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
57
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