1// SPDX-License-Identifier: GPL-2.0
 2
 3#include <linux/bitfield.h>
 4#include <linux/extable.h>
 5#include <linux/string.h>
 6#include <linux/errno.h>
 7#include <linux/panic.h>
 8#include <asm/asm-extable.h>
 9#include <asm/extable.h>
10
11const struct exception_table_entry *s390_search_extables(unsigned long addr)
12{
13	const struct exception_table_entry *fixup;
14	size_t num;
15
16	fixup = search_exception_tables(addr);
17	if (fixup)
18		return fixup;
19	num = __stop_amode31_ex_table - __start_amode31_ex_table;
20	return search_extable(__start_amode31_ex_table, num, addr);
21}
22
23static bool ex_handler_fixup(const struct exception_table_entry *ex, struct pt_regs *regs)
24{
25	regs->psw.addr = extable_fixup(ex);
26	return true;
27}
28
29static bool ex_handler_ua_store(const struct exception_table_entry *ex, struct pt_regs *regs)
30{
31	unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
32
33	regs->gprs[reg_err] = -EFAULT;
34	regs->psw.addr = extable_fixup(ex);
35	return true;
36}
37
38static bool ex_handler_ua_load_mem(const struct exception_table_entry *ex, struct pt_regs *regs)
39{
40	unsigned int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
41	unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
42	size_t len = FIELD_GET(EX_DATA_LEN, ex->data);
43
44	regs->gprs[reg_err] = -EFAULT;
45	memset((void *)regs->gprs[reg_addr], 0, len);
46	regs->psw.addr = extable_fixup(ex);
47	return true;
48}
49
50static bool ex_handler_ua_load_reg(const struct exception_table_entry *ex, struct pt_regs *regs)
51{
52	unsigned int reg_zero = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
53	unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
54
55	regs->gprs[reg_err] = -EFAULT;
56	regs->gprs[reg_zero] = 0;
57	regs->psw.addr = extable_fixup(ex);
58	return true;
59}
60
61bool fixup_exception(struct pt_regs *regs)
62{
63	const struct exception_table_entry *ex;
64
65	ex = s390_search_extables(instruction_pointer(regs));
66	if (!ex)
67		return false;
68	switch (ex->type) {
69	case EX_TYPE_FIXUP:
70		return ex_handler_fixup(ex, regs);
71	case EX_TYPE_BPF:
72		return ex_handler_bpf(ex, regs);
73	case EX_TYPE_UA_STORE:
74		return ex_handler_ua_store(ex, regs);
75	case EX_TYPE_UA_LOAD_MEM:
76		return ex_handler_ua_load_mem(ex, regs);
77	case EX_TYPE_UA_LOAD_REG:
78		return ex_handler_ua_load_reg(ex, regs);
79	}
80	panic("invalid exception table entry");
81}