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/arch/frv/mm/extable.c

https://bitbucket.org/thekraven/iscream_thunderc-2.6.35
C | 74 lines | 44 code | 10 blank | 20 comment | 12 complexity | b77c3633fe4a6d0579c87fa181df0998 MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
 1/*
 2 * linux/arch/frv/mm/extable.c
 3 */
 4
 5#include <linux/module.h>
 6#include <linux/spinlock.h>
 7#include <asm/uaccess.h>
 8
 9extern const struct exception_table_entry __attribute__((aligned(8))) __start___ex_table[];
10extern const struct exception_table_entry __attribute__((aligned(8))) __stop___ex_table[];
11extern const void __memset_end, __memset_user_error_lr, __memset_user_error_handler;
12extern const void __memcpy_end, __memcpy_user_error_lr, __memcpy_user_error_handler;
13extern spinlock_t modlist_lock;
14
15/*****************************************************************************/
16/*
17 *
18 */
19static inline unsigned long search_one_table(const struct exception_table_entry *first,
20					     const struct exception_table_entry *last,
21					     unsigned long value)
22{
23        while (first <= last) {
24		const struct exception_table_entry __attribute__((aligned(8))) *mid;
25		long diff;
26
27		mid = (last - first) / 2 + first;
28		diff = mid->insn - value;
29                if (diff == 0)
30                        return mid->fixup;
31                else if (diff < 0)
32                        first = mid + 1;
33                else
34                        last = mid - 1;
35        }
36        return 0;
37} /* end search_one_table() */
38
39/*****************************************************************************/
40/*
41 * see if there's a fixup handler available to deal with a kernel fault
42 */
43unsigned long search_exception_table(unsigned long pc)
44{
45	const struct exception_table_entry *extab;
46
47	/* determine if the fault lay during a memcpy_user or a memset_user */
48	if (__frame->lr == (unsigned long) &__memset_user_error_lr &&
49	    (unsigned long) &memset <= pc && pc < (unsigned long) &__memset_end
50	    ) {
51		/* the fault occurred in a protected memset
52		 * - we search for the return address (in LR) instead of the program counter
53		 * - it was probably during a clear_user()
54		 */
55		return (unsigned long) &__memset_user_error_handler;
56	}
57
58	if (__frame->lr == (unsigned long) &__memcpy_user_error_lr &&
59	    (unsigned long) &memcpy <= pc && pc < (unsigned long) &__memcpy_end
60	    ) {
61		/* the fault occurred in a protected memset
62		 * - we search for the return address (in LR) instead of the program counter
63		 * - it was probably during a copy_to/from_user()
64		 */
65		return (unsigned long) &__memcpy_user_error_handler;
66	}
67
68	extab = search_exception_tables(pc);
69	if (extab)
70		return extab->fixup;
71
72	return 0;
73
74} /* end search_exception_table() */