forked from Minki/linux
91b0f5ec53
We currently place mmaps just below the stack on 32bit, but leave them in the middle of the address space on 64bit: 00100000-00120000 r-xp 00100000 00:00 0 [vdso] 10000000-10010000 r-xp 00000000 08:06 179534 /tmp/sleep 10010000-10020000 rw-p 00000000 08:06 179534 /tmp/sleep 10020000-10130000 rw-p 10020000 00:00 0 [heap] 40000000000-40000030000 r-xp 00000000 08:06 440743 /lib64/ld-2.9.so 40000030000-40000040000 rw-p 00020000 08:06 440743 /lib64/ld-2.9.so 40000050000-400001f0000 r-xp 00000000 08:06 440671 /lib64/libc-2.9.so 400001f0000-40000200000 r--p 00190000 08:06 440671 /lib64/libc-2.9.so 40000200000-40000220000 rw-p 001a0000 08:06 440671 /lib64/libc-2.9.so 40000220000-40008230000 rw-p 40000220000 00:00 0 fffffbc0000-fffffd10000 rw-p fffffeb0000 00:00 0 [stack] Right now it isn't an issue, but at some stage we will run into mmap or hugetlb allocation issues. Using the same layout as 32bit gives us a some breathing room. This matches what x86-64 is doing too. 00100000-00103000 r-xp 00100000 00:00 0 [vdso] 10000000-10001000 r-xp 00000000 08:06 554894 /tmp/test 10010000-10011000 r--p 00000000 08:06 554894 /tmp/test 10011000-10012000 rw-p 00001000 08:06 554894 /tmp/test 10012000-10113000 rw-p 10012000 00:00 0 [heap] fffefdf7000-ffff7df8000 rw-p fffefdf7000 00:00 0 ffff7df8000-ffff7f97000 r-xp 00000000 08:06 130591 /lib64/libc-2.9.so ffff7f97000-ffff7fa6000 ---p 0019f000 08:06 130591 /lib64/libc-2.9.so ffff7fa6000-ffff7faa000 r--p 0019e000 08:06 130591 /lib64/libc-2.9.so ffff7faa000-ffff7fc0000 rw-p 001a2000 08:06 130591 /lib64/libc-2.9.so ffff7fc0000-ffff7fc4000 rw-p ffff7fc0000 00:00 0 ffff7fc4000-ffff7fec000 r-xp 00000000 08:06 130663 /lib64/ld-2.9.so ffff7fee000-ffff7ff0000 rw-p ffff7fee000 00:00 0 ffff7ffa000-ffff7ffb000 rw-p ffff7ffa000 00:00 0 ffff7ffb000-ffff7ffc000 r--p 00027000 08:06 130663 /lib64/ld-2.9.so ffff7ffc000-ffff7fff000 rw-p 00028000 08:06 130663 /lib64/ld-2.9.so ffff7fff000-ffff8000000 rw-p ffff7fff000 00:00 0 fffffc59000-fffffc6e000 rw-p ffffffeb000 00:00 0 [stack] Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
80 lines
2.1 KiB
C
80 lines
2.1 KiB
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/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(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 inline int mmap_is_legacy(void)
|
|
{
|
|
if (current->personality & ADDR_COMPAT_LAYOUT)
|
|
return 1;
|
|
|
|
if (current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY)
|
|
return 1;
|
|
|
|
return sysctl_legacy_va_layout;
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
/*
|
|
* Fall back to the standard layout if the personality
|
|
* bit is set, or if the expected stack growth is unlimited:
|
|
*/
|
|
if (mmap_is_legacy()) {
|
|
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->get_unmapped_area = arch_get_unmapped_area_topdown;
|
|
mm->unmap_area = arch_unmap_area_topdown;
|
|
}
|
|
}
|