arch/sparc/mm/extable.c

   1 /*
   2  * linux/arch/sparc/mm/extable.c
   3  */
   4
   5 #include <linux/module.h>
   6 #include <asm/uaccess.h>
   7
   8 void sort_extable(struct exception_table_entry *start,
   9                   struct exception_table_entry *finish)
  10 {
  11 }
  12
  13 /* Caller knows they are in a range if ret->fixup == 0 */
  14 const struct exception_table_entry *
  15 search_extable(const struct exception_table_entry *start,
  16                const struct exception_table_entry *last,
  17                unsigned long value)
  18 {
  19         const struct exception_table_entry *walk;
  20
  21         /* Single insn entries are encoded as:
  22          *      word 1: insn address
  23          *      word 2: fixup code address
  24          *
  25          * Range entries are encoded as:
  26          *      word 1: first insn address
  27          *      word 2: 0
  28          *      word 3: last insn address + 4 bytes
  29          *      word 4: fixup code address
  30          *
  31          * Deleted entries are encoded as:
  32          *      word 1: unused
  33          *      word 2: -1
  34          *
  35          * See asm/uaccess.h for more details.
  36          */
  37
  38         /* 1. Try to find an exact match. */
  39         for (walk = start; walk <= last; walk++) {
  40                 if (walk->fixup == 0) {
  41                         /* A range entry, skip both parts. */
  42                         walk++;
  43                         continue;
  44                 }
  45
  46                 /* A deleted entry; see trim_init_extable */
  47                 if (walk->fixup == -1)
  48                         continue;
  49
  50                 if (walk->insn == value)
  51                         return walk;
  52         }
  53
  54         /* 2. Try to find a range match. */
  55         for (walk = start; walk <= (last - 1); walk++) {
  56                 if (walk->fixup)
  57                         continue;
  58
  59                 if (walk[0].insn <= value && walk[1].insn > value)
  60                         return walk;
  61
  62                 walk++;
  63         }
  64
  65         return NULL;
  66 }
  67
  68 #ifdef CONFIG_MODULES
  69 /* We could memmove them around; easier to mark the trimmed ones. */
  70 void trim_init_extable(struct module *m)
  71 {
  72         unsigned int i;
  73         bool range;
  74
  75         for (i = 0; i < m->num_exentries; i += range ? 2 : 1) {
  76                 range = m->extable[i].fixup == 0;
  77
  78                 if (within_module_init(m->extable[i].insn, m)) {
  79                         m->extable[i].fixup = -1;
  80                         if (range)
  81                                 m->extable[i+1].fixup = -1;
  82                 }
  83                 if (range)
  84                         i++;
  85         }
  86 }
  87 #endif /* CONFIG_MODULES */
  88
  89 /* Special extable search, which handles ranges.  Returns fixup */
  90 unsigned long search_extables_range(unsigned long addr, unsigned long *g2)
  91 {
  92         const struct exception_table_entry *entry;
  93
  94         entry = search_exception_tables(addr);
  95         if (!entry)
  96                 return 0;
  97
  98         /* Inside range?  Fix g2 and return correct fixup */
  99         if (!entry->fixup) {
 100                 *g2 = (addr - entry->insn) / 4;
 101                 return (entry + 1)->fixup;
 102         }
 103
 104         return entry->fixup;
 105 }