--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/mm.h>
+#include <linux/mm_types.h>
+#include <linux/hugetlb.h>
+#include <linux/bitops.h>
+#include <linux/mmu_notifier.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+
+/**
+ * struct apply_as - Closure structure for apply_as_range
+ * @base: struct pfn_range_apply we derive from
+ * @start: Address of first modified pte
+ * @end: Address of last modified pte + 1
+ * @total: Total number of modified ptes
+ * @vma: Pointer to the struct vm_area_struct we're currently operating on
+ */
+struct apply_as {
+ struct pfn_range_apply base;
+ unsigned long start;
+ unsigned long end;
+ unsigned long total;
+ struct vm_area_struct *vma;
+};
+
+/**
+ * apply_pt_wrprotect - Leaf pte callback to write-protect a pte
+ * @pte: Pointer to the pte
+ * @token: Page table token, see apply_to_pfn_range()
+ * @addr: The virtual page address
+ * @closure: Pointer to a struct pfn_range_apply embedded in a
+ * struct apply_as
+ *
+ * The function write-protects a pte and records the range in
+ * virtual address space of touched ptes for efficient range TLB flushes.
+ *
+ * Return: Always zero.
+ */
+static int apply_pt_wrprotect(pte_t *pte, pgtable_t token,
+ unsigned long addr,
+ struct pfn_range_apply *closure)
+{
+ struct apply_as *aas = container_of(closure, typeof(*aas), base);
+ pte_t ptent = *pte;
+
+ if (pte_write(ptent)) {
+ pte_t old_pte = ptep_modify_prot_start(aas->vma, addr, pte);
+
+ ptent = pte_wrprotect(old_pte);
+ ptep_modify_prot_commit(aas->vma, addr, pte, old_pte, ptent);
+ aas->total++;
+ aas->start = min(aas->start, addr);
+ aas->end = max(aas->end, addr + PAGE_SIZE);
+ }
+
+ return 0;
+}
+
+/**
+ * struct apply_as_clean - Closure structure for apply_as_clean
+ * @base: struct apply_as we derive from
+ * @bitmap_pgoff: Address_space Page offset of the first bit in @bitmap
+ * @bitmap: Bitmap with one bit for each page offset in the address_space range
+ * covered.
+ * @start: Address_space page offset of first modified pte relative
+ * to @bitmap_pgoff
+ * @end: Address_space page offset of last modified pte relative
+ * to @bitmap_pgoff
+ */
+struct apply_as_clean {
+ struct apply_as base;
+ pgoff_t bitmap_pgoff;
+ unsigned long *bitmap;
+ pgoff_t start;
+ pgoff_t end;
+};
+
+/**
+ * apply_pt_clean - Leaf pte callback to clean a pte
+ * @pte: Pointer to the pte
+ * @token: Page table token, see apply_to_pfn_range()
+ * @addr: The virtual page address
+ * @closure: Pointer to a struct pfn_range_apply embedded in a
+ * struct apply_as_clean
+ *
+ * The function cleans a pte and records the range in
+ * virtual address space of touched ptes for efficient TLB flushes.
+ * It also records dirty ptes in a bitmap representing page offsets
+ * in the address_space, as well as the first and last of the bits
+ * touched.
+ *
+ * Return: Always zero.
+ */
+static int apply_pt_clean(pte_t *pte, pgtable_t token,
+ unsigned long addr,
+ struct pfn_range_apply *closure)
+{
+ struct apply_as *aas = container_of(closure, typeof(*aas), base);
+ struct apply_as_clean *clean = container_of(aas, typeof(*clean), base);
+ pte_t ptent = *pte;
+
+ if (pte_dirty(ptent)) {
+ pgoff_t pgoff = ((addr - aas->vma->vm_start) >> PAGE_SHIFT) +
+ aas->vma->vm_pgoff - clean->bitmap_pgoff;
+ pte_t old_pte = ptep_modify_prot_start(aas->vma, addr, pte);
+
+ ptent = pte_mkclean(old_pte);
+ ptep_modify_prot_commit(aas->vma, addr, pte, old_pte, ptent);
+
+ aas->total++;
+ aas->start = min(aas->start, addr);
+ aas->end = max(aas->end, addr + PAGE_SIZE);
+
+ __set_bit(pgoff, clean->bitmap);
+ clean->start = min(clean->start, pgoff);
+ clean->end = max(clean->end, pgoff + 1);
+ }
+
+ return 0;
+}
+
+/**
+ * apply_as_range - Apply a pte callback to all PTEs pointing into a range
+ * of an address_space.
+ * @mapping: Pointer to the struct address_space
+ * @aas: Closure structure
+ * @first_index: First page offset in the address_space
+ * @nr: Number of incremental page offsets to cover
+ *
+ * Return: Number of ptes touched. Note that this number might be larger
+ * than @nr if there are overlapping vmas
+ */
+static unsigned long apply_as_range(struct address_space *mapping,
+ struct apply_as *aas,
+ pgoff_t first_index, pgoff_t nr)
+{
+ struct vm_area_struct *vma;
+ pgoff_t vba, vea, cba, cea;
+ unsigned long start_addr, end_addr;
+ struct mmu_notifier_range range;
+
+ i_mmap_lock_read(mapping);
+ vma_interval_tree_foreach(vma, &mapping->i_mmap, first_index,
+ first_index + nr - 1) {
+ unsigned long vm_flags = READ_ONCE(vma->vm_flags);
+
+ /*
+ * We can only do advisory flag tests below, since we can't
+ * require the vm's mmap_sem to be held to protect the flags.
+ * Therefore, callers that strictly depend on specific mmap
+ * flags to remain constant throughout the operation must
+ * either ensure those flags are immutable for all relevant
+ * vmas or can't use this function. Fixing this properly would
+ * require the vma::vm_flags to be protected by a separate
+ * lock taken after the i_mmap_lock
+ */
+
+ /* Skip non-applicable VMAs */
+ if ((vm_flags & (VM_SHARED | VM_WRITE)) !=
+ (VM_SHARED | VM_WRITE))
+ continue;
+
+ /* Warn on and skip VMAs whose flags indicate illegal usage */
+ if (WARN_ON((vm_flags & (VM_HUGETLB | VM_IO)) != VM_IO))
+ continue;
+
+ /* Clip to the vma */
+ vba = vma->vm_pgoff;
+ vea = vba + vma_pages(vma);
+ cba = first_index;
+ cba = max(cba, vba);
+ cea = first_index + nr;
+ cea = min(cea, vea);
+
+ /* Translate to virtual address */
+ start_addr = ((cba - vba) << PAGE_SHIFT) + vma->vm_start;
+ end_addr = ((cea - vba) << PAGE_SHIFT) + vma->vm_start;
+ if (start_addr >= end_addr)
+ continue;
+
+ aas->base.mm = vma->vm_mm;
+ aas->vma = vma;
+ aas->start = end_addr;
+ aas->end = start_addr;
+
+ mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE, 0,
+ vma, vma->vm_mm, start_addr, end_addr);
+ mmu_notifier_invalidate_range_start(&range);
+
+ /* Needed when we only change protection? */
+ flush_cache_range(vma, start_addr, end_addr);
+
+ /*
+ * We're not using tlb_gather_mmu() since typically
+ * only a small subrange of PTEs are affected.
+ */
+ inc_tlb_flush_pending(vma->vm_mm);
+
+ /* Should not error since aas->base.alloc == 0 */
+ WARN_ON(apply_to_pfn_range(&aas->base, start_addr,
+ end_addr - start_addr));
+ if (aas->end > aas->start)
+ flush_tlb_range(vma, aas->start, aas->end);
+
+ mmu_notifier_invalidate_range_end(&range);
+ dec_tlb_flush_pending(vma->vm_mm);
+ }
+ i_mmap_unlock_read(mapping);
+
+ return aas->total;
+}
+
+/**
+ * apply_as_wrprotect - Write-protect all ptes in an address_space range
+ * @mapping: The address_space we want to write protect
+ * @first_index: The first page offset in the range
+ * @nr: Number of incremental page offsets to cover
+ *
+ * WARNING: This function should only be used for address spaces whose
+ * vmas are marked VM_IO and that do not contain huge pages.
+ * To avoid interference with COW'd pages, vmas not marked VM_SHARED are
+ * simply skipped.
+ *
+ * Return: The number of ptes actually write-protected. Note that
+ * already write-protected ptes are not counted.
+ */
+unsigned long apply_as_wrprotect(struct address_space *mapping,
+ pgoff_t first_index, pgoff_t nr)
+{
+ struct apply_as aas = {
+ .base = {
+ .alloc = 0,
+ .ptefn = apply_pt_wrprotect,
+ },
+ .total = 0,
+ };
+
+ return apply_as_range(mapping, &aas, first_index, nr);
+}
+EXPORT_SYMBOL_GPL(apply_as_wrprotect);
+
+/**
+ * apply_as_clean - Clean all ptes in an address_space range
+ * @mapping: The address_space we want to clean
+ * @first_index: The first page offset in the range
+ * @nr: Number of incremental page offsets to cover
+ * @bitmap_pgoff: The page offset of the first bit in @bitmap
+ * @bitmap: Pointer to a bitmap of at least @nr bits. The bitmap needs to
+ * cover the whole range @first_index..@first_index + @nr.
+ * @start: Pointer to number of the first set bit in @bitmap.
+ * is modified as new bits are set by the function.
+ * @end: Pointer to the number of the last set bit in @bitmap.
+ * none set. The value is modified as new bits are set by the function.
+ *
+ * Note: When this function returns there is no guarantee that a CPU has
+ * not already dirtied new ptes. However it will not clean any ptes not
+ * reported in the bitmap.
+ *
+ * If a caller needs to make sure all dirty ptes are picked up and none
+ * additional are added, it first needs to write-protect the address-space
+ * range and make sure new writers are blocked in page_mkwrite() or
+ * pfn_mkwrite(). And then after a TLB flush following the write-protection
+ * pick up all dirty bits.
+ *
+ * WARNING: This function should only be used for address spaces whose
+ * vmas are marked VM_IO and that do not contain huge pages.
+ * To avoid interference with COW'd pages, vmas not marked VM_SHARED are
+ * simply skipped.
+ *
+ * Return: The number of dirty ptes actually cleaned.
+ */
+unsigned long apply_as_clean(struct address_space *mapping,
+ pgoff_t first_index, pgoff_t nr,
+ pgoff_t bitmap_pgoff,
+ unsigned long *bitmap,
+ pgoff_t *start,
+ pgoff_t *end)
+{
+ bool none_set = (*start >= *end);
+ struct apply_as_clean clean = {
+ .base = {
+ .base = {
+ .alloc = 0,
+ .ptefn = apply_pt_clean,
+ },
+ .total = 0,
+ },
+ .bitmap_pgoff = bitmap_pgoff,
+ .bitmap = bitmap,
+ .start = none_set ? nr : *start,
+ .end = none_set ? 0 : *end,
+ };
+ unsigned long ret = apply_as_range(mapping, &clean.base, first_index,
+ nr);
+
+ *start = clean.start;
+ *end = clean.end;
+ return ret;
+}
+EXPORT_SYMBOL_GPL(apply_as_clean);
projects / users / willy / xarray.git / commitdiff