1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * arch/arm/probes/kprobes/checkers-thumb.c |
4 | * |
5 | * Copyright (C) 2014 Huawei Inc. |
6 | */ |
7 | |
8 | #include <linux/kernel.h> |
9 | #include "../decode.h" |
10 | #include "../decode-thumb.h" |
11 | #include "checkers.h" |
12 | |
13 | static enum probes_insn __kprobes t32_check_stack(probes_opcode_t insn, |
14 | struct arch_probes_insn *asi, |
15 | const struct decode_header *h) |
16 | { |
17 | /* |
18 | * PROBES_T32_LDMSTM, PROBES_T32_LDRDSTRD and PROBES_T32_LDRSTR |
19 | * may get here. Simply mark all normal insns as STACK_USE_NONE. |
20 | */ |
21 | static const union decode_item table[] = { |
22 | |
23 | /* |
24 | * First, filter out all ldr insns to make our life easier. |
25 | * Following load insns may come here: |
26 | * LDM, LDRD, LDR. |
27 | * In T32 encoding, bit 20 is enough for distinguishing |
28 | * load and store. All load insns have this bit set, when |
29 | * all store insns have this bit clear. |
30 | */ |
31 | DECODE_CUSTOM (0x00100000, 0x00100000, STACK_USE_NONE), |
32 | |
33 | /* |
34 | * Mark all 'STR{,B,H}, Rt, [Rn, Rm]' as STACK_USE_UNKNOWN |
35 | * if Rn or Rm is SP. T32 doesn't encode STRD. |
36 | */ |
37 | /* xx | Rn | Rt | | Rm |*/ |
38 | /* STR (register) 1111 1000 0100 xxxx xxxx 0000 00xx xxxx */ |
39 | /* STRB (register) 1111 1000 0000 xxxx xxxx 0000 00xx xxxx */ |
40 | /* STRH (register) 1111 1000 0010 xxxx xxxx 0000 00xx xxxx */ |
41 | /* INVALID INSN 1111 1000 0110 xxxx xxxx 0000 00xx xxxx */ |
42 | /* By Introducing INVALID INSN, bit 21 and 22 can be ignored. */ |
43 | DECODE_OR (0xff9f0fc0, 0xf80d0000), |
44 | DECODE_CUSTOM (0xff900fcf, 0xf800000d, STACK_USE_UNKNOWN), |
45 | |
46 | |
47 | /* xx | Rn | Rt | PUW| imm8 |*/ |
48 | /* STR (imm 8) 1111 1000 0100 1101 xxxx 110x xxxx xxxx */ |
49 | /* STRB (imm 8) 1111 1000 0000 1101 xxxx 110x xxxx xxxx */ |
50 | /* STRH (imm 8) 1111 1000 0010 1101 xxxx 110x xxxx xxxx */ |
51 | /* INVALID INSN 1111 1000 0110 1101 xxxx 110x xxxx xxxx */ |
52 | /* Only consider U == 0 and P == 1: strx rx, [sp, #-<imm>] */ |
53 | DECODE_CUSTOM (0xff9f0e00, 0xf80d0c00, STACK_USE_FIXED_0XX), |
54 | |
55 | /* For STR{,B,H} (imm 12), offset is always positive, so ignore them. */ |
56 | |
57 | /* P U W | Rn | Rt | Rt2| imm8 |*/ |
58 | /* STRD (immediate) 1110 1001 01x0 1101 xxxx xxxx xxxx xxxx */ |
59 | /* |
60 | * Only consider U == 0 and P == 1. |
61 | * Also note that STRD in T32 encoding is special: |
62 | * imm = ZeroExtend(imm8:'00', 32) |
63 | */ |
64 | DECODE_CUSTOM (0xffdf0000, 0xe94d0000, STACK_USE_T32STRD), |
65 | |
66 | /* | Rn | */ |
67 | /* STMDB 1110 1001 00x0 1101 xxxx xxxx xxxx xxxx */ |
68 | DECODE_CUSTOM (0xffdf0000, 0xe90d0000, STACK_USE_STMDX), |
69 | |
70 | /* fall through */ |
71 | DECODE_CUSTOM (0, 0, STACK_USE_NONE), |
72 | DECODE_END |
73 | }; |
74 | |
75 | return probes_decode_insn(insn, asi, table, false, false, stack_check_actions, NULL); |
76 | } |
77 | |
78 | const struct decode_checker t32_stack_checker[NUM_PROBES_T32_ACTIONS] = { |
79 | [PROBES_T32_LDMSTM] = {.checker = t32_check_stack}, |
80 | [PROBES_T32_LDRDSTRD] = {.checker = t32_check_stack}, |
81 | [PROBES_T32_LDRSTR] = {.checker = t32_check_stack}, |
82 | }; |
83 | |
84 | /* |
85 | * See following comments. This insn must be 'push'. |
86 | */ |
87 | static enum probes_insn __kprobes t16_check_stack(probes_opcode_t insn, |
88 | struct arch_probes_insn *asi, |
89 | const struct decode_header *h) |
90 | { |
91 | unsigned int reglist = insn & 0x1ff; |
92 | asi->stack_space = hweight32(reglist) * 4; |
93 | return INSN_GOOD; |
94 | } |
95 | |
96 | /* |
97 | * T16 encoding is simple: only the 'push' insn can need extra stack space. |
98 | * Other insns, like str, can only use r0-r7 as Rn. |
99 | */ |
100 | const struct decode_checker t16_stack_checker[NUM_PROBES_T16_ACTIONS] = { |
101 | [PROBES_T16_PUSH] = {.checker = t16_check_stack}, |
102 | }; |
103 | |