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,
51				   bool pair, struct pt_regs *regs)
52{
53	unsigned int reg_zero = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
54	unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
55
56	regs->gprs[reg_err] = -EFAULT;
57	regs->gprs[reg_zero] = 0;
58	if (pair)
59		regs->gprs[reg_zero + 1] = 0;
60	regs->psw.addr = extable_fixup(ex);
61	return true;
62}
63
64static bool ex_handler_zeropad(const struct exception_table_entry *ex, struct pt_regs *regs)
65{
66	unsigned int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
67	unsigned int reg_data = FIELD_GET(EX_DATA_REG_ERR, ex->data);
68	unsigned long data, addr, offset;
69
70	addr = regs->gprs[reg_addr];
71	offset = addr & (sizeof(unsigned long) - 1);
72	addr &= ~(sizeof(unsigned long) - 1);
73	data = *(unsigned long *)addr;
74	data <<= BITS_PER_BYTE * offset;
75	regs->gprs[reg_data] = data;
76	regs->psw.addr = extable_fixup(ex);
77	return true;
78}
79
80bool fixup_exception(struct pt_regs *regs)
81{
82	const struct exception_table_entry *ex;
83
84	ex = s390_search_extables(instruction_pointer(regs));
85	if (!ex)
86		return false;
87	switch (ex->type) {
88	case EX_TYPE_FIXUP:
89		return ex_handler_fixup(ex, regs);
90	case EX_TYPE_BPF:
91		return ex_handler_bpf(ex, regs);
92	case EX_TYPE_UA_STORE:
93		return ex_handler_ua_store(ex, regs);
94	case EX_TYPE_UA_LOAD_MEM:
95		return ex_handler_ua_load_mem(ex, regs);
96	case EX_TYPE_UA_LOAD_REG:
97		return ex_handler_ua_load_reg(ex, false, regs);
98	case EX_TYPE_UA_LOAD_REGPAIR:
99		return ex_handler_ua_load_reg(ex, true, regs);
100	case EX_TYPE_ZEROPAD:
101		return ex_handler_zeropad(ex, regs);
102	}
103	panic("invalid exception table entry");
104}
105