1 /* 2 * Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c. 3 * 4 * Copyright (C) 2004 Paul Mackerras, IBM Corp. 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12 #include <linux/module.h> 13 #include <linux/init.h> 14 #include <linux/sort.h> 15 #include <asm/uaccess.h> 16 17 #ifndef ARCH_HAS_SORT_EXTABLE 18 /* 19 * The exception table needs to be sorted so that the binary 20 * search that we use to find entries in it works properly. 21 * This is used both for the kernel exception table and for 22 * the exception tables of modules that get loaded. 23 */ 24 static int cmp_ex(const void *a, const void *b) 25 { 26 const struct exception_table_entry *x = a, *y = b; 27 28 /* avoid overflow */ 29 if (x->insn > y->insn) 30 return 1; 31 if (x->insn < y->insn) 32 return -1; 33 return 0; 34 } 35 36 void sort_extable(struct exception_table_entry *start, 37 struct exception_table_entry *finish) 38 { 39 sort(start, finish - start, sizeof(struct exception_table_entry), 40 cmp_ex, NULL); 41 } 42 #endif 43 44 #ifndef ARCH_HAS_SEARCH_EXTABLE 45 /* 46 * Search one exception table for an entry corresponding to the 47 * given instruction address, and return the address of the entry, 48 * or NULL if none is found. 49 * We use a binary search, and thus we assume that the table is 50 * already sorted. 51 */ 52 const struct exception_table_entry * 53 search_extable(const struct exception_table_entry *first, 54 const struct exception_table_entry *last, 55 unsigned long value) 56 { 57 while (first <= last) { 58 const struct exception_table_entry *mid; 59 60 mid = ((last - first) >> 1) + first; 61 /* 62 * careful, the distance between value and insn 63 * can be larger than MAX_LONG: 64 */ 65 if (mid->insn < value) 66 first = mid + 1; 67 else if (mid->insn > value) 68 last = mid - 1; 69 else 70 return mid; 71 } 72 return NULL; 73 } 74 #endif 75