| 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/module.h>
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| 13 | #include <linux/init.h>
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| 14 | #include <linux/sort.h>
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| 15 | #include <asm/uaccess.h>
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| 16 |
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| 17 | #ifndef ARCH_HAS_SORT_EXTABLE
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| 18 | |
| 19 | * The exception table needs to be sorted so that the binary
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| 20 | * search that we use to find entries in it works properly.
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| 21 | * This is used both for the kernel exception table and for
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| 22 | * the exception tables of modules that get loaded.
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| 23 |
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| 24 | static int cmp_ex(const void *a, const void *b)
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| 25 | {
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| 26 | const struct exception_table_entry *x = a, *y = b;
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| 27 |
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| 28 |
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| 29 | if (x->insn > y->insn)
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| 30 | return 1;
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| 31 | if (x->insn < y->insn)
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| 32 | return -1;
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| 33 | return 0;
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| 34 | }
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| 35 |
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| 36 | void sort_extable(struct exception_table_entry *start,
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| 37 | struct exception_table_entry *finish)
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| 38 | {
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| 39 | sort(start, finish - start, sizeof(struct exception_table_entry),
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| 40 | cmp_ex, NULL);
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| 41 | }
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| 42 |
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| 43 | #ifdef CONFIG_MODULES
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| 44 | |
| 45 | * If the exception table is sorted, any referring to the module init
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| 46 | * will be at the beginning or the end.
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| 47 |
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| 48 | void trim_init_extable(struct module *m)
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| 49 | {
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| 50 |
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| 51 | while (m->num_exentries && within_module_init(m->extable[0].insn, m)) {
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| 52 | m->extable++;
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| 53 | m->num_exentries--;
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| 54 | }
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| 55 |
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| 56 | while (m->num_exentries &&
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| 57 | within_module_init(m->extable[m->num_exentries-1].insn, m))
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| 58 | m->num_exentries--;
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| 59 | }
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| 60 | #endif
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| 61 | #endif
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| 62 |
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| 63 | #ifndef ARCH_HAS_SEARCH_EXTABLE
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| 64 | |
| 65 | * Search one exception table for an entry corresponding to the
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| 66 | * given instruction address, and return the address of the entry,
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| 67 | * or NULL if none is found.
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| 68 | * We use a binary search, and thus we assume that the table is
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| 69 | * already sorted.
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| 70 |
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| 71 | const struct exception_table_entry *
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| 72 | search_extable(const struct exception_table_entry *first,
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| 73 | const struct exception_table_entry *last,
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| 74 | unsigned long value)
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| 75 | {
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| 76 | while (first <= last) {
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| 77 | const struct exception_table_entry *mid;
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| 78 |
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| 79 | mid = ((last - first) >> 1) + first;
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| 80 | |
| 81 | * careful, the distance between value and insn
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| 82 | * can be larger than MAX_LONG:
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| 83 |
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| 84 | if (mid->insn < value)
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| 85 | first = mid + 1;
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| 86 | else if (mid->insn > value)
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| 87 | last = mid - 1;
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| 88 | else
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| 89 | return mid;
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| 90 | }
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| 91 | return NULL;
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| 92 | }
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| 93 | #endif
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