[S390] use generic RCU page-table freeing code

Replace the s390 specific rcu page-table freeing code with the
generic variant. This requires to duplicate the definition for the
struct mmu_table_batch as s390 does not use the generic tlb flush
code.

While we are at it remove the restriction that page table fragments
can not be reused after a single fragment has been freed with rcu
and split out allocation and freeing of page tables with pgstes.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 46 insertions, 56 deletions

diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h
index f6314af3b354..38e71ebcd3c2 100644
--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -17,15 +17,15 @@
 #include <linux/gfp.h>
 #include <linux/mm.h>
 
-#define check_pgt_cache()       do {} while (0)
-
 unsigned long *crst_table_alloc(struct mm_struct *);
 void crst_table_free(struct mm_struct *, unsigned long *);
-void crst_table_free_rcu(struct mm_struct *, unsigned long *);
 
 unsigned long *page_table_alloc(struct mm_struct *);
 void page_table_free(struct mm_struct *, unsigned long *);
-void page_table_free_rcu(struct mm_struct *, unsigned long *);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+void page_table_free_rcu(struct mmu_gather *, unsigned long *);
+void __tlb_remove_table(void *_table);
+#endif
 
 static inline void clear_table(unsigned long *s, unsigned long val, size_t n)
 {
diff --git a/arch/s390/include/asm/tlb.h b/arch/s390/include/asm/tlb.h
index 77eee5477a52..c687a2c83462 100644
--- a/arch/s390/include/asm/tlb.h
+++ b/arch/s390/include/asm/tlb.h
@@ -26,67 +26,60 @@
 #include <linux/swap.h>
 #include <asm/processor.h>
 #include <asm/pgalloc.h>
-#include <asm/smp.h>
 #include <asm/tlbflush.h>
 
 struct mmu_gather {
         struct mm_struct *mm;
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+        struct mmu_table_batch *batch;
+#endif
         unsigned int fullmm;
-        unsigned int nr_ptes;
-        unsigned int nr_pxds;
-        unsigned int max;
-        void **array;
-        void *local[8];
+        unsigned int need_flush;
 };
 
-static inline void __tlb_alloc_page(struct mmu_gather *tlb)
-{
-        unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+struct mmu_table_batch {
+        struct rcu_head         rcu;
+        unsigned int            nr;
+        void                    *tables[0];
+};
 
-        if (addr) {
-                tlb->array = (void *) addr;
-                tlb->max = PAGE_SIZE / sizeof(void *);
-        }
-}
+#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);
+#endif
 
 static inline void tlb_gather_mmu(struct mmu_gather *tlb,
                                   struct mm_struct *mm,
                                   unsigned int full_mm_flush)
 {
         tlb->mm = mm;
-        tlb->max = ARRAY_SIZE(tlb->local);
-        tlb->array = tlb->local;
         tlb->fullmm = full_mm_flush;
+        tlb->need_flush = 0;
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+        tlb->batch = NULL;
+#endif
         if (tlb->fullmm)
                 __tlb_flush_mm(mm);
-        else
-                __tlb_alloc_page(tlb);
-        tlb->nr_ptes = 0;
-        tlb->nr_pxds = tlb->max;
 }
 
 static inline void tlb_flush_mmu(struct mmu_gather *tlb)
 {
-        if (!tlb->fullmm && (tlb->nr_ptes > 0 || tlb->nr_pxds < tlb->max))
-                __tlb_flush_mm(tlb->mm);
-        while (tlb->nr_ptes > 0)
-                page_table_free_rcu(tlb->mm, tlb->array[--tlb->nr_ptes]);
-        while (tlb->nr_pxds < tlb->max)
-                crst_table_free_rcu(tlb->mm, tlb->array[tlb->nr_pxds++]);
+        if (!tlb->need_flush)
+                return;
+        tlb->need_flush = 0;
+        __tlb_flush_mm(tlb->mm);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+        tlb_table_flush(tlb);
+#endif
 }
 
 static inline void tlb_finish_mmu(struct mmu_gather *tlb,
                                   unsigned long start, unsigned long end)
 {
         tlb_flush_mmu(tlb);
-
-        rcu_table_freelist_finish();
-
-        /* keep the page table cache within bounds */
-        check_pgt_cache();
-
-        if (tlb->array != tlb->local)
-                free_pages((unsigned long) tlb->array, 0);
 }
 
 /*
@@ -112,12 +105,11 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 static inline void pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
                                 unsigned long address)
 {
-        if (!tlb->fullmm) {
-                tlb->array[tlb->nr_ptes++] = pte;
-                if (tlb->nr_ptes >= tlb->nr_pxds)
-                        tlb_flush_mmu(tlb);
-        } else
-                page_table_free(tlb->mm, (unsigned long *) pte);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+        if (!tlb->fullmm)
+                return page_table_free_rcu(tlb, (unsigned long *) pte);
+#endif
+        page_table_free(tlb->mm, (unsigned long *) pte);
 }
 
 /*
@@ -133,12 +125,11 @@ static inline void pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
 #ifdef __s390x__
         if (tlb->mm->context.asce_limit <= (1UL << 31))
                 return;
-        if (!tlb->fullmm) {
-                tlb->array[--tlb->nr_pxds] = pmd;
-                if (tlb->nr_ptes >= tlb->nr_pxds)
-                        tlb_flush_mmu(tlb);
-        } else
-                crst_table_free(tlb->mm, (unsigned long *) pmd);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+        if (!tlb->fullmm)
+                return tlb_remove_table(tlb, pmd);
+#endif
+        crst_table_free(tlb->mm, (unsigned long *) pmd);
 #endif
 }
 
@@ -155,12 +146,11 @@ static inline void pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
 #ifdef __s390x__
         if (tlb->mm->context.asce_limit <= (1UL << 42))
                 return;
-        if (!tlb->fullmm) {
-                tlb->array[--tlb->nr_pxds] = pud;
-                if (tlb->nr_ptes >= tlb->nr_pxds)
-                        tlb_flush_mmu(tlb);
-        } else
-                crst_table_free(tlb->mm, (unsigned long *) pud);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+        if (!tlb->fullmm)
+                return tlb_remove_table(tlb, pud);
+#endif
+        crst_table_free(tlb->mm, (unsigned long *) pud);
 #endif
 }