On Tue, 14 Feb 2017 10:01:43 +0000
"Jon Medhurst (Tixy)" <t...@linaro.org> wrote:
> On Tue, 2017-02-14 at 00:03 +0900, Masami Hiramatsu wrote:
> > This is arm port of commit 6a5022a56ac3 ("kprobes/x86: Allow to
> > handle reentered kprobe on single-stepping")
> >
> > Since the FIQ handlers can interrupt in the single stepping
> > (or preparing the single stepping, do_debug etc.), we should
> > consider a kprobe is hit in the NMI handler. Even in that
> > case, the kprobe is allowed to be reentered as same as the
> > kprobes hit in kprobe handlers
> > (KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE).
> >
> > The real issue will happen when a kprobe hit while another
>
> Could to with 'is' being inserted above ^^^
> (I know this is a copy of the x86 commit message)
Ah! yes, it should be corrected.
>
> > reentered kprobe is processing (KPROBE_REENTER), because
> > we already consumed a saved-area for the previous kprobe.
> >
> > Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
> > ---
>
> Acked-by: Jon Medhurst <t...@linaro.org>
Thank you!
>
> > arch/arm/probes/kprobes/core.c | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c
> > index a4ec240..264fedb 100644
> > --- a/arch/arm/probes/kprobes/core.c
> > +++ b/arch/arm/probes/kprobes/core.c
> > @@ -270,6 +270,7 @@ void __kprobes kprobe_handler(struct pt_regs *regs)
> > switch (kcb->kprobe_status) {
> > case KPROBE_HIT_ACTIVE:
> > case KPROBE_HIT_SSDONE:
> > + case KPROBE_HIT_SS:
> > /* A pre- or post-handler probe got us here. */
> > kprobes_inc_nmissed_count(p);
> > save_previous_kprobe(kcb);
> > @@ -278,6 +279,11 @@ void __kprobes kprobe_handler(struct pt_regs *regs)
> > singlestep(p, regs, kcb);
> > restore_previous_kprobe(kcb);
> > break;
> > + case KPROBE_REENTER:
> > + /* A nested probe was hit in FIQ, it is a BUG */
> > + pr_warn("Unrecoverable kprobe detected at
> > %p.\n",
> > + p->addr);
> > + /* fall through */
> > default:
> > /* impossible cases */
> > BUG();
> >
--
Masami Hiramatsu <mhira...@kernel.org>
