1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * arch/arm/probes/kprobes/checkers-common.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 enum probes_insn checker_stack_use_none(probes_opcode_t insn,
14 		struct arch_probes_insn *asi,
15 		const struct decode_header *h)
16 {
17 	asi->stack_space = 0;
18 	return INSN_GOOD_NO_SLOT;
19 }
20 
21 enum probes_insn checker_stack_use_unknown(probes_opcode_t insn,
22 		struct arch_probes_insn *asi,
23 		const struct decode_header *h)
24 {
25 	asi->stack_space = -1;
26 	return INSN_GOOD_NO_SLOT;
27 }
28 
29 #ifdef CONFIG_THUMB2_KERNEL
30 enum probes_insn checker_stack_use_imm_0xx(probes_opcode_t insn,
31 		struct arch_probes_insn *asi,
32 		const struct decode_header *h)
33 {
34 	int imm = insn & 0xff;
35 	asi->stack_space = imm;
36 	return INSN_GOOD_NO_SLOT;
37 }
38 
39 /*
40  * Different from other insn uses imm8, the real addressing offset of
41  * STRD in T32 encoding should be imm8 * 4. See ARMARM description.
42  */
43 enum probes_insn checker_stack_use_t32strd(probes_opcode_t insn,
44 		struct arch_probes_insn *asi,
45 		const struct decode_header *h)
46 {
47 	int imm = insn & 0xff;
48 	asi->stack_space = imm << 2;
49 	return INSN_GOOD_NO_SLOT;
50 }
51 #else
52 enum probes_insn checker_stack_use_imm_x0x(probes_opcode_t insn,
53 		struct arch_probes_insn *asi,
54 		const struct decode_header *h)
55 {
56 	int imm = ((insn & 0xf00) >> 4) + (insn & 0xf);
57 	asi->stack_space = imm;
58 	return INSN_GOOD_NO_SLOT;
59 }
60 #endif
61 
62 enum probes_insn checker_stack_use_imm_xxx(probes_opcode_t insn,
63 		struct arch_probes_insn *asi,
64 		const struct decode_header *h)
65 {
66 	int imm = insn & 0xfff;
67 	asi->stack_space = imm;
68 	return INSN_GOOD_NO_SLOT;
69 }
70 
71 enum probes_insn checker_stack_use_stmdx(probes_opcode_t insn,
72 		struct arch_probes_insn *asi,
73 		const struct decode_header *h)
74 {
75 	unsigned int reglist = insn & 0xffff;
76 	int pbit = insn & (1 << 24);
77 	asi->stack_space = (hweight32(reglist) - (!pbit ? 1 : 0)) * 4;
78 
79 	return INSN_GOOD_NO_SLOT;
80 }
81 
82 const union decode_action stack_check_actions[] = {
83 	[STACK_USE_NONE] = {.decoder = checker_stack_use_none},
84 	[STACK_USE_UNKNOWN] = {.decoder = checker_stack_use_unknown},
85 #ifdef CONFIG_THUMB2_KERNEL
86 	[STACK_USE_FIXED_0XX] = {.decoder = checker_stack_use_imm_0xx},
87 	[STACK_USE_T32STRD] = {.decoder = checker_stack_use_t32strd},
88 #else
89 	[STACK_USE_FIXED_X0X] = {.decoder = checker_stack_use_imm_x0x},
90 #endif
91 	[STACK_USE_FIXED_XXX] = {.decoder = checker_stack_use_imm_xxx},
92 	[STACK_USE_STMDX] = {.decoder = checker_stack_use_stmdx},
93 };
94