arch/sparc/mm/extable.c

   1 /*
   2  * linux/arch/sparc/mm/extable.c
   3  */
   4
   5 #include <asm/uaccess.h>
   6
   7 void sort_extable(struct exception_table_entry *start,
   8                   struct exception_table_entry *finish)
   9 {
  10 }
  11
  12 /* Caller knows they are in a range if ret->fixup == 0 */
  13 const struct exception_table_entry *
  14 search_extable(const struct exception_table_entry *start,
  15                const struct exception_table_entry *last,
  16                unsigned long value)
  17 {
  18         const struct exception_table_entry *walk;
  19
  20         /* Single insn entries are encoded as:
  21          *      word 1: insn address
  22          *      word 2: fixup code address
  23          *
  24          * Range entries are encoded as:
  25          *      word 1: first insn address
  26          *      word 2: 0
  27          *      word 3: last insn address + 4 bytes
  28          *      word 4: fixup code address
  29          *
  30          * Deleted entries are encoded as:
  31          *      word 1: unused
  32          *      word 2: -1
  33          *
  34          * See asm/uaccess.h for more details.
  35          */
  36
  37         /* 1. Try to find an exact match. */
  38         for (walk = start; walk <= last; walk++) {
  39                 if (walk->fixup == 0) {
  40                         /* A range entry, skip both parts. */
  41                         walk++;
  42                         continue;
  43                 }
  44
  45                 /* A deleted entry; see trim_init_extable */
  46                 if (walk->fixup == -1)
  47                         continue;
  48
  49                 if (walk->insn == value)
  50                         return walk;
  51         }
  52
  53         /* 2. Try to find a range match. */
  54         for (walk = start; walk <= (last - 1); walk++) {
  55                 if (walk->fixup)
  56                         continue;
  57
  58                 if (walk[0].insn <= value && walk[1].insn > value)
  59                         return walk;
  60
  61                 walk++;
  62         }
  63
  64         return NULL;
  65 }
  66
  67 #ifdef CONFIG_MODULES
  68 /* We could memmove them around; easier to mark the trimmed ones. */
  69 void trim_init_extable(struct module *m)
  70 {
  71         unsigned int i;
  72         bool range;
  73
  74         for (i = 0; i < m->num_exentries; i += range ? 2 : 1) {
  75                 range = m->extable[i].fixup == 0;
  76
  77                 if (within_module_init(m->extable[i].insn, m)) {
  78                         m->extable[i].fixup = -1;
  79                         if (range)
  80                                 m->extable[i+1].fixup = -1;
  81                 }
  82                 if (range)
  83                         i++;
  84         }
  85 }
  86 #endif /* CONFIG_MODULES */
  87
  88 /* Special extable search, which handles ranges.  Returns fixup */
  89 unsigned long search_extables_range(unsigned long addr, unsigned long *g2)
  90 {
  91         const struct exception_table_entry *entry;
  92
  93         entry = search_exception_tables(addr);
  94         if (!entry)
  95                 return 0;
  96
  97         /* Inside range?  Fix g2 and return correct fixup */
  98         if (!entry->fixup) {
  99                 *g2 = (addr - entry->insn) / 4;
 100                 return (entry + 1)->fixup;
 101         }
 102
 103         return entry->fixup;
 104 }