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Commit 1cabd2f8 authored by Naveen N. Rao's avatar Naveen N. Rao Committed by Michael Ellerman
Browse files

powerpc/kprobes: Factor out code to emulate instruction into a helper 



Factor out code to emulate instruction into a try_to_emulate()
helper function. This makes no functional changes.

Acked-by: default avatarAnanth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent a64e3f35

arch/powerpc/kernel/kprobes.c

+31 −21
Original line number Diff line number Diff line
@@ -207,6 +207,35 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, 
	regs->link = (unsigned long)kretprobe_trampoline;

}



int __kprobes try_to_emulate(struct kprobe *p, struct pt_regs *regs)

{

	int ret;

	unsigned int insn = *p->ainsn.insn;



	/* regs->nip is also adjusted if emulate_step returns 1 */

	ret = emulate_step(regs, insn);

	if (ret > 0) {

		/*

		 * Once this instruction has been boosted

		 * successfully, set the boostable flag

		 */

		if (unlikely(p->ainsn.boostable == 0))

			p->ainsn.boostable = 1;

	} else if (ret < 0) {

		/*

		 * We don't allow kprobes on mtmsr(d)/rfi(d), etc.

		 * So, we should never get here... but, its still

		 * good to catch them, just in case...

		 */

		printk("Can't step on instruction %x\n", insn);

		BUG();

	} else if (ret == 0)

		/* This instruction can't be boosted */

		p->ainsn.boostable = -1;



	return ret;

}



int __kprobes kprobe_handler(struct pt_regs *regs)

{

	struct kprobe *p;
@@ -302,18 +331,9 @@ int __kprobes kprobe_handler(struct pt_regs *regs) 


ss_probe:

	if (p->ainsn.boostable >= 0) {

		unsigned int insn = *p->ainsn.insn;

		ret = try_to_emulate(p, regs);



		/* regs->nip is also adjusted if emulate_step returns 1 */

		ret = emulate_step(regs, insn);

		if (ret > 0) {

			/*

			 * Once this instruction has been boosted

			 * successfully, set the boostable flag

			 */

			if (unlikely(p->ainsn.boostable == 0))

				p->ainsn.boostable = 1;



			if (p->post_handler)

				p->post_handler(p, regs, 0);
@@ -321,17 +341,7 @@ int __kprobes kprobe_handler(struct pt_regs *regs) 
			reset_current_kprobe();

			preempt_enable_no_resched();

			return 1;

		} else if (ret < 0) {

			/*

			 * We don't allow kprobes on mtmsr(d)/rfi(d), etc.

			 * So, we should never get here... but, its still

			 * good to catch them, just in case...

			 */

			printk("Can't step on instruction %x\n", insn);

			BUG();

		} else if (ret == 0)

			/* This instruction can't be boosted */

			p->ainsn.boostable = -1;

		}

	}

	prepare_singlestep(p, regs);

	kcb->kprobe_status = KPROBE_HIT_SS;