LXR linux/arch/alpha/include/asm/extable.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _ASM_EXTABLE_H
   3#define _ASM_EXTABLE_H
   4
   5/*
   6 * About the exception table:
   7 *
   8 * - insn is a 32-bit pc-relative offset from the faulting insn.
   9 * - nextinsn is a 16-bit offset off of the faulting instruction
  10 *   (not off of the *next* instruction as branches are).
  11 * - errreg is the register in which to place -EFAULT.
  12 * - valreg is the final target register for the load sequence
  13 *   and will be zeroed.
  14 *
  15 * Either errreg or valreg may be $31, in which case nothing happens.
  16 *
  17 * The exception fixup information "just so happens" to be arranged
  18 * as in a MEM format instruction.  This lets us emit our three
  19 * values like so:
  20 *
  21 *      lda valreg, nextinsn(errreg)
  22 *
  23 */
  24
  25struct exception_table_entry
  26{
  27        signed int insn;
  28        union exception_fixup {
  29                unsigned unit;
  30                struct {
  31                        signed int nextinsn : 16;
  32                        unsigned int errreg : 5;
  33                        unsigned int valreg : 5;
  34                } bits;
  35        } fixup;
  36};
  37
  38/* Returns the new pc */
  39#define fixup_exception(map_reg, _fixup, pc)                    \
  40({                                                              \
  41        if ((_fixup)->fixup.bits.valreg != 31)                  \
  42                map_reg((_fixup)->fixup.bits.valreg) = 0;       \
  43        if ((_fixup)->fixup.bits.errreg != 31)                  \
  44                map_reg((_fixup)->fixup.bits.errreg) = -EFAULT; \
  45        (pc) + (_fixup)->fixup.bits.nextinsn;                   \
  46})
  47
  48#define ARCH_HAS_RELATIVE_EXTABLE
  49
  50#define swap_ex_entry_fixup(a, b, tmp, delta)                   \
  51        do {                                                    \
  52                (a)->fixup.unit = (b)->fixup.unit;              \
  53                (b)->fixup.unit = (tmp).fixup.unit;             \
  54        } while (0)
  55
  56#endif
  57