1 /*
2 * linux/arch/sparc/mm/extable.c
3 */
4
5 #include <linux/module.h>
6 #include <asm/uaccess.h>
7
sort_extable(struct exception_table_entry * start,struct exception_table_entry * finish)8 void sort_extable(struct exception_table_entry *start,
9 struct exception_table_entry *finish)
10 {
11 }
12
13 /* Caller knows they are in a range if ret->fixup == 0 */
14 const struct exception_table_entry *
search_extable(const struct exception_table_entry * start,const struct exception_table_entry * last,unsigned long value)15 search_extable(const struct exception_table_entry *start,
16 const struct exception_table_entry *last,
17 unsigned long value)
18 {
19 const struct exception_table_entry *walk;
20
21 /* Single insn entries are encoded as:
22 * word 1: insn address
23 * word 2: fixup code address
24 *
25 * Range entries are encoded as:
26 * word 1: first insn address
27 * word 2: 0
28 * word 3: last insn address + 4 bytes
29 * word 4: fixup code address
30 *
31 * Deleted entries are encoded as:
32 * word 1: unused
33 * word 2: -1
34 *
35 * See asm/uaccess.h for more details.
36 */
37
38 /* 1. Try to find an exact match. */
39 for (walk = start; walk <= last; walk++) {
40 if (walk->fixup == 0) {
41 /* A range entry, skip both parts. */
42 walk++;
43 continue;
44 }
45
46 /* A deleted entry; see trim_init_extable */
47 if (walk->fixup == -1)
48 continue;
49
50 if (walk->insn == value)
51 return walk;
52 }
53
54 /* 2. Try to find a range match. */
55 for (walk = start; walk <= (last - 1); walk++) {
56 if (walk->fixup)
57 continue;
58
59 if (walk[0].insn <= value && walk[1].insn > value)
60 return walk;
61
62 walk++;
63 }
64
65 return NULL;
66 }
67
68 #ifdef CONFIG_MODULES
69 /* We could memmove them around; easier to mark the trimmed ones. */
trim_init_extable(struct module * m)70 void trim_init_extable(struct module *m)
71 {
72 unsigned int i;
73 bool range;
74
75 for (i = 0; i < m->num_exentries; i += range ? 2 : 1) {
76 range = m->extable[i].fixup == 0;
77
78 if (within_module_init(m->extable[i].insn, m)) {
79 m->extable[i].fixup = -1;
80 if (range)
81 m->extable[i+1].fixup = -1;
82 }
83 if (range)
84 i++;
85 }
86 }
87 #endif /* CONFIG_MODULES */
88
89 /* Special extable search, which handles ranges. Returns fixup */
search_extables_range(unsigned long addr,unsigned long * g2)90 unsigned long search_extables_range(unsigned long addr, unsigned long *g2)
91 {
92 const struct exception_table_entry *entry;
93
94 entry = search_exception_tables(addr);
95 if (!entry)
96 return 0;
97
98 /* Inside range? Fix g2 and return correct fixup */
99 if (!entry->fixup) {
100 *g2 = (addr - entry->insn) / 4;
101 return (entry + 1)->fixup;
102 }
103
104 return entry->fixup;
105 }
106