1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __S390_EXTABLE_H
3#define __S390_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 * - Address of an instruction that is allowed to fault.
12 * - Address at which the program should continue.
13 * - Optional address of handler that takes pt_regs * argument and runs in
14 *   interrupt context.
15 *
16 * No registers are modified, so it is entirely up to the continuation code
17 * to figure out what to do.
18 *
19 * All the routines below use bits of fixup code that are out of line
20 * with the main instruction path.  This means when everything is well,
21 * we don't even have to jump over them.  Further, they do not intrude
22 * on our cache or tlb entries.
23 */
24
25struct exception_table_entry
26{
27	int insn, fixup;
28	long handler;
29};
30
31extern struct exception_table_entry *__start_dma_ex_table;
32extern struct exception_table_entry *__stop_dma_ex_table;
33
34const struct exception_table_entry *s390_search_extables(unsigned long addr);
35
36static inline unsigned long extable_fixup(const struct exception_table_entry *x)
37{
38	return (unsigned long)&x->fixup + x->fixup;
39}
40
41typedef bool (*ex_handler_t)(const struct exception_table_entry *,
42			     struct pt_regs *);
43
44static inline ex_handler_t
45ex_fixup_handler(const struct exception_table_entry *x)
46{
47	if (likely(!x->handler))
48		return NULL;
49	return (ex_handler_t)((unsigned long)&x->handler + x->handler);
50}
51
52static inline bool ex_handle(const struct exception_table_entry *x,
53			     struct pt_regs *regs)
54{
55	ex_handler_t handler = ex_fixup_handler(x);
56
57	if (unlikely(handler))
58		return handler(x, regs);
59	regs->psw.addr = extable_fixup(x);
60	return true;
61}
62
63#define ARCH_HAS_RELATIVE_EXTABLE
64
65static inline void swap_ex_entry_fixup(struct exception_table_entry *a,
66				       struct exception_table_entry *b,
67				       struct exception_table_entry tmp,
68				       int delta)
69{
70	a->fixup = b->fixup + delta;
71	b->fixup = tmp.fixup - delta;
72	a->handler = b->handler;
73	if (a->handler)
74		a->handler += delta;
75	b->handler = tmp.handler;
76	if (b->handler)
77		b->handler -= delta;
78}
79#define swap_ex_entry_fixup swap_ex_entry_fixup
80
81#endif
82