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 * SPDX-License-Identifier:     GPL-2.0+
   8 */
   9#include <common.h>
  10
  11/*
  12 * The exception table consists of pairs of addresses: the first is the
  13 * address of an instruction that is allowed to fault, and the second is
  14 * the address at which the program should continue.  No registers are
  15 * modified, so it is entirely up to the continuation code to figure out
  16 * what to do.
  17 *
  18 * All the routines below use bits of fixup code that are out of line
  19 * with the main instruction path.  This means when everything is well,
  20 * we don't even have to jump over them.  Further, they do not intrude
  21 * on our cache or tlb entries.
  22 */
  23
  24DECLARE_GLOBAL_DATA_PTR;
  25
  26struct exception_table_entry
  27{
  28        unsigned long insn, fixup;
  29};
  30
  31extern const struct exception_table_entry __start___ex_table[];
  32extern const struct exception_table_entry __stop___ex_table[];
  33
  34static inline unsigned long
  35search_one_table(const struct exception_table_entry *first,
  36                 const struct exception_table_entry *last,
  37                 unsigned long value)
  38{
  39        long diff;
  40        while (first <= last) {
  41                diff = first->insn - value;
  42                if (diff == 0)
  43                        return first->fixup;
  44                first++;
  45        }
  46
  47        return 0;
  48}
  49
  50unsigned long
  51search_exception_table(unsigned long addr)
  52{
  53        unsigned long ret;
  54
  55        /* There is only the kernel to search.  */
  56        ret = search_one_table(__start___ex_table, __stop___ex_table-1, addr);
  57        /* if the serial port does not hang in exception, printf can be used */
  58#if !defined(CONFIG_SYS_SERIAL_HANG_IN_EXCEPTION)
  59        debug("Bus Fault @ 0x%08lx, fixup 0x%08lx\n", addr, ret);
  60#endif
  61        if (ret) return ret;
  62
  63        return 0;
  64}
  65