arch/alpha/mm/extable.c

   1 /*
   2  * linux/arch/alpha/mm/extable.c
   3  */
   4
   5 #include <linux/module.h>
   6 #include <linux/sort.h>
   7 #include <asm/uaccess.h>
   8
   9 static inline unsigned long ex_to_addr(const struct exception_table_entry *x)
  10 {
  11         return (unsigned long)&x->insn + x->insn;
  12 }
  13
  14 static void swap_ex(void *a, void *b, int size)
  15 {
  16         struct exception_table_entry *ex_a = a, *ex_b = b;
  17         unsigned long addr_a = ex_to_addr(ex_a), addr_b = ex_to_addr(ex_b);
  18         unsigned int t = ex_a->fixup.unit;
  19
  20         ex_a->fixup.unit = ex_b->fixup.unit;
  21         ex_b->fixup.unit = t;
  22         ex_a->insn = (int)(addr_b - (unsigned long)&ex_a->insn);
  23         ex_b->insn = (int)(addr_a - (unsigned long)&ex_b->insn);
  24 }
  25
  26 /*
  27  * The exception table needs to be sorted so that the binary
  28  * search that we use to find entries in it works properly.
  29  * This is used both for the kernel exception table and for
  30  * the exception tables of modules that get loaded.
  31  */
  32 static int cmp_ex(const void *a, const void *b)
  33 {
  34         const struct exception_table_entry *x = a, *y = b;
  35
  36         /* avoid overflow */
  37         if (ex_to_addr(x) > ex_to_addr(y))
  38                 return 1;
  39         if (ex_to_addr(x) < ex_to_addr(y))
  40                 return -1;
  41         return 0;
  42 }
  43
  44 void sort_extable(struct exception_table_entry *start,
  45                   struct exception_table_entry *finish)
  46 {
  47         sort(start, finish - start, sizeof(struct exception_table_entry),
  48              cmp_ex, swap_ex);
  49 }
  50
  51 #ifdef CONFIG_MODULES
  52 /*
  53  * Any entry referring to the module init will be at the beginning or
  54  * the end.
  55  */
  56 void trim_init_extable(struct module *m)
  57 {
  58         /*trim the beginning*/
  59         while (m->num_exentries &&
  60                within_module_init(ex_to_addr(&m->extable[0]), m)) {
  61                 m->extable++;
  62                 m->num_exentries--;
  63         }
  64         /*trim the end*/
  65         while (m->num_exentries &&
  66                within_module_init(ex_to_addr(&m->extable[m->num_exentries-1]),
  67                                   m))
  68                 m->num_exentries--;
  69 }
  70 #endif /* CONFIG_MODULES */
  71
  72 const struct exception_table_entry *
  73 search_extable(const struct exception_table_entry *first,
  74                const struct exception_table_entry *last,
  75                unsigned long value)
  76 {
  77         while (first <= last) {
  78                 const struct exception_table_entry *mid;
  79                 unsigned long mid_value;
  80
  81                 mid = (last - first) / 2 + first;
  82                 mid_value = ex_to_addr(mid);
  83                 if (mid_value == value)
  84                         return mid;
  85                 else if (mid_value < value)
  86                         first = mid+1;
  87                 else
  88                         last = mid-1;
  89         }
  90
  91         return NULL;
  92 }