Gerald Schaefer | 59f35d5 | 2006-12-04 15:40:45 +0100 | [diff] [blame] | 1 | /* |
| 2 | * arch/s390/lib/uaccess_pt.c |
| 3 | * |
| 4 | * User access functions based on page table walks. |
| 5 | * |
| 6 | * Copyright IBM Corp. 2006 |
| 7 | * Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com) |
| 8 | */ |
| 9 | |
| 10 | #include <linux/errno.h> |
Gerald Schaefer | 59f35d5 | 2006-12-04 15:40:45 +0100 | [diff] [blame] | 11 | #include <linux/mm.h> |
Heiko Carstens | 2215591 | 2006-12-08 15:53:49 +0100 | [diff] [blame] | 12 | #include <asm/uaccess.h> |
Gerald Schaefer | 59f35d5 | 2006-12-04 15:40:45 +0100 | [diff] [blame] | 13 | #include <asm/futex.h> |
| 14 | |
| 15 | static inline int __handle_fault(struct mm_struct *mm, unsigned long address, |
| 16 | int write_access) |
| 17 | { |
| 18 | struct vm_area_struct *vma; |
| 19 | int ret = -EFAULT; |
| 20 | |
| 21 | down_read(&mm->mmap_sem); |
| 22 | vma = find_vma(mm, address); |
| 23 | if (unlikely(!vma)) |
| 24 | goto out; |
| 25 | if (unlikely(vma->vm_start > address)) { |
| 26 | if (!(vma->vm_flags & VM_GROWSDOWN)) |
| 27 | goto out; |
| 28 | if (expand_stack(vma, address)) |
| 29 | goto out; |
| 30 | } |
| 31 | |
| 32 | if (!write_access) { |
| 33 | /* page not present, check vm flags */ |
| 34 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) |
| 35 | goto out; |
| 36 | } else { |
| 37 | if (!(vma->vm_flags & VM_WRITE)) |
| 38 | goto out; |
| 39 | } |
| 40 | |
| 41 | survive: |
| 42 | switch (handle_mm_fault(mm, vma, address, write_access)) { |
| 43 | case VM_FAULT_MINOR: |
| 44 | current->min_flt++; |
| 45 | break; |
| 46 | case VM_FAULT_MAJOR: |
| 47 | current->maj_flt++; |
| 48 | break; |
| 49 | case VM_FAULT_SIGBUS: |
| 50 | goto out_sigbus; |
| 51 | case VM_FAULT_OOM: |
| 52 | goto out_of_memory; |
| 53 | default: |
| 54 | BUG(); |
| 55 | } |
| 56 | ret = 0; |
| 57 | out: |
| 58 | up_read(&mm->mmap_sem); |
| 59 | return ret; |
| 60 | |
| 61 | out_of_memory: |
| 62 | up_read(&mm->mmap_sem); |
Heiko Carstens | 2215591 | 2006-12-08 15:53:49 +0100 | [diff] [blame] | 63 | if (is_init(current)) { |
Gerald Schaefer | 59f35d5 | 2006-12-04 15:40:45 +0100 | [diff] [blame] | 64 | yield(); |
Heiko Carstens | 2215591 | 2006-12-08 15:53:49 +0100 | [diff] [blame] | 65 | down_read(&mm->mmap_sem); |
Gerald Schaefer | 59f35d5 | 2006-12-04 15:40:45 +0100 | [diff] [blame] | 66 | goto survive; |
| 67 | } |
| 68 | printk("VM: killing process %s\n", current->comm); |
| 69 | return ret; |
| 70 | |
| 71 | out_sigbus: |
| 72 | up_read(&mm->mmap_sem); |
| 73 | current->thread.prot_addr = address; |
| 74 | current->thread.trap_no = 0x11; |
| 75 | force_sig(SIGBUS, current); |
| 76 | return ret; |
| 77 | } |
| 78 | |
| 79 | static inline size_t __user_copy_pt(unsigned long uaddr, void *kptr, |
| 80 | size_t n, int write_user) |
| 81 | { |
| 82 | struct mm_struct *mm = current->mm; |
| 83 | unsigned long offset, pfn, done, size; |
| 84 | pgd_t *pgd; |
| 85 | pmd_t *pmd; |
| 86 | pte_t *pte; |
| 87 | void *from, *to; |
| 88 | |
| 89 | done = 0; |
| 90 | retry: |
| 91 | spin_lock(&mm->page_table_lock); |
| 92 | do { |
| 93 | pgd = pgd_offset(mm, uaddr); |
| 94 | if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) |
| 95 | goto fault; |
| 96 | |
| 97 | pmd = pmd_offset(pgd, uaddr); |
| 98 | if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) |
| 99 | goto fault; |
| 100 | |
| 101 | pte = pte_offset_map(pmd, uaddr); |
| 102 | if (!pte || !pte_present(*pte) || |
| 103 | (write_user && !pte_write(*pte))) |
| 104 | goto fault; |
| 105 | |
| 106 | pfn = pte_pfn(*pte); |
| 107 | if (!pfn_valid(pfn)) |
| 108 | goto out; |
| 109 | |
| 110 | offset = uaddr & (PAGE_SIZE - 1); |
| 111 | size = min(n - done, PAGE_SIZE - offset); |
| 112 | if (write_user) { |
| 113 | to = (void *)((pfn << PAGE_SHIFT) + offset); |
| 114 | from = kptr + done; |
| 115 | } else { |
| 116 | from = (void *)((pfn << PAGE_SHIFT) + offset); |
| 117 | to = kptr + done; |
| 118 | } |
| 119 | memcpy(to, from, size); |
| 120 | done += size; |
| 121 | uaddr += size; |
| 122 | } while (done < n); |
| 123 | out: |
| 124 | spin_unlock(&mm->page_table_lock); |
| 125 | return n - done; |
| 126 | fault: |
| 127 | spin_unlock(&mm->page_table_lock); |
| 128 | if (__handle_fault(mm, uaddr, write_user)) |
| 129 | return n - done; |
| 130 | goto retry; |
| 131 | } |
| 132 | |
| 133 | size_t copy_from_user_pt(size_t n, const void __user *from, void *to) |
| 134 | { |
| 135 | size_t rc; |
| 136 | |
| 137 | if (segment_eq(get_fs(), KERNEL_DS)) { |
| 138 | memcpy(to, (void __kernel __force *) from, n); |
| 139 | return 0; |
| 140 | } |
| 141 | rc = __user_copy_pt((unsigned long) from, to, n, 0); |
| 142 | if (unlikely(rc)) |
| 143 | memset(to + n - rc, 0, rc); |
| 144 | return rc; |
| 145 | } |
| 146 | |
| 147 | size_t copy_to_user_pt(size_t n, void __user *to, const void *from) |
| 148 | { |
| 149 | if (segment_eq(get_fs(), KERNEL_DS)) { |
| 150 | memcpy((void __kernel __force *) to, from, n); |
| 151 | return 0; |
| 152 | } |
| 153 | return __user_copy_pt((unsigned long) to, (void *) from, n, 1); |
| 154 | } |