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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>
This commit is contained in:
Harvey Harrison 2008-01-30 13:31:10 +01:00 committed by Ingo Molnar
parent f3f20de87c
commit 675a081360
4 changed files with 53 additions and 128 deletions
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2
arch/x86/mm/Makefile_32
View File

@ -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

3
arch/x86/mm/Makefile_64
View File

@ -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

95
arch/x86/mm/mmap_64.c → arch/x86/mm/mmap.c
View File

@ -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;
}

81
arch/x86/mm/mmap_32.c
View File

@ -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;
}
}