1 files changed, 205 insertions, 0 deletions
diff --git a/arch/s390/include/asm/tlb.h b/arch/s390/include/asm/tlb.h
new file mode 100644
index 000000000..1df28a8e2
--- /dev/null
+++ b/arch/s390/include/asm/tlb.h
@@ -0,0 +1,205 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _S390_TLB_H
+#define _S390_TLB_H
+
+/*
+ * TLB flushing on s390 is complicated. The following requirement
+ * from the principles of operation is the most arduous:
+ *
+ * "A valid table entry must not be changed while it is attached
+ * to any CPU and may be used for translation by that CPU except to
+ * (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY,
+ * or INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page
+ * table entry, or (3) make a change by means of a COMPARE AND SWAP
+ * AND PURGE instruction that purges the TLB."
+ *
+ * The modification of a pte of an active mm struct therefore is
+ * a two step process: i) invalidate the pte, ii) store the new pte.
+ * This is true for the page protection bit as well.
+ * The only possible optimization is to flush at the beginning of
+ * a tlb_gather_mmu cycle if the mm_struct is currently not in use.
+ *
+ * Pages used for the page tables is a different story. FIXME: more
+ */
+
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <asm/processor.h>
+#include <asm/pgalloc.h>
+#include <asm/tlbflush.h>
+
+struct mmu_gather {
+	struct mm_struct *mm;
+	struct mmu_table_batch *batch;
+	unsigned int fullmm;
+	unsigned long start, end;
+};
+
+struct mmu_table_batch {
+	struct rcu_head		rcu;
+	unsigned int		nr;
+	void			*tables[0];
+};
+
+#define MAX_TABLE_BATCH		\
+	((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *))
+
+extern void tlb_table_flush(struct mmu_gather *tlb);
+extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
+
+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));
+	tlb->batch = NULL;
+}
+
+static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
+{
+	__tlb_flush_mm_lazy(tlb->mm);
+}
+
+static inline void tlb_flush_mmu_free(struct mmu_gather *tlb)
+{
+	tlb_table_flush(tlb);
+}
+
+
+static inline void tlb_flush_mmu(struct mmu_gather *tlb)
+{
+	tlb_flush_mmu_tlbonly(tlb);
+	tlb_flush_mmu_free(tlb);
+}
+
+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_flush_mmu(tlb);
+}
+
+/*
+ * Release the page cache reference for a pte removed by
+ * tlb_ptep_clear_flush. In both flush modes the tlb for a page cache page
+ * has already been freed, so just do free_page_and_swap_cache.
+ */
+static inline bool __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+	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)
+{
+	free_page_and_swap_cache(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);
+}
+
+static inline void tlb_flush_pmd_range(struct mmu_gather *tlb,
+				unsigned long address, unsigned long size)
+{
+	/*
+	 * the range might exceed the original range that was provided to
+	 * tlb_gather_mmu(), so we need to update it despite the fact it is
+	 * usually not updated.
+	 */
+	if (tlb->start > address)
+		tlb->start = address;
+	if (tlb->end < address + size)
+		tlb->end = address + size;
+}
+
+/*
+ * pte_free_tlb frees a pte table and clears the CRSTE for the
+ * page table from the tlb.
+ */
+static inline void pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
+				unsigned long address)
+{
+	page_table_free_rcu(tlb, (unsigned long *) pte, address);
+}
+
+/*
+ * pmd_free_tlb frees a pmd table and clears the CRSTE for the
+ * segment table entry from the tlb.
+ * If the mm uses a two level page table the single pmd is freed
+ * as the pgd. pmd_free_tlb checks the asce_limit against 2GB
+ * to avoid the double free of the pmd in this case.
+ */
+static inline void pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
+				unsigned long address)
+{
+	if (mm_pmd_folded(tlb->mm))
+		return;
+	pgtable_pmd_page_dtor(virt_to_page(pmd));
+	tlb_remove_table(tlb, pmd);
+}
+
+/*
+ * p4d_free_tlb frees a pud table and clears the CRSTE for the
+ * region second table entry from the tlb.
+ * If the mm uses a four level page table the single p4d is freed
+ * as the pgd. p4d_free_tlb checks the asce_limit against 8PB
+ * to avoid the double free of the p4d in this case.
+ */
+static inline void p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d,
+				unsigned long address)
+{
+	if (mm_p4d_folded(tlb->mm))
+		return;
+	tlb_remove_table(tlb, p4d);
+}
+
+/*
+ * pud_free_tlb frees a pud table and clears the CRSTE for the
+ * region third table entry from the tlb.
+ * If the mm uses a three level page table the single pud is freed
+ * as the pgd. pud_free_tlb checks the asce_limit against 4TB
+ * to avoid the double free of the pud in this case.
+ */
+static inline void pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
+				unsigned long address)
+{
+	if (mm_pud_folded(tlb->mm))
+		return;
+	tlb_remove_table(tlb, pud);
+}
+
+#define tlb_start_vma(tlb, vma)			do { } while (0)
+#define tlb_end_vma(tlb, vma)			do { } while (0)
+#define tlb_remove_tlb_entry(tlb, ptep, addr)	do { } while (0)
+#define tlb_remove_pmd_tlb_entry(tlb, pmdp, addr)	do { } while (0)
+#define tlb_migrate_finish(mm)			do { } while (0)
+#define tlb_flush_pmd_range(tlb, addr, sz)	do { } 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)
+{
+}
+
+#endif /* _S390_TLB_H */