/*
- * linux/arch/x86-64/mm/mmap.c
- *
- * flexible mmap layout support
+ * Flexible mmap layout support
*
* Based on code by Ingo Molnar and Andi Kleen, copyrighted
* as follows:
* 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
- *
*/
#include <linux/personality.h>
#include <linux/random.h>
#include <linux/limits.h>
#include <linux/sched.h>
-#include <asm/ia32.h>
/*
* Top of mmap area (just below the process stack).
#define MIN_GAP (128*1024*1024)
#define MAX_GAP (TASK_SIZE/6*5)
-static 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 int mmap_is_32(void)
+/*
+ * True on X86_32 or when emulating IA32 on X86_64
+ */
+static int mmap_is_ia32(void)
{
+#ifdef CONFIG_X86_32
+ return 1;
+#endif
#ifdef CONFIG_IA32_EMULATION
if (test_thread_flag(TIF_IA32))
return 1;
return sysctl_legacy_va_layout;
}
+static unsigned long mmap_rnd(void)
+{
+ unsigned long rnd = 0;
+
+ /*
+ * 8 bits of randomness in 32bit mmaps, 20 address space bits
+ * 28 bits of randomness in 64bit mmaps, 40 address space bits
+ */
+ if (current->flags & PF_RANDOMIZE) {
+ if (mmap_is_ia32())
+ rnd = (long)get_random_int() % (1<<8);
+ else
+ rnd = (long)(get_random_int() % (1<<28));
+ }
+ return rnd << PAGE_SHIFT;
+}
+
+static 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 PAGE_ALIGN(TASK_SIZE - gap - mmap_rnd());
+}
+
+/*
+ * Bottom-up (legacy) layout on X86_32 did not support randomization, X86_64
+ * does, but not when emulating X86_32
+ */
+static unsigned long mmap_legacy_base(void)
+{
+ if (mmap_is_ia32())
+ return TASK_UNMAPPED_BASE;
+ else
+ return TASK_UNMAPPED_BASE + mmap_rnd();
+}
+
/*
* 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)
{
- int rnd = 0;
- 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)
- */
- rnd = get_random_int() & 0xfffffff;
- }
-
- /*
- * Fall back to the standard layout if the personality
- * bit is set, or if the expected stack growth is unlimited:
- */
- if (mmap_is_32()) {
-#ifdef CONFIG_IA32_EMULATION
- /* ia32_pick_mmap_layout has its own. */
- return ia32_pick_mmap_layout(mm);
-#endif
- } else if (mmap_is_legacy()) {
- mm->mmap_base = TASK_UNMAPPED_BASE;
+ if (mmap_is_legacy()) {
+ mm->mmap_base = mmap_legacy_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;
- if (current->flags & PF_RANDOMIZE)
- rnd = -rnd;
}
- if (current->flags & PF_RANDOMIZE)
- mm->mmap_base += ((long)rnd) << PAGE_SHIFT;
}
+++ /dev/null
-/*
- * linux/arch/i386/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/random.h>
-#include <linux/sched.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 = current->signal->rlim[RLIMIT_STACK].rlim_cur;
- 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:
- */
-#ifdef CONFIG_X86_32
-void arch_pick_mmap_layout(struct mm_struct *mm)
-#else
-void ia32_pick_mmap_layout(struct mm_struct *mm)
-#endif
-{
- /*
- * Fall back to the standard layout if the personality
- * bit is set, or if the expected stack growth is unlimited:
- */
- if (sysctl_legacy_va_layout ||
- (current->personality & ADDR_COMPAT_LAYOUT) ||
- current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY) {
- 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);
- mm->get_unmapped_area = arch_get_unmapped_area_topdown;
- mm->unmap_area = arch_unmap_area_topdown;
- }
-}
projects / linux-2.6 / commitdiff