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a272858a3c
This adds support to the generic search_extable() and sort_extable() implementations for dealing with exception table entries whose fields contain relative offsets rather than absolute addresses. Acked-by: Helge Deller <deller@gmx.de> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> Acked-by: H. Peter Anvin <hpa@linux.intel.com> Acked-by: Tony Luck <tony.luck@intel.com> Acked-by: Will Deacon <will.deacon@arm.com> Acked-by: Richard Henderson <rth@twiddle.net> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
126 lines
3.1 KiB
C
126 lines
3.1 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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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 <asm/uaccess.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_SORT_EXTABLE
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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(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, 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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#endif /* !ARCH_HAS_SORT_EXTABLE */
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#ifndef ARCH_HAS_SEARCH_EXTABLE
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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 *first,
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const struct exception_table_entry *last,
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unsigned long value)
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{
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while (first <= last) {
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const struct exception_table_entry *mid;
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mid = ((last - first) >> 1) + first;
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/*
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* careful, the distance between value and insn
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* can be larger than MAX_LONG:
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*/
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if (ex_to_insn(mid) < value)
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first = mid + 1;
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else if (ex_to_insn(mid) > value)
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last = mid - 1;
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else
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return mid;
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}
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return NULL;
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}
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#endif
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