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1#include <linux/module.h>
2#include <linux/spinlock.h>
3#include <asm/uaccess.h>
4
5
6int fixup_exception(struct pt_regs *regs)
7{
8 const struct exception_table_entry *fixup;
9
10#ifdef CONFIG_PNPBIOS
11 if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs))) {
12 extern u32 pnp_bios_fault_eip, pnp_bios_fault_esp;
13 extern u32 pnp_bios_is_utter_crap;
14 pnp_bios_is_utter_crap = 1;
15 printk(KERN_CRIT "PNPBIOS fault.. attempting recovery.\n");
16 __asm__ volatile(
17 "movl %0, %%esp\n\t"
18 "jmp *%1\n\t"
19 : : "g" (pnp_bios_fault_esp), "g" (pnp_bios_fault_eip));
20 panic("do_trap: can't hit this");
21 }
22#endif
23
24 fixup = search_exception_tables(regs->ip);
25 if (fixup) {
26 /* If fixup is less than 16, it means uaccess error */
27 if (fixup->fixup < 16) {
28 current_thread_info()->uaccess_err = -EFAULT;
29 regs->ip += fixup->fixup;
30 return 1;
31 }
32 regs->ip = fixup->fixup;
33 return 1;
34 }
35
36 return 0;
37}
1#include <linux/module.h>
2#include <linux/spinlock.h>
3#include <linux/sort.h>
4#include <asm/uaccess.h>
5
6static inline unsigned long
7ex_insn_addr(const struct exception_table_entry *x)
8{
9 return (unsigned long)&x->insn + x->insn;
10}
11static inline unsigned long
12ex_fixup_addr(const struct exception_table_entry *x)
13{
14 return (unsigned long)&x->fixup + x->fixup;
15}
16
17int fixup_exception(struct pt_regs *regs)
18{
19 const struct exception_table_entry *fixup;
20 unsigned long new_ip;
21
22#ifdef CONFIG_PNPBIOS
23 if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs))) {
24 extern u32 pnp_bios_fault_eip, pnp_bios_fault_esp;
25 extern u32 pnp_bios_is_utter_crap;
26 pnp_bios_is_utter_crap = 1;
27 printk(KERN_CRIT "PNPBIOS fault.. attempting recovery.\n");
28 __asm__ volatile(
29 "movl %0, %%esp\n\t"
30 "jmp *%1\n\t"
31 : : "g" (pnp_bios_fault_esp), "g" (pnp_bios_fault_eip));
32 panic("do_trap: can't hit this");
33 }
34#endif
35
36 fixup = search_exception_tables(regs->ip);
37 if (fixup) {
38 new_ip = ex_fixup_addr(fixup);
39
40 if (fixup->fixup - fixup->insn >= 0x7ffffff0 - 4) {
41 /* Special hack for uaccess_err */
42 current_thread_info()->uaccess_err = 1;
43 new_ip -= 0x7ffffff0;
44 }
45 regs->ip = new_ip;
46 return 1;
47 }
48
49 return 0;
50}
51
52/* Restricted version used during very early boot */
53int __init early_fixup_exception(unsigned long *ip)
54{
55 const struct exception_table_entry *fixup;
56 unsigned long new_ip;
57
58 fixup = search_exception_tables(*ip);
59 if (fixup) {
60 new_ip = ex_fixup_addr(fixup);
61
62 if (fixup->fixup - fixup->insn >= 0x7ffffff0 - 4) {
63 /* uaccess handling not supported during early boot */
64 return 0;
65 }
66
67 *ip = new_ip;
68 return 1;
69 }
70
71 return 0;
72}
73
74/*
75 * Search one exception table for an entry corresponding to the
76 * given instruction address, and return the address of the entry,
77 * or NULL if none is found.
78 * We use a binary search, and thus we assume that the table is
79 * already sorted.
80 */
81const struct exception_table_entry *
82search_extable(const struct exception_table_entry *first,
83 const struct exception_table_entry *last,
84 unsigned long value)
85{
86 while (first <= last) {
87 const struct exception_table_entry *mid;
88 unsigned long addr;
89
90 mid = ((last - first) >> 1) + first;
91 addr = ex_insn_addr(mid);
92 if (addr < value)
93 first = mid + 1;
94 else if (addr > value)
95 last = mid - 1;
96 else
97 return mid;
98 }
99 return NULL;
100}
101
102/*
103 * The exception table needs to be sorted so that the binary
104 * search that we use to find entries in it works properly.
105 * This is used both for the kernel exception table and for
106 * the exception tables of modules that get loaded.
107 *
108 */
109static int cmp_ex(const void *a, const void *b)
110{
111 const struct exception_table_entry *x = a, *y = b;
112
113 /*
114 * This value will always end up fittin in an int, because on
115 * both i386 and x86-64 the kernel symbol-reachable address
116 * space is < 2 GiB.
117 *
118 * This compare is only valid after normalization.
119 */
120 return x->insn - y->insn;
121}
122
123void sort_extable(struct exception_table_entry *start,
124 struct exception_table_entry *finish)
125{
126 struct exception_table_entry *p;
127 int i;
128
129 /* Convert all entries to being relative to the start of the section */
130 i = 0;
131 for (p = start; p < finish; p++) {
132 p->insn += i;
133 i += 4;
134 p->fixup += i;
135 i += 4;
136 }
137
138 sort(start, finish - start, sizeof(struct exception_table_entry),
139 cmp_ex, NULL);
140
141 /* Denormalize all entries */
142 i = 0;
143 for (p = start; p < finish; p++) {
144 p->insn -= i;
145 i += 4;
146 p->fixup -= i;
147 i += 4;
148 }
149}
150
151#ifdef CONFIG_MODULES
152/*
153 * If the exception table is sorted, any referring to the module init
154 * will be at the beginning or the end.
155 */
156void trim_init_extable(struct module *m)
157{
158 /*trim the beginning*/
159 while (m->num_exentries &&
160 within_module_init(ex_insn_addr(&m->extable[0]), m)) {
161 m->extable++;
162 m->num_exentries--;
163 }
164 /*trim the end*/
165 while (m->num_exentries &&
166 within_module_init(ex_insn_addr(&m->extable[m->num_exentries-1]), m))
167 m->num_exentries--;
168}
169#endif /* CONFIG_MODULES */