85 lines
2.2 KiB
C
85 lines
2.2 KiB
C
/*
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* arch/sh/mm/extable_64.c
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*
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* Copyright (C) 2003 Richard Curnow
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* Copyright (C) 2003, 2004 Paul Mundt
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*
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* Cloned from the 2.5 SH version..
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <linux/bsearch.h>
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#include <linux/rwsem.h>
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#include <linux/extable.h>
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#include <linux/uaccess.h>
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extern unsigned long copy_user_memcpy, copy_user_memcpy_end;
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extern void __copy_user_fixup(void);
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static const struct exception_table_entry __copy_user_fixup_ex = {
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.fixup = (unsigned long)&__copy_user_fixup,
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};
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/*
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* Some functions that may trap due to a bad user-mode address have too
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* many loads and stores in them to make it at all practical to label
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* each one and put them all in the main exception table.
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*
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* In particular, the fast memcpy routine is like this. It's fix-up is
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* just to fall back to a slow byte-at-a-time copy, which is handled the
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* conventional way. So it's functionally OK to just handle any trap
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* occurring in the fast memcpy with that fixup.
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*/
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static const struct exception_table_entry *check_exception_ranges(unsigned long addr)
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{
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if ((addr >= (unsigned long)©_user_memcpy) &&
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(addr <= (unsigned long)©_user_memcpy_end))
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return &__copy_user_fixup_ex;
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return NULL;
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}
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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 > _elt->insn)
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return 1;
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if (_key < _elt->insn)
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return -1;
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return 0;
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}
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/* Simple binary search */
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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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const struct exception_table_entry *mid;
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mid = check_exception_ranges(value);
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if (mid)
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return mid;
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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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int fixup_exception(struct pt_regs *regs)
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{
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const struct exception_table_entry *fixup;
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fixup = search_exception_tables(regs->pc);
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if (fixup) {
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regs->pc = fixup->fixup;
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return 1;
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}
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return 0;
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}
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