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
  25 struct 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