arch/ia64/mm/extable.c

   1 /*
   2  * Kernel exception handling table support.  Derived from arch/alpha/mm/extable.c.
   3  *
   4  * Copyright (C) 1998, 1999, 2001-2002, 2004 Hewlett-Packard Co
   5  *      David Mosberger-Tang <davidm@hpl.hp.com>
   6  */
   7
   8 #include <linux/sort.h>
   9
  10 #include <asm/uaccess.h>
  11 #include <linux/module.h>
  12
  13 static int cmp_ex(const void *a, const void *b)
  14 {
  15         const struct exception_table_entry *l = a, *r = b;
  16         u64 lip = (u64) &l->addr + l->addr;
  17         u64 rip = (u64) &r->addr + r->addr;
  18
  19         /* avoid overflow */
  20         if (lip > rip)
  21                 return 1;
  22         if (lip < rip)
  23                 return -1;
  24         return 0;
  25 }
  26
  27 static void swap_ex(void *a, void *b, int size)
  28 {
  29         struct exception_table_entry *l = a, *r = b, tmp;
  30         u64 delta = (u64) r - (u64) l;
  31
  32         tmp = *l;
  33         l->addr = r->addr + delta;
  34         l->cont = r->cont + delta;
  35         r->addr = tmp.addr - delta;
  36         r->cont = tmp.cont - delta;
  37 }
  38
  39 /*
  40  * Sort the exception table. It's usually already sorted, but there
  41  * may be unordered entries due to multiple text sections (such as the
  42  * .init text section). Note that the exception-table-entries contain
  43  * location-relative addresses, which requires a bit of care during
  44  * sorting to avoid overflows in the offset members (e.g., it would
  45  * not be safe to make a temporary copy of an exception-table entry on
  46  * the stack, because the stack may be more than 2GB away from the
  47  * exception-table).
  48  */
  49 void sort_extable (struct exception_table_entry *start,
  50                    struct exception_table_entry *finish)
  51 {
  52         sort(start, finish - start, sizeof(struct exception_table_entry),
  53              cmp_ex, swap_ex);
  54 }
  55
  56 static inline unsigned long ex_to_addr(const struct exception_table_entry *x)
  57 {
  58         return (unsigned long)&x->addr + x->addr;
  59 }
  60
  61 #ifdef CONFIG_MODULES
  62 /*
  63  * Any entry referring to the module init will be at the beginning or
  64  * the end.
  65  */
  66 void trim_init_extable(struct module *m)
  67 {
  68         /*trim the beginning*/
  69         while (m->num_exentries &&
  70                within_module_init(ex_to_addr(&m->extable[0]), m)) {
  71                 m->extable++;
  72                 m->num_exentries--;
  73         }
  74         /*trim the end*/
  75         while (m->num_exentries &&
  76                within_module_init(ex_to_addr(&m->extable[m->num_exentries-1]),
  77                                   m))
  78                 m->num_exentries--;
  79 }
  80 #endif /* CONFIG_MODULES */
  81
  82 const struct exception_table_entry *
  83 search_extable (const struct exception_table_entry *first,
  84                 const struct exception_table_entry *last,
  85                 unsigned long ip)
  86 {
  87         const struct exception_table_entry *mid;
  88         unsigned long mid_ip;
  89         long diff;
  90
  91         while (first <= last) {
  92                 mid = &first[(last - first)/2];
  93                 mid_ip = (u64) &mid->addr + mid->addr;
  94                 diff = mid_ip - ip;
  95                 if (diff == 0)
  96                         return mid;
  97                 else if (diff < 0)
  98                         first = mid + 1;
  99                 else
 100                         last = mid - 1;
 101         }
 102         return NULL;
 103 }
 104
 105 void
 106 ia64_handle_exception (struct pt_regs *regs, const struct exception_table_entry *e)
 107 {
 108         long fix = (u64) &e->cont + e->cont;
 109
 110         regs->r8 = -EFAULT;
 111         if (fix & 4)
 112                 regs->r9 = 0;
 113         regs->cr_iip = fix & ~0xf;
 114         ia64_psr(regs)->ri = fix & 0x3;         /* set continuation slot number */
 115 }