// SPDX-License-Identifier: GPL-2.0
#include <linux/pagewalk.h>
#include <linux/highmem.h>
#include <linux/sched.h>
#include <linux/hugetlb.h>
static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
pte_t *pte;
int err = 0;
const struct mm_walk_ops *ops = walk->ops;
pte = pte_offset_map(pmd, addr);
for (;;) {
err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
if (err)
break;
addr += PAGE_SIZE;
if (addr == end)
break;
pte++;
}
pte_unmap(pte);
return err;
}
static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
pmd_t *pmd;
unsigned long next;
const struct mm_walk_ops *ops = walk->ops;
int err = 0;
pmd = pmd_offset(pud, addr);
do {
again:
next = pmd_addr_end(addr, end);
if (pmd_none(*pmd) || !walk->vma) {
if (ops->pte_hole)
err = ops->pte_hole(addr, next, walk);
if (err)
break;
continue;
}
/*
* This implies that each ->pmd_entry() handler
* needs to know about pmd_trans_huge() pmds
*/
if (ops->pmd_entry)
err = ops->pmd_entry(pmd, addr, next, walk);
if (err)
break;
/*
* Check this here so we only break down trans_huge
* pages when we _need_ to
*/
if (!ops->pte_entry)
continue;
split_huge_pmd(walk->vma, pmd, addr);
if (pmd_trans_unstable(pmd))
goto again;
err = walk_pte_range(pmd, addr, next, walk);
if (err)
break;
} while (pmd++, addr = next, addr != end);
return err;
}
static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
pud_t *pud;
unsigned long next;
const struct mm_walk_ops *ops = walk->ops;
int err = 0;
pud = pud_offset(p4d, addr);
do {
again:
next = pud_addr_end(addr, end);
if (pud_none(*pud) || !walk->vma) {
if (ops->pte_hole)
err = ops->pte_hole(addr, next, walk);
if (err)
break;
continue;
}
if (ops->pud_entry) {
spinlock_t *ptl = pud_trans_huge_lock(pud, walk->vma);
if (ptl) {
err = ops->pud_entry(pud, addr, next, walk);
spin_unlock(ptl);
if (err)
break;
continue;
}
}
split_huge_pud(walk->vma, pud, addr);
if (pud_none(*pud))
goto again;
if (ops->pmd_entry || ops->pte_entry)
err = walk_pmd_range(pud, addr, next, walk);
if (err)
break;
} while (pud++, addr = next, addr != end);
return err;
}
static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
p4d_t *p4d;
unsigned long next;
const struct mm_walk_ops *ops = walk->ops;
int err = 0;
p4d = p4d_offset(pgd, addr);
do {
next = p4d_addr_end(addr, end);
if (p4d_none_or_clear_bad(p4d)) {
if (ops->pte_hole)
err = ops->pte_hole(addr, next, walk);
if (err)
break;
continue;
}
if (ops->pmd_entry || ops->pte_entry)
err = walk_pud_range(p4d, addr, next, walk);
if (err)
break;
} while (p4d++, addr = next, addr != end);
return err;
}
static int walk_pgd_range(unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
pgd_t *pgd;
unsigned long next;
const struct mm_walk_ops *ops = walk->ops;
int err = 0;
pgd = pgd_offset(walk->mm, addr);
do {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd)) {
if (ops->pte_hole)
err = ops->pte_hole(addr, next, walk);
if (err)
break;
continue;
}
if (ops->pmd_entry || ops->pte_entry)
err = walk_p4d_range(pgd, addr, next, walk);
if (err)
break;
} while (pgd++, addr = next, addr != end);
return err;
}
#ifdef [31mCONFIG_HUGETLB_PAGE[0m
static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
unsigned long end)
{
unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
return boundary < end ? boundary : end;
}
static int walk_hugetlb_range(unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
struct vm_area_struct *vma = walk->vma;
struct hstate *h = hstate_vma(vma);
unsigned long next;
unsigned long hmask = huge_page_mask(h);
unsigned long sz = huge_page_size(h);
pte_t *pte;
const struct mm_walk_ops *ops = walk->ops;
int err = 0;
do {
next = hugetlb_entry_end(h, addr, end);
pte = huge_pte_offset(walk->mm, addr & hmask, sz);
if (pte)
err = ops->hugetlb_entry(pte, hmask, addr, next, walk);
else if (ops->pte_hole)
err = ops->pte_hole(addr, next, walk);
if (err)
break;
} while (addr = next, addr != end);
return err;
}
#else /* CONFIG_HUGETLB_PAGE */
static int walk_hugetlb_range(unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
return 0;
}
#endif /* CONFIG_HUGETLB_PAGE */
/*
* Decide whether we really walk over the current vma on [@start, @end)
* or skip it via the returned value. Return 0 if we do walk over the
* current vma, and return 1 if we skip the vma. Negative values means
* error, where we abort the current walk.
*/
static int walk_page_test(unsigned long start, unsigned long end,
struct mm_walk *walk)
{
struct vm_area_struct *vma = walk->vma;
const struct mm_walk_ops *ops = walk->ops;
if (ops->test_walk)
return ops->test_walk(start, end, walk);
/*
* vma(VM_PFNMAP) doesn't have any valid struct pages behind VM_PFNMAP
* range, so we don't walk over it as we do for normal vmas. However,
* Some callers are interested in handling hole range and they don't
* want to just ignore any single address range. Such users certainly
* define their ->pte_hole() callbacks, so let's delegate them to handle
* vma(VM_PFNMAP).
*/
if (vma->vm_flags & VM_PFNMAP) {
int err = 1;
if (ops->pte_hole)
err = ops->pte_hole(start, end, walk);
return err ? err : 1;
}
return 0;
}
static int __walk_page_range(unsigned long start, unsigned long end,
struct mm_walk *walk)
{
int err = 0;
struct vm_area_struct *vma = walk->vma;
if (vma && is_vm_hugetlb_page(vma)) {
if (walk->ops->hugetlb_entry)
err = walk_hugetlb_range(start, end, walk);
} else
err = walk_pgd_range(start, end, walk);
return err;
}
/**
* walk_page_range - walk page table with caller specific callbacks
* @mm: mm_struct representing the target process of page table walk
* @start: start address of the virtual address range
* @end: end address of the virtual address range
* @ops: operation to call during the walk
* @private: private data for callbacks' usage
*
* Recursively walk the page table tree of the process represented by @mm
* within the virtual address range [@start, @end). During walking, we can do
* some caller-specific works for each entry, by setting up pmd_entry(),
* pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these
* callbacks, the associated entries/pages are just ignored.
* The return values of these callbacks are commonly defined like below:
*
* - 0 : succeeded to handle the current entry, and if you don't reach the
* end address yet, continue to walk.
* - >0 : succeeded to handle the current entry, and return to the caller
* with caller specific value.
* - <0 : failed to handle the current entry, and return to the caller
* with error code.
*
* Before starting to walk page table, some callers want to check whether
* they really want to walk over the current vma, typically by checking
* its vm_flags. walk_page_test() and @ops->test_walk() are used for this
* purpose.
*
* struct mm_walk keeps current values of some common data like vma and pmd,
* which are useful for the access from callbacks. If you want to pass some
* caller-specific data to callbacks, @private should be helpful.
*
* Locking:
* Callers of walk_page_range() and walk_page_vma() should hold @mm->mmap_sem,
* because these function traverse vma list and/or access to vma's data.
*/
int walk_page_range(struct mm_struct *mm, unsigned long start,
unsigned long end, const struct mm_walk_ops *ops,
void *private)
{
int err = 0;
unsigned long next;
struct vm_area_struct *vma;
struct mm_walk walk = {
.ops = ops,
.mm = mm,
.private = private,
};
if (start >= end)
return -EINVAL;
if (!walk.mm)
return -EINVAL;
lockdep_assert_held(&walk.mm->mmap_sem);
vma = find_vma(walk.mm, start);
do {
if (!vma) { /* after the last vma */
walk.vma = NULL;
next = end;
} else if (start < vma->vm_start) { /* outside vma */
walk.vma = NULL;
next = min(end, vma->vm_start);
} else { /* inside vma */
walk.vma = vma;
next = min(end, vma->vm_end);
vma = vma->vm_next;
err = walk_page_test(start, next, &walk);
if (err > 0) {
/*
* positive return values are purely for
* controlling the pagewalk, so should never
* be passed to the callers.
*/
err = 0;
continue;
}
if (err < 0)
break;
}
if (walk.vma || walk.ops->pte_hole)
err = __walk_page_range(start, next, &walk);
if (err)
break;
} while (start = next, start < end);
return err;
}
int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
void *private)
{
struct mm_walk walk = {
.ops = ops,
.mm = vma->vm_mm,
.vma = vma,
.private = private,
};
int err;
if (!walk.mm)
return -EINVAL;
lockdep_assert_held(&walk.mm->mmap_sem);
err = walk_page_test(vma->vm_start, vma->vm_end, &walk);
if (err > 0)
return 0;
if (err < 0)
return err;
return __walk_page_range(vma->vm_start, vma->vm_end, &walk);
}