x86: unify mmap_{32|64}.c

mmap_is_ia32 always true for X86_32, or while emulating IA32 on X86_64

Randomization not supported on X86_32 in legacy layout.  Both layouts allow
randomization on X86_64.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

4 files changed, 53 insertions, 128 deletions

diff --git a/arch/x86/mm/Makefile_32 b/arch/x86/mm/Makefile_32
index 362b4ad082de..a01aca79dc69 100644
--- a/arch/x86/mm/Makefile_32
+++ b/arch/x86/mm/Makefile_32
@@ -2,7 +2,7 @@
 # Makefile for the linux i386-specific parts of the memory manager.
 #
 
-obj-y   := init_32.o pgtable_32.o fault_32.o ioremap_32.o extable_32.o pageattr_32.o mmap_32.o
+obj-y   := init_32.o pgtable_32.o fault_32.o ioremap_32.o extable_32.o pageattr_32.o mmap.o
 
 obj-$(CONFIG_NUMA) += discontig_32.o
 obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
diff --git a/arch/x86/mm/Makefile_64 b/arch/x86/mm/Makefile_64
index d18baed54fc6..b5a74486c3aa 100644
--- a/arch/x86/mm/Makefile_64
+++ b/arch/x86/mm/Makefile_64
@@ -2,9 +2,8 @@
 # Makefile for the linux x86_64-specific parts of the memory manager.
 #
 
-obj-y    := init_64.o fault_64.o ioremap_64.o extable_64.o pageattr_64.o mmap_64.o
+obj-y    := init_64.o fault_64.o ioremap_64.o extable_64.o pageattr_64.o mmap.o
 obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
 obj-$(CONFIG_NUMA) += numa_64.o
 obj-$(CONFIG_K8_NUMA) += k8topology_64.o
 obj-$(CONFIG_ACPI_NUMA) += srat_64.o
-obj-$(CONFIG_IA32_EMULATION) += mmap_32.o
diff --git a/arch/x86/mm/mmap_64.c b/arch/x86/mm/mmap.c
index 119bf34ec529..56fe7124fbec 100644
--- a/arch/x86/mm/mmap_64.c
+++ b/arch/x86/mm/mmap.c
@@ -1,7 +1,5 @@
 /*
- *  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:
@@ -24,7 +22,6 @@
  * 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>
@@ -32,7 +29,6 @@
 #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).
@@ -42,20 +38,14 @@
 #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;
@@ -74,43 +64,60 @@ static int mmap_is_legacy(void)
         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;
 }
diff --git a/arch/x86/mm/mmap_32.c b/arch/x86/mm/mmap_32.c
deleted file mode 100644
index d490662e4af4..000000000000
--- a/arch/x86/mm/mmap_32.c
+++ /dev/null
@@ -1,81 +0,0 @@
-/*
- *  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;
-        }
-}