4D_FOLDED +void p4d_clear_bad(p4d_t *p4d) +{ + p4d_ERROR(*p4d); + p4d_clear(p4d); +} +#endif + +#ifndef __PAGETABLE_PUD_FOLDED +void pud_clear_bad(pud_t *pud) +{ + pud_ERROR(*pud); + pud_clear(pud); +} +#endif + +/* + * Note that the pmd variant below can't be stub'ed out just as for p4d/pud + * above. pmd folding is special and typically pmd_* macros refer to upper + * level even when folded + */ +void pmd_clear_bad(pmd_t *pmd) +{ + pmd_ERROR(*pmd); + pmd_clear(pmd); +} + +#ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS +/* + * Only sets the access flags (dirty, accessed), as well as write + * permission. Furthermore, we know it always gets set to a "more + * permissive" setting, which allows most architectures to optimize + * this. We return whether the PTE actually changed, which in turn + * instructs the caller to do things like update__mmu_cache. This + * used to be done in the caller, but sparc needs minor faults to + * force that call on sun4c so we changed this macro slightly + */ +int ptep_set_access_flags(struct vm_area_struct *vma, + unsigned long address, pte_t *ptep, + pte_t entry, int dirty) +{ + int changed = !pte_same(ptep_get(ptep), entry); + if (changed) { + set_pte_at(vma->vm_mm, address, ptep, entry); + flush_tlb_fix_spurious_fault(vma, address, ptep); + } + return changed; +} +#endif + +#ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH +int ptep_clear_flush_young(struct vm_area_struct *vma, + unsigned long address, pte_t *ptep) +{ + int young; + young = ptep_test_and_clear_young(vma, address, ptep); + if (young) + flush_tlb_page(vma, address); + return young; +} +#endif + +#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH +pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address, + pte_t *ptep) +{ + struct mm_struct *mm = (vma)->vm_mm; + pte_t pte; + pte = ptep_get_and_clear(mm, address, ptep); + if (pte_accessible(mm, pte)) + flush_tlb_page(vma, address); + return pte; +} +#endif + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + +#ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS +int pmdp_set_access_flags(struct vm_area_struct *vma, + unsigned long address, pmd_t *pmdp, + pmd_t entry, int dirty) +{ + int changed = !pmd_same(*pmdp, entry); + VM_BUG_ON(address & ~HPAGE_PMD_MASK); + if (changed) { + set_pmd_at(vma->vm_mm, address, pmdp, entry); + flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); + } + return changed; +} +#endif + +#ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH +int pmdp_clear_flush_young(struct vm_area_struct *vma, + unsigned long address, pmd_t *pmdp) +{ + int young; + VM_BUG_ON(address & ~HPAGE_PMD_MASK); + young = pmdp_test_and_clear_young(vma, address, pmdp); + if (young) + flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); + return young; +} +#endif + +#ifndef __HAVE_ARCH_PMDP_HUGE_CLEAR_FLUSH +pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmdp) +{ + pmd_t pmd; + VM_BUG_ON(address & ~HPAGE_PMD_MASK); + VM_BUG_ON(pmd_present(*pmdp) && !pmd_trans_huge(*pmdp) && + !pmd_devmap(*pmdp)); + pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp); + flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); + return pmd; +} + +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD +pud_t pudp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address, + pud_t *pudp) +{ + pud_t pud; + + VM_BUG_ON(address & ~HPAGE_PUD_MASK); + VM_BUG_ON(!pud_trans_huge(*pudp) && !pud_devmap(*pudp)); + pud = pudp_huge_get_and_clear(vma->vm_mm, address, pudp); + flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE); + return pud; +} +#endif +#endif + +#ifndef __HAVE_ARCH_PGTABLE_DEPOSIT +void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp, + pgtable_t pgtable) +{ + assert_spin_locked(pmd_lockptr(mm, pmdp)); + + /* FIFO */ + if (!pmd_huge_pte(mm, pmdp)) + INIT_LIST_HEAD(&pgtable->lru); + else + list_add(&pgtable->lru, &pmd_huge_pte(mm, pmdp)->lru); + pmd_huge_pte(mm, pmdp) = pgtable; +} +#endif + +#ifndef __HAVE_ARCH_PGTABLE_WITHDRAW +/* no "address" argument so destroys page coloring of some arch */ +pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp) +{ + pgtable_t pgtable; + + assert_spin_locked(pmd_lockptr(mm, pmdp)); + + /* FIFO */ + pgtable = pmd_huge_pte(mm, pmdp); + pmd_huge_pte(mm, pmdp) = list_first_entry_or_null(&pgtable->lru, + struct page, lru); + if (pmd_huge_pte(mm, pmdp)) + list_del(&pgtable->lru); + return pgtable; +} +#endif + +#ifndef __HAVE_ARCH_PMDP_INVALIDATE +pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmdp) +{ + pmd_t old = pmdp_establish(vma, address, pmdp, pmd_mkinvalid(*pmdp)); + flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); + return old; +} +#endif + +#ifndef __HAVE_ARCH_PMDP_INVALIDATE_AD +pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmdp) +{ + return pmdp_invalidate(vma, address, pmdp); +} +#endif + +#ifndef pmdp_collapse_flush +pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmdp) +{ + /* + * pmd and hugepage pte format are same. So we could + * use the same function. + */ + pmd_t pmd; + + VM_BUG_ON(address & ~HPAGE_PMD_MASK); + VM_BUG_ON(pmd_trans_huge(*pmdp)); + pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp); + + /* collapse entails shooting down ptes not pmd */ + flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); + return pmd; +} +#endif + +/* arch define pte_free_defer in asm/pgalloc.h for its own implementation */ +#ifndef pte_free_defer +static void pte_free_now(struct rcu_head *head) +{ + struct page *page; + + page = container_of(head, struct page, rcu_head); + pte_free(NULL /* mm not passed and not used */, (pgtable_t)page); +} + +void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable) +{ + struct page *page; + + page = pgtable; + call_rcu(&page->rcu_head, pte_free_now); +} +#endif /* pte_free_defer */ +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ + +#if defined(CONFIG_GUP_GET_PXX_LOW_HIGH) && \ + (defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RCU)) +/* + * See the comment above ptep_get_lockless() in include/linux/pgtable.h: + * the barriers in pmdp_get_lockless() cannot guarantee that the value in + * pmd_high actually belongs with the value in pmd_low; but holding interrupts + * off blocks the TLB flush between present updates, which guarantees that a + * successful __pte_offset_map() points to a page from matched halves. + */ +static unsigned long pmdp_get_lockless_start(void) +{ + unsigned long irqflags; + + local_irq_save(irqflags); + return irqflags; +} +static void pmdp_get_lockless_end(unsigned long irqflags) +{ + local_irq_restore(irqflags); +} +#else +static unsigned long pmdp_get_lockless_start(void) { return 0; } +static void pmdp_get_lockless_end(unsigned long irqflags) { } +#endif + +pte_t *__pte_offset_map(pmd_t *pmd, unsigned long addr, pmd_t *pmdvalp) +{ + unsigned long irqflags; + pmd_t pmdval; + + rcu_read_lock(); + irqflags = pmdp_get_lockless_start(); + pmdval = pmdp_get_lockless(pmd); + pmdp_get_lockless_end(irqflags); + + if (pmdvalp) + *pmdvalp = pmdval; + if (unlikely(pmd_none(pmdval) || is_pmd_migration_entry(pmdval))) + goto nomap; + if (unlikely(pmd_trans_huge(pmdval) || pmd_devmap(pmdval))) + goto nomap; + if (unlikely(pmd_bad(pmdval))) { + pmd_clear_bad(pmd); + goto nomap; + } + return __pte_map(&pmdval, addr); +nomap: + rcu_read_unlock(); + return NULL; +} + +pte_t *pte_offset_map_nolock(struct mm_struct *mm, pmd_t *pmd, + unsigned long addr, spinlock_t **ptlp) +{ + pmd_t pmdval; + pte_t *pte; + + pte = __pte_offset_map(pmd, addr, &pmdval); + if (likely(pte)) + *ptlp = pte_lockptr(mm, &pmdval); + return pte; +} + +/* + * pte_offset_map_lock(mm, pmd, addr, ptlp), and its internal implementation + * __pte_offset_map_lock() below, is usually called with the pmd pointer for + * addr, reached by walking down the mm's pgd, p4d, pud for addr: either while + * holding mmap_lock or vma lock for read or for write; or in truncate or rmap + * context, while holding file's i_mmap_lock or anon_vma lock for read (or for + * write). In a few cases, it may be used with pmd pointing to a pmd_t already + * copied to or constructed on the stack. + * + * When successful, it returns the pte pointer for addr, with its page table + * kmapped if necessary (when CONFIG_HIGHPTE), and locked against concurrent + * modification by software, with a pointer to that spinlock in ptlp (in some + * configs mm->page_table_lock, in SPLIT_PTLOCK configs a spinlock in table's + * struct page). pte_unmap_unlock(pte, ptl) to unlock and unmap afterwards. + * + * But it is unsuccessful, returning NULL with *ptlp unchanged, if there is no + * page table at *pmd: if, for example, the page table has just been removed, + * or replaced by the huge pmd of a THP. (When successful, *pmd is rechecked + * after acquiring the ptlock, and retried internally if it changed: so that a + * page table can be safely removed or replaced by THP while holding its lock.) + * + * pte_offset_map(pmd, addr), and its internal helper __pte_offset_map() above, + * just returns the pte pointer for addr, its page table kmapped if necessary; + * or NULL if there is no page table at *pmd. It does not attempt to lock the + * page table, so cannot normally be used when the page table is to be updated, + * or when entries read must be stable. But it does take rcu_read_lock(): so + * that even when page table is racily removed, it remains a valid though empty + * and disconnected table. Until pte_unmap(pte) unmaps and rcu_read_unlock()s + * afterwards. + * + * pte_offset_map_nolock(mm, pmd, addr, ptlp), above, is like pte_offset_map(); + * but when successful, it also outputs a pointer to the spinlock in ptlp - as + * pte_offset_map_lock() does, but in this case without locking it. This helps + * the caller to avoid a later pte_lockptr(mm, *pmd), which might by that time + * act on a changed *pmd: pte_offset_map_nolock() provides the correct spinlock + * pointer for the page table that it returns. In principle, the caller should + * recheck *pmd once the lock is taken; in practice, no callsite needs that - + * either the mmap_lock for write, or pte_same() check on contents, is enough. + * + * Note that free_pgtables(), used after unmapping detached vmas, or when + * exiting the whole mm, does not take page table lock before freeing a page + * table, and may not use RCU at all: "outsiders" like khugepaged should avoid + * pte_offset_map() and co once the vma is detached from mm or mm_users is zero. + */ +pte_t *__pte_offset_map_lock(struct mm_struct *mm, pmd_t *pmd, + unsigned long addr, spinlock_t **ptlp) +{ + spinlock_t *ptl; + pmd_t pmdval; + pte_t *pte; +again: + pte = __pte_offset_map(pmd, addr, &pmdval); + if (unlikely(!pte)) + return pte; + ptl = pte_lockptr(mm, &pmdval); + spin_lock(ptl); + if (likely(pmd_same(pmdval, pmdp_get_lockless(pmd)))) { + *ptlp = ptl; + return pte; + } + pte_unmap_unlock(pte, ptl); + goto again; +} |