1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __PARISC_EXTABLE_H
3#define __PARISC_EXTABLE_H
4
5#include <asm/ptrace.h>
6#include <linux/compiler.h>
7
8/*
9 * The exception table consists of three addresses:
10 *
11 * - A relative address to the instruction that is allowed to fault.
12 * - A relative address at which the program should continue (fixup routine)
13 * - An asm statement which specifies which CPU register will
14 *   receive -EFAULT when an exception happens if the lowest bit in
15 *   the fixup address is set.
16 *
17 * Note: The register specified in the err_opcode instruction will be
18 * modified at runtime if a fault happens. Register %r0 will be ignored.
19 *
20 * Since relative addresses are used, 32bit values are sufficient even on
21 * 64bit kernel.
22 */
23
24struct pt_regs;
25int fixup_exception(struct pt_regs *regs);
26
27#define ARCH_HAS_RELATIVE_EXTABLE
28struct exception_table_entry {
29	int insn;	/* relative address of insn that is allowed to fault. */
30	int fixup;	/* relative address of fixup routine */
31	int err_opcode; /* sample opcode with register which holds error code */
32};
33
34#define ASM_EXCEPTIONTABLE_ENTRY( fault_addr, except_addr, opcode )\
35	".section __ex_table,\"aw\"\n"			   \
36	".align 4\n"					   \
37	".word (" #fault_addr " - .), (" #except_addr " - .)\n" \
38	opcode "\n"					   \
39	".previous\n"
40
41/*
42 * ASM_EXCEPTIONTABLE_ENTRY_EFAULT() creates a special exception table entry
43 * (with lowest bit set) for which the fault handler in fixup_exception() will
44 * load -EFAULT on fault into the register specified by the err_opcode instruction,
45 * and zeroes the target register in case of a read fault in get_user().
46 */
47#define ASM_EXCEPTIONTABLE_VAR(__err_var)		\
48	int __err_var = 0
49#define ASM_EXCEPTIONTABLE_ENTRY_EFAULT( fault_addr, except_addr, register )\
50	ASM_EXCEPTIONTABLE_ENTRY( fault_addr, except_addr + 1, "or %%r0,%%r0," register)
51
52static inline void swap_ex_entry_fixup(struct exception_table_entry *a,
53				       struct exception_table_entry *b,
54				       struct exception_table_entry tmp,
55				       int delta)
56{
57	a->fixup = b->fixup + delta;
58	b->fixup = tmp.fixup - delta;
59	a->err_opcode = b->err_opcode;
60	b->err_opcode = tmp.err_opcode;
61}
62#define swap_ex_entry_fixup swap_ex_entry_fixup
63
64#endif
65