fedora core 6 1.2949 + vserver 2.2.0

[linux-2.6.git] / arch / x86_64 / mm / mmap.c

diff --git a/arch/x86_64/mm/mmap.c b/arch/x86_64/mm/mmap.c
index 43e9b99..432d2aa 100644 (file)
--- 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;
 }
-