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>
diff --git a/arch/alpha/mm/extable.c b/arch/alpha/mm/extable.c
index dc7aeda..62dc379 100644
--- a/arch/alpha/mm/extable.c
+++ b/arch/alpha/mm/extable.c
@@ -3,11 +3,49 @@
*/
#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 *
@@ -20,7 +58,7 @@
unsigned long mid_value;
mid = (last - first) / 2 + first;
- mid_value = (unsigned long)&mid->insn + mid->insn;
+ mid_value = ex_to_addr(mid);
if (mid_value == value)
return mid;
else if (mid_value < value)