linux/arch/ia64/mm/extable.c
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   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 <asm/module.h>
  12
  13static 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
  27static 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 */
  49void 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
  56const struct exception_table_entry *
  57search_extable (const struct exception_table_entry *first,
  58                const struct exception_table_entry *last,
  59                unsigned long ip)
  60{
  61        const struct exception_table_entry *mid;
  62        unsigned long mid_ip;
  63        long diff;
  64
  65        while (first <= last) {
  66                mid = &first[(last - first)/2];
  67                mid_ip = (u64) &mid->addr + mid->addr;
  68                diff = mid_ip - ip;
  69                if (diff == 0)
  70                        return mid;
  71                else if (diff < 0)
  72                        first = mid + 1;
  73                else
  74                        last = mid - 1;
  75        }
  76        return NULL;
  77}
  78
  79void
  80ia64_handle_exception (struct pt_regs *regs, const struct exception_table_entry *e)
  81{
  82        long fix = (u64) &e->cont + e->cont;
  83
  84        regs->r8 = -EFAULT;
  85        if (fix & 4)
  86                regs->r9 = 0;
  87        regs->cr_iip = fix & ~0xf;
  88        ia64_psr(regs)->ri = fix & 0x3;         /* set continuation slot number */
  89}
  90