Linux Kernel  3.7.1
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extable.c
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1 /*
2  * linux/arch/frv/mm/extable.c
3  */
4 
5 #include <linux/module.h>
6 #include <linux/spinlock.h>
7 #include <asm/uaccess.h>
8 
11 extern const void __memset_end, __memset_user_error_lr, __memset_user_error_handler;
12 extern const void __memcpy_end, __memcpy_user_error_lr, __memcpy_user_error_handler;
13 extern spinlock_t modlist_lock;
14 
15 /*****************************************************************************/
16 /*
17  *
18  */
19 static inline unsigned long search_one_table(const struct exception_table_entry *first,
20  const struct exception_table_entry *last,
21  unsigned long value)
22 {
23  while (first <= last) {
24  const struct exception_table_entry __attribute__((aligned(8))) *mid;
25  long diff;
26 
27  mid = (last - first) / 2 + first;
28  diff = mid->insn - value;
29  if (diff == 0)
30  return mid->fixup;
31  else if (diff < 0)
32  first = mid + 1;
33  else
34  last = mid - 1;
35  }
36  return 0;
37 } /* end search_one_table() */
38 
39 /*****************************************************************************/
40 /*
41  * see if there's a fixup handler available to deal with a kernel fault
42  */
43 unsigned long search_exception_table(unsigned long pc)
44 {
45  const struct exception_table_entry *extab;
46 
47  /* determine if the fault lay during a memcpy_user or a memset_user */
48  if (__frame->lr == (unsigned long) &__memset_user_error_lr &&
49  (unsigned long) &memset <= pc && pc < (unsigned long) &__memset_end
50  ) {
51  /* the fault occurred in a protected memset
52  * - we search for the return address (in LR) instead of the program counter
53  * - it was probably during a clear_user()
54  */
55  return (unsigned long) &__memset_user_error_handler;
56  }
57 
58  if (__frame->lr == (unsigned long) &__memcpy_user_error_lr &&
59  (unsigned long) &memcpy <= pc && pc < (unsigned long) &__memcpy_end
60  ) {
61  /* the fault occurred in a protected memset
62  * - we search for the return address (in LR) instead of the program counter
63  * - it was probably during a copy_to/from_user()
64  */
65  return (unsigned long) &__memcpy_user_error_handler;
66  }
67 
68  extab = search_exception_tables(pc);
69  if (extab)
70  return extab->fixup;
71 
72  return 0;
73 
74 } /* end search_exception_table() */