forked from Minki/linux
8f3e474f3c
To correctly handle 32-bit and 64-bit mmap() syscalls in 64bit applications its required to have separate address bases to place a mapping. The tasksize can be used as an indicator to select the proper parameters for mmap_base(). This requires the following changes: - Add task_size argument to mmap_base() and make the calculation based on it. - Provide mmap_legacy_base() as a seperate function - Use the new functions in arch_pick_mmap_layout() [ tglx: Massaged changelog ] Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com> Cc: 0x7f454c46@gmail.com Cc: linux-mm@kvack.org Cc: Andy Lutomirski <luto@kernel.org> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Borislav Petkov <bp@suse.de> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Link: http://lkml.kernel.org/r/20170306141721.9188-3-dsafonov@virtuozzo.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
141 lines
3.6 KiB
C
141 lines
3.6 KiB
C
/*
|
|
* Flexible mmap layout support
|
|
*
|
|
* Based on code by Ingo Molnar and Andi Kleen, copyrighted
|
|
* as follows:
|
|
*
|
|
* Copyright 2003-2009 Red Hat Inc.
|
|
* All Rights Reserved.
|
|
* Copyright 2005 Andi Kleen, SUSE Labs.
|
|
* Copyright 2007 Jiri Kosina, SUSE Labs.
|
|
*
|
|
* 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
|
|
*/
|
|
|
|
#include <linux/personality.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/random.h>
|
|
#include <linux/limits.h>
|
|
#include <linux/sched/signal.h>
|
|
#include <linux/sched/mm.h>
|
|
#include <asm/elf.h>
|
|
|
|
struct va_alignment __read_mostly va_align = {
|
|
.flags = -1,
|
|
};
|
|
|
|
static inline unsigned long tasksize_32bit(void)
|
|
{
|
|
return IA32_PAGE_OFFSET;
|
|
}
|
|
|
|
static unsigned long stack_maxrandom_size(unsigned long task_size)
|
|
{
|
|
unsigned long max = 0;
|
|
if ((current->flags & PF_RANDOMIZE) &&
|
|
!(current->personality & ADDR_NO_RANDOMIZE)) {
|
|
max = (-1UL) & __STACK_RND_MASK(task_size == tasksize_32bit());
|
|
max <<= PAGE_SHIFT;
|
|
}
|
|
|
|
return max;
|
|
}
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
# define mmap32_rnd_bits mmap_rnd_compat_bits
|
|
# define mmap64_rnd_bits mmap_rnd_bits
|
|
#else
|
|
# define mmap32_rnd_bits mmap_rnd_bits
|
|
# define mmap64_rnd_bits mmap_rnd_bits
|
|
#endif
|
|
|
|
#define SIZE_128M (128 * 1024 * 1024UL)
|
|
|
|
static int mmap_is_legacy(void)
|
|
{
|
|
if (current->personality & ADDR_COMPAT_LAYOUT)
|
|
return 1;
|
|
|
|
if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
|
|
return 1;
|
|
|
|
return sysctl_legacy_va_layout;
|
|
}
|
|
|
|
static unsigned long arch_rnd(unsigned int rndbits)
|
|
{
|
|
return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
|
|
}
|
|
|
|
unsigned long arch_mmap_rnd(void)
|
|
{
|
|
return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits);
|
|
}
|
|
|
|
static unsigned long mmap_base(unsigned long rnd, unsigned long task_size)
|
|
{
|
|
unsigned long gap = rlimit(RLIMIT_STACK);
|
|
unsigned long gap_min, gap_max;
|
|
|
|
/*
|
|
* Top of mmap area (just below the process stack).
|
|
* Leave an at least ~128 MB hole with possible stack randomization.
|
|
*/
|
|
gap_min = SIZE_128M + stack_maxrandom_size(task_size);
|
|
gap_max = (task_size / 6) * 5;
|
|
|
|
if (gap < gap_min)
|
|
gap = gap_min;
|
|
else if (gap > gap_max)
|
|
gap = gap_max;
|
|
|
|
return PAGE_ALIGN(task_size - gap - rnd);
|
|
}
|
|
|
|
static unsigned long mmap_legacy_base(unsigned long rnd,
|
|
unsigned long task_size)
|
|
{
|
|
return __TASK_UNMAPPED_BASE(task_size) + 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)
|
|
{
|
|
unsigned long random_factor = 0UL;
|
|
|
|
if (current->flags & PF_RANDOMIZE)
|
|
random_factor = arch_mmap_rnd();
|
|
|
|
mm->mmap_legacy_base = mmap_legacy_base(random_factor, TASK_SIZE);
|
|
|
|
if (mmap_is_legacy()) {
|
|
mm->mmap_base = mm->mmap_legacy_base;
|
|
mm->get_unmapped_area = arch_get_unmapped_area;
|
|
} else {
|
|
mm->mmap_base = mmap_base(random_factor, TASK_SIZE);
|
|
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
|
|
}
|
|
}
|
|
|
|
const char *arch_vma_name(struct vm_area_struct *vma)
|
|
{
|
|
if (vma->vm_flags & VM_MPX)
|
|
return "[mpx]";
|
|
return NULL;
|
|
}
|