1 files changed, 132 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..3a5c8fb59
--- /dev/null
+++ b/arch/s390/include/asm/tlb.h
@@ -0,0 +1,132 @@
+/* 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
+ */
+
+void __tlb_remove_table(void *_table);
+static inline void tlb_flush(struct mmu_gather *tlb);
+static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
+					  struct page *page, int page_size);
+
+#define tlb_flush tlb_flush
+#define pte_free_tlb pte_free_tlb
+#define pmd_free_tlb pmd_free_tlb
+#define p4d_free_tlb p4d_free_tlb
+#define pud_free_tlb pud_free_tlb
+
+#include <asm/tlbflush.h>
+#include <asm-generic/tlb.h>
+
+/*
+ * 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_size(struct mmu_gather *tlb,
+					  struct page *page, int page_size)
+{
+	free_page_and_swap_cache(page);
+	return false;
+}
+
+static inline void tlb_flush(struct mmu_gather *tlb)
+{
+	__tlb_flush_mm_lazy(tlb->mm);
+}
+
+/*
+ * 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)
+{
+	__tlb_adjust_range(tlb, address, PAGE_SIZE);
+	tlb->mm->context.flush_mm = 1;
+	tlb->freed_tables = 1;
+	tlb->cleared_pmds = 1;
+	/*
+	 * page_table_free_rcu takes care of the allocation bit masks
+	 * of the 2K table fragments in the 4K page table page,
+	 * then calls tlb_remove_table.
+	 */
+	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_adjust_range(tlb, address, PAGE_SIZE);
+	tlb->mm->context.flush_mm = 1;
+	tlb->freed_tables = 1;
+	tlb->cleared_puds = 1;
+	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_adjust_range(tlb, address, PAGE_SIZE);
+	tlb->mm->context.flush_mm = 1;
+	tlb->freed_tables = 1;
+	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->mm->context.flush_mm = 1;
+	tlb->freed_tables = 1;
+	tlb->cleared_p4ds = 1;
+	tlb_remove_table(tlb, pud);
+}
+
+
+#endif /* _S390_TLB_H */