static void __kprobes prepare_singlestep()

in kernel/kprobes.c [144:200]

• 43 lines of code
• 13 McCabe index (conditional complexity)

static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
{
	__this_cpu_write(saved_current_opcode.addr, (kprobe_opcode_t *)regs->pc);

	if (p != NULL) {
		struct kprobe *op1, *op2;

		arch_disarm_kprobe(p);

		op1 = this_cpu_ptr(&saved_next_opcode);
		op2 = this_cpu_ptr(&saved_next_opcode2);

		if (OPCODE_JSR(p->opcode) || OPCODE_JMP(p->opcode)) {
			unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
			op1->addr = (kprobe_opcode_t *) regs->regs[reg_nr];
		} else if (OPCODE_BRA(p->opcode) || OPCODE_BSR(p->opcode)) {
			unsigned long disp = (p->opcode & 0x0FFF);
			op1->addr =
			    (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);

		} else if (OPCODE_BRAF(p->opcode) || OPCODE_BSRF(p->opcode)) {
			unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
			op1->addr =
			    (kprobe_opcode_t *) (regs->pc + 4 +
						 regs->regs[reg_nr]);

		} else if (OPCODE_RTS(p->opcode)) {
			op1->addr = (kprobe_opcode_t *) regs->pr;

		} else if (OPCODE_BF(p->opcode) || OPCODE_BT(p->opcode)) {
			unsigned long disp = (p->opcode & 0x00FF);
			/* case 1 */
			op1->addr = p->addr + 1;
			/* case 2 */
			op2->addr =
			    (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
			op2->opcode = *(op2->addr);
			arch_arm_kprobe(op2);

		} else if (OPCODE_BF_S(p->opcode) || OPCODE_BT_S(p->opcode)) {
			unsigned long disp = (p->opcode & 0x00FF);
			/* case 1 */
			op1->addr = p->addr + 2;
			/* case 2 */
			op2->addr =
			    (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
			op2->opcode = *(op2->addr);
			arch_arm_kprobe(op2);

		} else {
			op1->addr = p->addr + 1;
		}

		op1->opcode = *(op1->addr);
		arch_arm_kprobe(op1);
	}
}