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-rw-r--r--arch/s390/mm/pgalloc.c331
1 files changed, 331 insertions, 0 deletions
diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c
new file mode 100644
index 000000000..e8b5962ac
--- /dev/null
+++ b/arch/s390/mm/pgalloc.c
@@ -0,0 +1,331 @@
+/*
+ * Page table allocation functions
+ *
+ * Copyright IBM Corp. 2016
+ * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#include <linux/mm.h>
+#include <linux/sysctl.h>
+#include <asm/mmu_context.h>
+#include <asm/pgalloc.h>
+#include <asm/gmap.h>
+#include <asm/tlb.h>
+#include <asm/tlbflush.h>
+
+#ifdef CONFIG_PGSTE
+
+static int page_table_allocate_pgste_min = 0;
+static int page_table_allocate_pgste_max = 1;
+int page_table_allocate_pgste = 0;
+EXPORT_SYMBOL(page_table_allocate_pgste);
+
+static struct ctl_table page_table_sysctl[] = {
+ {
+ .procname = "allocate_pgste",
+ .data = &page_table_allocate_pgste,
+ .maxlen = sizeof(int),
+ .mode = S_IRUGO | S_IWUSR,
+ .proc_handler = proc_dointvec,
+ .extra1 = &page_table_allocate_pgste_min,
+ .extra2 = &page_table_allocate_pgste_max,
+ },
+ { }
+};
+
+static struct ctl_table page_table_sysctl_dir[] = {
+ {
+ .procname = "vm",
+ .maxlen = 0,
+ .mode = 0555,
+ .child = page_table_sysctl,
+ },
+ { }
+};
+
+static int __init page_table_register_sysctl(void)
+{
+ return register_sysctl_table(page_table_sysctl_dir) ? 0 : -ENOMEM;
+}
+__initcall(page_table_register_sysctl);
+
+#endif /* CONFIG_PGSTE */
+
+unsigned long *crst_table_alloc(struct mm_struct *mm)
+{
+ struct page *page = alloc_pages(GFP_KERNEL, 2);
+
+ if (!page)
+ return NULL;
+ return (unsigned long *) page_to_phys(page);
+}
+
+void crst_table_free(struct mm_struct *mm, unsigned long *table)
+{
+ free_pages((unsigned long) table, 2);
+}
+
+static void __crst_table_upgrade(void *arg)
+{
+ struct mm_struct *mm = arg;
+
+ if (current->active_mm == mm) {
+ clear_user_asce();
+ set_user_asce(mm);
+ }
+ __tlb_flush_local();
+}
+
+int crst_table_upgrade(struct mm_struct *mm)
+{
+ unsigned long *table, *pgd;
+
+ /* upgrade should only happen from 3 to 4 levels */
+ BUG_ON(mm->context.asce_limit != (1UL << 42));
+
+ table = crst_table_alloc(mm);
+ if (!table)
+ return -ENOMEM;
+
+ spin_lock_bh(&mm->page_table_lock);
+ pgd = (unsigned long *) mm->pgd;
+ crst_table_init(table, _REGION2_ENTRY_EMPTY);
+ pgd_populate(mm, (pgd_t *) table, (pud_t *) pgd);
+ mm->pgd = (pgd_t *) table;
+ mm->context.asce_limit = 1UL << 53;
+ mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
+ _ASCE_USER_BITS | _ASCE_TYPE_REGION2;
+ mm->task_size = mm->context.asce_limit;
+ spin_unlock_bh(&mm->page_table_lock);
+
+ on_each_cpu(__crst_table_upgrade, mm, 0);
+ return 0;
+}
+
+void crst_table_downgrade(struct mm_struct *mm)
+{
+ pgd_t *pgd;
+
+ /* downgrade should only happen from 3 to 2 levels (compat only) */
+ BUG_ON(mm->context.asce_limit != (1UL << 42));
+
+ if (current->active_mm == mm) {
+ clear_user_asce();
+ __tlb_flush_mm(mm);
+ }
+
+ pgd = mm->pgd;
+ mm->pgd = (pgd_t *) (pgd_val(*pgd) & _REGION_ENTRY_ORIGIN);
+ mm->context.asce_limit = 1UL << 31;
+ mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
+ _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT;
+ mm->task_size = mm->context.asce_limit;
+ crst_table_free(mm, (unsigned long *) pgd);
+
+ if (current->active_mm == mm)
+ set_user_asce(mm);
+}
+
+static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits)
+{
+ unsigned int old, new;
+
+ do {
+ old = atomic_read(v);
+ new = old ^ bits;
+ } while (atomic_cmpxchg(v, old, new) != old);
+ return new;
+}
+
+/*
+ * page table entry allocation/free routines.
+ */
+unsigned long *page_table_alloc(struct mm_struct *mm)
+{
+ unsigned long *table;
+ struct page *page;
+ unsigned int mask, bit;
+
+ /* Try to get a fragment of a 4K page as a 2K page table */
+ if (!mm_alloc_pgste(mm)) {
+ table = NULL;
+ spin_lock_bh(&mm->context.list_lock);
+ if (!list_empty(&mm->context.pgtable_list)) {
+ page = list_first_entry(&mm->context.pgtable_list,
+ struct page, lru);
+ mask = atomic_read(&page->_mapcount);
+ mask = (mask | (mask >> 4)) & 3;
+ if (mask != 3) {
+ table = (unsigned long *) page_to_phys(page);
+ bit = mask & 1; /* =1 -> second 2K */
+ if (bit)
+ table += PTRS_PER_PTE;
+ atomic_xor_bits(&page->_mapcount, 1U << bit);
+ list_del(&page->lru);
+ }
+ }
+ spin_unlock_bh(&mm->context.list_lock);
+ if (table)
+ return table;
+ }
+ /* Allocate a fresh page */
+ page = alloc_page(GFP_KERNEL|__GFP_REPEAT);
+ if (!page)
+ return NULL;
+ if (!pgtable_page_ctor(page)) {
+ __free_page(page);
+ return NULL;
+ }
+ /* Initialize page table */
+ table = (unsigned long *) page_to_phys(page);
+ if (mm_alloc_pgste(mm)) {
+ /* Return 4K page table with PGSTEs */
+ atomic_set(&page->_mapcount, 3);
+ clear_table(table, _PAGE_INVALID, PAGE_SIZE/2);
+ clear_table(table + PTRS_PER_PTE, 0, PAGE_SIZE/2);
+ } else {
+ /* Return the first 2K fragment of the page */
+ atomic_set(&page->_mapcount, 1);
+ clear_table(table, _PAGE_INVALID, PAGE_SIZE);
+ spin_lock_bh(&mm->context.list_lock);
+ list_add(&page->lru, &mm->context.pgtable_list);
+ spin_unlock_bh(&mm->context.list_lock);
+ }
+ return table;
+}
+
+void page_table_free(struct mm_struct *mm, unsigned long *table)
+{
+ struct page *page;
+ unsigned int bit, mask;
+
+ page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+ if (!mm_alloc_pgste(mm)) {
+ /* Free 2K page table fragment of a 4K page */
+ bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t));
+ spin_lock_bh(&mm->context.list_lock);
+ mask = atomic_xor_bits(&page->_mapcount, 1U << bit);
+ if (mask & 3)
+ list_add(&page->lru, &mm->context.pgtable_list);
+ else
+ list_del(&page->lru);
+ spin_unlock_bh(&mm->context.list_lock);
+ if (mask != 0)
+ return;
+ }
+
+ pgtable_page_dtor(page);
+ atomic_set(&page->_mapcount, -1);
+ __free_page(page);
+}
+
+void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table,
+ unsigned long vmaddr)
+{
+ struct mm_struct *mm;
+ struct page *page;
+ unsigned int bit, mask;
+
+ mm = tlb->mm;
+ page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+ if (mm_alloc_pgste(mm)) {
+ gmap_unlink(mm, table, vmaddr);
+ table = (unsigned long *) (__pa(table) | 3);
+ tlb_remove_table(tlb, table);
+ return;
+ }
+ bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t));
+ spin_lock_bh(&mm->context.list_lock);
+ mask = atomic_xor_bits(&page->_mapcount, 0x11U << bit);
+ if (mask & 3)
+ list_add_tail(&page->lru, &mm->context.pgtable_list);
+ else
+ list_del(&page->lru);
+ spin_unlock_bh(&mm->context.list_lock);
+ table = (unsigned long *) (__pa(table) | (1U << bit));
+ tlb_remove_table(tlb, table);
+}
+
+static void __tlb_remove_table(void *_table)
+{
+ unsigned int mask = (unsigned long) _table & 3;
+ void *table = (void *)((unsigned long) _table ^ mask);
+ struct page *page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+
+ switch (mask) {
+ case 0: /* pmd or pud */
+ free_pages((unsigned long) table, 2);
+ break;
+ case 1: /* lower 2K of a 4K page table */
+ case 2: /* higher 2K of a 4K page table */
+ if (atomic_xor_bits(&page->_mapcount, mask << 4) != 0)
+ break;
+ /* fallthrough */
+ case 3: /* 4K page table with pgstes */
+ pgtable_page_dtor(page);
+ atomic_set(&page->_mapcount, -1);
+ __free_page(page);
+ break;
+ }
+}
+
+static void tlb_remove_table_smp_sync(void *arg)
+{
+ /* Simply deliver the interrupt */
+}
+
+static void tlb_remove_table_one(void *table)
+{
+ /*
+ * This isn't an RCU grace period and hence the page-tables cannot be
+ * assumed to be actually RCU-freed.
+ *
+ * It is however sufficient for software page-table walkers that rely
+ * on IRQ disabling. See the comment near struct mmu_table_batch.
+ */
+ smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
+ __tlb_remove_table(table);
+}
+
+static void tlb_remove_table_rcu(struct rcu_head *head)
+{
+ struct mmu_table_batch *batch;
+ int i;
+
+ batch = container_of(head, struct mmu_table_batch, rcu);
+
+ for (i = 0; i < batch->nr; i++)
+ __tlb_remove_table(batch->tables[i]);
+
+ free_page((unsigned long)batch);
+}
+
+void tlb_table_flush(struct mmu_gather *tlb)
+{
+ struct mmu_table_batch **batch = &tlb->batch;
+
+ if (*batch) {
+ call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
+ *batch = NULL;
+ }
+}
+
+void tlb_remove_table(struct mmu_gather *tlb, void *table)
+{
+ struct mmu_table_batch **batch = &tlb->batch;
+
+ tlb->mm->context.flush_mm = 1;
+ if (*batch == NULL) {
+ *batch = (struct mmu_table_batch *)
+ __get_free_page(GFP_NOWAIT | __GFP_NOWARN);
+ if (*batch == NULL) {
+ __tlb_flush_mm_lazy(tlb->mm);
+ tlb_remove_table_one(table);
+ return;
+ }
+ (*batch)->nr = 0;
+ }
+ (*batch)->tables[(*batch)->nr++] = table;
+ if ((*batch)->nr == MAX_TABLE_BATCH)
+ tlb_flush_mmu(tlb);
+}