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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
/*
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* flexible mmap layout support
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*
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* Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
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* All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*
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* Started by Ingo Molnar <mingo@elte.hu>
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*/
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#include <linux/personality.h>
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#include <linux/mm.h>
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#include <linux/sched.h>
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/*
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* Top of mmap area (just below the process stack).
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*
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* Leave an at least ~128 MB hole.
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*/
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#define MIN_GAP (128*1024*1024)
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#define MAX_GAP (TASK_SIZE/6*5)
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static inline unsigned long mmap_base(void)
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{
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unsigned long gap = current->signal->rlim[RLIMIT_STACK].rlim_cur;
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if (gap < MIN_GAP)
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gap = MIN_GAP;
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else if (gap > MAX_GAP)
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gap = MAX_GAP;
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return TASK_SIZE - (gap & PAGE_MASK);
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}
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static inline int mmap_is_legacy(void)
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{
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if (current->personality & ADDR_COMPAT_LAYOUT)
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return 1;
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if (current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY)
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return 1;
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return sysctl_legacy_va_layout;
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}
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/*
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* This function, called very early during the creation of a new
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* process VM image, sets up which VM layout function to use:
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*/
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void arch_pick_mmap_layout(struct mm_struct *mm)
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{
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/*
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* Fall back to the standard layout if the personality
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* bit is set, or if the expected stack growth is unlimited:
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*/
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if (mmap_is_legacy()) {
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mm->mmap_base = TASK_UNMAPPED_BASE;
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mm->get_unmapped_area = arch_get_unmapped_area;
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mm->unmap_area = arch_unmap_area;
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} else {
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mm->mmap_base = mmap_base();
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mm->get_unmapped_area = arch_get_unmapped_area_topdown;
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mm->unmap_area = arch_unmap_area_topdown;
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}
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}
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