LXR linux/mm/pt

   1// SPDX-License-Identifier: GPL-2.0
   2#include <linux/hugetlb.h>
   3#include <asm-generic/tlb.h>
   4#include <asm/pgalloc.h>
   5
   6#include "internal.h"
   7
   8bool reclaim_pt_is_enabled(unsigned long start, unsigned long end,
   9                           struct zap_details *details)
  10{
  11        return details && details->reclaim_pt && (end - start >= PMD_SIZE);
  12}
  13
  14bool try_get_and_clear_pmd(struct mm_struct *mm, pmd_t *pmd, pmd_t *pmdval)
  15{
  16        spinlock_t *pml = pmd_lockptr(mm, pmd);
  17
  18        if (!spin_trylock(pml))
  19                return false;
  20
  21        *pmdval = pmdp_get_lockless(pmd);
  22        pmd_clear(pmd);
  23        spin_unlock(pml);
  24
  25        return true;
  26}
  27
  28void free_pte(struct mm_struct *mm, unsigned long addr, struct mmu_gather *tlb,
  29              pmd_t pmdval)
  30{
  31        pte_free_tlb(tlb, pmd_pgtable(pmdval), addr);
  32        mm_dec_nr_ptes(mm);
  33}
  34
  35void try_to_free_pte(struct mm_struct *mm, pmd_t *pmd, unsigned long addr,
  36                     struct mmu_gather *tlb)
  37{
  38        pmd_t pmdval;
  39        spinlock_t *pml, *ptl = NULL;
  40        pte_t *start_pte, *pte;
  41        int i;
  42
  43        pml = pmd_lock(mm, pmd);
  44        start_pte = pte_offset_map_rw_nolock(mm, pmd, addr, &pmdval, &ptl);
  45        if (!start_pte)
  46                goto out_ptl;
  47        if (ptl != pml)
  48                spin_lock_nested(ptl, SINGLE_DEPTH_NESTING);
  49
  50        /* Check if it is empty PTE page */
  51        for (i = 0, pte = start_pte; i < PTRS_PER_PTE; i++, pte++) {
  52                if (!pte_none(ptep_get(pte)))
  53                        goto out_ptl;
  54        }
  55        pte_unmap(start_pte);
  56
  57        pmd_clear(pmd);
  58
  59        if (ptl != pml)
  60                spin_unlock(ptl);
  61        spin_unlock(pml);
  62
  63        free_pte(mm, addr, tlb, pmdval);
  64
  65        return;
  66out_ptl:
  67        if (start_pte)
  68                pte_unmap_unlock(start_pte, ptl);
  69        if (ptl != pml)
  70                spin_unlock(pml);
  71}
  72