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- #include <linux/module.h>
- #include <linux/sort.h>
- #include <asm/uaccess.h>
- /*
- * Search one exception table for an entry corresponding to the
- * given instruction address, and return the address of the entry,
- * or NULL if none is found.
- * We use a binary search, and thus we assume that the table is
- * already sorted.
- */
- const struct exception_table_entry *
- search_extable(const struct exception_table_entry *first,
- const struct exception_table_entry *last,
- unsigned long value)
- {
- const struct exception_table_entry *mid;
- unsigned long addr;
- while (first <= last) {
- mid = ((last - first) >> 1) + first;
- addr = extable_insn(mid);
- if (addr < value)
- first = mid + 1;
- else if (addr > value)
- last = mid - 1;
- else
- return mid;
- }
- return NULL;
- }
- /*
- * The exception table needs to be sorted so that the binary
- * search that we use to find entries in it works properly.
- * This is used both for the kernel exception table and for
- * the exception tables of modules that get loaded.
- *
- */
- static int cmp_ex(const void *a, const void *b)
- {
- const struct exception_table_entry *x = a, *y = b;
- /* This compare is only valid after normalization. */
- return x->insn - y->insn;
- }
- void sort_extable(struct exception_table_entry *start,
- struct exception_table_entry *finish)
- {
- struct exception_table_entry *p;
- int i;
- /* Normalize entries to being relative to the start of the section */
- for (p = start, i = 0; p < finish; p++, i += 8) {
- p->insn += i;
- p->fixup += i + 4;
- }
- sort(start, finish - start, sizeof(*start), cmp_ex, NULL);
- /* Denormalize all entries */
- for (p = start, i = 0; p < finish; p++, i += 8) {
- p->insn -= i;
- p->fixup -= i + 4;
- }
- }
- #ifdef CONFIG_MODULES
- /*
- * If the exception table is sorted, any referring to the module init
- * will be at the beginning or the end.
- */
- void trim_init_extable(struct module *m)
- {
- /* Trim the beginning */
- while (m->num_exentries &&
- within_module_init(extable_insn(&m->extable[0]), m)) {
- m->extable++;
- m->num_exentries--;
- }
- /* Trim the end */
- while (m->num_exentries &&
- within_module_init(extable_insn(&m->extable[m->num_exentries-1]), m))
- m->num_exentries--;
- }
- #endif /* CONFIG_MODULES */
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