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608 lines
16 KiB
608 lines
16 KiB
// SPDX-License-Identifier: GPL-2.0 |
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#include <linux/pagewalk.h> |
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#include <linux/highmem.h> |
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#include <linux/sched.h> |
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#include <linux/hugetlb.h> |
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|
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/* |
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* We want to know the real level where a entry is located ignoring any |
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* folding of levels which may be happening. For example if p4d is folded then |
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* a missing entry found at level 1 (p4d) is actually at level 0 (pgd). |
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*/ |
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static int real_depth(int depth) |
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{ |
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if (depth == 3 && PTRS_PER_PMD == 1) |
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depth = 2; |
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if (depth == 2 && PTRS_PER_PUD == 1) |
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depth = 1; |
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if (depth == 1 && PTRS_PER_P4D == 1) |
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depth = 0; |
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return depth; |
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} |
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|
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static int walk_pte_range_inner(pte_t *pte, unsigned long addr, |
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unsigned long end, struct mm_walk *walk) |
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{ |
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const struct mm_walk_ops *ops = walk->ops; |
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int err = 0; |
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|
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for (;;) { |
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err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk); |
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if (err) |
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break; |
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if (addr >= end - PAGE_SIZE) |
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break; |
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addr += PAGE_SIZE; |
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pte++; |
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} |
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return err; |
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} |
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|
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static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, |
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struct mm_walk *walk) |
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{ |
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pte_t *pte; |
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int err = 0; |
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spinlock_t *ptl; |
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|
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if (walk->no_vma) { |
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pte = pte_offset_map(pmd, addr); |
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err = walk_pte_range_inner(pte, addr, end, walk); |
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pte_unmap(pte); |
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} else { |
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pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); |
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err = walk_pte_range_inner(pte, addr, end, walk); |
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pte_unmap_unlock(pte, ptl); |
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} |
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|
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return err; |
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} |
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|
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#ifdef CONFIG_ARCH_HAS_HUGEPD |
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static int walk_hugepd_range(hugepd_t *phpd, unsigned long addr, |
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unsigned long end, struct mm_walk *walk, int pdshift) |
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{ |
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int err = 0; |
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const struct mm_walk_ops *ops = walk->ops; |
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int shift = hugepd_shift(*phpd); |
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int page_size = 1 << shift; |
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|
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if (!ops->pte_entry) |
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return 0; |
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|
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if (addr & (page_size - 1)) |
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return 0; |
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for (;;) { |
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pte_t *pte; |
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|
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spin_lock(&walk->mm->page_table_lock); |
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pte = hugepte_offset(*phpd, addr, pdshift); |
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err = ops->pte_entry(pte, addr, addr + page_size, walk); |
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spin_unlock(&walk->mm->page_table_lock); |
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if (err) |
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break; |
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if (addr >= end - page_size) |
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break; |
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addr += page_size; |
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} |
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return err; |
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} |
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#else |
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static int walk_hugepd_range(hugepd_t *phpd, unsigned long addr, |
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unsigned long end, struct mm_walk *walk, int pdshift) |
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{ |
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return 0; |
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} |
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#endif |
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static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, |
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struct mm_walk *walk) |
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{ |
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pmd_t *pmd; |
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unsigned long next; |
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const struct mm_walk_ops *ops = walk->ops; |
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int err = 0; |
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int depth = real_depth(3); |
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|
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pmd = pmd_offset(pud, addr); |
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do { |
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again: |
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next = pmd_addr_end(addr, end); |
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if (pmd_none(*pmd) || (!walk->vma && !walk->no_vma)) { |
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if (ops->pte_hole) |
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err = ops->pte_hole(addr, next, depth, walk); |
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if (err) |
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break; |
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continue; |
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} |
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walk->action = ACTION_SUBTREE; |
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|
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/* |
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* This implies that each ->pmd_entry() handler |
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* needs to know about pmd_trans_huge() pmds |
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*/ |
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if (ops->pmd_entry) |
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err = ops->pmd_entry(pmd, addr, next, walk); |
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if (err) |
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break; |
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if (walk->action == ACTION_AGAIN) |
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goto again; |
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|
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/* |
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* Check this here so we only break down trans_huge |
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* pages when we _need_ to |
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*/ |
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if ((!walk->vma && (pmd_leaf(*pmd) || !pmd_present(*pmd))) || |
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walk->action == ACTION_CONTINUE || |
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!(ops->pte_entry)) |
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continue; |
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if (walk->vma) { |
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split_huge_pmd(walk->vma, pmd, addr); |
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if (pmd_trans_unstable(pmd)) |
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goto again; |
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} |
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if (is_hugepd(__hugepd(pmd_val(*pmd)))) |
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err = walk_hugepd_range((hugepd_t *)pmd, addr, next, walk, PMD_SHIFT); |
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else |
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err = walk_pte_range(pmd, addr, next, walk); |
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if (err) |
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break; |
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} while (pmd++, addr = next, addr != end); |
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return err; |
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} |
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static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, |
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struct mm_walk *walk) |
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{ |
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pud_t *pud; |
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unsigned long next; |
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const struct mm_walk_ops *ops = walk->ops; |
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int err = 0; |
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int depth = real_depth(2); |
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pud = pud_offset(p4d, addr); |
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do { |
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again: |
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next = pud_addr_end(addr, end); |
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if (pud_none(*pud) || (!walk->vma && !walk->no_vma)) { |
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if (ops->pte_hole) |
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err = ops->pte_hole(addr, next, depth, walk); |
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if (err) |
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break; |
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continue; |
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} |
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walk->action = ACTION_SUBTREE; |
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if (ops->pud_entry) |
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err = ops->pud_entry(pud, addr, next, walk); |
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if (err) |
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break; |
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if (walk->action == ACTION_AGAIN) |
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goto again; |
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if ((!walk->vma && (pud_leaf(*pud) || !pud_present(*pud))) || |
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walk->action == ACTION_CONTINUE || |
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!(ops->pmd_entry || ops->pte_entry)) |
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continue; |
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if (walk->vma) |
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split_huge_pud(walk->vma, pud, addr); |
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if (pud_none(*pud)) |
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goto again; |
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if (is_hugepd(__hugepd(pud_val(*pud)))) |
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err = walk_hugepd_range((hugepd_t *)pud, addr, next, walk, PUD_SHIFT); |
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else |
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err = walk_pmd_range(pud, addr, next, walk); |
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if (err) |
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break; |
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} while (pud++, addr = next, addr != end); |
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return err; |
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} |
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static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end, |
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struct mm_walk *walk) |
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{ |
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p4d_t *p4d; |
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unsigned long next; |
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const struct mm_walk_ops *ops = walk->ops; |
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int err = 0; |
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int depth = real_depth(1); |
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p4d = p4d_offset(pgd, addr); |
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do { |
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next = p4d_addr_end(addr, end); |
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if (p4d_none_or_clear_bad(p4d)) { |
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if (ops->pte_hole) |
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err = ops->pte_hole(addr, next, depth, walk); |
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if (err) |
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break; |
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continue; |
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} |
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if (ops->p4d_entry) { |
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err = ops->p4d_entry(p4d, addr, next, walk); |
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if (err) |
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break; |
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} |
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if (is_hugepd(__hugepd(p4d_val(*p4d)))) |
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err = walk_hugepd_range((hugepd_t *)p4d, addr, next, walk, P4D_SHIFT); |
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else if (ops->pud_entry || ops->pmd_entry || ops->pte_entry) |
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err = walk_pud_range(p4d, addr, next, walk); |
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if (err) |
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break; |
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} while (p4d++, addr = next, addr != end); |
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return err; |
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} |
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static int walk_pgd_range(unsigned long addr, unsigned long end, |
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struct mm_walk *walk) |
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{ |
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pgd_t *pgd; |
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unsigned long next; |
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const struct mm_walk_ops *ops = walk->ops; |
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int err = 0; |
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if (walk->pgd) |
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pgd = walk->pgd + pgd_index(addr); |
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else |
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pgd = pgd_offset(walk->mm, addr); |
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do { |
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next = pgd_addr_end(addr, end); |
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if (pgd_none_or_clear_bad(pgd)) { |
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if (ops->pte_hole) |
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err = ops->pte_hole(addr, next, 0, walk); |
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if (err) |
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break; |
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continue; |
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} |
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if (ops->pgd_entry) { |
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err = ops->pgd_entry(pgd, addr, next, walk); |
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if (err) |
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break; |
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} |
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if (is_hugepd(__hugepd(pgd_val(*pgd)))) |
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err = walk_hugepd_range((hugepd_t *)pgd, addr, next, walk, PGDIR_SHIFT); |
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else if (ops->p4d_entry || ops->pud_entry || ops->pmd_entry || ops->pte_entry) |
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err = walk_p4d_range(pgd, addr, next, walk); |
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if (err) |
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break; |
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} while (pgd++, addr = next, addr != end); |
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return err; |
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} |
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#ifdef CONFIG_HUGETLB_PAGE |
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static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr, |
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unsigned long end) |
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{ |
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unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h); |
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return boundary < end ? boundary : end; |
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} |
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static int walk_hugetlb_range(unsigned long addr, unsigned long end, |
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struct mm_walk *walk) |
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{ |
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struct vm_area_struct *vma = walk->vma; |
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struct hstate *h = hstate_vma(vma); |
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unsigned long next; |
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unsigned long hmask = huge_page_mask(h); |
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unsigned long sz = huge_page_size(h); |
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pte_t *pte; |
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const struct mm_walk_ops *ops = walk->ops; |
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int err = 0; |
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do { |
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next = hugetlb_entry_end(h, addr, end); |
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pte = huge_pte_offset(walk->mm, addr & hmask, sz); |
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if (pte) |
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err = ops->hugetlb_entry(pte, hmask, addr, next, walk); |
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else if (ops->pte_hole) |
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err = ops->pte_hole(addr, next, -1, walk); |
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if (err) |
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break; |
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} while (addr = next, addr != end); |
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return err; |
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} |
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#else /* CONFIG_HUGETLB_PAGE */ |
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static int walk_hugetlb_range(unsigned long addr, unsigned long end, |
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struct mm_walk *walk) |
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{ |
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return 0; |
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} |
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#endif /* CONFIG_HUGETLB_PAGE */ |
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/* |
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* Decide whether we really walk over the current vma on [@start, @end) |
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* or skip it via the returned value. Return 0 if we do walk over the |
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* current vma, and return 1 if we skip the vma. Negative values means |
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* error, where we abort the current walk. |
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*/ |
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static int walk_page_test(unsigned long start, unsigned long end, |
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struct mm_walk *walk) |
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{ |
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struct vm_area_struct *vma = walk->vma; |
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const struct mm_walk_ops *ops = walk->ops; |
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if (ops->test_walk) |
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return ops->test_walk(start, end, walk); |
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/* |
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* vma(VM_PFNMAP) doesn't have any valid struct pages behind VM_PFNMAP |
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* range, so we don't walk over it as we do for normal vmas. However, |
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* Some callers are interested in handling hole range and they don't |
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* want to just ignore any single address range. Such users certainly |
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* define their ->pte_hole() callbacks, so let's delegate them to handle |
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* vma(VM_PFNMAP). |
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*/ |
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if (vma->vm_flags & VM_PFNMAP) { |
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int err = 1; |
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if (ops->pte_hole) |
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err = ops->pte_hole(start, end, -1, walk); |
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return err ? err : 1; |
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} |
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return 0; |
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} |
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static int __walk_page_range(unsigned long start, unsigned long end, |
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struct mm_walk *walk) |
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{ |
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int err = 0; |
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struct vm_area_struct *vma = walk->vma; |
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const struct mm_walk_ops *ops = walk->ops; |
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if (vma && ops->pre_vma) { |
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err = ops->pre_vma(start, end, walk); |
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if (err) |
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return err; |
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} |
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if (vma && is_vm_hugetlb_page(vma)) { |
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if (ops->hugetlb_entry) |
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err = walk_hugetlb_range(start, end, walk); |
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} else |
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err = walk_pgd_range(start, end, walk); |
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if (vma && ops->post_vma) |
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ops->post_vma(walk); |
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return err; |
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} |
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/** |
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* walk_page_range - walk page table with caller specific callbacks |
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* @mm: mm_struct representing the target process of page table walk |
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* @start: start address of the virtual address range |
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* @end: end address of the virtual address range |
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* @ops: operation to call during the walk |
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* @private: private data for callbacks' usage |
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* |
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* Recursively walk the page table tree of the process represented by @mm |
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* within the virtual address range [@start, @end). During walking, we can do |
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* some caller-specific works for each entry, by setting up pmd_entry(), |
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* pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these |
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* callbacks, the associated entries/pages are just ignored. |
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* The return values of these callbacks are commonly defined like below: |
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* |
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* - 0 : succeeded to handle the current entry, and if you don't reach the |
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* end address yet, continue to walk. |
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* - >0 : succeeded to handle the current entry, and return to the caller |
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* with caller specific value. |
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* - <0 : failed to handle the current entry, and return to the caller |
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* with error code. |
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* |
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* Before starting to walk page table, some callers want to check whether |
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* they really want to walk over the current vma, typically by checking |
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* its vm_flags. walk_page_test() and @ops->test_walk() are used for this |
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* purpose. |
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* |
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* If operations need to be staged before and committed after a vma is walked, |
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* there are two callbacks, pre_vma() and post_vma(). Note that post_vma(), |
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* since it is intended to handle commit-type operations, can't return any |
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* errors. |
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* |
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* struct mm_walk keeps current values of some common data like vma and pmd, |
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* which are useful for the access from callbacks. If you want to pass some |
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* caller-specific data to callbacks, @private should be helpful. |
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* |
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* Locking: |
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* Callers of walk_page_range() and walk_page_vma() should hold @mm->mmap_lock, |
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* because these function traverse vma list and/or access to vma's data. |
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*/ |
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int walk_page_range(struct mm_struct *mm, unsigned long start, |
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unsigned long end, const struct mm_walk_ops *ops, |
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void *private) |
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{ |
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int err = 0; |
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unsigned long next; |
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struct vm_area_struct *vma; |
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struct mm_walk walk = { |
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.ops = ops, |
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.mm = mm, |
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.private = private, |
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}; |
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if (start >= end) |
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return -EINVAL; |
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if (!walk.mm) |
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return -EINVAL; |
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mmap_assert_locked(walk.mm); |
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vma = find_vma(walk.mm, start); |
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do { |
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if (!vma) { /* after the last vma */ |
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walk.vma = NULL; |
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next = end; |
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} else if (start < vma->vm_start) { /* outside vma */ |
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walk.vma = NULL; |
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next = min(end, vma->vm_start); |
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} else { /* inside vma */ |
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walk.vma = vma; |
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next = min(end, vma->vm_end); |
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vma = vma->vm_next; |
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err = walk_page_test(start, next, &walk); |
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if (err > 0) { |
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/* |
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* positive return values are purely for |
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* controlling the pagewalk, so should never |
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* be passed to the callers. |
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*/ |
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err = 0; |
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continue; |
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} |
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if (err < 0) |
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break; |
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} |
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if (walk.vma || walk.ops->pte_hole) |
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err = __walk_page_range(start, next, &walk); |
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if (err) |
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break; |
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} while (start = next, start < end); |
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return err; |
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} |
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|
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/* |
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* Similar to walk_page_range() but can walk any page tables even if they are |
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* not backed by VMAs. Because 'unusual' entries may be walked this function |
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* will also not lock the PTEs for the pte_entry() callback. This is useful for |
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* walking the kernel pages tables or page tables for firmware. |
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*/ |
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int walk_page_range_novma(struct mm_struct *mm, unsigned long start, |
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unsigned long end, const struct mm_walk_ops *ops, |
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pgd_t *pgd, |
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void *private) |
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{ |
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struct mm_walk walk = { |
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.ops = ops, |
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.mm = mm, |
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.pgd = pgd, |
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.private = private, |
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.no_vma = true |
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}; |
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|
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if (start >= end || !walk.mm) |
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return -EINVAL; |
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mmap_assert_locked(walk.mm); |
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|
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return __walk_page_range(start, end, &walk); |
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} |
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|
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int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops, |
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void *private) |
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{ |
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struct mm_walk walk = { |
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.ops = ops, |
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.mm = vma->vm_mm, |
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.vma = vma, |
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.private = private, |
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}; |
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int err; |
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|
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if (!walk.mm) |
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return -EINVAL; |
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mmap_assert_locked(walk.mm); |
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err = walk_page_test(vma->vm_start, vma->vm_end, &walk); |
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if (err > 0) |
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return 0; |
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if (err < 0) |
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return err; |
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return __walk_page_range(vma->vm_start, vma->vm_end, &walk); |
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} |
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|
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/** |
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* walk_page_mapping - walk all memory areas mapped into a struct address_space. |
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* @mapping: Pointer to the struct address_space |
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* @first_index: First page offset in the address_space |
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* @nr: Number of incremental page offsets to cover |
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* @ops: operation to call during the walk |
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* @private: private data for callbacks' usage |
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* |
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* This function walks all memory areas mapped into a struct address_space. |
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* The walk is limited to only the given page-size index range, but if |
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* the index boundaries cross a huge page-table entry, that entry will be |
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* included. |
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* |
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* Also see walk_page_range() for additional information. |
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* |
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* Locking: |
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* This function can't require that the struct mm_struct::mmap_lock is held, |
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* since @mapping may be mapped by multiple processes. Instead |
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* @mapping->i_mmap_rwsem must be held. This might have implications in the |
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* callbacks, and it's up tho the caller to ensure that the |
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* struct mm_struct::mmap_lock is not needed. |
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* |
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* Also this means that a caller can't rely on the struct |
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* vm_area_struct::vm_flags to be constant across a call, |
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* except for immutable flags. Callers requiring this shouldn't use |
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* this function. |
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* |
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* Return: 0 on success, negative error code on failure, positive number on |
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* caller defined premature termination. |
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*/ |
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int walk_page_mapping(struct address_space *mapping, pgoff_t first_index, |
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pgoff_t nr, const struct mm_walk_ops *ops, |
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void *private) |
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{ |
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struct mm_walk walk = { |
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.ops = ops, |
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.private = private, |
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}; |
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struct vm_area_struct *vma; |
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pgoff_t vba, vea, cba, cea; |
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unsigned long start_addr, end_addr; |
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int err = 0; |
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|
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lockdep_assert_held(&mapping->i_mmap_rwsem); |
|
vma_interval_tree_foreach(vma, &mapping->i_mmap, first_index, |
|
first_index + nr - 1) { |
|
/* Clip to the vma */ |
|
vba = vma->vm_pgoff; |
|
vea = vba + vma_pages(vma); |
|
cba = first_index; |
|
cba = max(cba, vba); |
|
cea = first_index + nr; |
|
cea = min(cea, vea); |
|
|
|
start_addr = ((cba - vba) << PAGE_SHIFT) + vma->vm_start; |
|
end_addr = ((cea - vba) << PAGE_SHIFT) + vma->vm_start; |
|
if (start_addr >= end_addr) |
|
continue; |
|
|
|
walk.vma = vma; |
|
walk.mm = vma->vm_mm; |
|
|
|
err = walk_page_test(vma->vm_start, vma->vm_end, &walk); |
|
if (err > 0) { |
|
err = 0; |
|
break; |
|
} else if (err < 0) |
|
break; |
|
|
|
err = __walk_page_range(start_addr, end_addr, &walk); |
|
if (err) |
|
break; |
|
} |
|
|
|
return err; |
|
}
|
|
|