| 1 |
62 |
marcus.erl |
/*
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| 2 |
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* mm/mremap.c
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| 3 |
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*
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| 4 |
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* (C) Copyright 1996 Linus Torvalds
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*
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* Address space accounting code <alan@redhat.com>
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* (C) Copyright 2002 Red Hat Inc, All Rights Reserved
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| 8 |
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*/
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| 9 |
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#include <linux/mm.h>
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| 11 |
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#include <linux/hugetlb.h>
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| 12 |
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#include <linux/slab.h>
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| 13 |
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#include <linux/shm.h>
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| 14 |
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#include <linux/mman.h>
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| 15 |
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#include <linux/swap.h>
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| 16 |
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#include <linux/capability.h>
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| 17 |
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#include <linux/fs.h>
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| 18 |
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#include <linux/highmem.h>
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| 19 |
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#include <linux/security.h>
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| 20 |
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#include <linux/syscalls.h>
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| 22 |
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#include <asm/uaccess.h>
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| 23 |
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#include <asm/cacheflush.h>
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| 24 |
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#include <asm/tlbflush.h>
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| 26 |
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static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
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| 27 |
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{
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| 28 |
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pgd_t *pgd;
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| 29 |
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pud_t *pud;
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| 30 |
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pmd_t *pmd;
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| 31 |
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| 32 |
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pgd = pgd_offset(mm, addr);
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| 33 |
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if (pgd_none_or_clear_bad(pgd))
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| 34 |
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return NULL;
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| 35 |
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| 36 |
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pud = pud_offset(pgd, addr);
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| 37 |
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if (pud_none_or_clear_bad(pud))
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| 38 |
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return NULL;
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| 39 |
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|
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| 40 |
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pmd = pmd_offset(pud, addr);
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| 41 |
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if (pmd_none_or_clear_bad(pmd))
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| 42 |
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return NULL;
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| 43 |
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| 44 |
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return pmd;
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| 45 |
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}
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| 47 |
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static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr)
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| 48 |
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{
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| 49 |
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pgd_t *pgd;
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| 50 |
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pud_t *pud;
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| 51 |
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pmd_t *pmd;
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| 52 |
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| 53 |
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pgd = pgd_offset(mm, addr);
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| 54 |
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pud = pud_alloc(mm, pgd, addr);
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| 55 |
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if (!pud)
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| 56 |
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return NULL;
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| 57 |
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| 58 |
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pmd = pmd_alloc(mm, pud, addr);
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| 59 |
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if (!pmd)
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| 60 |
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return NULL;
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| 61 |
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| 62 |
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if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr))
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| 63 |
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return NULL;
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| 64 |
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| 65 |
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return pmd;
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| 66 |
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}
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| 67 |
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| 68 |
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static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
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| 69 |
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unsigned long old_addr, unsigned long old_end,
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| 70 |
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struct vm_area_struct *new_vma, pmd_t *new_pmd,
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| 71 |
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unsigned long new_addr)
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| 72 |
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{
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| 73 |
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struct address_space *mapping = NULL;
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| 74 |
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struct mm_struct *mm = vma->vm_mm;
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| 75 |
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pte_t *old_pte, *new_pte, pte;
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| 76 |
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spinlock_t *old_ptl, *new_ptl;
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| 77 |
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| 78 |
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if (vma->vm_file) {
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| 79 |
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/*
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| 80 |
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* Subtle point from Rajesh Venkatasubramanian: before
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| 81 |
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* moving file-based ptes, we must lock vmtruncate out,
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| 82 |
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* since it might clean the dst vma before the src vma,
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| 83 |
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* and we propagate stale pages into the dst afterward.
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| 84 |
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*/
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| 85 |
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mapping = vma->vm_file->f_mapping;
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| 86 |
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spin_lock(&mapping->i_mmap_lock);
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| 87 |
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if (new_vma->vm_truncate_count &&
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| 88 |
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new_vma->vm_truncate_count != vma->vm_truncate_count)
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| 89 |
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new_vma->vm_truncate_count = 0;
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| 90 |
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}
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| 91 |
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| 92 |
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/*
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| 93 |
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* We don't have to worry about the ordering of src and dst
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| 94 |
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* pte locks because exclusive mmap_sem prevents deadlock.
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| 95 |
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*/
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| 96 |
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old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
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| 97 |
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new_pte = pte_offset_map_nested(new_pmd, new_addr);
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| 98 |
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new_ptl = pte_lockptr(mm, new_pmd);
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| 99 |
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if (new_ptl != old_ptl)
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| 100 |
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spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
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| 101 |
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arch_enter_lazy_mmu_mode();
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| 102 |
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| 103 |
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for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
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| 104 |
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new_pte++, new_addr += PAGE_SIZE) {
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| 105 |
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if (pte_none(*old_pte))
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| 106 |
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continue;
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| 107 |
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pte = ptep_clear_flush(vma, old_addr, old_pte);
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| 108 |
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pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
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| 109 |
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set_pte_at(mm, new_addr, new_pte, pte);
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| 110 |
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}
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| 111 |
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| 112 |
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arch_leave_lazy_mmu_mode();
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| 113 |
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if (new_ptl != old_ptl)
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| 114 |
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spin_unlock(new_ptl);
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| 115 |
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pte_unmap_nested(new_pte - 1);
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| 116 |
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pte_unmap_unlock(old_pte - 1, old_ptl);
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| 117 |
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if (mapping)
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| 118 |
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spin_unlock(&mapping->i_mmap_lock);
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| 119 |
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}
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| 120 |
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| 121 |
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#define LATENCY_LIMIT (64 * PAGE_SIZE)
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| 122 |
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| 123 |
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unsigned long move_page_tables(struct vm_area_struct *vma,
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| 124 |
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unsigned long old_addr, struct vm_area_struct *new_vma,
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| 125 |
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unsigned long new_addr, unsigned long len)
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| 126 |
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{
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| 127 |
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unsigned long extent, next, old_end;
|
| 128 |
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pmd_t *old_pmd, *new_pmd;
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| 129 |
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|
|
| 130 |
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old_end = old_addr + len;
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| 131 |
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flush_cache_range(vma, old_addr, old_end);
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| 132 |
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|
| 133 |
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for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
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| 134 |
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cond_resched();
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| 135 |
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next = (old_addr + PMD_SIZE) & PMD_MASK;
|
| 136 |
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if (next - 1 > old_end)
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| 137 |
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next = old_end;
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| 138 |
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extent = next - old_addr;
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| 139 |
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old_pmd = get_old_pmd(vma->vm_mm, old_addr);
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| 140 |
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if (!old_pmd)
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| 141 |
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continue;
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| 142 |
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new_pmd = alloc_new_pmd(vma->vm_mm, new_addr);
|
| 143 |
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if (!new_pmd)
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| 144 |
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break;
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| 145 |
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next = (new_addr + PMD_SIZE) & PMD_MASK;
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| 146 |
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if (extent > next - new_addr)
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| 147 |
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extent = next - new_addr;
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| 148 |
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if (extent > LATENCY_LIMIT)
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| 149 |
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extent = LATENCY_LIMIT;
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| 150 |
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move_ptes(vma, old_pmd, old_addr, old_addr + extent,
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| 151 |
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new_vma, new_pmd, new_addr);
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| 152 |
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}
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| 153 |
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| 154 |
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return len + old_addr - old_end; /* how much done */
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| 155 |
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}
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| 156 |
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| 157 |
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static unsigned long move_vma(struct vm_area_struct *vma,
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| 158 |
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unsigned long old_addr, unsigned long old_len,
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| 159 |
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unsigned long new_len, unsigned long new_addr)
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| 160 |
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{
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| 161 |
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struct mm_struct *mm = vma->vm_mm;
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| 162 |
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struct vm_area_struct *new_vma;
|
| 163 |
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unsigned long vm_flags = vma->vm_flags;
|
| 164 |
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unsigned long new_pgoff;
|
| 165 |
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unsigned long moved_len;
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| 166 |
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unsigned long excess = 0;
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| 167 |
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unsigned long hiwater_vm;
|
| 168 |
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int split = 0;
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| 169 |
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|
|
| 170 |
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/*
|
| 171 |
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* We'd prefer to avoid failure later on in do_munmap:
|
| 172 |
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* which may split one vma into three before unmapping.
|
| 173 |
|
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*/
|
| 174 |
|
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if (mm->map_count >= sysctl_max_map_count - 3)
|
| 175 |
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return -ENOMEM;
|
| 176 |
|
|
|
| 177 |
|
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new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
|
| 178 |
|
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new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
|
| 179 |
|
|
if (!new_vma)
|
| 180 |
|
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return -ENOMEM;
|
| 181 |
|
|
|
| 182 |
|
|
moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len);
|
| 183 |
|
|
if (moved_len < old_len) {
|
| 184 |
|
|
/*
|
| 185 |
|
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* On error, move entries back from new area to old,
|
| 186 |
|
|
* which will succeed since page tables still there,
|
| 187 |
|
|
* and then proceed to unmap new area instead of old.
|
| 188 |
|
|
*/
|
| 189 |
|
|
move_page_tables(new_vma, new_addr, vma, old_addr, moved_len);
|
| 190 |
|
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vma = new_vma;
|
| 191 |
|
|
old_len = new_len;
|
| 192 |
|
|
old_addr = new_addr;
|
| 193 |
|
|
new_addr = -ENOMEM;
|
| 194 |
|
|
}
|
| 195 |
|
|
|
| 196 |
|
|
/* Conceal VM_ACCOUNT so old reservation is not undone */
|
| 197 |
|
|
if (vm_flags & VM_ACCOUNT) {
|
| 198 |
|
|
vma->vm_flags &= ~VM_ACCOUNT;
|
| 199 |
|
|
excess = vma->vm_end - vma->vm_start - old_len;
|
| 200 |
|
|
if (old_addr > vma->vm_start &&
|
| 201 |
|
|
old_addr + old_len < vma->vm_end)
|
| 202 |
|
|
split = 1;
|
| 203 |
|
|
}
|
| 204 |
|
|
|
| 205 |
|
|
/*
|
| 206 |
|
|
* If we failed to move page tables we still do total_vm increment
|
| 207 |
|
|
* since do_munmap() will decrement it by old_len == new_len.
|
| 208 |
|
|
*
|
| 209 |
|
|
* Since total_vm is about to be raised artificially high for a
|
| 210 |
|
|
* moment, we need to restore high watermark afterwards: if stats
|
| 211 |
|
|
* are taken meanwhile, total_vm and hiwater_vm appear too high.
|
| 212 |
|
|
* If this were a serious issue, we'd add a flag to do_munmap().
|
| 213 |
|
|
*/
|
| 214 |
|
|
hiwater_vm = mm->hiwater_vm;
|
| 215 |
|
|
mm->total_vm += new_len >> PAGE_SHIFT;
|
| 216 |
|
|
vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
|
| 217 |
|
|
|
| 218 |
|
|
if (do_munmap(mm, old_addr, old_len) < 0) {
|
| 219 |
|
|
/* OOM: unable to split vma, just get accounts right */
|
| 220 |
|
|
vm_unacct_memory(excess >> PAGE_SHIFT);
|
| 221 |
|
|
excess = 0;
|
| 222 |
|
|
}
|
| 223 |
|
|
mm->hiwater_vm = hiwater_vm;
|
| 224 |
|
|
|
| 225 |
|
|
/* Restore VM_ACCOUNT if one or two pieces of vma left */
|
| 226 |
|
|
if (excess) {
|
| 227 |
|
|
vma->vm_flags |= VM_ACCOUNT;
|
| 228 |
|
|
if (split)
|
| 229 |
|
|
vma->vm_next->vm_flags |= VM_ACCOUNT;
|
| 230 |
|
|
}
|
| 231 |
|
|
|
| 232 |
|
|
if (vm_flags & VM_LOCKED) {
|
| 233 |
|
|
mm->locked_vm += new_len >> PAGE_SHIFT;
|
| 234 |
|
|
if (new_len > old_len)
|
| 235 |
|
|
make_pages_present(new_addr + old_len,
|
| 236 |
|
|
new_addr + new_len);
|
| 237 |
|
|
}
|
| 238 |
|
|
|
| 239 |
|
|
return new_addr;
|
| 240 |
|
|
}
|
| 241 |
|
|
|
| 242 |
|
|
/*
|
| 243 |
|
|
* Expand (or shrink) an existing mapping, potentially moving it at the
|
| 244 |
|
|
* same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
|
| 245 |
|
|
*
|
| 246 |
|
|
* MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
|
| 247 |
|
|
* This option implies MREMAP_MAYMOVE.
|
| 248 |
|
|
*/
|
| 249 |
|
|
unsigned long do_mremap(unsigned long addr,
|
| 250 |
|
|
unsigned long old_len, unsigned long new_len,
|
| 251 |
|
|
unsigned long flags, unsigned long new_addr)
|
| 252 |
|
|
{
|
| 253 |
|
|
struct mm_struct *mm = current->mm;
|
| 254 |
|
|
struct vm_area_struct *vma;
|
| 255 |
|
|
unsigned long ret = -EINVAL;
|
| 256 |
|
|
unsigned long charged = 0;
|
| 257 |
|
|
|
| 258 |
|
|
if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
|
| 259 |
|
|
goto out;
|
| 260 |
|
|
|
| 261 |
|
|
if (addr & ~PAGE_MASK)
|
| 262 |
|
|
goto out;
|
| 263 |
|
|
|
| 264 |
|
|
old_len = PAGE_ALIGN(old_len);
|
| 265 |
|
|
new_len = PAGE_ALIGN(new_len);
|
| 266 |
|
|
|
| 267 |
|
|
/*
|
| 268 |
|
|
* We allow a zero old-len as a special case
|
| 269 |
|
|
* for DOS-emu "duplicate shm area" thing. But
|
| 270 |
|
|
* a zero new-len is nonsensical.
|
| 271 |
|
|
*/
|
| 272 |
|
|
if (!new_len)
|
| 273 |
|
|
goto out;
|
| 274 |
|
|
|
| 275 |
|
|
/* new_addr is only valid if MREMAP_FIXED is specified */
|
| 276 |
|
|
if (flags & MREMAP_FIXED) {
|
| 277 |
|
|
if (new_addr & ~PAGE_MASK)
|
| 278 |
|
|
goto out;
|
| 279 |
|
|
if (!(flags & MREMAP_MAYMOVE))
|
| 280 |
|
|
goto out;
|
| 281 |
|
|
|
| 282 |
|
|
if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)
|
| 283 |
|
|
goto out;
|
| 284 |
|
|
|
| 285 |
|
|
/* Check if the location we're moving into overlaps the
|
| 286 |
|
|
* old location at all, and fail if it does.
|
| 287 |
|
|
*/
|
| 288 |
|
|
if ((new_addr <= addr) && (new_addr+new_len) > addr)
|
| 289 |
|
|
goto out;
|
| 290 |
|
|
|
| 291 |
|
|
if ((addr <= new_addr) && (addr+old_len) > new_addr)
|
| 292 |
|
|
goto out;
|
| 293 |
|
|
|
| 294 |
|
|
ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
|
| 295 |
|
|
if (ret)
|
| 296 |
|
|
goto out;
|
| 297 |
|
|
|
| 298 |
|
|
ret = do_munmap(mm, new_addr, new_len);
|
| 299 |
|
|
if (ret)
|
| 300 |
|
|
goto out;
|
| 301 |
|
|
}
|
| 302 |
|
|
|
| 303 |
|
|
/*
|
| 304 |
|
|
* Always allow a shrinking remap: that just unmaps
|
| 305 |
|
|
* the unnecessary pages..
|
| 306 |
|
|
* do_munmap does all the needed commit accounting
|
| 307 |
|
|
*/
|
| 308 |
|
|
if (old_len >= new_len) {
|
| 309 |
|
|
ret = do_munmap(mm, addr+new_len, old_len - new_len);
|
| 310 |
|
|
if (ret && old_len != new_len)
|
| 311 |
|
|
goto out;
|
| 312 |
|
|
ret = addr;
|
| 313 |
|
|
if (!(flags & MREMAP_FIXED) || (new_addr == addr))
|
| 314 |
|
|
goto out;
|
| 315 |
|
|
old_len = new_len;
|
| 316 |
|
|
}
|
| 317 |
|
|
|
| 318 |
|
|
/*
|
| 319 |
|
|
* Ok, we need to grow.. or relocate.
|
| 320 |
|
|
*/
|
| 321 |
|
|
ret = -EFAULT;
|
| 322 |
|
|
vma = find_vma(mm, addr);
|
| 323 |
|
|
if (!vma || vma->vm_start > addr)
|
| 324 |
|
|
goto out;
|
| 325 |
|
|
if (is_vm_hugetlb_page(vma)) {
|
| 326 |
|
|
ret = -EINVAL;
|
| 327 |
|
|
goto out;
|
| 328 |
|
|
}
|
| 329 |
|
|
/* We can't remap across vm area boundaries */
|
| 330 |
|
|
if (old_len > vma->vm_end - addr)
|
| 331 |
|
|
goto out;
|
| 332 |
|
|
if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {
|
| 333 |
|
|
if (new_len > old_len)
|
| 334 |
|
|
goto out;
|
| 335 |
|
|
}
|
| 336 |
|
|
if (vma->vm_flags & VM_LOCKED) {
|
| 337 |
|
|
unsigned long locked, lock_limit;
|
| 338 |
|
|
locked = mm->locked_vm << PAGE_SHIFT;
|
| 339 |
|
|
lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
|
| 340 |
|
|
locked += new_len - old_len;
|
| 341 |
|
|
ret = -EAGAIN;
|
| 342 |
|
|
if (locked > lock_limit && !capable(CAP_IPC_LOCK))
|
| 343 |
|
|
goto out;
|
| 344 |
|
|
}
|
| 345 |
|
|
if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) {
|
| 346 |
|
|
ret = -ENOMEM;
|
| 347 |
|
|
goto out;
|
| 348 |
|
|
}
|
| 349 |
|
|
|
| 350 |
|
|
if (vma->vm_flags & VM_ACCOUNT) {
|
| 351 |
|
|
charged = (new_len - old_len) >> PAGE_SHIFT;
|
| 352 |
|
|
if (security_vm_enough_memory(charged))
|
| 353 |
|
|
goto out_nc;
|
| 354 |
|
|
}
|
| 355 |
|
|
|
| 356 |
|
|
/* old_len exactly to the end of the area..
|
| 357 |
|
|
* And we're not relocating the area.
|
| 358 |
|
|
*/
|
| 359 |
|
|
if (old_len == vma->vm_end - addr &&
|
| 360 |
|
|
!((flags & MREMAP_FIXED) && (addr != new_addr)) &&
|
| 361 |
|
|
(old_len != new_len || !(flags & MREMAP_MAYMOVE))) {
|
| 362 |
|
|
unsigned long max_addr = TASK_SIZE;
|
| 363 |
|
|
if (vma->vm_next)
|
| 364 |
|
|
max_addr = vma->vm_next->vm_start;
|
| 365 |
|
|
/* can we just expand the current mapping? */
|
| 366 |
|
|
if (max_addr - addr >= new_len) {
|
| 367 |
|
|
int pages = (new_len - old_len) >> PAGE_SHIFT;
|
| 368 |
|
|
|
| 369 |
|
|
vma_adjust(vma, vma->vm_start,
|
| 370 |
|
|
addr + new_len, vma->vm_pgoff, NULL);
|
| 371 |
|
|
|
| 372 |
|
|
mm->total_vm += pages;
|
| 373 |
|
|
vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
|
| 374 |
|
|
if (vma->vm_flags & VM_LOCKED) {
|
| 375 |
|
|
mm->locked_vm += pages;
|
| 376 |
|
|
make_pages_present(addr + old_len,
|
| 377 |
|
|
addr + new_len);
|
| 378 |
|
|
}
|
| 379 |
|
|
ret = addr;
|
| 380 |
|
|
goto out;
|
| 381 |
|
|
}
|
| 382 |
|
|
}
|
| 383 |
|
|
|
| 384 |
|
|
/*
|
| 385 |
|
|
* We weren't able to just expand or shrink the area,
|
| 386 |
|
|
* we need to create a new one and move it..
|
| 387 |
|
|
*/
|
| 388 |
|
|
ret = -ENOMEM;
|
| 389 |
|
|
if (flags & MREMAP_MAYMOVE) {
|
| 390 |
|
|
if (!(flags & MREMAP_FIXED)) {
|
| 391 |
|
|
unsigned long map_flags = 0;
|
| 392 |
|
|
if (vma->vm_flags & VM_MAYSHARE)
|
| 393 |
|
|
map_flags |= MAP_SHARED;
|
| 394 |
|
|
|
| 395 |
|
|
new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
|
| 396 |
|
|
vma->vm_pgoff, map_flags);
|
| 397 |
|
|
if (new_addr & ~PAGE_MASK) {
|
| 398 |
|
|
ret = new_addr;
|
| 399 |
|
|
goto out;
|
| 400 |
|
|
}
|
| 401 |
|
|
|
| 402 |
|
|
ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);
|
| 403 |
|
|
if (ret)
|
| 404 |
|
|
goto out;
|
| 405 |
|
|
}
|
| 406 |
|
|
ret = move_vma(vma, addr, old_len, new_len, new_addr);
|
| 407 |
|
|
}
|
| 408 |
|
|
out:
|
| 409 |
|
|
if (ret & ~PAGE_MASK)
|
| 410 |
|
|
vm_unacct_memory(charged);
|
| 411 |
|
|
out_nc:
|
| 412 |
|
|
return ret;
|
| 413 |
|
|
}
|
| 414 |
|
|
|
| 415 |
|
|
asmlinkage unsigned long sys_mremap(unsigned long addr,
|
| 416 |
|
|
unsigned long old_len, unsigned long new_len,
|
| 417 |
|
|
unsigned long flags, unsigned long new_addr)
|
| 418 |
|
|
{
|
| 419 |
|
|
unsigned long ret;
|
| 420 |
|
|
|
| 421 |
|
|
down_write(¤t->mm->mmap_sem);
|
| 422 |
|
|
ret = do_mremap(addr, old_len, new_len, flags, new_addr);
|
| 423 |
|
|
up_write(¤t->mm->mmap_sem);
|
| 424 |
|
|
return ret;
|
| 425 |
|
|
}
|
