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/config.h>
   9 #include <linux/sort.h>
  10
  11 #include <asm/uaccess.h>
  12 #include <asm/module.h>
  13
  14 static int cmp_ex(const void *a, const void *b)
  15 {
  16         const struct exception_table_entry *l = a, *r = b;
  17         u64 lip = (u64) &l->addr + l->addr;
  18         u64 rip = (u64) &r->addr + r->addr;
  19
  20         /* avoid overflow */
  21         if (lip > rip)
  22                 return 1;
  23         if (lip < rip)
  24                 return -1;
  25         return 0;
  26 }
  27
  28 static void swap_ex(void *a, void *b, int size)
  29 {
  30         struct exception_table_entry *l = a, *r = b, tmp;
  31         u64 delta = (u64) r - (u64) l;
  32
  33         tmp = *l;
  34         l->addr = r->addr + delta;
  35         l->cont = r->cont + delta;
  36         r->addr = tmp.addr - delta;
  37         r->cont = tmp.cont - delta;
  38 }
  39
  40 /*
  41  * Sort the exception table. It's usually already sorted, but there
  42  * may be unordered entries due to multiple text sections (such as the
  43  * .init text section). Note that the exception-table-entries contain
  44  * location-relative addresses, which requires a bit of care during
  45  * sorting to avoid overflows in the offset members (e.g., it would
  46  * not be safe to make a temporary copy of an exception-table entry on
  47  * the stack, because the stack may be more than 2GB away from the
  48  * exception-table).
  49  */
  50 void sort_extable (struct exception_table_entry *start,
  51                    struct exception_table_entry *finish)
  52 {
  53         sort(start, finish - start, sizeof(struct exception_table_entry),
  54              cmp_ex, swap_ex);
  55 }
  56
  57 const struct exception_table_entry *
  58 search_extable (const struct exception_table_entry *first,
  59                 const struct exception_table_entry *last,
  60                 unsigned long ip)
  61 {
  62         const struct exception_table_entry *mid;
  63         unsigned long mid_ip;
  64         long diff;
  65
  66         while (first <= last) {
  67                 mid = &first[(last - first)/2];
  68                 mid_ip = (u64) &mid->addr + mid->addr;
  69                 diff = mid_ip - ip;
  70                 if (diff == 0)
  71                         return mid;
  72                 else if (diff < 0)
  73                         first = mid + 1;
  74                 else
  75                         last = mid - 1;
  76         }
  77         return NULL;
  78 }
  79
  80 void
  81 ia64_handle_exception (struct pt_regs *regs, const struct exception_table_entry *e)
  82 {
  83         long fix = (u64) &e->cont + e->cont;
  84
  85         regs->r8 = -EFAULT;
  86         if (fix & 4)
  87                 regs->r9 = 0;
  88         regs->cr_iip = fix & ~0xf;
  89         ia64_psr(regs)->ri = fix & 0x3;         /* set continuation slot number */
  90 }