1 files changed, 86 insertions, 0 deletions

diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
new file mode 100644
index 000000000000..fb187e5a54b4
--- /dev/null
+++ b/arch/s390/mm/mmap.c
@@ -0,0 +1,86 @@
+/*
+ *  linux/arch/s390/mm/mmap.c
+ *
+ *  flexible mmap layout support
+ *
+ * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *
+ * Started by Ingo Molnar <mingo@elte.hu>
+ */
+
+#include <linux/personality.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+
+/*
+ * Top of mmap area (just below the process stack).
+ *
+ * Leave an at least ~128 MB hole.
+ */
+#define MIN_GAP (128*1024*1024)
+#define MAX_GAP (TASK_SIZE/6*5)
+
+static inline unsigned long mmap_base(void)
+{
+        unsigned long gap = current->signal->rlim[RLIMIT_STACK].rlim_cur;
+
+        if (gap < MIN_GAP)
+                gap = MIN_GAP;
+        else if (gap > MAX_GAP)
+                gap = MAX_GAP;
+
+        return TASK_SIZE - (gap & PAGE_MASK);
+}
+
+static inline int mmap_is_legacy(void)
+{
+#ifdef CONFIG_ARCH_S390X
+        /*
+         * Force standard allocation for 64 bit programs.
+         */
+        if (!test_thread_flag(TIF_31BIT))
+                return 1;
+#endif
+        return sysctl_legacy_va_layout ||
+            (current->personality & ADDR_COMPAT_LAYOUT) ||
+            current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY;
+}
+
+/*
+ * This function, called very early during the creation of a new
+ * process VM image, sets up which VM layout function to use:
+ */
+void arch_pick_mmap_layout(struct mm_struct *mm)
+{
+        /*
+         * Fall back to the standard layout if the personality
+         * bit is set, or if the expected stack growth is unlimited:
+         */
+        if (mmap_is_legacy()) {
+                mm->mmap_base = TASK_UNMAPPED_BASE;
+                mm->get_unmapped_area = arch_get_unmapped_area;
+                mm->unmap_area = arch_unmap_area;
+        } else {
+                mm->mmap_base = mmap_base();
+                mm->get_unmapped_area = arch_get_unmapped_area_topdown;
+                mm->unmap_area = arch_unmap_area_topdown;
+        }
+}
+EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
+