1 files changed, 93 insertions, 0 deletions
diff --git a/arch/tile/mm/mmap.c b/arch/tile/mm/mmap.c
new file mode 100644
index 000000000..851a94e6a
--- /dev/null
+++ b/arch/tile/mm/mmap.c
@@ -0,0 +1,93 @@
+/*
+ * Copyright 2010 Tilera Corporation. 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, version 2.
+ *
+ *   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, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ *
+ * Taken from the i386 architecture and simplified.
+ */
+
+#include <linux/mm.h>
+#include <linux/random.h>
+#include <linux/limits.h>
+#include <linux/sched.h>
+#include <linux/mman.h>
+#include <linux/compat.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(struct mm_struct *mm)
+{
+	unsigned long gap = rlimit(RLIMIT_STACK);
+	unsigned long random_factor = 0;
+
+	if (current->flags & PF_RANDOMIZE)
+		random_factor = get_random_int() % (1024*1024);
+
+	if (gap < MIN_GAP)
+		gap = MIN_GAP;
+	else if (gap > MAX_GAP)
+		gap = MAX_GAP;
+
+	return PAGE_ALIGN(TASK_SIZE - gap - random_factor);
+}
+
+/*
+ * 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)
+{
+#if !defined(__tilegx__)
+	int is_32bit = 1;
+#elif defined(CONFIG_COMPAT)
+	int is_32bit = is_compat_task();
+#else
+	int is_32bit = 0;
+#endif
+	unsigned long random_factor = 0UL;
+
+	/*
+	 *  8 bits of randomness in 32bit mmaps, 24 address space bits
+	 * 12 bits of randomness in 64bit mmaps, 28 address space bits
+	 */
+	if (current->flags & PF_RANDOMIZE) {
+		if (is_32bit)
+			random_factor = get_random_int() % (1<<8);
+		else
+			random_factor = get_random_int() % (1<<12);
+
+		random_factor <<= PAGE_SHIFT;
+	}
+
+	/*
+	 * Use standard layout if the expected stack growth is unlimited
+	 * or we are running native 64 bits.
+	 */
+	if (rlimit(RLIMIT_STACK) == RLIM_INFINITY) {
+		mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
+		mm->get_unmapped_area = arch_get_unmapped_area;
+	} else {
+		mm->mmap_base = mmap_base(mm);
+		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
+	}
+}
+
+unsigned long arch_randomize_brk(struct mm_struct *mm)
+{
+	unsigned long range_end = mm->brk + 0x02000000;
+	return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
+}