LXR linux/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
  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
  56static 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 */
  66void 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
  82const struct exception_table_entry *
  83search_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
 105void
 106ia64_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}
 116