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
25 struct exception_table_entry
26 {
27 int insn, fixup;
28 long handler;
29 };
30
31 extern struct exception_table_entry *__start_dma_ex_table;
32 extern struct exception_table_entry *__stop_dma_ex_table;
33
34 const struct exception_table_entry *s390_search_extables(unsigned long addr);
35
extable_fixup(const struct exception_table_entry * x)36 static inline unsigned long extable_fixup(const struct exception_table_entry *x)
37 {
38 return (unsigned long)&x->fixup + x->fixup;
39 }
40
41 typedef bool (*ex_handler_t)(const struct exception_table_entry *,
42 struct pt_regs *);
43
44 static inline ex_handler_t
ex_fixup_handler(const struct exception_table_entry * x)45 ex_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
ex_handle(const struct exception_table_entry * x,struct pt_regs * regs)52 static 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
swap_ex_entry_fixup(struct exception_table_entry * a,struct exception_table_entry * b,struct exception_table_entry tmp,int delta)65 static 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 + delta;
73 b->handler = tmp.handler - delta;
74 }
75
76 #endif
77
