X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fx86_64%2Fmm%2Fmmap.c;h=432d2aa8d9ab7ed6ece828c65a085b593ab80ae5;hb=97bf2856c6014879bd04983a3e9dfcdac1e7fe85;hp=43e9b99bdf25d6419afce6e81bab3c361e5f174d;hpb=76828883507a47dae78837ab5dec5a5b4513c667;p=linux-2.6.git

diff --git a/arch/x86_64/mm/mmap.c b/arch/x86_64/mm/mmap.c
index 43e9b99bd..432d2aa8d 100644
--- a/arch/x86_64/mm/mmap.c
+++ b/arch/x86_64/mm/mmap.c
@@ -1,30 +1,87 @@
-/* Copyright 2005 Andi Kleen, SuSE Labs.
- * Licensed under GPL, v.2
+/*
+ *  linux/arch/x86-64/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/config.h>
+
+#include <linux/personality.h>
 #include <linux/mm.h>
-#include <linux/sched.h>
 #include <linux/random.h>
-#include <asm/ia32.h>
 
-/* Notebook: move the mmap code from sys_x86_64.c over here. */
+/*
+ * 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)
+{
+	/*
+	 * Force standard allocation for 64 bit programs.
+	 */
+	if (!test_thread_flag(TIF_IA32))
+		return 1;
+
+	if (current->personality & ADDR_COMPAT_LAYOUT)
+		return 1;
+
+	if (current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY)
+		return 1;
+
+	return sysctl_legacy_va_layout;
+}
+
+/*
+ * 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)
 {
-#ifdef CONFIG_IA32_EMULATION
-	if (current_thread_info()->flags & _TIF_IA32)
-		return ia32_pick_mmap_layout(mm);
-#endif
-	mm->mmap_base = TASK_UNMAPPED_BASE;
-	if (current->flags & PF_RANDOMIZE) {
-		/* Add 28bit randomness which is about 40bits of address space
-		   because mmap base has to be page aligned.
- 		   or ~1/128 of the total user VM
-	   	   (total user address space is 47bits) */
-		unsigned rnd = get_random_int() & 0xfffffff;
-		mm->mmap_base += ((unsigned long)rnd) << PAGE_SHIFT;
+	/*
+	 * 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;
 	}
-	mm->get_unmapped_area = arch_get_unmapped_area;
-	mm->unmap_area = arch_unmap_area;
 }
-