LXR uboot/arch/powerpc/lib/extable.c

   1/*
   2 * Copyright (C) 1999  Magnus Damm <kieraypc01.p.y.kie.era.ericsson.se>
   3 *
   4 * (C) Copyright 2000
   5 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   6 *
   7 * See file CREDITS for list of people who contributed to this
   8 * project.
   9 *
  10 * This program is free software; you can redistribute it and/or
  11 * modify it under the terms of the GNU General Public License as
  12 * published by the Free Software Foundation; either version 2 of
  13 * the License, or (at your option) any later version.
  14 *
  15 * This program is distributed in the hope that it will be useful,
  16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 * GNU General Public License for more details.
  19 *
  20 * You should have received a copy of the GNU General Public License
  21 * along with this program; if not, write to the Free Software
  22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  23 * MA 02111-1307 USA
  24 */
  25#include <common.h>
  26
  27/*
  28 * The exception table consists of pairs of addresses: the first is the
  29 * address of an instruction that is allowed to fault, and the second is
  30 * the address at which the program should continue.  No registers are
  31 * modified, so it is entirely up to the continuation code to figure out
  32 * what to do.
  33 *
  34 * All the routines below use bits of fixup code that are out of line
  35 * with the main instruction path.  This means when everything is well,
  36 * we don't even have to jump over them.  Further, they do not intrude
  37 * on our cache or tlb entries.
  38 */
  39
  40DECLARE_GLOBAL_DATA_PTR;
  41
  42struct exception_table_entry
  43{
  44        unsigned long insn, fixup;
  45};
  46
  47extern const struct exception_table_entry __start___ex_table[];
  48extern const struct exception_table_entry __stop___ex_table[];
  49
  50static inline unsigned long
  51search_one_table(const struct exception_table_entry *first,
  52                 const struct exception_table_entry *last,
  53                 unsigned long value)
  54{
  55        long diff;
  56        while (first <= last) {
  57                diff = first->insn - value;
  58                if (diff == 0)
  59                        return first->fixup;
  60                first++;
  61        }
  62
  63        return 0;
  64}
  65
  66int     ex_tab_message = 1;
  67
  68unsigned long
  69search_exception_table(unsigned long addr)
  70{
  71        unsigned long ret;
  72
  73        /* There is only the kernel to search.  */
  74        ret = search_one_table(__start___ex_table, __stop___ex_table-1, addr);
  75        /* if the serial port does not hang in exception, printf can be used */
  76#if !defined(CONFIG_SYS_SERIAL_HANG_IN_EXCEPTION)
  77        if (ex_tab_message)
  78                debug("Bus Fault @ 0x%08lx, fixup 0x%08lx\n", addr, ret);
  79#endif
  80        if (ret) return ret;
  81
  82        return 0;
  83}
  84