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lib/extable.c
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// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c. * * Copyright (C) 2004 Paul Mackerras, IBM Corp. |
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*/ |
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#include <linux/bsearch.h> |
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#include <linux/module.h> #include <linux/init.h> #include <linux/sort.h> |
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#include <linux/uaccess.h> |
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#include <linux/extable.h> |
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#ifndef ARCH_HAS_RELATIVE_EXTABLE #define ex_to_insn(x) ((x)->insn) #else static inline unsigned long ex_to_insn(const struct exception_table_entry *x) { return (unsigned long)&x->insn + x->insn; } #endif |
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#ifndef ARCH_HAS_RELATIVE_EXTABLE #define swap_ex NULL #else static void swap_ex(void *a, void *b, int size) { struct exception_table_entry *x = a, *y = b, tmp; int delta = b - a; tmp = *x; x->insn = y->insn + delta; y->insn = tmp.insn - delta; #ifdef swap_ex_entry_fixup swap_ex_entry_fixup(x, y, tmp, delta); #else x->fixup = y->fixup + delta; y->fixup = tmp.fixup - delta; #endif } #endif /* ARCH_HAS_RELATIVE_EXTABLE */ |
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/* * The exception table needs to be sorted so that the binary * search that we use to find entries in it works properly. * This is used both for the kernel exception table and for * the exception tables of modules that get loaded. */ |
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static int cmp_ex_sort(const void *a, const void *b) |
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{ const struct exception_table_entry *x = a, *y = b; /* avoid overflow */ |
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if (ex_to_insn(x) > ex_to_insn(y)) |
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return 1; |
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if (ex_to_insn(x) < ex_to_insn(y)) |
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return -1; return 0; } void sort_extable(struct exception_table_entry *start, struct exception_table_entry *finish) { sort(start, finish - start, sizeof(struct exception_table_entry), |
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cmp_ex_sort, swap_ex); |
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} |
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#ifdef CONFIG_MODULES /* * If the exception table is sorted, any referring to the module init * will be at the beginning or the end. */ void trim_init_extable(struct module *m) { /*trim the beginning*/ |
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while (m->num_exentries && within_module_init(ex_to_insn(&m->extable[0]), m)) { |
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m->extable++; m->num_exentries--; } /*trim the end*/ while (m->num_exentries && |
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within_module_init(ex_to_insn(&m->extable[m->num_exentries - 1]), m)) |
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m->num_exentries--; } #endif /* CONFIG_MODULES */ |
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static int cmp_ex_search(const void *key, const void *elt) { const struct exception_table_entry *_elt = elt; unsigned long _key = *(unsigned long *)key; /* avoid overflow */ if (_key > ex_to_insn(_elt)) return 1; if (_key < ex_to_insn(_elt)) return -1; return 0; } |
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/* * Search one exception table for an entry corresponding to the * given instruction address, and return the address of the entry, * or NULL if none is found. * We use a binary search, and thus we assume that the table is * already sorted. */ const struct exception_table_entry * |
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search_extable(const struct exception_table_entry *base, const size_t num, |
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unsigned long value) { |
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return bsearch(&value, base, num, sizeof(struct exception_table_entry), cmp_ex_search); |
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} |