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extable.c

/*
 * Kernel exception handling table support.  Derived from arch/alpha/mm/extable.c.
 *
 * Copyright (C) 1998, 1999, 2001-2002, 2004 Hewlett-Packard Co
 *    David Mosberger-Tang <davidm@hpl.hp.com>
 */

#include <linux/sort.h>

#include <asm/uaccess.h>
#include <asm/module.h>

static int cmp_ex(const void *a, const void *b)
{
      const struct exception_table_entry *l = a, *r = b;
      u64 lip = (u64) &l->addr + l->addr;
      u64 rip = (u64) &r->addr + r->addr;

      /* avoid overflow */
      if (lip > rip)
            return 1;
      if (lip < rip)
            return -1;
      return 0;
}

static void swap_ex(void *a, void *b, int size)
{
      struct exception_table_entry *l = a, *r = b, tmp;
      u64 delta = (u64) r - (u64) l;

      tmp = *l;
      l->addr = r->addr + delta;
      l->cont = r->cont + delta;
      r->addr = tmp.addr - delta;
      r->cont = tmp.cont - delta;
}

/*
 * Sort the exception table. It's usually already sorted, but there
 * may be unordered entries due to multiple text sections (such as the
 * .init text section). Note that the exception-table-entries contain
 * location-relative addresses, which requires a bit of care during
 * sorting to avoid overflows in the offset members (e.g., it would
 * not be safe to make a temporary copy of an exception-table entry on
 * the stack, because the stack may be more than 2GB away from the
 * exception-table).
 */
void sort_extable (struct exception_table_entry *start,
               struct exception_table_entry *finish)
{
      sort(start, finish - start, sizeof(struct exception_table_entry),
           cmp_ex, swap_ex);
}

const struct exception_table_entry *
search_extable (const struct exception_table_entry *first,
            const struct exception_table_entry *last,
            unsigned long ip)
{
      const struct exception_table_entry *mid;
      unsigned long mid_ip;
      long diff;

        while (first <= last) {
            mid = &first[(last - first)/2];
            mid_ip = (u64) &mid->addr + mid->addr;
            diff = mid_ip - ip;
                if (diff == 0)
                        return mid;
                else if (diff < 0)
                        first = mid + 1;
                else
                        last = mid - 1;
        }
        return NULL;
}

void
ia64_handle_exception (struct pt_regs *regs, const struct exception_table_entry *e)
{
      long fix = (u64) &e->cont + e->cont;

      regs->r8 = -EFAULT;
      if (fix & 4)
            regs->r9 = 0;
      regs->cr_iip = fix & ~0xf;
      ia64_psr(regs)->ri = fix & 0x3;           /* set continuation slot number */
}

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