1/*
2 * arch/arm/probes/kprobes/checkers-common.c
3 *
4 * Copyright (C) 2014 Huawei Inc.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13 * General Public License for more details.
14 */
15
16#include <linux/kernel.h>
17#include "../decode.h"
18#include "../decode-arm.h"
19#include "checkers.h"
20
21enum probes_insn checker_stack_use_none(probes_opcode_t insn,
22		struct arch_probes_insn *asi,
23		const struct decode_header *h)
24{
25	asi->stack_space = 0;
26	return INSN_GOOD_NO_SLOT;
27}
28
29enum probes_insn checker_stack_use_unknown(probes_opcode_t insn,
30		struct arch_probes_insn *asi,
31		const struct decode_header *h)
32{
33	asi->stack_space = -1;
34	return INSN_GOOD_NO_SLOT;
35}
36
37#ifdef CONFIG_THUMB2_KERNEL
38enum probes_insn checker_stack_use_imm_0xx(probes_opcode_t insn,
39		struct arch_probes_insn *asi,
40		const struct decode_header *h)
41{
42	int imm = insn & 0xff;
43	asi->stack_space = imm;
44	return INSN_GOOD_NO_SLOT;
45}
46
47/*
48 * Different from other insn uses imm8, the real addressing offset of
49 * STRD in T32 encoding should be imm8 * 4. See ARMARM description.
50 */
51enum probes_insn checker_stack_use_t32strd(probes_opcode_t insn,
52		struct arch_probes_insn *asi,
53		const struct decode_header *h)
54{
55	int imm = insn & 0xff;
56	asi->stack_space = imm << 2;
57	return INSN_GOOD_NO_SLOT;
58}
59#else
60enum probes_insn checker_stack_use_imm_x0x(probes_opcode_t insn,
61		struct arch_probes_insn *asi,
62		const struct decode_header *h)
63{
64	int imm = ((insn & 0xf00) >> 4) + (insn & 0xf);
65	asi->stack_space = imm;
66	return INSN_GOOD_NO_SLOT;
67}
68#endif
69
70enum probes_insn checker_stack_use_imm_xxx(probes_opcode_t insn,
71		struct arch_probes_insn *asi,
72		const struct decode_header *h)
73{
74	int imm = insn & 0xfff;
75	asi->stack_space = imm;
76	return INSN_GOOD_NO_SLOT;
77}
78
79enum probes_insn checker_stack_use_stmdx(probes_opcode_t insn,
80		struct arch_probes_insn *asi,
81		const struct decode_header *h)
82{
83	unsigned int reglist = insn & 0xffff;
84	int pbit = insn & (1 << 24);
85	asi->stack_space = (hweight32(reglist) - (!pbit ? 1 : 0)) * 4;
86
87	return INSN_GOOD_NO_SLOT;
88}
89
90const union decode_action stack_check_actions[] = {
91	[STACK_USE_NONE] = {.decoder = checker_stack_use_none},
92	[STACK_USE_UNKNOWN] = {.decoder = checker_stack_use_unknown},
93#ifdef CONFIG_THUMB2_KERNEL
94	[STACK_USE_FIXED_0XX] = {.decoder = checker_stack_use_imm_0xx},
95	[STACK_USE_T32STRD] = {.decoder = checker_stack_use_t32strd},
96#else
97	[STACK_USE_FIXED_X0X] = {.decoder = checker_stack_use_imm_x0x},
98#endif
99	[STACK_USE_FIXED_XXX] = {.decoder = checker_stack_use_imm_xxx},
100	[STACK_USE_STMDX] = {.decoder = checker_stack_use_stmdx},
101};
102