1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * arch/arm/probes/kprobes/checkers-arm.c |
4 | * |
5 | * Copyright (C) 2014 Huawei Inc. |
6 | */ |
7 | |
8 | #include <linux/kernel.h> |
9 | #include "../decode.h" |
10 | #include "../decode-arm.h" |
11 | #include "checkers.h" |
12 | |
13 | static enum probes_insn __kprobes arm_check_stack(probes_opcode_t insn, |
14 | struct arch_probes_insn *asi, |
15 | const struct decode_header *h) |
16 | { |
17 | /* |
18 | * PROBES_LDRSTRD, PROBES_LDMSTM, PROBES_STORE, |
19 | * PROBES_STORE_EXTRA may get here. Simply mark all normal |
20 | * insns as STACK_USE_NONE. |
21 | */ |
22 | static const union decode_item table[] = { |
23 | /* |
24 | * 'STR{,D,B,H}, Rt, [Rn, Rm]' should be marked as UNKNOWN |
25 | * if Rn or Rm is SP. |
26 | * x |
27 | * STR (register) cccc 011x x0x0 xxxx xxxx xxxx xxxx xxxx |
28 | * STRB (register) cccc 011x x1x0 xxxx xxxx xxxx xxxx xxxx |
29 | */ |
30 | DECODE_OR (0x0e10000f, 0x0600000d), |
31 | DECODE_OR (0x0e1f0000, 0x060d0000), |
32 | |
33 | /* |
34 | * x |
35 | * STRD (register) cccc 000x x0x0 xxxx xxxx xxxx 1111 xxxx |
36 | * STRH (register) cccc 000x x0x0 xxxx xxxx xxxx 1011 xxxx |
37 | */ |
38 | DECODE_OR (0x0e5000bf, 0x000000bd), |
39 | DECODE_CUSTOM (0x0e5f00b0, 0x000d00b0, STACK_USE_UNKNOWN), |
40 | |
41 | /* |
42 | * For PROBES_LDMSTM, only stmdx sp, [...] need to examine |
43 | * |
44 | * Bit B/A (bit 24) encodes arithmetic operation order. 1 means |
45 | * before, 0 means after. |
46 | * Bit I/D (bit 23) encodes arithmetic operation. 1 means |
47 | * increment, 0 means decrement. |
48 | * |
49 | * So: |
50 | * B I |
51 | * / / |
52 | * A D | Rn | |
53 | * STMDX SP, [...] cccc 100x 00x0 xxxx xxxx xxxx xxxx xxxx |
54 | */ |
55 | DECODE_CUSTOM (0x0edf0000, 0x080d0000, STACK_USE_STMDX), |
56 | |
57 | /* P U W | Rn | Rt | imm12 |*/ |
58 | /* STR (immediate) cccc 010x x0x0 1101 xxxx xxxx xxxx xxxx */ |
59 | /* STRB (immediate) cccc 010x x1x0 1101 xxxx xxxx xxxx xxxx */ |
60 | /* P U W | Rn | Rt |imm4| |imm4|*/ |
61 | /* STRD (immediate) cccc 000x x1x0 1101 xxxx xxxx 1111 xxxx */ |
62 | /* STRH (immediate) cccc 000x x1x0 1101 xxxx xxxx 1011 xxxx */ |
63 | /* |
64 | * index = (P == '1'); add = (U == '1'). |
65 | * Above insns with: |
66 | * index == 0 (str{,d,h} rx, [sp], #+/-imm) or |
67 | * add == 1 (str{,d,h} rx, [sp, #+<imm>]) |
68 | * should be STACK_USE_NONE. |
69 | * Only str{,b,d,h} rx,[sp,#-n] (P == 1 and U == 0) are |
70 | * required to be examined. |
71 | */ |
72 | /* STR{,B} Rt,[SP,#-n] cccc 0101 0xx0 1101 xxxx xxxx xxxx xxxx */ |
73 | DECODE_CUSTOM (0x0f9f0000, 0x050d0000, STACK_USE_FIXED_XXX), |
74 | |
75 | /* STR{D,H} Rt,[SP,#-n] cccc 0001 01x0 1101 xxxx xxxx 1x11 xxxx */ |
76 | DECODE_CUSTOM (0x0fdf00b0, 0x014d00b0, STACK_USE_FIXED_X0X), |
77 | |
78 | /* fall through */ |
79 | DECODE_CUSTOM (0, 0, STACK_USE_NONE), |
80 | DECODE_END |
81 | }; |
82 | |
83 | return probes_decode_insn(insn, asi, table, false, false, stack_check_actions, NULL); |
84 | } |
85 | |
86 | const struct decode_checker arm_stack_checker[NUM_PROBES_ARM_ACTIONS] = { |
87 | [PROBES_LDRSTRD] = {.checker = arm_check_stack}, |
88 | [PROBES_STORE_EXTRA] = {.checker = arm_check_stack}, |
89 | [PROBES_STORE] = {.checker = arm_check_stack}, |
90 | [PROBES_LDMSTM] = {.checker = arm_check_stack}, |
91 | }; |
92 | |
93 | static enum probes_insn __kprobes arm_check_regs_nouse(probes_opcode_t insn, |
94 | struct arch_probes_insn *asi, |
95 | const struct decode_header *h) |
96 | { |
97 | asi->register_usage_flags = 0; |
98 | return INSN_GOOD; |
99 | } |
100 | |
101 | static enum probes_insn arm_check_regs_normal(probes_opcode_t insn, |
102 | struct arch_probes_insn *asi, |
103 | const struct decode_header *h) |
104 | { |
105 | u32 regs = h->type_regs.bits >> DECODE_TYPE_BITS; |
106 | int i; |
107 | |
108 | asi->register_usage_flags = 0; |
109 | for (i = 0; i < 5; regs >>= 4, insn >>= 4, i++) |
110 | if (regs & 0xf) |
111 | asi->register_usage_flags |= 1 << (insn & 0xf); |
112 | |
113 | return INSN_GOOD; |
114 | } |
115 | |
116 | |
117 | static enum probes_insn arm_check_regs_ldmstm(probes_opcode_t insn, |
118 | struct arch_probes_insn *asi, |
119 | const struct decode_header *h) |
120 | { |
121 | unsigned int reglist = insn & 0xffff; |
122 | unsigned int rn = (insn >> 16) & 0xf; |
123 | asi->register_usage_flags = reglist | (1 << rn); |
124 | return INSN_GOOD; |
125 | } |
126 | |
127 | static enum probes_insn arm_check_regs_mov_ip_sp(probes_opcode_t insn, |
128 | struct arch_probes_insn *asi, |
129 | const struct decode_header *h) |
130 | { |
131 | /* Instruction is 'mov ip, sp' i.e. 'mov r12, r13' */ |
132 | asi->register_usage_flags = (1 << 12) | (1<< 13); |
133 | return INSN_GOOD; |
134 | } |
135 | |
136 | /* |
137 | * | Rn |Rt/d| | Rm | |
138 | * LDRD (register) cccc 000x x0x0 xxxx xxxx xxxx 1101 xxxx |
139 | * STRD (register) cccc 000x x0x0 xxxx xxxx xxxx 1111 xxxx |
140 | * | Rn |Rt/d| |imm4L| |
141 | * LDRD (immediate) cccc 000x x1x0 xxxx xxxx xxxx 1101 xxxx |
142 | * STRD (immediate) cccc 000x x1x0 xxxx xxxx xxxx 1111 xxxx |
143 | * |
144 | * Such instructions access Rt/d and its next register, so different |
145 | * from others, a specific checker is required to handle this extra |
146 | * implicit register usage. |
147 | */ |
148 | static enum probes_insn arm_check_regs_ldrdstrd(probes_opcode_t insn, |
149 | struct arch_probes_insn *asi, |
150 | const struct decode_header *h) |
151 | { |
152 | int rdt = (insn >> 12) & 0xf; |
153 | arm_check_regs_normal(insn, asi, h); |
154 | asi->register_usage_flags |= 1 << (rdt + 1); |
155 | return INSN_GOOD; |
156 | } |
157 | |
158 | |
159 | const struct decode_checker arm_regs_checker[NUM_PROBES_ARM_ACTIONS] = { |
160 | [PROBES_MRS] = {.checker = arm_check_regs_normal}, |
161 | [PROBES_SATURATING_ARITHMETIC] = {.checker = arm_check_regs_normal}, |
162 | [PROBES_MUL1] = {.checker = arm_check_regs_normal}, |
163 | [PROBES_MUL2] = {.checker = arm_check_regs_normal}, |
164 | [PROBES_MUL_ADD_LONG] = {.checker = arm_check_regs_normal}, |
165 | [PROBES_MUL_ADD] = {.checker = arm_check_regs_normal}, |
166 | [PROBES_LOAD] = {.checker = arm_check_regs_normal}, |
167 | [PROBES_LOAD_EXTRA] = {.checker = arm_check_regs_normal}, |
168 | [PROBES_STORE] = {.checker = arm_check_regs_normal}, |
169 | [PROBES_STORE_EXTRA] = {.checker = arm_check_regs_normal}, |
170 | [PROBES_DATA_PROCESSING_REG] = {.checker = arm_check_regs_normal}, |
171 | [PROBES_DATA_PROCESSING_IMM] = {.checker = arm_check_regs_normal}, |
172 | [PROBES_SEV] = {.checker = arm_check_regs_nouse}, |
173 | [PROBES_WFE] = {.checker = arm_check_regs_nouse}, |
174 | [PROBES_SATURATE] = {.checker = arm_check_regs_normal}, |
175 | [PROBES_REV] = {.checker = arm_check_regs_normal}, |
176 | [PROBES_MMI] = {.checker = arm_check_regs_normal}, |
177 | [PROBES_PACK] = {.checker = arm_check_regs_normal}, |
178 | [PROBES_EXTEND] = {.checker = arm_check_regs_normal}, |
179 | [PROBES_EXTEND_ADD] = {.checker = arm_check_regs_normal}, |
180 | [PROBES_BITFIELD] = {.checker = arm_check_regs_normal}, |
181 | [PROBES_LDMSTM] = {.checker = arm_check_regs_ldmstm}, |
182 | [PROBES_MOV_IP_SP] = {.checker = arm_check_regs_mov_ip_sp}, |
183 | [PROBES_LDRSTRD] = {.checker = arm_check_regs_ldrdstrd}, |
184 | }; |
185 | |