1
  +   ˆl–Ü4ý( ©³( 	Å€fàB¦-ÿË„iÖ_†I|¥+ÂÉ ?÷     /* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_PGTABLE_H
#define _LINUX_PGTABLE_H

#include <linux/pfn.h>
#include <asm/pgtable.h>

#define PMD_ORDER	(PMD_SHIFT - PAGE_SHIFT)
#define PUD_ORDER	(PUD_SHIFT - PAGE_SHIFT)

#ifndef __ASSEMBLY__
#ifdef CONFIG_MMU

#include <linux/mm_types.h>
#include <linux/bug.h>
#include <linux/errno.h>
#include <asm-generic/pgtable_uffd.h>
#include <linux/page_table_check.h>

#if 5 - defined(__PAGETABLE_P4D_FOLDED) - defined(__PAGETABLE_PUD_FOLDED) - \
	defined(__PAGETABLE_PMD_FOLDED) != CONFIG_PGTABLE_LEVELS
#error CONFIG_PGTABLE_LEVELS is not consistent with __PAGETABLE_{P4D,PUD,PMD}_FOLDED
#endif

/*
 * On almost all architectures and configurations, 0 can be used as the
 * upper ceiling to free_pgtables(): on many architectures it has the same
 * effect as using TASK_SIZE.  However, there is one configuration which
 * must impose a more careful limit, to avoid freeing kernel pgtables.
 */
#ifndef USER_PGTABLES_CEILING
#define USER_PGTABLES_CEILING	0UL
#endif

/*
 * This defines the first usable user address. Platforms
 * can override its value with custom FIRST_USER_ADDRESS
 * defined in their respective <asm/pgtable.h>.
 */
#ifndef FIRST_USER_ADDRESS
#define FIRST_USER_ADDRESS	0UL
#endif

/*
 * This defines the generic helper for accessing PMD page
 * table page. Although platforms can still override this
 * via their respective <asm/pgtable.h>.
 */
#ifndef pmd_pgtable
#define pmd_pgtable(pmd) pmd_page(pmd)
#endif

/*
 * A page table page can be thought of an array like this: pXd_t[PTRS_PER_PxD]
 *
 * The pXx_index() functions return the index of the entry in the page
 * table page which would control the given virtual address
 *
 * As these functions may be used by the same code for different levels of
 * the page table folding, they are always available, regardless of
 * CONFIG_PGTABLE_LEVELS value. For the folded levels they simply return 0
 * because in such cases PTRS_PER_PxD equals 1.
 */

static inline unsigned long pte_index(unsigned long address)
{
	return (address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
}

#ifndef pmd_index
static inline unsigned long pmd_index(unsigned long address)
{
	return (address >> PMD_SHIFT) & (PTRS_PER_PMD - 1);
}
#define pmd_index pmd_index
#endif

#ifndef pud_index
static inline unsigned long pud_index(unsigned long address)
{
	return (address >> PUD_SHIFT) & (PTRS_PER_PUD - 1);
}
#define pud_index pud_index
#endif

#ifndef pgd_index
/* Must be a compile-time constant, so implement it as a macro */
#define pgd_index(a)  (((a) >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1))
#endif

#ifndef pte_offset_kernel
static inline pte_t *pte_offset_kernel(pmd_t *pmd, unsigned long address)
{
	return (pte_t *)pmd_page_vaddr(*pmd) + pte_index(address);
}
#define pte_offset_kernel pte_offset_kernel
#endif

#ifdef CONFIG_HIGHPTE
#define __pte_map(pmd, address) \
	((pte_t *)kmap_local_page(pmd_page(*(pmd))) + pte_index((address)))
#define pte_unmap(pte)	do {	\
	kunmap_local((pte));	\
	rcu_read_unlock();	\
} while (0)
#else
static inline pte_t *__pte_map(pmd_t *pmd, unsigned long address)
{
	return pte_offset_kernel(pmd, address);
}
static inline void pte_unmap(pte_t *pte)
{
	rcu_read_unlock();
}
#endif

void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable);

/* Find an entry in the second-level page table.. */
#ifndef pmd_offset
static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
{
	return pud_pgtable(*pud) + pmd_index(address);
}
#define pmd_offset pmd_offset
#endif

#ifndef pud_offset
static inline pud_t *pud_offset(p4d_t *p4d, unsigned long address)
{
	return p4d_pgtable(*p4d) + pud_index(address);
}
#define pud_offset pud_offset
#endif

static inline pgd_t *pgd_offset_pgd(pgd_t *pgd, unsigned long address)
{
	return (pgd + pgd_index(address));
};

/*
 * a shortcut to get a pgd_t in a given mm
 */
#ifndef pgd_offset
#define pgd_offset(mm, address)		pgd_offset_pgd((mm)->pgd, (address))
#endif

/*
 * a shortcut which implies the use of the kernel's pgd, instead
 * of a process's
 */
#i