LXR linux/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
   9static inline unsigned long ex_to_addr(const struct exception_table_entry *x)
  10{
  11        return (unsigned long)&x->insn + x->insn;
  12}
  13
  14static 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 */
  32static 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
  44void 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 */
  56void 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
  72const struct exception_table_entry *
  73search_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}
  93