1 files changed, 46 insertions, 32 deletions

diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index 869efbaed3e..9b436c21195 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -1,6 +1,4 @@
 /*
- *  linux/arch/s390/mm/mmap.c
- *
  *  flexible mmap layout support
  *
  * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
@@ -26,18 +24,51 @@
 
 #include <linux/personality.h>
 #include <linux/mm.h>
+#include <linux/mman.h>
 #include <linux/module.h>
+#include <linux/random.h>
+#include <linux/compat.h>
 #include <asm/pgalloc.h>
-#include <asm/compat.h>
+
+static unsigned long stack_maxrandom_size(void)
+{
+	if (!(current->flags & PF_RANDOMIZE))
+		return 0;
+	if (current->personality & ADDR_NO_RANDOMIZE)
+		return 0;
+	return STACK_RND_MASK << PAGE_SHIFT;
+}
 
 /*
  * Top of mmap area (just below the process stack).
  *
- * Leave an at least ~128 MB hole.
+ * Leave at least a ~32 MB hole.
  */
-#define MIN_GAP (128*1024*1024)
+#define MIN_GAP (32*1024*1024)
 #define MAX_GAP (STACK_TOP/6*5)
 
+static inline int mmap_is_legacy(void)
+{
+	if (current->personality & ADDR_COMPAT_LAYOUT)
+		return 1;
+	if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
+		return 1;
+	return sysctl_legacy_va_layout;
+}
+
+static unsigned long mmap_rnd(void)
+{
+	if (!(current->flags & PF_RANDOMIZE))
+		return 0;
+	/* 8MB randomization for mmap_base */
+	return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
+}
+
+static unsigned long mmap_base_legacy(void)
+{
+	return TASK_UNMAPPED_BASE + mmap_rnd();
+}
+
 static inline unsigned long mmap_base(void)
 {
 	unsigned long gap = rlimit(RLIMIT_STACK);
@@ -46,22 +77,8 @@ static inline unsigned long mmap_base(void)
 		gap = MIN_GAP;
 	else if (gap > MAX_GAP)
 		gap = MAX_GAP;
-
-	return STACK_TOP - (gap & PAGE_MASK);
-}
-
-static inline int mmap_is_legacy(void)
-{
-#ifdef CONFIG_64BIT
-	/*
-	 * Force standard allocation for 64 bit programs.
-	 */
-	if (!is_compat_task())
-		return 1;
-#endif
-	return sysctl_legacy_va_layout ||
-	    (current->personality & ADDR_COMPAT_LAYOUT) ||
-	    rlimit(RLIMIT_STACK) == RLIM_INFINITY;
+	gap &= PAGE_MASK;
+	return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap;
 }
 
 #ifndef CONFIG_64BIT
@@ -77,23 +94,23 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
 	 * bit is set, or if the expected stack growth is unlimited:
 	 */
 	if (mmap_is_legacy()) {
-		mm->mmap_base = TASK_UNMAPPED_BASE;
+		mm->mmap_base = mmap_base_legacy();
 		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);
 
 #else
 
-int s390_mmap_check(unsigned long addr, unsigned long len)
+int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags)
 {
-	if (!is_compat_task() &&
-	    len >= TASK_SIZE && TASK_SIZE < (1UL << 53))
+	if (is_compat_task() || (TASK_SIZE >= (1UL << 53)))
+		return 0;
+	if (!(flags & MAP_FIXED))
+		addr = 0;
+	if ((addr + len) >= TASK_SIZE)
 		return crst_table_upgrade(current->mm, 1UL << 53);
 	return 0;
 }
@@ -152,15 +169,12 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
 	 * bit is set, or if the expected stack growth is unlimited:
 	 */
 	if (mmap_is_legacy()) {
-		mm->mmap_base = TASK_UNMAPPED_BASE;
+		mm->mmap_base = mmap_base_legacy();
 		mm->get_unmapped_area = s390_get_unmapped_area;
-		mm->unmap_area = arch_unmap_area;
 	} else {
 		mm->mmap_base = mmap_base();
 		mm->get_unmapped_area = s390_get_unmapped_area_topdown;
-		mm->unmap_area = arch_unmap_area_topdown;
 	}
 }
-EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
 
 #endif