1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Common helper functions for kprobes and uprobes
4 *
5 * Copyright IBM Corp. 2014
6 */
7
8 #include <linux/errno.h>
9 #include <asm/kprobes.h>
10 #include <asm/dis.h>
11
12 int probe_is_prohibited_opcode(u16 *insn)
13 {
14 if (!is_known_insn((unsigned char *)insn))
15 return -EINVAL;
16 switch (insn[0] >> 8) {
17 case 0x0c: /* bassm */
18 case 0x0b: /* bsm */
19 case 0x83: /* diag */
20 case 0x44: /* ex */
21 case 0xac: /* stnsm */
22 case 0xad: /* stosm */
23 return -EINVAL;
24 case 0xc6:
25 switch (insn[0] & 0x0f) {
26 case 0x00: /* exrl */
27 return -EINVAL;
28 }
29 }
30 switch (insn[0]) {
31 case 0x0101: /* pr */
32 case 0xb25a: /* bsa */
33 case 0xb240: /* bakr */
34 case 0xb258: /* bsg */
35 case 0xb218: /* pc */
36 case 0xb228: /* pt */
37 case 0xb98d: /* epsw */
38 case 0xe560: /* tbegin */
39 case 0xe561: /* tbeginc */
40 case 0xb2f8: /* tend */
41 return -EINVAL;
42 }
43 return 0;
44 }
45
46 int probe_get_fixup_type(u16 *insn)
47 {
48 /* default fixup method */
49 int fixup = FIXUP_PSW_NORMAL;
50
51 switch (insn[0] >> 8) {
52 case 0x05: /* balr */
53 case 0x0d: /* basr */
54 fixup = FIXUP_RETURN_REGISTER;
55 /* if r2 = 0, no branch will be taken */
56 if ((insn[0] & 0x0f) == 0)
57 fixup |= FIXUP_BRANCH_NOT_TAKEN;
58 break;
59 case 0x06: /* bctr */
60 case 0x07: /* bcr */
61 fixup = FIXUP_BRANCH_NOT_TAKEN;
62 break;
63 case 0x45: /* bal */
64 case 0x4d: /* bas */
65 fixup = FIXUP_RETURN_REGISTER;
66 break;
67 case 0x47: /* bc */
68 case 0x46: /* bct */
69 case 0x86: /* bxh */
70 case 0x87: /* bxle */
71 fixup = FIXUP_BRANCH_NOT_TAKEN;
72 break;
73 case 0x82: /* lpsw */
74 fixup = FIXUP_NOT_REQUIRED;
75 break;
76 case 0xb2: /* lpswe */
77 if ((insn[0] & 0xff) == 0xb2)
78 fixup = FIXUP_NOT_REQUIRED;
79 break;
80 case 0xa7: /* bras */
81 if ((insn[0] & 0x0f) == 0x05)
82 fixup |= FIXUP_RETURN_REGISTER;
83 break;
84 case 0xc0:
85 if ((insn[0] & 0x0f) == 0x05) /* brasl */
86 fixup |= FIXUP_RETURN_REGISTER;
87 break;
88 case 0xeb:
89 switch (insn[2] & 0xff) {
90 case 0x44: /* bxhg */
91 case 0x45: /* bxleg */
92 fixup = FIXUP_BRANCH_NOT_TAKEN;
93 break;
94 }
95 break;
96 case 0xe3: /* bctg */
97 if ((insn[2] & 0xff) == 0x46)
98 fixup = FIXUP_BRANCH_NOT_TAKEN;
99 break;
100 case 0xec:
101 switch (insn[2] & 0xff) {
102 case 0xe5: /* clgrb */
103 case 0xe6: /* cgrb */
104 case 0xf6: /* crb */
105 case 0xf7: /* clrb */
106 case 0xfc: /* cgib */
107 case 0xfd: /* cglib */
108 case 0xfe: /* cib */
109 case 0xff: /* clib */
110 fixup = FIXUP_BRANCH_NOT_TAKEN;
111 break;
112 }
113 break;
114 }
115 return fixup;
116 }
117
118 int probe_is_insn_relative_long(u16 *insn)
119 {
120 /* Check if we have a RIL-b or RIL-c format instruction which
121 * we need to modify in order to avoid instruction emulation. */
122 switch (insn[0] >> 8) {
123 case 0xc0:
124 if ((insn[0] & 0x0f) == 0x00) /* larl */
125 return true;
126 break;
127 case 0xc4:
128 switch (insn[0] & 0x0f) {
129 case 0x02: /* llhrl */
130 case 0x04: /* lghrl */
131 case 0x05: /* lhrl */
132 case 0x06: /* llghrl */
133 case 0x07: /* sthrl */
134 case 0x08: /* lgrl */
135 case 0x0b: /* stgrl */
136 case 0x0c: /* lgfrl */
137 case 0x0d: /* lrl */
138 case 0x0e: /* llgfrl */
139 case 0x0f: /* strl */
140 return true;
141 }
142 break;
143 case 0xc6:
144 switch (insn[0] & 0x0f) {
145 case 0x02: /* pfdrl */
146 case 0x04: /* cghrl */
147 case 0x05: /* chrl */
148 case 0x06: /* clghrl */
149 case 0x07: /* clhrl */
150 case 0x08: /* cgrl */
151 case 0x0a: /* clgrl */
152 case 0x0c: /* cgfrl */
153 case 0x0d: /* crl */
154 case 0x0e: /* clgfrl */
155 case 0x0f: /* clrl */
156 return true;
157 }
158 break;
159 }
160 return false;
161 }