| 1 | |
| 2 | * Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c.
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| 3 | *
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| 4 | * Copyright (C) 2004 Paul Mackerras, IBM Corp.
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| 5 | *
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| 6 | * This program is free software; you can redistribute it and/or
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| 7 | * modify it under the terms of the GNU General Public License
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| 8 | * as published by the Free Software Foundation; either version
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| 9 | * 2 of the License, or (at your option) any later version.
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| 10 |
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| 11 |
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| 12 | #include <linux/bsearch.h>
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| 13 | #include <linux/module.h>
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| 14 | #include <linux/init.h>
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| 15 | #include <linux/sort.h>
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| 16 | #include <linux/uaccess.h>
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| 17 |
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| 18 | #ifndef ARCH_HAS_RELATIVE_EXTABLE
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| 19 | #define ex_to_insn(x) ((x)->insn)
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| 20 | #else
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| 21 | static inline unsigned long ex_to_insn(const struct exception_table_entry *x)
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| 22 | {
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| 23 | return (unsigned long)&x->insn + x->insn;
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| 24 | }
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| 25 | #endif
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| 26 |
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| 27 | #ifndef ARCH_HAS_SORT_EXTABLE
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| 28 | #ifndef ARCH_HAS_RELATIVE_EXTABLE
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| 29 | #define swap_ex NULL
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| 30 | #else
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| 31 | static void swap_ex(void *a, void *b, int size)
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| 32 | {
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| 33 | struct exception_table_entry *x = a, *y = b, tmp;
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| 34 | int delta = b - a;
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| 35 |
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| 36 | tmp = *x;
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| 37 | x->insn = y->insn + delta;
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| 38 | y->insn = tmp.insn - delta;
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| 39 |
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| 40 | #ifdef swap_ex_entry_fixup
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| 41 | swap_ex_entry_fixup(x, y, tmp, delta);
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| 42 | #else
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| 43 | x->fixup = y->fixup + delta;
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| 44 | y->fixup = tmp.fixup - delta;
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| 45 | #endif
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| 46 | }
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| 47 | #endif
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| 48 |
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| 49 | |
| 50 | * The exception table needs to be sorted so that the binary
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| 51 | * search that we use to find entries in it works properly.
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| 52 | * This is used both for the kernel exception table and for
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| 53 | * the exception tables of modules that get loaded.
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| 54 |
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| 55 | static int cmp_ex_sort(const void *a, const void *b)
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| 56 | {
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| 57 | const struct exception_table_entry *x = a, *y = b;
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| 58 |
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| 59 |
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| 60 | if (ex_to_insn(x) > ex_to_insn(y))
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| 61 | return 1;
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| 62 | if (ex_to_insn(x) < ex_to_insn(y))
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| 63 | return -1;
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| 64 | return 0;
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| 65 | }
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| 66 |
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| 67 | void sort_extable(struct exception_table_entry *start,
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| 68 | struct exception_table_entry *finish)
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| 69 | {
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| 70 | sort(start, finish - start, sizeof(struct exception_table_entry),
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| 71 | cmp_ex_sort, swap_ex);
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| 72 | }
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| 73 |
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| 74 | #ifdef CONFIG_MODULES
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| 75 | |
| 76 | * If the exception table is sorted, any referring to the module init
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| 77 | * will be at the beginning or the end.
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| 78 |
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| 79 | void trim_init_extable(struct module *m)
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| 80 | {
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| 81 |
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| 82 | while (m->num_exentries &&
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| 83 | within_module_init(ex_to_insn(&m->extable[0]), m)) {
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| 84 | m->extable++;
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| 85 | m->num_exentries--;
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| 86 | }
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| 87 |
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| 88 | while (m->num_exentries &&
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| 89 | within_module_init(ex_to_insn(&m->extable[m->num_exentries - 1]),
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| 90 | m))
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| 91 | m->num_exentries--;
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| 92 | }
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| 93 | #endif
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| 94 | #endif
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| 95 |
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| 96 | #ifndef ARCH_HAS_SEARCH_EXTABLE
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| 97 |
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| 98 | static int cmp_ex_search(const void *key, const void *elt)
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| 99 | {
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| 100 | const struct exception_table_entry *_elt = elt;
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| 101 | unsigned long _key = *(unsigned long *)key;
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| 102 |
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| 103 |
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| 104 | if (_key > ex_to_insn(_elt))
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| 105 | return 1;
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| 106 | if (_key < ex_to_insn(_elt))
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| 107 | return -1;
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| 108 | return 0;
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| 109 | }
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| 110 |
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| 111 | |
| 112 | * Search one exception table for an entry corresponding to the
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| 113 | * given instruction address, and return the address of the entry,
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| 114 | * or NULL if none is found.
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| 115 | * We use a binary search, and thus we assume that the table is
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| 116 | * already sorted.
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| 117 |
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| 118 | const struct exception_table_entry *
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| 119 | search_extable(const struct exception_table_entry *base,
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| 120 | const size_t num,
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| 121 | unsigned long value)
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| 122 | {
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| 123 | return bsearch(&value, base, num,
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| 124 | sizeof(struct exception_table_entry), cmp_ex_search);
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| 125 | }
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| 126 | #endif
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