path: root/include/linux/pgtable.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_PGTABLE_H
#define _LINUX_PGTABLE_H

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

#ifndef __ASSEMBLY__
#ifdef CONFIG_MMU

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

/*
 * 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

#if defined(CONFIG_HIGHPTE)
#define pte_offset_map(dir, address)				\
	((pte_t *)kmap_atomic(pmd_page(*(dir))) +		\
	 pte_index((address)))
#define pte_unmap(pte) kunmap_atomic((pte))
#else
#define pte_offset_map(dir, address)	pte_offset_kernel((dir), (address))
#define pte_unmap(pte) ((void)(pte))	/* NOP */
#endif

/* 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 (pmd_t *)pud_page_vaddr(*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 (pud_t *)p4d_page_vaddr(*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
 */
#ifndef pgd_offset_k
#define pgd_offset_k(address)		pgd_offset(&init_mm, (address))
#endif

/*
 * In many cases it is known that a virtual address is mapped at PMD or PTE
 * level, so instead of traversing all the page table levels, we can get a
 * pointer to the PMD entry in user or kernel page table or translate a virtual
 * address to the pointer in the PTE in the kernel page tables with simple
 * helpers.
 */
static inline pmd_t *pmd_off(struct mm_struct *mm, unsigned long va)
{
	return pmd_offset(pud_offset(p4d_offset(pgd_offset(mm, va), va), va), va);
}

static inline pmd_t *pmd_off_k(unsigned long va)
{
	return pmd_offset(pud_offset(p4d_offset(pgd_offset_k(va), va), va), va);
}

static inline pte_t *virt_to_kpte(unsigned long vaddr)
{
	pmd_t *pmd = pmd_off_k(vaddr);

	return pmd_none(*pmd) ? NULL : pte_offset_kernel(pmd, vaddr);
}

#ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
extern int ptep_set_access_flags(struct vm_area_struct *vma,
				 unsigned long address, pte_t *ptep,
				 pte_t entry, int dirty);
#endif

#ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
extern int pmdp_set_access_flags(struct vm_area_struct *vma,
				 unsigned long address, pmd_t *pmdp,
				 pmd_t entry, int dirty);
extern int pudp_set_access_flags(struct vm_area_struct *vma,
				 unsigned long address, pud_t *pudp,
				 pud_t entry, int dirty);
#else
static inline int pmdp_set_access_flags(struct vm_area_struct *vma,
					unsigned long address, pmd_t *pmdp,
					pmd_t entry, int dirty)
{
	BUILD_BUG();
	return 0;
}
static inline int pudp_set_access_flags(struct vm_area_struct *vma,
					unsigned long address, pud_t *pud