v4.19.13 snapshot.
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
new file mode 100644
index 0000000..cf2af04
--- /dev/null
+++ b/mm/pgtable-generic.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * mm/pgtable-generic.c
+ *
+ * Generic pgtable methods declared in asm-generic/pgtable.h
+ *
+ * Copyright (C) 2010 Linus Torvalds
+ */
+
+#include <linux/pagemap.h>
+#include <asm/tlb.h>
+#include <asm-generic/pgtable.h>
+
+/*
+ * If a p?d_bad entry is found while walking page tables, report
+ * the error, before resetting entry to p?d_none. Usually (but
+ * very seldom) called out from the p?d_none_or_clear_bad macros.
+ */
+
+void pgd_clear_bad(pgd_t *pgd)
+{
+ pgd_ERROR(*pgd);
+ pgd_clear(pgd);
+}
+
+void p4d_clear_bad(p4d_t *p4d)
+{
+ p4d_ERROR(*p4d);
+ p4d_clear(p4d);
+}
+
+void pud_clear_bad(pud_t *pud)
+{
+ pud_ERROR(*pud);
+ pud_clear(pud);
+}
+
+void pmd_clear_bad(pmd_t *pmd)
+{
+ pmd_ERROR(*pmd);
+ pmd_clear(pmd);
+}
+
+#ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
+/*
+ * Only sets the access flags (dirty, accessed), as well as write
+ * permission. Furthermore, we know it always gets set to a "more
+ * permissive" setting, which allows most architectures to optimize
+ * this. We return whether the PTE actually changed, which in turn
+ * instructs the caller to do things like update__mmu_cache. This
+ * used to be done in the caller, but sparc needs minor faults to
+ * force that call on sun4c so we changed this macro slightly
+ */
+int ptep_set_access_flags(struct vm_area_struct *vma,
+ unsigned long address, pte_t *ptep,
+ pte_t entry, int dirty)
+{
+ int changed = !pte_same(*ptep, entry);
+ if (changed) {
+ set_pte_at(vma->vm_mm, address, ptep, entry);
+ flush_tlb_fix_spurious_fault(vma, address);
+ }
+ return changed;
+}
+#endif
+
+#ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
+int ptep_clear_flush_young(struct vm_area_struct *vma,
+ unsigned long address, pte_t *ptep)
+{
+ int young;
+ young = ptep_test_and_clear_young(vma, address, ptep);
+ if (young)
+ flush_tlb_page(vma, address);
+ return young;
+}
+#endif
+
+#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH
+pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address,
+ pte_t *ptep)
+{
+ struct mm_struct *mm = (vma)->vm_mm;
+ pte_t pte;
+ pte = ptep_get_and_clear(mm, address, ptep);
+ if (pte_accessible(mm, pte))
+ flush_tlb_page(vma, address);
+ return pte;
+}
+#endif
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+
+#ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
+int pmdp_set_access_flags(struct vm_area_struct *vma,
+ unsigned long address, pmd_t *pmdp,
+ pmd_t entry, int dirty)
+{
+ int changed = !pmd_same(*pmdp, entry);
+ VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+ if (changed) {
+ set_pmd_at(vma->vm_mm, address, pmdp, entry);
+ flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+ }
+ return changed;
+}
+#endif
+
+#ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
+int pmdp_clear_flush_young(struct vm_area_struct *vma,
+ unsigned long address, pmd_t *pmdp)
+{
+ int young;
+ VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+ young = pmdp_test_and_clear_young(vma, address, pmdp);
+ if (young)
+ flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+ return young;
+}
+#endif
+
+#ifndef __HAVE_ARCH_PMDP_HUGE_CLEAR_FLUSH
+pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
+ pmd_t *pmdp)
+{
+ pmd_t pmd;
+ VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+ VM_BUG_ON((pmd_present(*pmdp) && !pmd_trans_huge(*pmdp) &&
+ !pmd_devmap(*pmdp)) || !pmd_present(*pmdp));
+ pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
+ flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+ return pmd;
+}
+
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+pud_t pudp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
+ pud_t *pudp)
+{
+ pud_t pud;
+
+ VM_BUG_ON(address & ~HPAGE_PUD_MASK);
+ VM_BUG_ON(!pud_trans_huge(*pudp) && !pud_devmap(*pudp));
+ pud = pudp_huge_get_and_clear(vma->vm_mm, address, pudp);
+ flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
+ return pud;
+}
+#endif
+#endif
+
+#ifndef __HAVE_ARCH_PGTABLE_DEPOSIT
+void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
+ pgtable_t pgtable)
+{
+ assert_spin_locked(pmd_lockptr(mm, pmdp));
+
+ /* FIFO */
+ if (!pmd_huge_pte(mm, pmdp))
+ INIT_LIST_HEAD(&pgtable->lru);
+ else
+ list_add(&pgtable->lru, &pmd_huge_pte(mm, pmdp)->lru);
+ pmd_huge_pte(mm, pmdp) = pgtable;
+}
+#endif
+
+#ifndef __HAVE_ARCH_PGTABLE_WITHDRAW
+/* no "address" argument so destroys page coloring of some arch */
+pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
+{
+ pgtable_t pgtable;
+
+ assert_spin_locked(pmd_lockptr(mm, pmdp));
+
+ /* FIFO */
+ pgtable = pmd_huge_pte(mm, pmdp);
+ pmd_huge_pte(mm, pmdp) = list_first_entry_or_null(&pgtable->lru,
+ struct page, lru);
+ if (pmd_huge_pte(mm, pmdp))
+ list_del(&pgtable->lru);
+ return pgtable;
+}
+#endif
+
+#ifndef __HAVE_ARCH_PMDP_INVALIDATE
+pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
+ pmd_t *pmdp)
+{
+ pmd_t old = pmdp_establish(vma, address, pmdp, pmd_mknotpresent(*pmdp));
+ flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+ return old;
+}
+#endif
+
+#ifndef pmdp_collapse_flush
+pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
+ pmd_t *pmdp)
+{
+ /*
+ * pmd and hugepage pte format are same. So we could
+ * use the same function.
+ */
+ pmd_t pmd;
+
+ VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+ VM_BUG_ON(pmd_trans_huge(*pmdp));
+ pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
+
+ /* collapse entails shooting down ptes not pmd */
+ flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+ return pmd;
+}
+#endif
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */