initial_commit

1 files changed, 93 insertions, 0 deletions

diff --git a/lib/extable.c b/lib/extable.c
new file mode 100644
index 00000000..4cac81ec
--- /dev/null
+++ b/lib/extable.c
@@ -0,0 +1,93 @@
+/*
+ * 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/module.h>
+#include <linux/init.h>
+#include <linux/sort.h>
+#include <asm/uaccess.h>
+
+#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);
+}
+
+#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(m->extable[0].insn, m)) {
+		m->extable++;
+		m->num_exentries--;
+	}
+	/*trim the end*/
+	while (m->num_exentries &&
+		within_module_init(m->extable[m->num_exentries-1].insn, m))
+		m->num_exentries--;
+}
+#endif /* CONFIG_MODULES */
+#endif /* !ARCH_HAS_SORT_EXTABLE */
+
+#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) >> 1) + first;
+		/*
+		 * careful, the distance between value and insn
+		 * can be larger than MAX_LONG:
+		 */
+		if (mid->insn < value)
+			first = mid + 1;
+		else if (mid->insn > value)
+			last = mid - 1;
+		else
+			return mid;
+        }
+        return NULL;
+}
+#endif