[PATCH] x86_64: Flexmap for 32bit and randomized mappings for 64bit

Another try at this.

For 32bit follow the 32bit implementation from Ingo -
mappings are growing down from the end of stack now
and vary randomly by 1GB.

Randomized mappings for 64bit just vary the normal mmap break
by 1TB. I didn't bother implementing full flex mmap for 64bit
because it shouldn't be needed there.

Cc: mingo@elte.hu

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Andi Kleen 2006-01-17 07:03:38 +01:00 committed by Linus Torvalds
parent 562795fe57
commit 8817210d4d
6 changed files with 115 additions and 2 deletions

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@ -3,7 +3,8 @@
#
obj-$(CONFIG_IA32_EMULATION) := ia32entry.o sys_ia32.o ia32_signal.o tls32.o \
ia32_binfmt.o fpu32.o ptrace32.o syscall32.o syscall32_syscall.o
ia32_binfmt.o fpu32.o ptrace32.o syscall32.o syscall32_syscall.o \
mmap32.o
sysv-$(CONFIG_SYSVIPC) := ipc32.o
obj-$(CONFIG_IA32_EMULATION) += $(sysv-y)

78
arch/x86_64/ia32/mmap32.c Normal file
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@ -0,0 +1,78 @@
/*
* linux/arch/x86_64/ia32/mm/mmap.c
*
* flexible mmap layout support
*
* Based on the i386 version which was
*
* 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>
/*
* 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:
*/
void ia32_pick_mmap_layout(struct mm_struct *mm)
{
/*
* 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;
}
}

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@ -2,7 +2,7 @@
# Makefile for the linux x86_64-specific parts of the memory manager.
#
obj-y := init.o fault.o ioremap.o extable.o pageattr.o
obj-y := init.o fault.o ioremap.o extable.o pageattr.o mmap.o
obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
obj-$(CONFIG_NUMA) += numa.o
obj-$(CONFIG_K8_NUMA) += k8topology.o

30
arch/x86_64/mm/mmap.c Normal file
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@ -0,0 +1,30 @@
/* Copyright 2005 Andi Kleen, SuSE Labs.
* Licensed under GPL, v.2
*/
#include <linux/config.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. */
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;
}
mm->get_unmapped_area = arch_get_unmapped_area;
mm->unmap_area = arch_unmap_area;
}

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@ -169,6 +169,8 @@ int ia32_child_tls(struct task_struct *p, struct pt_regs *childregs);
struct linux_binprm;
extern int ia32_setup_arg_pages(struct linux_binprm *bprm,
unsigned long stack_top, int exec_stack);
struct mm_struct;
extern void ia32_pick_mmap_layout(struct mm_struct *mm);
#endif

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@ -477,4 +477,6 @@ extern unsigned long boot_option_idle_override;
/* Boot loader type from the setup header */
extern int bootloader_type;
#define HAVE_ARCH_PICK_MMAP_LAYOUT 1
#endif /* __ASM_X86_64_PROCESSOR_H */