Version:  2.6.24 2.6.25 2.6.26 2.6.27 2.6.28

Architecture:  x86 m68k m68knommu mips powerpc sh blackfin

Linux/lib/extable.c

  1 /*
  2  * Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c.
  3  *
  4  * Copyright (C) 2004 Paul Mackerras, IBM Corp.
  5  *
  6  * This program is free software; you can redistribute it and/or
  7  * modify it under the terms of the GNU General Public License
  8  * as published by the Free Software Foundation; either version
  9  * 2 of the License, or (at your option) any later version.
 10  */
 11 
 12 #include <linux/module.h>
 13 #include <linux/init.h>
 14 #include <linux/sort.h>
 15 #include <asm/uaccess.h>
 16 
 17 #ifndef ARCH_HAS_SORT_EXTABLE
 18 /*
 19  * The exception table needs to be sorted so that the binary
 20  * search that we use to find entries in it works properly.
 21  * This is used both for the kernel exception table and for
 22  * the exception tables of modules that get loaded.
 23  */
 24 static int cmp_ex(const void *a, const void *b)
 25 {
 26         const struct exception_table_entry *x = a, *y = b;
 27 
 28         /* avoid overflow */
 29         if (x->insn > y->insn)
 30                 return 1;
 31         if (x->insn < y->insn)
 32                 return -1;
 33         return 0;
 34 }
 35 
 36 void sort_extable(struct exception_table_entry *start,
 37                   struct exception_table_entry *finish)
 38 {
 39         sort(start, finish - start, sizeof(struct exception_table_entry),
 40              cmp_ex, NULL);
 41 }
 42 #endif
 43 
 44 #ifndef ARCH_HAS_SEARCH_EXTABLE
 45 /*
 46  * Search one exception table for an entry corresponding to the
 47  * given instruction address, and return the address of the entry,
 48  * or NULL if none is found.
 49  * We use a binary search, and thus we assume that the table is
 50  * already sorted.
 51  */
 52 const struct exception_table_entry *
 53 search_extable(const struct exception_table_entry *first,
 54                const struct exception_table_entry *last,
 55                unsigned long value)
 56 {
 57         while (first <= last) {
 58                 const struct exception_table_entry *mid;
 59 
 60                 mid = ((last - first) >> 1) + first;
 61                 /*
 62                  * careful, the distance between value and insn
 63                  * can be larger than MAX_LONG:
 64                  */
 65                 if (mid->insn < value)
 66                         first = mid + 1;
 67                 else if (mid->insn > value)
 68                         last = mid - 1;
 69                 else
 70                         return mid;
 71         }
 72         return NULL;
 73 }
 74 #endif
 75

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