Thomas Gleixner | 2874c5f | 2019-05-27 08:55:01 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3 | * Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c. |
| 4 | * |
| 5 | * Copyright (C) 2004 Paul Mackerras, IBM Corp. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 6 | */ |
| 7 | |
Thomas Meyer | a94c33d | 2017-07-10 15:51:58 -0700 | [diff] [blame] | 8 | #include <linux/bsearch.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 9 | #include <linux/module.h> |
| 10 | #include <linux/init.h> |
| 11 | #include <linux/sort.h> |
Linus Torvalds | 7c0f6ba | 2016-12-24 11:46:01 -0800 | [diff] [blame] | 12 | #include <linux/uaccess.h> |
Valdis Kletnieks | 8e72a7a | 2019-09-25 16:46:26 -0700 | [diff] [blame] | 13 | #include <linux/extable.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 14 | |
Ard Biesheuvel | a272858 | 2016-01-01 12:39:09 +0100 | [diff] [blame] | 15 | #ifndef ARCH_HAS_RELATIVE_EXTABLE |
| 16 | #define ex_to_insn(x) ((x)->insn) |
| 17 | #else |
| 18 | static inline unsigned long ex_to_insn(const struct exception_table_entry *x) |
| 19 | { |
| 20 | return (unsigned long)&x->insn + x->insn; |
| 21 | } |
| 22 | #endif |
| 23 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 24 | #ifndef ARCH_HAS_SORT_EXTABLE |
Ard Biesheuvel | a272858 | 2016-01-01 12:39:09 +0100 | [diff] [blame] | 25 | #ifndef ARCH_HAS_RELATIVE_EXTABLE |
| 26 | #define swap_ex NULL |
| 27 | #else |
| 28 | static void swap_ex(void *a, void *b, int size) |
| 29 | { |
| 30 | struct exception_table_entry *x = a, *y = b, tmp; |
| 31 | int delta = b - a; |
| 32 | |
| 33 | tmp = *x; |
| 34 | x->insn = y->insn + delta; |
| 35 | y->insn = tmp.insn - delta; |
| 36 | |
| 37 | #ifdef swap_ex_entry_fixup |
| 38 | swap_ex_entry_fixup(x, y, tmp, delta); |
| 39 | #else |
| 40 | x->fixup = y->fixup + delta; |
| 41 | y->fixup = tmp.fixup - delta; |
| 42 | #endif |
| 43 | } |
| 44 | #endif /* ARCH_HAS_RELATIVE_EXTABLE */ |
| 45 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 46 | /* |
| 47 | * The exception table needs to be sorted so that the binary |
| 48 | * search that we use to find entries in it works properly. |
| 49 | * This is used both for the kernel exception table and for |
| 50 | * the exception tables of modules that get loaded. |
| 51 | */ |
Thomas Meyer | a94c33d | 2017-07-10 15:51:58 -0700 | [diff] [blame] | 52 | static int cmp_ex_sort(const void *a, const void *b) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 53 | { |
| 54 | const struct exception_table_entry *x = a, *y = b; |
| 55 | |
| 56 | /* avoid overflow */ |
Ard Biesheuvel | a272858 | 2016-01-01 12:39:09 +0100 | [diff] [blame] | 57 | if (ex_to_insn(x) > ex_to_insn(y)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 58 | return 1; |
Ard Biesheuvel | a272858 | 2016-01-01 12:39:09 +0100 | [diff] [blame] | 59 | if (ex_to_insn(x) < ex_to_insn(y)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 60 | return -1; |
| 61 | return 0; |
| 62 | } |
| 63 | |
| 64 | void sort_extable(struct exception_table_entry *start, |
| 65 | struct exception_table_entry *finish) |
| 66 | { |
| 67 | sort(start, finish - start, sizeof(struct exception_table_entry), |
Thomas Meyer | a94c33d | 2017-07-10 15:51:58 -0700 | [diff] [blame] | 68 | cmp_ex_sort, swap_ex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 69 | } |
Rusty Russell | ad6561d | 2009-06-12 21:47:03 -0600 | [diff] [blame] | 70 | |
| 71 | #ifdef CONFIG_MODULES |
| 72 | /* |
| 73 | * If the exception table is sorted, any referring to the module init |
| 74 | * will be at the beginning or the end. |
| 75 | */ |
| 76 | void trim_init_extable(struct module *m) |
| 77 | { |
| 78 | /*trim the beginning*/ |
Ard Biesheuvel | a272858 | 2016-01-01 12:39:09 +0100 | [diff] [blame] | 79 | while (m->num_exentries && |
| 80 | within_module_init(ex_to_insn(&m->extable[0]), m)) { |
Rusty Russell | ad6561d | 2009-06-12 21:47:03 -0600 | [diff] [blame] | 81 | m->extable++; |
| 82 | m->num_exentries--; |
| 83 | } |
| 84 | /*trim the end*/ |
| 85 | while (m->num_exentries && |
Ard Biesheuvel | a272858 | 2016-01-01 12:39:09 +0100 | [diff] [blame] | 86 | within_module_init(ex_to_insn(&m->extable[m->num_exentries - 1]), |
| 87 | m)) |
Rusty Russell | ad6561d | 2009-06-12 21:47:03 -0600 | [diff] [blame] | 88 | m->num_exentries--; |
| 89 | } |
| 90 | #endif /* CONFIG_MODULES */ |
| 91 | #endif /* !ARCH_HAS_SORT_EXTABLE */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 92 | |
| 93 | #ifndef ARCH_HAS_SEARCH_EXTABLE |
Thomas Meyer | a94c33d | 2017-07-10 15:51:58 -0700 | [diff] [blame] | 94 | |
| 95 | static int cmp_ex_search(const void *key, const void *elt) |
| 96 | { |
| 97 | const struct exception_table_entry *_elt = elt; |
| 98 | unsigned long _key = *(unsigned long *)key; |
| 99 | |
| 100 | /* avoid overflow */ |
| 101 | if (_key > ex_to_insn(_elt)) |
| 102 | return 1; |
| 103 | if (_key < ex_to_insn(_elt)) |
| 104 | return -1; |
| 105 | return 0; |
| 106 | } |
| 107 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 108 | /* |
| 109 | * Search one exception table for an entry corresponding to the |
| 110 | * given instruction address, and return the address of the entry, |
| 111 | * or NULL if none is found. |
| 112 | * We use a binary search, and thus we assume that the table is |
| 113 | * already sorted. |
| 114 | */ |
| 115 | const struct exception_table_entry * |
Thomas Meyer | a94c33d | 2017-07-10 15:51:58 -0700 | [diff] [blame] | 116 | search_extable(const struct exception_table_entry *base, |
| 117 | const size_t num, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 118 | unsigned long value) |
| 119 | { |
Thomas Meyer | a94c33d | 2017-07-10 15:51:58 -0700 | [diff] [blame] | 120 | return bsearch(&value, base, num, |
| 121 | sizeof(struct exception_table_entry), cmp_ex_search); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 122 | } |
| 123 | #endif |