1 files changed, 439 insertions, 0 deletions
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
new file mode 100644
index 00000000..51b80b9d
--- /dev/null
+++ b/arch/s390/mm/pgtable.c
@@ -0,0 +1,439 @@
+/*
+ *    Copyright IBM Corp. 2007,2009
+ *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/gfp.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/smp.h>
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/quicklist.h>
+#include <linux/rcupdate.h>
+
+#include <asm/system.h>
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/tlb.h>
+#include <asm/tlbflush.h>
+#include <asm/mmu_context.h>
+
+#ifndef CONFIG_64BIT
+#define ALLOC_ORDER	1
+#define FRAG_MASK	0x0f
+#else
+#define ALLOC_ORDER	2
+#define FRAG_MASK	0x03
+#endif
+
+unsigned long VMALLOC_START = VMALLOC_END - VMALLOC_SIZE;
+EXPORT_SYMBOL(VMALLOC_START);
+
+static int __init parse_vmalloc(char *arg)
+{
+	if (!arg)
+		return -EINVAL;
+	VMALLOC_START = (VMALLOC_END - memparse(arg, &arg)) & PAGE_MASK;
+	return 0;
+}
+early_param("vmalloc", parse_vmalloc);
+
+unsigned long *crst_table_alloc(struct mm_struct *mm)
+{
+	struct page *page = alloc_pages(GFP_KERNEL, ALLOC_ORDER);
+
+	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, ALLOC_ORDER);
+}
+
+#ifdef CONFIG_64BIT
+int crst_table_upgrade(struct mm_struct *mm, unsigned long limit)
+{
+	unsigned long *table, *pgd;
+	unsigned long entry;
+
+	BUG_ON(limit > (1UL << 53));
+repeat:
+	table = crst_table_alloc(mm);
+	if (!table)
+		return -ENOMEM;
+	spin_lock_bh(&mm->page_table_lock);
+	if (mm->context.asce_limit < limit) {
+		pgd = (unsigned long *) mm->pgd;
+		if (mm->context.asce_limit <= (1UL << 31)) {
+			entry = _REGION3_ENTRY_EMPTY;
+			mm->context.asce_limit = 1UL << 42;
+			mm->context.asce_bits = _ASCE_TABLE_LENGTH |
+						_ASCE_USER_BITS |
+						_ASCE_TYPE_REGION3;
+		} else {
+			entry = _REGION2_ENTRY_EMPTY;
+			mm->context.asce_limit = 1UL << 53;
+			mm->context.asce_bits = _ASCE_TABLE_LENGTH |
+						_ASCE_USER_BITS |
+						_ASCE_TYPE_REGION2;
+		}
+		crst_table_init(table, entry);
+		pgd_populate(mm, (pgd_t *) table, (pud_t *) pgd);
+		mm->pgd = (pgd_t *) table;
+		mm->task_size = mm->context.asce_limit;
+		table = NULL;
+	}
+	spin_unlock_bh(&mm->page_table_lock);
+	if (table)
+		crst_table_free(mm, table);
+	if (mm->context.asce_limit < limit)
+		goto repeat;
+	update_mm(mm, current);
+	return 0;
+}
+
+void crst_table_downgrade(struct mm_struct *mm, unsigned long limit)
+{
+	pgd_t *pgd;
+
+	if (mm->context.asce_limit <= limit)
+		return;
+	__tlb_flush_mm(mm);
+	while (mm->context.asce_limit > limit) {
+		pgd = mm->pgd;
+		switch (pgd_val(*pgd) & _REGION_ENTRY_TYPE_MASK) {
+		case _REGION_ENTRY_TYPE_R2:
+			mm->context.asce_limit = 1UL << 42;
+			mm->context.asce_bits = _ASCE_TABLE_LENGTH |
+						_ASCE_USER_BITS |
+						_ASCE_TYPE_REGION3;
+			break;
+		case _REGION_ENTRY_TYPE_R3:
+			mm->context.asce_limit = 1UL << 31;
+			mm->context.asce_bits = _ASCE_TABLE_LENGTH |
+						_ASCE_USER_BITS |
+						_ASCE_TYPE_SEGMENT;
+			break;
+		default:
+			BUG();
+		}
+		mm->pgd = (pgd_t *) (pgd_val(*pgd) & _REGION_ENTRY_ORIGIN);
+		mm->task_size = mm->context.asce_limit;
+		crst_table_free(mm, (unsigned long *) pgd);
+	}
+	update_mm(mm, current);
+}
+#endif
+
+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.
+ */
+#ifdef CONFIG_PGSTE
+static inline unsigned long *page_table_alloc_pgste(struct mm_struct *mm)
+{
+	struct page *page;
+	unsigned long *table;
+
+	page = alloc_page(GFP_KERNEL|__GFP_REPEAT);
+	if (!page)
+		return NULL;
+	pgtable_page_ctor(page);
+	atomic_set(&page->_mapcount, 3);
+	table = (unsigned long *) page_to_phys(page);
+	clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE/2);
+	clear_table(table + PTRS_PER_PTE, 0, PAGE_SIZE/2);
+	return table;
+}
+
+static inline void page_table_free_pgste(unsigned long *table)
+{
+	struct page *page;
+
+	page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+	pgtable_page_ctor(page);
+	atomic_set(&page->_mapcount, -1);
+	__free_page(page);
+}
+#endif
+
+unsigned long *page_table_alloc(struct mm_struct *mm)
+{
+	struct page *page;
+	unsigned long *table;
+	unsigned int mask, bit;
+
+#ifdef CONFIG_PGSTE
+	if (mm_has_pgste(mm))
+		return page_table_alloc_pgste(mm);
+#endif
+	/* Allocate fragments of a 4K page as 1K/2K page table */
+	spin_lock_bh(&mm->context.list_lock);
+	mask = FRAG_MASK;
+	if (!list_empty(&mm->context.pgtable_list)) {
+		page = list_first_entry(&mm->context.pgtable_list,
+					struct page, lru);
+		table = (unsigned long *) page_to_phys(page);
+		mask = atomic_read(&page->_mapcount);
+		mask = mask | (mask >> 4);
+	}
+	if ((mask & FRAG_MASK) == FRAG_MASK) {
+		spin_unlock_bh(&mm->context.list_lock);
+		page = alloc_page(GFP_KERNEL|__GFP_REPEAT);
+		if (!page)
+			return NULL;
+		pgtable_page_ctor(page);
+		atomic_set(&page->_mapcount, 1);
+		table = (unsigned long *) page_to_phys(page);
+		clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE);
+		spin_lock_bh(&mm->context.list_lock);
+		list_add(&page->lru, &mm->context.pgtable_list);
+	} else {
+		for (bit = 1; mask & bit; bit <<= 1)
+			table += PTRS_PER_PTE;
+		mask = atomic_xor_bits(&page->_mapcount, bit);
+		if ((mask & FRAG_MASK) == FRAG_MASK)
+			list_del(&page->lru);
+	}
+	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;
+
+#ifdef CONFIG_PGSTE
+	if (mm_has_pgste(mm))
+		return page_table_free_pgste(table);
+#endif
+	/* Free 1K/2K page table fragment of a 4K page */
+	page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+	bit = 1 << ((__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t)));
+	spin_lock_bh(&mm->context.list_lock);
+	if ((atomic_read(&page->_mapcount) & FRAG_MASK) != FRAG_MASK)
+		list_del(&page->lru);
+	mask = atomic_xor_bits(&page->_mapcount, bit);
+	if (mask & FRAG_MASK)
+		list_add(&page->lru, &mm->context.pgtable_list);
+	spin_unlock_bh(&mm->context.list_lock);
+	if (mask == 0) {
+		pgtable_page_dtor(page);
+		atomic_set(&page->_mapcount, -1);
+		__free_page(page);
+	}
+}
+
+static void __page_table_free_rcu(void *table, unsigned bit)
+{
+	struct page *page;
+
+#ifdef CONFIG_PGSTE
+	if (bit == FRAG_MASK)
+		return page_table_free_pgste(table);
+#endif
+	/* Free 1K/2K page table fragment of a 4K page */
+	page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+	if (atomic_xor_bits(&page->_mapcount, bit) == 0) {
+		pgtable_page_dtor(page);
+		atomic_set(&page->_mapcount, -1);
+		__free_page(page);
+	}
+}
+
+void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table)
+{
+	struct mm_struct *mm;
+	struct page *page;
+	unsigned int bit, mask;
+
+	mm = tlb->mm;
+#ifdef CONFIG_PGSTE
+	if (mm_has_pgste(mm)) {
+		table = (unsigned long *) (__pa(table) | FRAG_MASK);
+		tlb_remove_table(tlb, table);
+		return;
+	}
+#endif
+	bit = 1 << ((__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t)));
+	page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+	spin_lock_bh(&mm->context.list_lock);
+	if ((atomic_read(&page->_mapcount) & FRAG_MASK) != FRAG_MASK)
+		list_del(&page->lru);
+	mask = atomic_xor_bits(&page->_mapcount, bit | (bit << 4));
+	if (mask & FRAG_MASK)
+		list_add_tail(&page->lru, &mm->context.pgtable_list);
+	spin_unlock_bh(&mm->context.list_lock);
+	table = (unsigned long *) (__pa(table) | (bit << 4));
+	tlb_remove_table(tlb, table);
+}
+
+void __tlb_remove_table(void *_table)
+{
+	const unsigned long mask = (FRAG_MASK << 4) | FRAG_MASK;
+	void *table = (void *)((unsigned long) _table & ~mask);
+	unsigned type = (unsigned long) _table & mask;
+
+	if (type)
+		__page_table_free_rcu(table, type);
+	else
+		free_pages((unsigned long) table, ALLOC_ORDER);
+}
+
+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) {
+		__tlb_flush_mm(tlb->mm);
+		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;
+
+	if (*batch == NULL) {
+		*batch = (struct mmu_table_batch *)
+			__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
+		if (*batch == NULL) {
+			__tlb_flush_mm(tlb->mm);
+			tlb_remove_table_one(table);
+			return;
+		}
+		(*batch)->nr = 0;
+	}
+	(*batch)->tables[(*batch)->nr++] = table;
+	if ((*batch)->nr == MAX_TABLE_BATCH)
+		tlb_table_flush(tlb);
+}
+
+/*
+ * switch on pgstes for its userspace process (for kvm)
+ */
+int s390_enable_sie(void)
+{
+	struct task_struct *tsk = current;
+	struct mm_struct *mm, *old_mm;
+
+	/* Do we have switched amode? If no, we cannot do sie */
+	if (user_mode == HOME_SPACE_MODE)
+		return -EINVAL;
+
+	/* Do we have pgstes? if yes, we are done */
+	if (mm_has_pgste(tsk->mm))
+		return 0;
+
+	/* lets check if we are allowed to replace the mm */
+	task_lock(tsk);
+	if (!tsk->mm || atomic_read(&tsk->mm->mm_users) > 1 ||
+#ifdef CONFIG_AIO
+	    !hlist_empty(&tsk->mm->ioctx_list) ||
+#endif
+	    tsk->mm != tsk->active_mm) {
+		task_unlock(tsk);
+		return -EINVAL;
+	}
+	task_unlock(tsk);
+
+	/* we copy the mm and let dup_mm create the page tables with_pgstes */
+	tsk->mm->context.alloc_pgste = 1;
+	mm = dup_mm(tsk);
+	tsk->mm->context.alloc_pgste = 0;
+	if (!mm)
+		return -ENOMEM;
+
+	/* Now lets check again if something happened */
+	task_lock(tsk);
+	if (!tsk->mm || atomic_read(&tsk->mm->mm_users) > 1 ||
+#ifdef CONFIG_AIO
+	    !hlist_empty(&tsk->mm->ioctx_list) ||
+#endif
+	    tsk->mm != tsk->active_mm) {
+		mmput(mm);
+		task_unlock(tsk);
+		return -EINVAL;
+	}
+
+	/* ok, we are alone. No ptrace, no threads, etc. */
+	old_mm = tsk->mm;
+	tsk->mm = tsk->active_mm = mm;
+	preempt_disable();
+	update_mm(mm, tsk);
+	atomic_inc(&mm->context.attach_count);
+	atomic_dec(&old_mm->context.attach_count);
+	cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
+	preempt_enable();
+	task_unlock(tsk);
+	mmput(old_mm);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(s390_enable_sie);
+
+#if defined(CONFIG_DEBUG_PAGEALLOC) && defined(CONFIG_HIBERNATION)
+bool kernel_page_present(struct page *page)
+{
+	unsigned long addr;
+	int cc;
+
+	addr = page_to_phys(page);
+	asm volatile(
+		"	lra	%1,0(%1)\n"
+		"	ipm	%0\n"
+		"	srl	%0,28"
+		: "=d" (cc), "+a" (addr) : : "cc");
+	return cc == 0;
+}
+#endif /* CONFIG_HIBERNATION && CONFIG_DEBUG_PAGEALLOC */