v4.19.13 snapshot.
diff --git a/arch/um/include/asm/tlb.h b/arch/um/include/asm/tlb.h
new file mode 100644
index 0000000..dce6db1
--- /dev/null
+++ b/arch/um/include/asm/tlb.h
@@ -0,0 +1,163 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __UM_TLB_H
+#define __UM_TLB_H
+
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <asm/percpu.h>
+#include <asm/pgalloc.h>
+#include <asm/tlbflush.h>
+
+#define tlb_start_vma(tlb, vma) do { } while (0)
+#define tlb_end_vma(tlb, vma) do { } while (0)
+#define tlb_flush(tlb) flush_tlb_mm((tlb)->mm)
+
+/* struct mmu_gather is an opaque type used by the mm code for passing around
+ * any data needed by arch specific code for tlb_remove_page.
+ */
+struct mmu_gather {
+ struct mm_struct *mm;
+ unsigned int need_flush; /* Really unmapped some ptes? */
+ unsigned long start;
+ unsigned long end;
+ unsigned int fullmm; /* non-zero means full mm flush */
+};
+
+static inline void __tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep,
+ unsigned long address)
+{
+ if (tlb->start > address)
+ tlb->start = address;
+ if (tlb->end < address + PAGE_SIZE)
+ tlb->end = address + PAGE_SIZE;
+}
+
+static inline void init_tlb_gather(struct mmu_gather *tlb)
+{
+ tlb->need_flush = 0;
+
+ tlb->start = TASK_SIZE;
+ tlb->end = 0;
+
+ if (tlb->fullmm) {
+ tlb->start = 0;
+ tlb->end = TASK_SIZE;
+ }
+}
+
+static inline void
+arch_tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
+ unsigned long start, unsigned long end)
+{
+ tlb->mm = mm;
+ tlb->start = start;
+ tlb->end = end;
+ tlb->fullmm = !(start | (end+1));
+
+ init_tlb_gather(tlb);
+}
+
+extern void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
+ unsigned long end);
+
+static inline void
+tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
+{
+ flush_tlb_mm_range(tlb->mm, tlb->start, tlb->end);
+}
+
+static inline void
+tlb_flush_mmu_free(struct mmu_gather *tlb)
+{
+ init_tlb_gather(tlb);
+}
+
+static inline void
+tlb_flush_mmu(struct mmu_gather *tlb)
+{
+ if (!tlb->need_flush)
+ return;
+
+ tlb_flush_mmu_tlbonly(tlb);
+ tlb_flush_mmu_free(tlb);
+}
+
+/* arch_tlb_finish_mmu
+ * Called at the end of the shootdown operation to free up any resources
+ * that were required.
+ */
+static inline void
+arch_tlb_finish_mmu(struct mmu_gather *tlb,
+ unsigned long start, unsigned long end, bool force)
+{
+ if (force) {
+ tlb->start = start;
+ tlb->end = end;
+ tlb->need_flush = 1;
+ }
+ tlb_flush_mmu(tlb);
+
+ /* keep the page table cache within bounds */
+ check_pgt_cache();
+}
+
+/* tlb_remove_page
+ * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)),
+ * while handling the additional races in SMP caused by other CPUs
+ * caching valid mappings in their TLBs.
+ */
+static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+ tlb->need_flush = 1;
+ free_page_and_swap_cache(page);
+ return false; /* avoid calling tlb_flush_mmu */
+}
+
+static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+ __tlb_remove_page(tlb, page);
+}
+
+static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
+ struct page *page, int page_size)
+{
+ return __tlb_remove_page(tlb, page);
+}
+
+static inline void tlb_remove_page_size(struct mmu_gather *tlb,
+ struct page *page, int page_size)
+{
+ return tlb_remove_page(tlb, page);
+}
+
+/**
+ * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
+ *
+ * Record the fact that pte's were really umapped in ->need_flush, so we can
+ * later optimise away the tlb invalidate. This helps when userspace is
+ * unmapping already-unmapped pages, which happens quite a lot.
+ */
+#define tlb_remove_tlb_entry(tlb, ptep, address) \
+ do { \
+ tlb->need_flush = 1; \
+ __tlb_remove_tlb_entry(tlb, ptep, address); \
+ } while (0)
+
+#define tlb_remove_huge_tlb_entry(h, tlb, ptep, address) \
+ tlb_remove_tlb_entry(tlb, ptep, address)
+
+#define tlb_remove_check_page_size_change tlb_remove_check_page_size_change
+static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
+ unsigned int page_size)
+{
+}
+
+#define pte_free_tlb(tlb, ptep, addr) __pte_free_tlb(tlb, ptep, addr)
+
+#define pud_free_tlb(tlb, pudp, addr) __pud_free_tlb(tlb, pudp, addr)
+
+#define pmd_free_tlb(tlb, pmdp, addr) __pmd_free_tlb(tlb, pmdp, addr)
+
+#define tlb_migrate_finish(mm) do {} while (0)
+
+#endif