diff options
Diffstat (limited to 'lib/extable.c')
-rw-r--r-- | lib/extable.c | 93 |
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 |