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/*
* arch/arm/kernel/kprobes-thumb.c
*
* Copyright (C) 2011 Jon Medhurst <tixy@yxit.co.uk>.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/kprobes.h>
#include "kprobes.h"
/*
* True if current instruction is in an IT block.
*/
#define in_it_block(cpsr) ((cpsr & 0x06000c00) != 0x00000000)
/*
* Return the condition code to check for the currently executing instruction.
* This is in ITSTATE<7:4> which is in CPSR<15:12> but is only valid if
* in_it_block returns true.
*/
#define current_cond(cpsr) ((cpsr >> 12) & 0xf)
static const union decode_item t16_table_1011[] = {
/* Miscellaneous 16-bit instructions */
/*
* If-Then, and hints
* 1011 1111 xxxx xxxx
*/
/* YIELD 1011 1111 0001 0000 */
DECODE_OR (0xffff, 0xbf10),
/* SEV 1011 1111 0100 0000 */
DECODE_EMULATE (0xffff, 0xbf40, kprobe_emulate_none),
/* NOP 1011 1111 0000 0000 */
/* WFE 1011 1111 0010 0000 */
/* WFI 1011 1111 0011 0000 */
DECODE_SIMULATE (0xffcf, 0xbf00, kprobe_simulate_nop),
/* Unassigned hints 1011 1111 xxxx 0000 */
DECODE_REJECT (0xff0f, 0xbf00),
DECODE_END
};
const union decode_item kprobe_decode_thumb16_table[] = {
/*
* Miscellaneous 16-bit instructions
* 1011 xxxx xxxx xxxx
*/
DECODE_TABLE (0xf000, 0xb000, t16_table_1011),
DECODE_END
};
static unsigned long __kprobes thumb_check_cc(unsigned long cpsr)
{
if (unlikely(in_it_block(cpsr)))
return kprobe_condition_checks[current_cond(cpsr)](cpsr);
return true;
}
static void __kprobes thumb16_singlestep(struct kprobe *p, struct pt_regs *regs)
{
regs->ARM_pc += 2;
p->ainsn.insn_handler(p, regs);
regs->ARM_cpsr = it_advance(regs->ARM_cpsr);
}
static void __kprobes thumb32_singlestep(struct kprobe *p, struct pt_regs *regs)
{
regs->ARM_pc += 4;
p->ainsn.insn_handler(p, regs);
regs->ARM_cpsr = it_advance(regs->ARM_cpsr);
}
enum kprobe_insn __kprobes
thumb16_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
asi->insn_singlestep = thumb16_singlestep;
asi->insn_check_cc = thumb_check_cc;
return kprobe_decode_insn(insn, asi, kprobe_decode_thumb16_table, true);
}
enum kprobe_insn __kprobes
thumb32_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
asi->insn_singlestep = thumb32_singlestep;
asi->insn_check_cc = thumb_check_cc;
return INSN_REJECTED;
}
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