mirror of
https://github.com/torvalds/linux.git
synced 2024-11-08 21:21:47 +00:00
eb608fb366
This is the s390 port of 70627654 "x86, extable: Switch to relative
exception table entries".
Reduces the size of our exception tables by 50% on 64 bit builds.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
82 lines
2.1 KiB
C
82 lines
2.1 KiB
C
#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 */
|