1 /* 2 * lib/extable.c 3 * Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c. 4 * 5 * Copyright (C) 2004 Paul Mackerras, IBM Corp. 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 10 * 2 of the License, or (at your option) any later version. 11 */ 12 13 #include <linux/config.h> 14 #include <linux/module.h> 15 #include <linux/init.h> 16 #include <linux/sort.h> 17 #include <asm/uaccess.h> 18 19 extern struct exception_table_entry __start___ex_table[]; 20 extern struct exception_table_entry __stop___ex_table[]; 21 22 #ifndef ARCH_HAS_SORT_EXTABLE 23 /* 24 * The exception table needs to be sorted so that the binary 25 * search that we use to find entries in it works properly. 26 * This is used both for the kernel exception table and for 27 * the exception tables of modules that get loaded. 28 */ 29 static int cmp_ex(const void *a, const void *b) 30 { 31 const struct exception_table_entry *x = a, *y = b; 32 33 /* avoid overflow */ 34 if (x->insn > y->insn) 35 return 1; 36 if (x->insn < y->insn) 37 return -1; 38 return 0; 39 } 40 41 void sort_extable(struct exception_table_entry *start, 42 struct exception_table_entry *finish) 43 { 44 sort(start, finish - start, sizeof(struct exception_table_entry), 45 cmp_ex, NULL); 46 } 47 #endif 48 49 #ifndef ARCH_HAS_SEARCH_EXTABLE 50 /* 51 * Search one exception table for an entry corresponding to the 52 * given instruction address, and return the address of the entry, 53 * or NULL if none is found. 54 * We use a binary search, and thus we assume that the table is 55 * already sorted. 56 */ 57 const struct exception_table_entry * 58 search_extable(const struct exception_table_entry *first, 59 const struct exception_table_entry *last, 60 unsigned long value) 61 { 62 while (first <= last) { 63 const struct exception_table_entry *mid; 64 65 mid = (last - first) / 2 + first; 66 /* 67 * careful, the distance between entries can be 68 * larger than 2GB: 69 */ 70 if (mid->insn < value) 71 first = mid + 1; 72 else if (mid->insn > value) 73 last = mid - 1; 74 else 75 return mid; 76 } 77 return NULL; 78 } 79 #endif 80