This IOCTL, PAGEMAP_SCAN on pagemap file can be used to get and/or clear
the info about page table entries. The following operations are supported
in this ioctl:
- Get the information if the pages have been written-to (PAGE_IS_WRITTEN),
file mapped (PAGE_IS_FILE), present (PAGE_IS_PRESENT), swapped
(PAGE_IS_SWAPPED) or page has pfn zero (PAGE_IS_PFNZERO).
- Find pages which have been written-to and/or write protect the pages
(atomic PM_SCAN_OP_GET + PM_SCAN_OP_WP)
This IOCTL can be extended to get information about more PTE bits. The
entire address range passed by user [start, end) is scanned until either
the user provided buffer is full or max_pages have been found.
Signed-off-by: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
---
Changes in v25:
- Do proper filtering on hole as well (hole got missed earlier)
Changes in v24:
- Place WP markers in case of hole as well
Changes in v23:
- Set vec_buf_index to 0 only when vec_buf_index is set
- Return -EFAULT instead of -EINVAL if vec is NULL
- Correctly return the walk ending address to the page granularity
Changes in v22:
- Interface change to return walk ending address to user:
- Replace [start start + len) with [start, end)
- Return the ending address of the address walk in start
Changes in v21:
- Abort walk instead of returning error if WP is to be performed on
partial hugetlb
- Changed the data types of some variables in pagemap_scan_private to
long
Changes in v20:
- Correct PAGE_IS_FILE and add PAGE_IS_PFNZERO
Changes in v19:
- Interface changes such as renaming, return mask and WP can be used
with any flags specified in masks
- Internal code changes
Changes in v18:
- Rebased on top of next-20230613
- ptep_get() updates
- remove pmd_trans_unstable() and add ACTION_AGAIN
- Review updates (Micheal)
Changes in v17:
- Rebased on next-20230606
- Made make_uffd_wp_*_pte() better and minor changes
Changes in v16:
- Fixed a corner case where kernel writes beyond user buffer by one
element
- Bring back exclusive PM_SCAN_OP_WP
- Cosmetic changes
Changes in v15:
- Build fix:
- Use generic tlb flush function in pagemap_scan_pmd_entry() instead of
using x86 specific flush function in do_pagemap_scan()
- Remove #ifdef from pagemap_scan_hugetlb_entry()
- Use mm instead of undefined vma->vm_mm
Changes in v14:
- Fix build error caused by #ifdef added at last minute in some configs
Changes in v13:
- Review updates
- mmap_read_lock_killable() instead of mmap_read_lock()
- Replace uffd_wp_range() with helpers which increases performance
drastically for OP_WP operations by reducing the number of tlb
flushing etc
- Add MMU_NOTIFY_PROTECTION_VMA notification for the memory range
Changes in v12:
- Add hugetlb support to cover all memory types
- Merge "userfaultfd: Define dummy uffd_wp_range()" with this patch
- Review updates to the code
Changes in v11:
- Find written pages in a better way
- Fix a corner case (thanks Paul)
- Improve the code/comments
- remove ENGAGE_WP + ! GET operation
- shorten the commit message in favour of moving documentation to
pagemap.rst
Changes in v10:
- move changes in tools/include/uapi/linux/fs.h to separate patch
- update commit message
Change in v8:
- Correct is_pte_uffd_wp()
- Improve readability and error checks
- Remove some un-needed code
Changes in v7:
- Rebase on top of latest next
- Fix some corner cases
- Base soft-dirty on the uffd wp async
- Update the terminologies
- Optimize the memory usage inside the ioctl
---
fs/proc/task_mmu.c | 591 ++++++++++++++++++++++++++++++++++++++++
include/linux/hugetlb.h | 1 +
include/uapi/linux/fs.h | 55 ++++
mm/hugetlb.c | 2 +-
4 files changed, 648 insertions(+), 1 deletion(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index cfab855fe7e9..596fdfdc4387 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -19,6 +19,7 @@
#include <linux/shmem_fs.h>
#include <linux/uaccess.h>
#include <linux/pkeys.h>
+#include <linux/minmax.h>
#include <asm/elf.h>
#include <asm/tlb.h>
@@ -1768,11 +1769,601 @@ static int pagemap_release(struct inode *inode, struct file *file)
return 0;
}
+#define PM_SCAN_REQUIRE_UFFD (1ULL << 63)
+
+#define PM_SCAN_FOUND_MAX_PAGES (1)
+#define PM_SCAN_END_WALK (-256)
+
+#define PM_SCAN_BITS_ALL (PAGE_IS_WRITTEN | PAGE_IS_FILE | \
+ PAGE_IS_PRESENT | PAGE_IS_SWAPPED | \
+ PAGE_IS_PFNZERO)
+#define PM_SCAN_OPS (PM_SCAN_OP_GET | PM_SCAN_OP_WP)
+#define IS_PM_SCAN_GET(flags) (flags & PM_SCAN_OP_GET)
+#define IS_PM_SCAN_WP(flags) (flags & PM_SCAN_OP_WP)
+
+#define PM_SCAN_FLAGS(wt, file, present, swap, pfnzero) \
+ ((wt) | ((file) << 1) | ((present) << 2) | \
+ ((swap) << 3) | ((pfnzero) << 4))
+
+struct pagemap_scan_private {
+ struct page_region *vec_buf, cur_buf;
+ unsigned long vec_buf_len, vec_buf_index, max_pages, found_pages;
+ unsigned long long flags, required_mask, anyof_mask, excluded_mask, return_mask, end_addr;
+};
+
+static inline bool is_pte_uffd_wp(pte_t pte)
+{
+ return (pte_present(pte) && pte_uffd_wp(pte)) ||
+ pte_swp_uffd_wp_any(pte);
+}
+
+static inline void make_uffd_wp_pte(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *pte)
+{
+ pte_t ptent = ptep_get(pte);
+
+ if (pte_present(ptent)) {
+ pte_t old_pte;
+
+ old_pte = ptep_modify_prot_start(vma, addr, pte);
+ ptent = pte_mkuffd_wp(ptent);
+ ptep_modify_prot_commit(vma, addr, pte, old_pte, ptent);
+ } else if (is_swap_pte(ptent)) {
+ ptent = pte_swp_mkuffd_wp(ptent);
+ set_pte_at(vma->vm_mm, addr, pte, ptent);
+ } else {
+ set_pte_at(vma->vm_mm, addr, pte,
+ make_pte_marker(PTE_MARKER_UFFD_WP));
+ }
+}
+
+static inline bool pagemap_scan_is_file(struct vm_area_struct *vma, pte_t ptent,
+ unsigned long addr)
+{
+ struct page *page = NULL;
+ swp_entry_t entry;
+
+ if (pte_present(ptent)) {
+ page = vm_normal_page(vma, addr, ptent);
+ } else {
+ entry = pte_to_swp_entry(ptent);
+ if (is_pfn_swap_entry(entry))
+ page = pfn_swap_entry_to_page(entry);
+ }
+
+ if (page && !PageAnon(page))
+ return true;
+
+ return false;
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline bool is_pmd_uffd_wp(pmd_t pmd)
+{
+ return (pmd_present(pmd) && pmd_uffd_wp(pmd)) ||
+ (is_swap_pmd(pmd) && pmd_swp_uffd_wp(pmd));
+}
+
+static inline void make_uffd_wp_pmd(struct vm_area_struct *vma,
+ unsigned long addr, pmd_t *pmdp)
+{
+ pmd_t old, pmd = *pmdp;
+
+ if (pmd_present(pmd)) {
+ old = pmdp_invalidate_ad(vma, addr, pmdp);
+ pmd = pmd_mkuffd_wp(old);
+ set_pmd_at(vma->vm_mm, addr, pmdp, pmd);
+ } else if (is_migration_entry(pmd_to_swp_entry(pmd))) {
+ pmd = pmd_swp_mkuffd_wp(pmd);
+ set_pmd_at(vma->vm_mm, addr, pmdp, pmd);
+ }
+}
+#endif
+
+#ifdef CONFIG_HUGETLB_PAGE
+static inline bool is_huge_pte_uffd_wp(pte_t pte)
+{
+ return (pte_present(pte) && huge_pte_uffd_wp(pte)) ||
+ pte_swp_uffd_wp_any(pte);
+}
+
+static inline void make_uffd_wp_huge_pte(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep,
+ pte_t ptent)
+{
+ if (is_hugetlb_entry_hwpoisoned(ptent) || is_pte_marker(ptent))
+ return;
+
+ if (is_hugetlb_entry_migration(ptent))
+ set_huge_pte_at(vma->vm_mm, addr, ptep,
+ pte_swp_mkuffd_wp(ptent));
+ else if (!huge_pte_none(ptent))
+ huge_ptep_modify_prot_commit(vma, addr, ptep, ptent,
+ huge_pte_mkuffd_wp(ptent));
+ else
+ set_huge_pte_at(vma->vm_mm, addr, ptep,
+ make_pte_marker(PTE_MARKER_UFFD_WP));
+}
+
+static inline bool pagemap_scan_is_huge_file(pte_t pte)
+{
+ if (pte_present(pte) && (!PageAnon(pte_page(pte))))
+ return true;
+
+ return false;
+}
+#endif
+
+static int pagemap_scan_test_walk(unsigned long start, unsigned long end,
+ struct mm_walk *walk)
+{
+ struct pagemap_scan_private *p = walk->private;
+ struct vm_area_struct *vma = walk->vma;
+
+ if ((p->flags & PM_SCAN_REQUIRE_UFFD) && (!userfaultfd_wp_async(vma) ||
+ !userfaultfd_wp_use_markers(vma)))
+ return -EPERM;
+
+ if (vma->vm_flags & VM_PFNMAP)
+ return 1;
+
+ return 0;
+}
+
+static int pagemap_scan_output(unsigned long bitmap,
+ struct pagemap_scan_private *p,
+ unsigned long addr, unsigned int n_pages)
+{
+ struct page_region *cur_buf = &p->cur_buf;
+
+ bitmap &= p->return_mask;
+
+ if (cur_buf->flags == bitmap &&
+ cur_buf->start + cur_buf->len * PAGE_SIZE == addr) {
+ cur_buf->len += n_pages;
+ p->found_pages += n_pages;
+ } else {
+ if (cur_buf->len) {
+ if (p->vec_buf_index >= p->vec_buf_len) {
+ p->end_addr = addr;
+ return PM_SCAN_END_WALK;
+ }
+
+ memcpy(&p->vec_buf[p->vec_buf_index], cur_buf,
+ sizeof(*p->vec_buf));
+ p->vec_buf_index++;
+ }
+
+ cur_buf->start = addr;
+ cur_buf->len = n_pages;
+ cur_buf->flags = bitmap;
+ p->found_pages += n_pages;
+ }
+
+ if (p->found_pages == p->max_pages) {
+ p->end_addr = addr + n_pages * PAGE_SIZE;
+ return PM_SCAN_FOUND_MAX_PAGES;
+ }
+
+ return 0;
+}
+
+static bool pagemap_scan_is_interesting_page(unsigned long bitmap,
+ struct pagemap_scan_private *p)
+{
+ if ((p->required_mask & bitmap) != p->required_mask)
+ return false;
+ if (p->anyof_mask && !(p->anyof_mask & bitmap))
+ return false;
+ if (p->excluded_mask & bitmap)
+ return false;
+
+ return true;
+}
+
+static int pagemap_scan_pmd_entry(pmd_t *pmd, unsigned long start,
+ unsigned long end, struct mm_walk *walk)
+{
+ bool is_written, flush = false, interesting = true;
+ struct pagemap_scan_private *p = walk->private;
+ struct vm_area_struct *vma = walk->vma;
+ unsigned long bitmap, addr = end;
+ pte_t *pte, *orig_pte, ptent;
+ spinlock_t *ptl;
+ int ret = 0;
+
+ arch_enter_lazy_mmu_mode();
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ ptl = pmd_trans_huge_lock(pmd, vma);
+ if (ptl) {
+ unsigned long n_pages = (end - start)/PAGE_SIZE;
+
+ if (n_pages > p->max_pages - p->found_pages)
+ n_pages = p->max_pages - p->found_pages;
+
+ is_written = !is_pmd_uffd_wp(*pmd);
+
+ bitmap = PM_SCAN_FLAGS(is_written, false,
+ pmd_present(*pmd), is_swap_pmd(*pmd),
+ pmd_present(*pmd) && is_zero_pfn(pmd_pfn(*pmd)));
+
+ if (IS_PM_SCAN_GET(p->flags))
+ interesting = pagemap_scan_is_interesting_page(bitmap, p);
+
+ if (interesting) {
+ /*
+ * Break huge page into small pages if the WP operation
+ * need to be performed is on a portion of the huge page.
+ */
+ if (is_written && IS_PM_SCAN_WP(p->flags) &&
+ n_pages < HPAGE_SIZE/PAGE_SIZE) {
+ spin_unlock(ptl);
+
+ split_huge_pmd(vma, pmd, start);
+ goto process_smaller_pages;
+ }
+
+ if (IS_PM_SCAN_GET(p->flags))
+ ret = pagemap_scan_output(bitmap, p, start, n_pages);
+
+ if (IS_PM_SCAN_WP(p->flags) && is_written && ret >= 0) {
+ make_uffd_wp_pmd(vma, start, pmd);
+ flush_tlb_range(vma, start, end);
+ }
+ }
+
+ spin_unlock(ptl);
+ arch_leave_lazy_mmu_mode();
+
+ return ret;
+ }
+
+process_smaller_pages:
+#endif
+
+ orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
+ if (!pte) {
+ walk->action = ACTION_AGAIN;
+ return 0;
+ }
+
+ for (addr = start; addr < end && !ret; pte++, addr += PAGE_SIZE) {
+ ptent = ptep_get(pte);
+ is_written = !is_pte_uffd_wp(ptent);
+
+ bitmap = PM_SCAN_FLAGS(is_written, pagemap_scan_is_file(vma, ptent, addr),
+ pte_present(ptent), is_swap_pte(ptent),
+ pte_present(ptent) && is_zero_pfn(pte_pfn(ptent)));
+
+ if (IS_PM_SCAN_GET(p->flags)) {
+ interesting = pagemap_scan_is_interesting_page(bitmap, p);
+ if (interesting)
+ ret = pagemap_scan_output(bitmap, p, addr, 1);
+ }
+
+ if (IS_PM_SCAN_WP(p->flags) && is_written && interesting &&
+ ret >= 0) {
+ make_uffd_wp_pte(vma, addr, pte);
+ flush = true;
+ }
+ }
+
+ if (flush)
+ flush_tlb_range(vma, start, addr);
+
+ pte_unmap_unlock(orig_pte, ptl);
+ arch_leave_lazy_mmu_mode();
+
+ cond_resched();
+ return ret;
+}
+
+#ifdef CONFIG_HUGETLB_PAGE
+static int pagemap_scan_hugetlb_entry(pte_t *ptep, unsigned long hmask,
+ unsigned long start, unsigned long end,
+ struct mm_walk *walk)
+{
+ unsigned long n_pages = (end - start)/PAGE_SIZE;
+ struct pagemap_scan_private *p = walk->private;
+ struct vm_area_struct *vma = walk->vma;
+ bool is_written, interesting = true;
+ struct hstate *h = hstate_vma(vma);
+ unsigned long bitmap;
+ spinlock_t *ptl;
+ int ret = 0;
+ pte_t ptent;
+
+ if (IS_PM_SCAN_WP(p->flags) && n_pages < HPAGE_SIZE/PAGE_SIZE) {
+ p->end_addr = start;
+ return -EINVAL;
+ }
+
+ if (n_pages > p->max_pages - p->found_pages)
+ n_pages = p->max_pages - p->found_pages;
+
+ if (IS_PM_SCAN_WP(p->flags)) {
+ i_mmap_lock_write(vma->vm_file->f_mapping);
+ ptl = huge_pte_lock(h, vma->vm_mm, ptep);
+ }
+
+ ptent = huge_ptep_get(ptep);
+ is_written = !is_huge_pte_uffd_wp(ptent);
+
+ bitmap = PM_SCAN_FLAGS(is_written, pagemap_scan_is_huge_file(ptent),
+ pte_present(ptent), is_swap_pte(ptent),
+ pte_present(ptent) && is_zero_pfn(pte_pfn(ptent)));
+
+ if (IS_PM_SCAN_GET(p->flags))
+ interesting = pagemap_scan_is_interesting_page(bitmap, p);
+
+ if (interesting) {
+ /*
+ * Partial hugetlb page clear isn't supported
+ */
+ if (is_written && IS_PM_SCAN_WP(p->flags) &&
+ n_pages < HPAGE_SIZE/PAGE_SIZE) {
+ ret = PM_SCAN_END_WALK;
+ p->end_addr = start;
+ goto unlock_and_return;
+ }
+
+ if (IS_PM_SCAN_GET(p->flags))
+ ret = pagemap_scan_output(bitmap, p, start, n_pages);
+
+ if (IS_PM_SCAN_WP(p->flags) && is_written && ret >= 0) {
+ make_uffd_wp_huge_pte(vma, start, ptep, ptent);
+ flush_hugetlb_tlb_range(vma, start, end);
+ }
+ }
+
+unlock_and_return:
+ if (IS_PM_SCAN_WP(p->flags)) {
+ spin_unlock(ptl);
+ i_mmap_unlock_write(vma->vm_file->f_mapping);
+ }
+
+ return ret;
+}
+#else
+#define pagemap_scan_hugetlb_entry NULL
+#endif
+
+static int pagemap_scan_pte_hole(unsigned long addr, unsigned long end,
+ int depth, struct mm_walk *walk)
+{
+ unsigned long n_pages = (end - addr)/PAGE_SIZE;
+ struct pagemap_scan_private *p = walk->private;
+ struct vm_area_struct *vma = walk->vma;
+ bool interesting = true;
+ unsigned long bitmap;
+ int ret = 0;
+
+ if (!vma)
+ return 0;
+
+ bitmap = PM_SCAN_FLAGS(false, false, false, false, false);
+
+ if (IS_PM_SCAN_GET(p->flags))
+ interesting = pagemap_scan_is_interesting_page(bitmap, p);
+
+ if (interesting) {
+ if (IS_PM_SCAN_GET(p->flags)) {
+ if (n_pages > p->max_pages - p->found_pages)
+ n_pages = p->max_pages - p->found_pages;
+
+ ret = pagemap_scan_output(bitmap, p, addr, n_pages);
+ }
+
+ if (IS_PM_SCAN_WP(p->flags) && !ret &&
+ uffd_wp_range(vma, addr, end - addr, true) < 0)
+ ret = -EINVAL;
+ }
+
+ return ret;
+}
+
+static const struct mm_walk_ops pagemap_scan_ops = {
+ .test_walk = pagemap_scan_test_walk,
+ .pmd_entry = pagemap_scan_pmd_entry,
+ .pte_hole = pagemap_scan_pte_hole,
+ .hugetlb_entry = pagemap_scan_hugetlb_entry,
+};
+
+static int pagemap_scan_args_valid(struct pm_scan_arg *arg, unsigned long start,
+ unsigned long end, struct page_region __user *vec)
+{
+ /* Detect illegal size, flags, len and masks */
+ if (arg->size != sizeof(struct pm_scan_arg))
+ return -EINVAL;
+ if (!arg->flags)
+ return -EINVAL;
+ if (arg->flags & ~PM_SCAN_OPS)
+ return -EINVAL;
+ if (!(end - start))
+ return -EINVAL;
+ if ((arg->required_mask | arg->anyof_mask | arg->excluded_mask |
+ arg->return_mask) & ~PM_SCAN_BITS_ALL)
+ return -EINVAL;
+ if (!arg->required_mask && !arg->anyof_mask &&
+ !arg->excluded_mask)
+ return -EINVAL;
+ if (!arg->return_mask)
+ return -EINVAL;
+
+ /* Validate memory range */
+ if (!IS_ALIGNED(start, PAGE_SIZE))
+ return -EINVAL;
+ if (!access_ok((void __user *)start, end - start))
+ return -EFAULT;
+
+ if (IS_PM_SCAN_GET(arg->flags)) {
+ if (arg->vec_len == 0)
+ return -EINVAL;
+ if (!vec)
+ return -EFAULT;
+ if (!access_ok((void __user *)vec,
+ arg->vec_len * sizeof(struct page_region)))
+ return -EFAULT;
+ }
+
+ if (IS_PM_SCAN_WP(arg->flags) && !IS_PM_SCAN_GET(arg->flags) &&
+ arg->max_pages)
+ return -EINVAL;
+
+ return 0;
+}
+
+static long do_pagemap_scan(struct mm_struct *mm, unsigned long __arg)
+{
+ struct pm_scan_arg __user *uarg = (struct pm_scan_arg __user *)__arg;
+ unsigned long long start, end, walk_start, walk_end;
+ unsigned long empty_slots, vec_index = 0;
+ struct mmu_notifier_range range;
+ struct page_region __user *vec;
+ struct pagemap_scan_private p;
+ struct pm_scan_arg arg;
+ int ret = 0;
+
+ if (copy_from_user(&arg, uarg, sizeof(arg)))
+ return -EFAULT;
+
+ start = untagged_addr((unsigned long)arg.start);
+ end = untagged_addr((unsigned long)arg.end);
+ vec = (struct page_region __user *)untagged_addr((unsigned long)arg.vec);
+
+ ret = pagemap_scan_args_valid(&arg, start, end, vec);
+ if (ret)
+ return ret;
+
+ p.max_pages = (arg.max_pages) ? arg.max_pages : ULONG_MAX;
+ p.found_pages = 0;
+ p.required_mask = arg.required_mask;
+ p.anyof_mask = arg.anyof_mask;
+ p.excluded_mask = arg.excluded_mask;
+ p.return_mask = arg.return_mask;
+ p.flags = arg.flags;
+ p.flags |= ((p.required_mask | p.anyof_mask | p.excluded_mask) &
+ PAGE_IS_WRITTEN) ? PM_SCAN_REQUIRE_UFFD : 0;
+ p.cur_buf.start = p.cur_buf.len = p.cur_buf.flags = 0;
+ p.vec_buf = NULL;
+ p.vec_buf_len = PAGEMAP_WALK_SIZE >> PAGE_SHIFT;
+ p.vec_buf_index = 0;
+ p.end_addr = 0;
+
+ /*
+ * Allocate smaller buffer to get output from inside the page walk
+ * functions and walk page range in PAGEMAP_WALK_SIZE size chunks. As
+ * we want to return output to user in compact form where no two
+ * consecutive regions should be continuous and have the same flags.
+ * So store the latest element in p.cur_buf between different walks and
+ * store the p.cur_buf at the end of the walk to the user buffer.
+ */
+ if (IS_PM_SCAN_GET(p.flags)) {
+ p.vec_buf = kmalloc_array(p.vec_buf_len, sizeof(*p.vec_buf),
+ GFP_KERNEL);
+ if (!p.vec_buf)
+ return -ENOMEM;
+ }
+
+ /*
+ * Protection change for the range is going to happen.
+ */
+ if (IS_PM_SCAN_WP(p.flags)) {
+ mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_VMA, 0,
+ mm, start, end);
+ mmu_notifier_invalidate_range_start(&range);
+ }
+
+ walk_start = walk_end = start;
+ while (walk_end < end && !ret) {
+ if (IS_PM_SCAN_GET(p.flags)) {
+ /*
+ * All data is copied to cur_buf first. When more data
+ * is found, we push cur_buf to vec_buf and copy new
+ * data to cur_buf. Subtract 1 from length as the
+ * index of cur_buf isn't counted in length.
+ */
+ empty_slots = arg.vec_len - vec_index;
+ p.vec_buf_len = min(p.vec_buf_len, empty_slots - 1);
+ }
+
+ ret = mmap_read_lock_killable(mm);
+ if (ret)
+ goto out;
+
+ walk_end = min((walk_start + PAGEMAP_WALK_SIZE) & PAGEMAP_WALK_MASK, end);
+
+ ret = walk_page_range(mm, walk_start, walk_end,
+ &pagemap_scan_ops, &p);
+ mmap_read_unlock(mm);
+
+ if (ret == PM_SCAN_FOUND_MAX_PAGES || ret == PM_SCAN_END_WALK)
+ arg.start = p.end_addr;
+
+ if (ret && ret != PM_SCAN_FOUND_MAX_PAGES &&
+ ret != PM_SCAN_END_WALK)
+ goto out;
+
+ if (p.vec_buf_index) {
+ if (copy_to_user(&vec[vec_index], p.vec_buf,
+ p.vec_buf_index * sizeof(*p.vec_buf))) {
+ /*
+ * Return error even though the OP succeeded
+ */
+ ret = -EFAULT;
+ goto out;
+ }
+ vec_index += p.vec_buf_index;
+ p.vec_buf_index = 0;
+ }
+ walk_start = walk_end;
+ }
+
+ if (p.cur_buf.len) {
+ if (copy_to_user(&vec[vec_index], &p.cur_buf, sizeof(p.cur_buf))) {
+ ret = -EFAULT;
+ goto out;
+ }
+ vec_index++;
+ }
+
+ ret = vec_index;
+
+out:
+ if (!p.end_addr)
+ arg.start = walk_start;
+ if (copy_to_user(&uarg->start, &arg.start, sizeof(arg.start)))
+ ret = -EFAULT;
+
+ if (IS_PM_SCAN_WP(p.flags))
+ mmu_notifier_invalidate_range_end(&range);
+
+ kfree(p.vec_buf);
+ return ret;
+}
+
+static long do_pagemap_cmd(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ struct mm_struct *mm = file->private_data;
+
+ switch (cmd) {
+ case PAGEMAP_SCAN:
+ return do_pagemap_scan(mm, arg);
+
+ default:
+ return -EINVAL;
+ }
+}
+
const struct file_operations proc_pagemap_operations = {
.llseek = mem_lseek, /* borrow this */
.read = pagemap_read,
.open = pagemap_open,
.release = pagemap_release,
+ .unlocked_ioctl = do_pagemap_cmd,
+ .compat_ioctl = do_pagemap_cmd,
};
#endif /* CONFIG_PROC_PAGE_MONITOR */
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 623e98d62df3..c44e7bde0339 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -259,6 +259,7 @@ long hugetlb_change_protection(struct vm_area_struct *vma,
unsigned long cp_flags);
bool is_hugetlb_entry_migration(pte_t pte);
+bool is_hugetlb_entry_hwpoisoned(pte_t pte);
void hugetlb_unshare_all_pmds(struct vm_area_struct *vma);
#else /* !CONFIG_HUGETLB_PAGE */
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index b7b56871029c..ac684d99e68f 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -305,4 +305,59 @@ typedef int __bitwise __kernel_rwf_t;
#define RWF_SUPPORTED (RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_NOWAIT |\
RWF_APPEND)
+/* Pagemap ioctl */
+#define PAGEMAP_SCAN _IOWR('f', 16, struct pm_scan_arg)
+
+/* Bits are set in flags of the page_region and masks in pm_scan_args */
+#define PAGE_IS_WRITTEN (1 << 0)
+#define PAGE_IS_FILE (1 << 1)
+#define PAGE_IS_PRESENT (1 << 2)
+#define PAGE_IS_SWAPPED (1 << 3)
+#define PAGE_IS_PFNZERO (1 << 4)
+
+/*
+ * struct page_region - Page region with flags
+ * @start: Start of the region
+ * @len: Length of the region in pages
+ * @bitmap: Bits sets for the region
+ */
+struct page_region {
+ __u64 start;
+ __u64 len;
+ __u64 flags;
+};
+
+/*
+ * struct pm_scan_arg - Pagemap ioctl argument
+ * @size: Size of the structure
+ * @flags: Flags for the IOCTL
+ * @start: Starting address of the region
+ * (Ending address of the walk is also returned in it)
+ * @end: Ending address of the region
+ * @vec: Address of page_region struct array for output
+ * @vec_len: Length of the page_region struct array
+ * @max_pages: Optional max return pages
+ * @required_mask: Required mask - All of these bits have to be set in the PTE
+ * @anyof_mask: Any mask - Any of these bits are set in the PTE
+ * @excluded_mask: Exclude mask - None of these bits are set in the PTE
+ * @return_mask: Bits that are to be reported in page_region
+ */
+struct pm_scan_arg {
+ __u64 size;
+ __u64 flags;
+ __u64 start;
+ __u64 end;
+ __u64 vec;
+ __u64 vec_len;
+ __u64 max_pages;
+ __u64 required_mask;
+ __u64 anyof_mask;
+ __u64 excluded_mask;
+ __u64 return_mask;
+};
+
+/* Supported flags */
+#define PM_SCAN_OP_GET (1 << 0)
+#define PM_SCAN_OP_WP (1 << 1)
+
#endif /* _UAPI_LINUX_FS_H */
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ee88a2a6649f..f7cefdcb114c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4981,7 +4981,7 @@ bool is_hugetlb_entry_migration(pte_t pte)
return false;
}
-static bool is_hugetlb_entry_hwpoisoned(pte_t pte)
+bool is_hugetlb_entry_hwpoisoned(pte_t pte)
{
swp_entry_t swp;
--
2.39.2
