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}