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 
9 extern const struct exception_table_entry __attribute__((aligned(8))) __start___ex_table[];
10 extern const struct exception_table_entry __attribute__((aligned(8))) __stop___ex_table[];
11 extern const void __memset_end, __memset_user_error_lr, __memset_user_error_handler;
12 extern const void __memcpy_end, __memcpy_user_error_lr, __memcpy_user_error_handler;
13 extern spinlock_t modlist_lock;
14 
15 /*****************************************************************************/
16 /*
17  *
18  */
search_one_table(const struct exception_table_entry * first,const struct exception_table_entry * last,unsigned long value)19 static 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  */
search_exception_table(unsigned long pc)43 unsigned 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() */
75