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6252d702c5
Add support for different number of page table levels dependent on the highest address used for a process. This will cause a 31 bit process to use a two level page table instead of the four level page table that is the default after the pud has been introduced. Likewise a normal 64 bit process will use three levels instead of four. Only if a process runs out of the 4 tera bytes which can be addressed with a three level page table the fourth level is dynamically added. Then the process can use up to 8 peta byte. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
152 lines
4.0 KiB
C
152 lines
4.0 KiB
C
/*
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* linux/arch/s390/mm/mmap.c
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*
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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/module.h>
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#include <asm/pgalloc.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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#ifdef CONFIG_64BIT
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/*
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* Force standard allocation for 64 bit programs.
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*/
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if (!test_thread_flag(TIF_31BIT))
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return 1;
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#endif
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return sysctl_legacy_va_layout ||
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(current->personality & ADDR_COMPAT_LAYOUT) ||
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current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY;
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}
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#ifndef CONFIG_64BIT
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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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EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
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#else
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static unsigned long
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s390_get_unmapped_area(struct file *filp, unsigned long addr,
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unsigned long len, unsigned long pgoff, unsigned long flags)
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{
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struct mm_struct *mm = current->mm;
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int rc;
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addr = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
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if (addr & ~PAGE_MASK)
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return addr;
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if (unlikely(mm->context.asce_limit < addr + len)) {
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rc = crst_table_upgrade(mm, addr + len);
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if (rc)
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return (unsigned long) rc;
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}
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return addr;
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}
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static unsigned long
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s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
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const unsigned long len, const unsigned long pgoff,
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const unsigned long flags)
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{
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struct mm_struct *mm = current->mm;
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unsigned long addr = addr0;
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int rc;
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addr = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
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if (addr & ~PAGE_MASK)
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return addr;
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if (unlikely(mm->context.asce_limit < addr + len)) {
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rc = crst_table_upgrade(mm, addr + len);
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if (rc)
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return (unsigned long) rc;
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}
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return addr;
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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 = s390_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 = s390_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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EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
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#endif
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