kernel_optimize_test/arch/alpha/mm/extable.c
Ivan Kokshaysky 08a42e86bc alpha: exception table sorting
Exception fixups for sections other than .text (like one in futex_init())
break the natural ordering of fixup entries, so sorting is required.

Without that the result of the exception table search depends on phase of
the moon.

Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Richard Henderson <rth@twiddle.net
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-05-02 15:36:10 -07:00

72 lines
1.9 KiB
C

/*
* linux/arch/alpha/mm/extable.c
*/
#include <linux/module.h>
#include <linux/sort.h>
#include <asm/uaccess.h>
static inline unsigned long ex_to_addr(const struct exception_table_entry *x)
{
return (unsigned long)&x->insn + x->insn;
}
static void swap_ex(void *a, void *b, int size)
{
struct exception_table_entry *ex_a = a, *ex_b = b;
unsigned long addr_a = ex_to_addr(ex_a), addr_b = ex_to_addr(ex_b);
unsigned int t = ex_a->fixup.unit;
ex_a->fixup.unit = ex_b->fixup.unit;
ex_b->fixup.unit = t;
ex_a->insn = (int)(addr_b - (unsigned long)&ex_a->insn);
ex_b->insn = (int)(addr_a - (unsigned long)&ex_b->insn);
}
/*
* 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;
/* avoid overflow */
if (ex_to_addr(x) > ex_to_addr(y))
return 1;
if (ex_to_addr(x) < ex_to_addr(y))
return -1;
return 0;
}
void sort_extable(struct exception_table_entry *start,
struct exception_table_entry *finish)
{
sort(start, finish - start, sizeof(struct exception_table_entry),
cmp_ex, swap_ex);
}
const struct exception_table_entry *
search_extable(const struct exception_table_entry *first,
const struct exception_table_entry *last,
unsigned long value)
{
while (first <= last) {
const struct exception_table_entry *mid;
unsigned long mid_value;
mid = (last - first) / 2 + first;
mid_value = ex_to_addr(mid);
if (mid_value == value)
return mid;
else if (mid_value < value)
first = mid+1;
else
last = mid-1;
}
return NULL;
}