// SPDX-License-Identifier: GPL-2.0
  
  #include <linux/pagewalk.h>
  #include <linux/ptdump.h>
  #include <linux/kasan.h>
  
  #ifdef CONFIG_KASAN
  /*
   * This is an optimization for KASAN=y case. Since all kasan page tables
   * eventually point to the kasan_early_shadow_page we could call note_page()
   * right away without walking through lower level page tables. This saves
   * us dozens of seconds (minutes for 5-level config) while checking for
   * W+X mapping or reading kernel_page_tables debugfs file.
   */
  static inline int note_kasan_page_table(struct mm_walk *walk,
  					unsigned long addr)
  {
  	struct ptdump_state *st = walk->private;

  	st->note_page(st, addr, 4, pte_val(kasan_early_shadow_pte[0]));

  
  	walk->action = ACTION_CONTINUE;
  
  	return 0;
  }
  #endif
  
  static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr,
  			    unsigned long next, struct mm_walk *walk)
  {
  	struct ptdump_state *st = walk->private;
  	pgd_t val = READ_ONCE(*pgd);
  
  #if CONFIG_PGTABLE_LEVELS > 4 && defined(CONFIG_KASAN)
  	if (pgd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_p4d)))
  		return note_kasan_page_table(walk, addr);
  #endif

  	if (st->effective_prot)
  		st->effective_prot(st, 0, pgd_val(val));

  	if (pgd_leaf(val))

  		st->note_page(st, addr, 0, pgd_val(val));

  
  	return 0;
  }
  
  static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
  			    unsigned long next, struct mm_walk *walk)
  {
  	struct ptdump_state *st = walk->private;
  	p4d_t val = READ_ONCE(*p4d);
  
  #if CONFIG_PGTABLE_LEVELS > 3 && defined(CONFIG_KASAN)
  	if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud)))
  		return note_kasan_page_table(walk, addr);
  #endif

  	if (st->effective_prot)
  		st->effective_prot(st, 1, p4d_val(val));

  	if (p4d_leaf(val))

  		st->note_page(st, addr, 1, p4d_val(val));

  
  	return 0;
  }
  
  static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
  			    unsigned long next, struct mm_walk *walk)
  {
  	struct ptdump_state *st = walk->private;
  	pud_t val = READ_ONCE(*pud);
  
  #if CONFIG_PGTABLE_LEVELS > 2 && defined(CONFIG_KASAN)
  	if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd)))
  		return note_kasan_page_table(walk, addr);
  #endif

  	if (st->effective_prot)
  		st->effective_prot(st, 2, pud_val(val));

  	if (pud_leaf(val))

  		st->note_page(st, addr, 2, pud_val(val));

  
  	return 0;
  }
  
  static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
  			    unsigned long next, struct mm_walk *walk)
  {
  	struct ptdump_state *st = walk->private;
  	pmd_t val = READ_ONCE(*pmd);
  
  #if defined(CONFIG_KASAN)
  	if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte)))
  		return note_kasan_page_table(walk, addr);
  #endif

  	if (st->effective_prot)
  		st->effective_prot(st, 3, pmd_val(val));

  	if (pmd_leaf(val))

  		st->note_page(st, addr, 3, pmd_val(val));

  
  	return 0;
  }
  
  static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
  			    unsigned long next, struct mm_walk *walk)
  {
  	struct ptdump_state *st = walk->private;

  	pte_t val = READ_ONCE(*pte);
  
  	if (st->effective_prot)
  		st->effective_prot(st, 4, pte_val(val));

  	st->note_page(st, addr, 4, pte_val(val));

  
  	return 0;
  }
  
  static int ptdump_hole(unsigned long addr, unsigned long next,
  		       int depth, struct mm_walk *walk)
  {
  	struct ptdump_state *st = walk->private;

  	st->note_page(st, addr, depth, 0);

  
  	return 0;
  }
  
  static const struct mm_walk_ops ptdump_ops = {
  	.pgd_entry	= ptdump_pgd_entry,
  	.p4d_entry	= ptdump_p4d_entry,
  	.pud_entry	= ptdump_pud_entry,
  	.pmd_entry	= ptdump_pmd_entry,
  	.pte_entry	= ptdump_pte_entry,
  	.pte_hole	= ptdump_hole,
  };

  void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd)

  {
  	const struct ptdump_range *range = st->range;

  	mmap_read_lock(mm);

  	while (range->start != range->end) {
  		walk_page_range_novma(mm, range->start, range->end,

  				      &ptdump_ops, pgd, st);

  		range++;
  	}

  	mmap_read_unlock(mm);

  
  	/* Flush out the last page */

  	st->note_page(st, 0, -1, 0);

  }