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