1 /*
2 * linux/arch/alpha/mm/extable.c
3 */
4
5 #include <linux/module.h>
6 #include <linux/sort.h>
7 #include <asm/uaccess.h>
8
ex_to_addr(const struct exception_table_entry * x)9 static inline unsigned long ex_to_addr(const struct exception_table_entry *x)
10 {
11 return (unsigned long)&x->insn + x->insn;
12 }
13
swap_ex(void * a,void * b,int size)14 static void swap_ex(void *a, void *b, int size)
15 {
16 struct exception_table_entry *ex_a = a, *ex_b = b;
17 unsigned long addr_a = ex_to_addr(ex_a), addr_b = ex_to_addr(ex_b);
18 unsigned int t = ex_a->fixup.unit;
19
20 ex_a->fixup.unit = ex_b->fixup.unit;
21 ex_b->fixup.unit = t;
22 ex_a->insn = (int)(addr_b - (unsigned long)&ex_a->insn);
23 ex_b->insn = (int)(addr_a - (unsigned long)&ex_b->insn);
24 }
25
26 /*
27 * The exception table needs to be sorted so that the binary
28 * search that we use to find entries in it works properly.
29 * This is used both for the kernel exception table and for
30 * the exception tables of modules that get loaded.
31 */
cmp_ex(const void * a,const void * b)32 static int cmp_ex(const void *a, const void *b)
33 {
34 const struct exception_table_entry *x = a, *y = b;
35
36 /* avoid overflow */
37 if (ex_to_addr(x) > ex_to_addr(y))
38 return 1;
39 if (ex_to_addr(x) < ex_to_addr(y))
40 return -1;
41 return 0;
42 }
43
sort_extable(struct exception_table_entry * start,struct exception_table_entry * finish)44 void sort_extable(struct exception_table_entry *start,
45 struct exception_table_entry *finish)
46 {
47 sort(start, finish - start, sizeof(struct exception_table_entry),
48 cmp_ex, swap_ex);
49 }
50
51 #ifdef CONFIG_MODULES
52 /*
53 * Any entry referring to the module init will be at the beginning or
54 * the end.
55 */
trim_init_extable(struct module * m)56 void trim_init_extable(struct module *m)
57 {
58 /*trim the beginning*/
59 while (m->num_exentries &&
60 within_module_init(ex_to_addr(&m->extable[0]), m)) {
61 m->extable++;
62 m->num_exentries--;
63 }
64 /*trim the end*/
65 while (m->num_exentries &&
66 within_module_init(ex_to_addr(&m->extable[m->num_exentries-1]),
67 m))
68 m->num_exentries--;
69 }
70 #endif /* CONFIG_MODULES */
71
72 const struct exception_table_entry *
search_extable(const struct exception_table_entry * first,const struct exception_table_entry * last,unsigned long value)73 search_extable(const struct exception_table_entry *first,
74 const struct exception_table_entry *last,
75 unsigned long value)
76 {
77 while (first <= last) {
78 const struct exception_table_entry *mid;
79 unsigned long mid_value;
80
81 mid = (last - first) / 2 + first;
82 mid_value = ex_to_addr(mid);
83 if (mid_value == value)
84 return mid;
85 else if (mid_value < value)
86 first = mid+1;
87 else
88 last = mid-1;
89 }
90
91 return NULL;
92 }
93