Commit d04c02f8 authored May 15, 2017 by Naveen N. Rao Committed by Michael Ellerman May 16, 2017

powerpc/kprobes: Fix handling of instruction emulation on probe re-entry

Commit 22d8b3de ("powerpc/kprobes: Emulate instructions on kprobe
handler re-entry") enabled emulating instructions on kprobe re-entry,
rather than single-stepping always. However, we didn't update the single
stepping code to only be run if the emulation fails. Also, we missed
re-enabling preemption if the instruction emulation was successful. Fix
those issues.

Fixes: 22d8b3de ("powerpc/kprobes: Emulate instructions on kprobe handler re-entry")
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

parent bbb075dd

arch/powerpc/kernel/kprobes.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -305,16 +305,17 @@ int kprobe_handler(struct pt_regs *regs)
		save_previous_kprobe(kcb);
		set_current_kprobe(p, regs, kcb);
		kprobes_inc_nmissed_count(p);
		prepare_singlestep(p, regs);
		kcb->kprobe_status = KPROBE_REENTER;
		if (p->ainsn.boostable >= 0) {
		ret = try_to_emulate(p, regs);

		if (ret > 0) {
		restore_previous_kprobe(kcb);
		preempt_enable_no_resched();
		return 1;
		}
		}
		prepare_singlestep(p, regs);
		return 1;
		} else {
		if (*addr != BREAKPOINT_INSTRUCTION) {