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-rw-r--r--mm/pagewalk.c163
1 files changed, 126 insertions, 37 deletions
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index ea0b9e606ad1..928df1638c30 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -4,26 +4,57 @@
#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)
+/*
+ * We want to know the real level where a entry is located ignoring any
+ * folding of levels which may be happening. For example if p4d is folded then
+ * a missing entry found at level 1 (p4d) is actually at level 0 (pgd).
+ */
+static int real_depth(int depth)
+{
+ if (depth == 3 && PTRS_PER_PMD == 1)
+ depth = 2;
+ if (depth == 2 && PTRS_PER_PUD == 1)
+ depth = 1;
+ if (depth == 1 && PTRS_PER_P4D == 1)
+ depth = 0;
+ return depth;
+}
+
+static int walk_pte_range_inner(pte_t *pte, unsigned long addr,
+ unsigned long end, struct mm_walk *walk)
{
- pte_t *pte;
- int err = 0;
const struct mm_walk_ops *ops = walk->ops;
- spinlock_t *ptl;
+ int err = 0;
- pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
for (;;) {
err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
if (err)
break;
- addr += PAGE_SIZE;
- if (addr == end)
+ if (addr >= end - PAGE_SIZE)
break;
+ addr += PAGE_SIZE;
pte++;
}
+ return err;
+}
+
+static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
+ struct mm_walk *walk)
+{
+ pte_t *pte;
+ int err = 0;
+ spinlock_t *ptl;
+
+ if (walk->no_vma) {
+ pte = pte_offset_map(pmd, addr);
+ err = walk_pte_range_inner(pte, addr, end, walk);
+ pte_unmap(pte);
+ } else {
+ pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+ err = walk_pte_range_inner(pte, addr, end, walk);
+ pte_unmap_unlock(pte, ptl);
+ }
- pte_unmap_unlock(pte, ptl);
return err;
}
@@ -34,18 +65,22 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
unsigned long next;
const struct mm_walk_ops *ops = walk->ops;
int err = 0;
+ int depth = real_depth(3);
pmd = pmd_offset(pud, addr);
do {
again:
next = pmd_addr_end(addr, end);
- if (pmd_none(*pmd) || !walk->vma) {
+ if (pmd_none(*pmd) || (!walk->vma && !walk->no_vma)) {
if (ops->pte_hole)
- err = ops->pte_hole(addr, next, walk);
+ err = ops->pte_hole(addr, next, depth, walk);
if (err)
break;
continue;
}
+
+ walk->action = ACTION_SUBTREE;
+
/*
* This implies that each ->pmd_entry() handler
* needs to know about pmd_trans_huge() pmds
@@ -55,16 +90,24 @@ again:
if (err)
break;
+ if (walk->action == ACTION_AGAIN)
+ goto again;
+
/*
* Check this here so we only break down trans_huge
* pages when we _need_ to
*/
- if (!ops->pte_entry)
+ if ((!walk->vma && (pmd_leaf(*pmd) || !pmd_present(*pmd))) ||
+ walk->action == ACTION_CONTINUE ||
+ !(ops->pte_entry))
continue;
- split_huge_pmd(walk->vma, pmd, addr);
- if (pmd_trans_unstable(pmd))
- goto again;
+ if (walk->vma) {
+ 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;
@@ -80,37 +123,41 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
unsigned long next;
const struct mm_walk_ops *ops = walk->ops;
int err = 0;
+ int depth = real_depth(2);
pud = pud_offset(p4d, addr);
do {
again:
next = pud_addr_end(addr, end);
- if (pud_none(*pud) || !walk->vma) {
+ if (pud_none(*pud) || (!walk->vma && !walk->no_vma)) {
if (ops->pte_hole)
- err = ops->pte_hole(addr, next, walk);
+ err = ops->pte_hole(addr, next, depth, walk);
if (err)
break;
continue;
}
- if (ops->pud_entry) {
- spinlock_t *ptl = pud_trans_huge_lock(pud, walk->vma);
+ walk->action = ACTION_SUBTREE;
- if (ptl) {
- err = ops->pud_entry(pud, addr, next, walk);
- spin_unlock(ptl);
- if (err)
- break;
- continue;
- }
- }
+ if (ops->pud_entry)
+ err = ops->pud_entry(pud, addr, next, walk);
+ if (err)
+ break;
+
+ if (walk->action == ACTION_AGAIN)
+ goto again;
- split_huge_pud(walk->vma, pud, addr);
+ if ((!walk->vma && (pud_leaf(*pud) || !pud_present(*pud))) ||
+ walk->action == ACTION_CONTINUE ||
+ !(ops->pmd_entry || ops->pte_entry))
+ continue;
+
+ if (walk->vma)
+ 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);
+ err = walk_pmd_range(pud, addr, next, walk);
if (err)
break;
} while (pud++, addr = next, addr != end);
@@ -125,18 +172,24 @@ static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
unsigned long next;
const struct mm_walk_ops *ops = walk->ops;
int err = 0;
+ int depth = real_depth(1);
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);
+ err = ops->pte_hole(addr, next, depth, walk);
if (err)
break;
continue;
}
- if (ops->pmd_entry || ops->pte_entry)
+ if (ops->p4d_entry) {
+ err = ops->p4d_entry(p4d, addr, next, walk);
+ if (err)
+ break;
+ }
+ if (ops->pud_entry || ops->pmd_entry || ops->pte_entry)
err = walk_pud_range(p4d, addr, next, walk);
if (err)
break;
@@ -153,17 +206,26 @@ static int walk_pgd_range(unsigned long addr, unsigned long end,
const struct mm_walk_ops *ops = walk->ops;
int err = 0;
- pgd = pgd_offset(walk->mm, addr);
+ if (walk->pgd)
+ pgd = walk->pgd + pgd_index(addr);
+ else
+ 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);
+ err = ops->pte_hole(addr, next, 0, walk);
if (err)
break;
continue;
}
- if (ops->pmd_entry || ops->pte_entry)
+ if (ops->pgd_entry) {
+ err = ops->pgd_entry(pgd, addr, next, walk);
+ if (err)
+ break;
+ }
+ if (ops->p4d_entry || ops->pud_entry || ops->pmd_entry ||
+ ops->pte_entry)
err = walk_p4d_range(pgd, addr, next, walk);
if (err)
break;
@@ -199,7 +261,7 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
if (pte)
err = ops->hugetlb_entry(pte, hmask, addr, next, walk);
else if (ops->pte_hole)
- err = ops->pte_hole(addr, next, walk);
+ err = ops->pte_hole(addr, next, -1, walk);
if (err)
break;
@@ -243,7 +305,7 @@ static int walk_page_test(unsigned long start, unsigned long end,
if (vma->vm_flags & VM_PFNMAP) {
int err = 1;
if (ops->pte_hole)
- err = ops->pte_hole(start, end, walk);
+ err = ops->pte_hole(start, end, -1, walk);
return err ? err : 1;
}
return 0;
@@ -369,6 +431,33 @@ int walk_page_range(struct mm_struct *mm, unsigned long start,
return err;
}
+/*
+ * Similar to walk_page_range() but can walk any page tables even if they are
+ * not backed by VMAs. Because 'unusual' entries may be walked this function
+ * will also not lock the PTEs for the pte_entry() callback. This is useful for
+ * walking the kernel pages tables or page tables for firmware.
+ */
+int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
+ unsigned long end, const struct mm_walk_ops *ops,
+ pgd_t *pgd,
+ void *private)
+{
+ struct mm_walk walk = {
+ .ops = ops,
+ .mm = mm,
+ .pgd = pgd,
+ .private = private,
+ .no_vma = true
+ };
+
+ if (start >= end || !walk.mm)
+ return -EINVAL;
+
+ lockdep_assert_held(&walk.mm->mmap_sem);
+
+ return __walk_page_range(start, end, &walk);
+}
+
int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
void *private)
{
generated by cgit v1.2.3 (git 2.39.1) at 2025-01-26 12:04:30 +0100