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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;
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;
}
#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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