1 #include <linux/module.h>
2 #include <linux/spinlock.h>
3 #include <linux/sort.h>
4 #include <asm/uaccess.h>
6 static inline unsigned long
7 ex_insn_addr(const struct exception_table_entry *x)
9 return (unsigned long)&x->insn + x->insn;
11 static inline unsigned long
12 ex_fixup_addr(const struct exception_table_entry *x)
14 return (unsigned long)&x->fixup + x->fixup;
17 int fixup_exception(struct pt_regs *regs)
19 const struct exception_table_entry *fixup;
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");
31 : : "g" (pnp_bios_fault_esp), "g" (pnp_bios_fault_eip));
32 panic("do_trap: can't hit this");
36 fixup = search_exception_tables(regs->ip);
38 new_ip = ex_fixup_addr(fixup);
40 if (fixup->fixup - fixup->insn >= 0x7ffffff0 - 4) {
41 /* Special hack for uaccess_err */
42 current_thread_info()->uaccess_err = 1;
52 /* Restricted version used during very early boot */
53 int __init early_fixup_exception(unsigned long *ip)
55 const struct exception_table_entry *fixup;
58 fixup = search_exception_tables(*ip);
60 new_ip = ex_fixup_addr(fixup);
62 if (fixup->fixup - fixup->insn >= 0x7ffffff0 - 4) {
63 /* uaccess handling not supported during early boot */
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
81 const struct exception_table_entry *
82 search_extable(const struct exception_table_entry *first,
83 const struct exception_table_entry *last,
86 while (first <= last) {
87 const struct exception_table_entry *mid;
90 mid = ((last - first) >> 1) + first;
91 addr = ex_insn_addr(mid);
94 else if (addr > value)
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.
109 static int cmp_ex(const void *a, const void *b)
111 const struct exception_table_entry *x = a, *y = b;
114 * This value will always end up fittin in an int, because on
115 * both i386 and x86-64 the kernel symbol-reachable address
118 * This compare is only valid after normalization.
120 return x->insn - y->insn;
123 void sort_extable(struct exception_table_entry *start,
124 struct exception_table_entry *finish)
126 struct exception_table_entry *p;
129 /* Convert all entries to being relative to the start of the section */
131 for (p = start; p < finish; p++) {
138 sort(start, finish - start, sizeof(struct exception_table_entry),
141 /* Denormalize all entries */
143 for (p = start; p < finish; p++) {
151 #ifdef CONFIG_MODULES
153 * If the exception table is sorted, any referring to the module init
154 * will be at the beginning or the end.
156 void trim_init_extable(struct module *m)
158 /*trim the beginning*/
159 while (m->num_exentries &&
160 within_module_init(ex_insn_addr(&m->extable[0]), m)) {
165 while (m->num_exentries &&
166 within_module_init(ex_insn_addr(&m->extable[m->num_exentries-1]), m))
169 #endif /* CONFIG_MODULES */