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
11 const 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
23 static 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
29 static 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
38 static 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
50 static 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
64 static 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
80 bool 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
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