nios2: Page table management

This patch adds support for page table management.

Signed-off-by: Ley Foon Tan <lftan@altera.com>

1 files changed, 74 insertions, 0 deletions

diff --git a/arch/nios2/mm/pgtable.c b/arch/nios2/mm/pgtable.c
new file mode 100644
index 0000000..61e24a2
--- /dev/null
+++ b/arch/nios2/mm/pgtable.c
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2009 Wind River Systems Inc
+ *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+
+#include <asm/pgtable.h>
+#include <asm/cpuinfo.h>
+
+/* pteaddr:
+ *   ptbase | vpn* | zero
+ *   31-22  | 21-2 | 1-0
+ *
+ *   *vpn is preserved on double fault
+ *
+ * tlbacc:
+ *   IG   |*flags| pfn
+ *   31-25|24-20 | 19-0
+ *
+ *   *crwxg
+ *
+ * tlbmisc:
+ *   resv  |way   |rd | we|pid |dbl|bad|perm|d
+ *   31-24 |23-20 |19 | 20|17-4|3  |2  |1   |0
+ *
+ */
+
+/*
+ * Initialize a new pgd / pmd table with invalid pointers.
+ */
+static void pgd_init(pgd_t *pgd)
+{
+	unsigned long *p = (unsigned long *) pgd;
+	int i;
+
+	for (i = 0; i < USER_PTRS_PER_PGD; i += 8) {
+		p[i + 0] = (unsigned long) invalid_pte_table;
+		p[i + 1] = (unsigned long) invalid_pte_table;
+		p[i + 2] = (unsigned long) invalid_pte_table;
+		p[i + 3] = (unsigned long) invalid_pte_table;
+		p[i + 4] = (unsigned long) invalid_pte_table;
+		p[i + 5] = (unsigned long) invalid_pte_table;
+		p[i + 6] = (unsigned long) invalid_pte_table;
+		p[i + 7] = (unsigned long) invalid_pte_table;
+	}
+}
+
+pgd_t *pgd_alloc(struct mm_struct *mm)
+{
+	pgd_t *ret, *init;
+
+	ret = (pgd_t *) __get_free_pages(GFP_KERNEL, PGD_ORDER);
+	if (ret) {
+		init = pgd_offset(&init_mm, 0UL);
+		pgd_init(ret);
+		memcpy(ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD,
+		       (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
+	}
+
+	return ret;
+}
+
+void __init pagetable_init(void)
+{
+	/* Initialize the entire pgd.  */
+	pgd_init(swapper_pg_dir);
+	pgd_init(swapper_pg_dir + USER_PTRS_PER_PGD);
+}