1 files changed, 79 insertions, 0 deletions

diff --git a/lib/extable.c b/lib/extable.c
new file mode 100644
index 000000000000..3f677a8f0c3c
--- /dev/null
+++ b/lib/extable.c
@@ -0,0 +1,79 @@
+/*
+ * lib/extable.c
+ * Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c.
+ *
+ * Copyright (C) 2004 Paul Mackerras, IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sort.h>
+#include <asm/uaccess.h>
+
+extern struct exception_table_entry __start___ex_table[];
+extern struct exception_table_entry __stop___ex_table[];
+
+#ifndef ARCH_HAS_SORT_EXTABLE
+/*
+ * 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 (x->insn > y->insn)
+                return 1;
+        if (x->insn < y->insn)
+                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, NULL);
+}
+#endif
+
+#ifndef ARCH_HAS_SEARCH_EXTABLE
+/*
+ * 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)
+{
+        while (first <= last) {
+                const struct exception_table_entry *mid;
+
+                mid = (last - first) / 2 + first;
+                /*
+                 * careful, the distance between entries can be
+                 * larger than 2GB:
+                 */
+                if (mid->insn < value)
+                        first = mid + 1;
+                else if (mid->insn > value)
+                        last = mid - 1;
+                else
+                        return mid;
+        }
+        return NULL;
+}
+#endif