1 files changed, 299 insertions, 0 deletions
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
new file mode 100644
index 0000000..ef3635b
--- /dev/null
+++ b/arch/s390/mm/pgtable.c
@@ -0,0 +1,299 @@
+/*
+ *  arch/s390/mm/pgtable.c
+ *
+ *    Copyright IBM Corp. 2007
+ *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/smp.h>
+#include <linux/highmem.h>
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/quicklist.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 TABLES_PER_PAGE	4
+#define FRAG_MASK	15UL
+#define SECOND_HALVES	10UL
+
+void clear_table_pgstes(unsigned long *table)
+{
+	clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE/4);
+	memset(table + 256, 0, PAGE_SIZE/4);
+	clear_table(table + 512, _PAGE_TYPE_EMPTY, PAGE_SIZE/4);
+	memset(table + 768, 0, PAGE_SIZE/4);
+}
+
+#else
+#define ALLOC_ORDER	2
+#define TABLES_PER_PAGE	2
+#define FRAG_MASK	3UL
+#define SECOND_HALVES	2UL
+
+void clear_table_pgstes(unsigned long *table)
+{
+	clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE/2);
+	memset(table + 256, 0, PAGE_SIZE/2);
+}
+
+#endif
+
+unsigned long *crst_table_alloc(struct mm_struct *mm, int noexec)
+{
+	struct page *page = alloc_pages(GFP_KERNEL, ALLOC_ORDER);
+
+	if (!page)
+		return NULL;
+	page->index = 0;
+	if (noexec) {
+		struct page *shadow = alloc_pages(GFP_KERNEL, ALLOC_ORDER);
+		if (!shadow) {
+			__free_pages(page, ALLOC_ORDER);
+			return NULL;
+		}
+		page->index = page_to_phys(shadow);
+	}
+	spin_lock(&mm->page_table_lock);
+	list_add(&page->lru, &mm->context.crst_list);
+	spin_unlock(&mm->page_table_lock);
+	return (unsigned long *) page_to_phys(page);
+}
+
+void crst_table_free(struct mm_struct *mm, unsigned long *table)
+{
+	unsigned long *shadow = get_shadow_table(table);
+	struct page *page = virt_to_page(table);
+
+	spin_lock(&mm->page_table_lock);
+	list_del(&page->lru);
+	spin_unlock(&mm->page_table_lock);
+	if (shadow)
+		free_pages((unsigned long) shadow, ALLOC_ORDER);
+	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, mm->context.noexec);
+	if (!table)
+		return -ENOMEM;
+	spin_lock(&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;
+		table = NULL;
+	}
+	spin_unlock(&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);
+		crst_table_free(mm, (unsigned long *) pgd);
+	}
+	update_mm(mm, current);
+}
+#endif
+
+/*
+ * page table entry allocation/free routines.
+ */
+unsigned long *page_table_alloc(struct mm_struct *mm)
+{
+	struct page *page;
+	unsigned long *table;
+	unsigned long bits;
+
+	bits = (mm->context.noexec || mm->context.has_pgste) ? 3UL : 1UL;
+	spin_lock(&mm->page_table_lock);
+	page = NULL;
+	if (!list_empty(&mm->context.pgtable_list)) {
+		page = list_first_entry(&mm->context.pgtable_list,
+					struct page, lru);
+		if ((page->flags & FRAG_MASK) == ((1UL << TABLES_PER_PAGE) - 1))
+			page = NULL;
+	}
+	if (!page) {
+		spin_unlock(&mm->page_table_lock);
+		page = alloc_page(GFP_KERNEL|__GFP_REPEAT);
+		if (!page)
+			return NULL;
+		pgtable_page_ctor(page);
+		page->flags &= ~FRAG_MASK;
+		table = (unsigned long *) page_to_phys(page);
+		if (mm->context.has_pgste)
+			clear_table_pgstes(table);
+		else
+			clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE);
+		spin_lock(&mm->page_table_lock);
+		list_add(&page->lru, &mm->context.pgtable_list);
+	}
+	table = (unsigned long *) page_to_phys(page);
+	while (page->flags & bits) {
+		table += 256;
+		bits <<= 1;
+	}
+	page->flags |= bits;
+	if ((page->flags & FRAG_MASK) == ((1UL << TABLES_PER_PAGE) - 1))
+		list_move_tail(&page->lru, &mm->context.pgtable_list);
+	spin_unlock(&mm->page_table_lock);
+	return table;
+}
+
+void page_table_free(struct mm_struct *mm, unsigned long *table)
+{
+	struct page *page;
+	unsigned long bits;
+
+	bits = (mm->context.noexec || mm->context.has_pgste) ? 3UL : 1UL;
+	bits <<= (__pa(table) & (PAGE_SIZE - 1)) / 256 / sizeof(unsigned long);
+	page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+	spin_lock(&mm->page_table_lock);
+	page->flags ^= bits;
+	if (page->flags & FRAG_MASK) {
+		/* Page now has some free pgtable fragments. */
+		list_move(&page->lru, &mm->context.pgtable_list);
+		page = NULL;
+	} else
+		/* All fragments of the 4K page have been freed. */
+		list_del(&page->lru);
+	spin_unlock(&mm->page_table_lock);
+	if (page) {
+		pgtable_page_dtor(page);
+		__free_page(page);
+	}
+}
+
+void disable_noexec(struct mm_struct *mm, struct task_struct *tsk)
+{
+	struct page *page;
+
+	spin_lock(&mm->page_table_lock);
+	/* Free shadow region and segment tables. */
+	list_for_each_entry(page, &mm->context.crst_list, lru)
+		if (page->index) {
+			free_pages((unsigned long) page->index, ALLOC_ORDER);
+			page->index = 0;
+		}
+	/* "Free" second halves of page tables. */
+	list_for_each_entry(page, &mm->context.pgtable_list, lru)
+		page->flags &= ~SECOND_HALVES;
+	spin_unlock(&mm->page_table_lock);
+	mm->context.noexec = 0;
+	update_mm(mm, tsk);
+}
+
+/*
+ * 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 pgstes? if yes, we are done */
+	if (tsk->mm->context.has_pgste)
+		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 ||
+	    tsk->mm != tsk->active_mm || tsk->mm->ioctx_list) {
+		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 ||
+	    tsk->mm != tsk->active_mm || tsk->mm->ioctx_list) {
+		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);
+	cpu_set(smp_processor_id(), mm->cpu_vm_mask);
+	preempt_enable();
+	task_unlock(tsk);
+	mmput(old_mm);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(s390_enable_sie);