arch/alpha/include/asm/extable.h

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