2 * arch/arm/kernel/kprobes-thumb.c
4 * Copyright (C) 2011 Jon Medhurst <tixy@yxit.co.uk>.
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.
11 #include <linux/kernel.h>
12 #include <linux/kprobes.h>
18 * True if current instruction is in an IT block.
20 #define in_it_block(cpsr) ((cpsr & 0x06000c00) != 0x00000000)
23 * Return the condition code to check for the currently executing instruction.
24 * This is in ITSTATE<7:4> which is in CPSR<15:12> but is only valid if
25 * in_it_block returns true.
27 #define current_cond(cpsr) ((cpsr >> 12) & 0xf)
29 static unsigned long __kprobes
30 t16_emulate_loregs(struct kprobe *p, struct pt_regs *regs)
32 unsigned long oldcpsr = regs->ARM_cpsr;
33 unsigned long newcpsr;
35 __asm__ __volatile__ (
36 "msr cpsr_fs, %[oldcpsr] \n\t"
37 "ldmia %[regs], {r0-r7} \n\t"
39 "stmia %[regs], {r0-r7} \n\t"
40 "mrs %[newcpsr], cpsr \n\t"
41 : [newcpsr] "=r" (newcpsr)
42 : [oldcpsr] "r" (oldcpsr), [regs] "r" (regs),
43 [fn] "r" (p->ainsn.insn_fn)
44 : "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
48 return (oldcpsr & ~APSR_MASK) | (newcpsr & APSR_MASK);
52 t16_emulate_loregs_rwflags(struct kprobe *p, struct pt_regs *regs)
54 regs->ARM_cpsr = t16_emulate_loregs(p, regs);
58 t16_emulate_loregs_noitrwflags(struct kprobe *p, struct pt_regs *regs)
60 unsigned long cpsr = t16_emulate_loregs(p, regs);
61 if (!in_it_block(cpsr))
62 regs->ARM_cpsr = cpsr;
65 static const union decode_item t16_table_1011[] = {
66 /* Miscellaneous 16-bit instructions */
73 /* YIELD 1011 1111 0001 0000 */
74 DECODE_OR (0xffff, 0xbf10),
75 /* SEV 1011 1111 0100 0000 */
76 DECODE_EMULATE (0xffff, 0xbf40, kprobe_emulate_none),
77 /* NOP 1011 1111 0000 0000 */
78 /* WFE 1011 1111 0010 0000 */
79 /* WFI 1011 1111 0011 0000 */
80 DECODE_SIMULATE (0xffcf, 0xbf00, kprobe_simulate_nop),
81 /* Unassigned hints 1011 1111 xxxx 0000 */
82 DECODE_REJECT (0xff0f, 0xbf00),
87 const union decode_item kprobe_decode_thumb16_table[] = {
90 * Shift (immediate), add, subtract, move, and compare
94 /* CMP (immediate) 0010 1xxx xxxx xxxx */
95 DECODE_EMULATE (0xf800, 0x2800, t16_emulate_loregs_rwflags),
97 /* ADD (register) 0001 100x xxxx xxxx */
98 /* SUB (register) 0001 101x xxxx xxxx */
99 /* LSL (immediate) 0000 0xxx xxxx xxxx */
100 /* LSR (immediate) 0000 1xxx xxxx xxxx */
101 /* ASR (immediate) 0001 0xxx xxxx xxxx */
102 /* ADD (immediate, Thumb) 0001 110x xxxx xxxx */
103 /* SUB (immediate, Thumb) 0001 111x xxxx xxxx */
104 /* MOV (immediate) 0010 0xxx xxxx xxxx */
105 /* ADD (immediate, Thumb) 0011 0xxx xxxx xxxx */
106 /* SUB (immediate, Thumb) 0011 1xxx xxxx xxxx */
107 DECODE_EMULATE (0xc000, 0x0000, t16_emulate_loregs_noitrwflags),
110 * 16-bit Thumb data-processing instructions
111 * 0100 00xx xxxx xxxx
114 /* TST (register) 0100 0010 00xx xxxx */
115 DECODE_EMULATE (0xffc0, 0x4200, t16_emulate_loregs_rwflags),
116 /* CMP (register) 0100 0010 10xx xxxx */
117 /* CMN (register) 0100 0010 11xx xxxx */
118 DECODE_EMULATE (0xff80, 0x4280, t16_emulate_loregs_rwflags),
119 /* AND (register) 0100 0000 00xx xxxx */
120 /* EOR (register) 0100 0000 01xx xxxx */
121 /* LSL (register) 0100 0000 10xx xxxx */
122 /* LSR (register) 0100 0000 11xx xxxx */
123 /* ASR (register) 0100 0001 00xx xxxx */
124 /* ADC (register) 0100 0001 01xx xxxx */
125 /* SBC (register) 0100 0001 10xx xxxx */
126 /* ROR (register) 0100 0001 11xx xxxx */
127 /* RSB (immediate) 0100 0010 01xx xxxx */
128 /* ORR (register) 0100 0011 00xx xxxx */
129 /* MUL 0100 0011 00xx xxxx */
130 /* BIC (register) 0100 0011 10xx xxxx */
131 /* MVN (register) 0100 0011 10xx xxxx */
132 DECODE_EMULATE (0xfc00, 0x4000, t16_emulate_loregs_noitrwflags),
135 * Miscellaneous 16-bit instructions
136 * 1011 xxxx xxxx xxxx
138 DECODE_TABLE (0xf000, 0xb000, t16_table_1011),
143 static unsigned long __kprobes thumb_check_cc(unsigned long cpsr)
145 if (unlikely(in_it_block(cpsr)))
146 return kprobe_condition_checks[current_cond(cpsr)](cpsr);
150 static void __kprobes thumb16_singlestep(struct kprobe *p, struct pt_regs *regs)
153 p->ainsn.insn_handler(p, regs);
154 regs->ARM_cpsr = it_advance(regs->ARM_cpsr);
157 static void __kprobes thumb32_singlestep(struct kprobe *p, struct pt_regs *regs)
160 p->ainsn.insn_handler(p, regs);
161 regs->ARM_cpsr = it_advance(regs->ARM_cpsr);
164 enum kprobe_insn __kprobes
165 thumb16_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi)
167 asi->insn_singlestep = thumb16_singlestep;
168 asi->insn_check_cc = thumb_check_cc;
169 return kprobe_decode_insn(insn, asi, kprobe_decode_thumb16_table, true);
172 enum kprobe_insn __kprobes
173 thumb32_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi)
175 asi->insn_singlestep = thumb32_singlestep;
176 asi->insn_check_cc = thumb_check_cc;
177 return INSN_REJECTED;