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-rw-r--r--arch/alpha/include/asm/extable.h56
1 files changed, 56 insertions, 0 deletions
diff --git a/arch/alpha/include/asm/extable.h b/arch/alpha/include/asm/extable.h
new file mode 100644
index 000000000..e42592390
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+++ b/arch/alpha/include/asm/extable.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_EXTABLE_H
+#define _ASM_EXTABLE_H
+
+/*
+ * About the exception table:
+ *
+ * - insn is a 32-bit pc-relative offset from the faulting insn.
+ * - nextinsn is a 16-bit offset off of the faulting instruction
+ * (not off of the *next* instruction as branches are).
+ * - errreg is the register in which to place -EFAULT.
+ * - valreg is the final target register for the load sequence
+ * and will be zeroed.
+ *
+ * Either errreg or valreg may be $31, in which case nothing happens.
+ *
+ * The exception fixup information "just so happens" to be arranged
+ * as in a MEM format instruction. This lets us emit our three
+ * values like so:
+ *
+ * lda valreg, nextinsn(errreg)
+ *
+ */
+
+struct exception_table_entry
+{
+ signed int insn;
+ union exception_fixup {
+ unsigned unit;
+ struct {
+ signed int nextinsn : 16;
+ unsigned int errreg : 5;
+ unsigned int valreg : 5;
+ } bits;
+ } fixup;
+};
+
+/* Returns the new pc */
+#define fixup_exception(map_reg, _fixup, pc) \
+({ \
+ if ((_fixup)->fixup.bits.valreg != 31) \
+ map_reg((_fixup)->fixup.bits.valreg) = 0; \
+ if ((_fixup)->fixup.bits.errreg != 31) \
+ map_reg((_fixup)->fixup.bits.errreg) = -EFAULT; \
+ (pc) + (_fixup)->fixup.bits.nextinsn; \
+})
+
+#define ARCH_HAS_RELATIVE_EXTABLE
+
+#define swap_ex_entry_fixup(a, b, tmp, delta) \
+ do { \
+ (a)->fixup.unit = (b)->fixup.unit; \
+ (b)->fixup.unit = (tmp).fixup.unit; \
+ } while (0)
+
+#endif