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Commit 8817210d authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
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[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: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 562795fe

arch/x86_64/ia32/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -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)

arch/x86_64/ia32/mmap32.c

0 → 100644
+78 −0
Original line number Diff line number Diff line 
/*

 *  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;

	}

}

arch/x86_64/mm/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/x86_64/mm/mmap.c

0 → 100644
+30 −0
Original line number Diff line number Diff line 
/* 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;

}

include/asm-x86_64/ia32.h

+2 −0
Original line number Diff line number Diff line
@@ -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