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/include/asm/uaccess.h b/arch/alpha/include/asm/uaccess.h
index 163f305..b49ec2f 100644 (file)
--- a/arch/alpha/include/asm/uaccess.h
+++ b/arch/alpha/include/asm/uaccess.h
@@ -507,5 +507,7 @@ struct exception_table_entry
        (pc) + (_fixup)->fixup.bits.nextinsn;                   \
 })
 
+#define ARCH_HAS_SORT_EXTABLE
+#define ARCH_HAS_SEARCH_EXTABLE
 
 #endif /* __ALPHA_UACCESS_H */

diff --git a/arch/alpha/mm/extable.c b/arch/alpha/mm/extable.c
index dc7aeda..62dc379 100644 (file)
--- 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 @@ search_extable(const struct exception_table_entry *first,
                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)