1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/arch/sparc/mm/extable.c
4 */
5
6 #include <linux/module.h>
7 #include <linux/extable.h>
8 #include <linux/uaccess.h>
9
sort_extable(struct exception_table_entry * start,struct exception_table_entry * finish)10 void sort_extable(struct exception_table_entry *start,
11 struct exception_table_entry *finish)
12 {
13 }
14
15 /* Caller knows they are in a range if ret->fixup == 0 */
16 const struct exception_table_entry *
search_extable(const struct exception_table_entry * base,const size_t num,unsigned long value)17 search_extable(const struct exception_table_entry *base,
18 const size_t num,
19 unsigned long value)
20 {
21 int i;
22
23 /* Single insn entries are encoded as:
24 * word 1: insn address
25 * word 2: fixup code address
26 *
27 * Range entries are encoded as:
28 * word 1: first insn address
29 * word 2: 0
30 * word 3: last insn address + 4 bytes
31 * word 4: fixup code address
32 *
33 * Deleted entries are encoded as:
34 * word 1: unused
35 * word 2: -1
36 *
37 * See asm/uaccess.h for more details.
38 */
39
40 /* 1. Try to find an exact match. */
41 for (i = 0; i < num; i++) {
42 if (base[i].fixup == 0) {
43 /* A range entry, skip both parts. */
44 i++;
45 continue;
46 }
47
48 /* A deleted entry; see trim_init_extable */
49 if (base[i].fixup == -1)
50 continue;
51
52 if (base[i].insn == value)
53 return &base[i];
54 }
55
56 /* 2. Try to find a range match. */
57 for (i = 0; i < (num - 1); i++) {
58 if (base[i].fixup)
59 continue;
60
61 if (base[i].insn <= value && base[i + 1].insn > value)
62 return &base[i];
63
64 i++;
65 }
66
67 return NULL;
68 }
69
70 #ifdef CONFIG_MODULES
71 /* We could memmove them around; easier to mark the trimmed ones. */
trim_init_extable(struct module * m)72 void trim_init_extable(struct module *m)
73 {
74 unsigned int i;
75 bool range;
76
77 for (i = 0; i < m->num_exentries; i += range ? 2 : 1) {
78 range = m->extable[i].fixup == 0;
79
80 if (within_module_init(m->extable[i].insn, m)) {
81 m->extable[i].fixup = -1;
82 if (range)
83 m->extable[i+1].fixup = -1;
84 }
85 if (range)
86 i++;
87 }
88 }
89 #endif /* CONFIG_MODULES */
90
91 /* Special extable search, which handles ranges. Returns fixup */
search_extables_range(unsigned long addr,unsigned long * g2)92 unsigned long search_extables_range(unsigned long addr, unsigned long *g2)
93 {
94 const struct exception_table_entry *entry;
95
96 entry = search_exception_tables(addr);
97 if (!entry)
98 return 0;
99
100 /* Inside range? Fix g2 and return correct fixup */
101 if (!entry->fixup) {
102 *g2 = (addr - entry->insn) / 4;
103 return (entry + 1)->fixup;
104 }
105
106 return entry->fixup;
107 }
108