Messages in this thread | | | Date | Fri, 20 Oct 2017 06:38:12 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH] Revert "kprobes: Warn if optprobe handler tries to change execution path" |
| |
On Tue, 17 Oct 2017 13:48:34 +0530 "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:
> This reverts commit e863d539614641 ("kprobes: Warn if optprobe handler > tries to change execution path"). > > On powerpc, we place a probe at kretprobe_trampoline to catch function > returns and with CONFIG_OPTPROBES, this probe gets optimized. This > works for us due to the way we handle the optprobe as described in > commit 762df10bad6954 ("powerpc/kprobes: Optimize kprobe > in kretprobe_trampoline()"). With the above commit, we end up with a > warning. As such, revert this change.
OK, so for ppc, optprobe can handle nip change.
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
I'll update the document too.
Thanks,
> > Reported-by: Michael Ellerman <mpe@ellerman.id.au> > Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> > --- > Discussion here: > https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1510995.html > > kernel/kprobes.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 2d28377a0e32..15fba7fe57c8 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -387,10 +387,7 @@ void opt_pre_handler(struct kprobe *p, struct pt_regs *regs) > list_for_each_entry_rcu(kp, &p->list, list) { > if (kp->pre_handler && likely(!kprobe_disabled(kp))) { > set_kprobe_instance(kp); > - if (kp->pre_handler(kp, regs)) { > - if (WARN_ON_ONCE(1)) > - pr_err("Optprobe ignores instruction pointer changing.(%pF)\n", p->addr); > - } > + kp->pre_handler(kp, regs); > } > reset_kprobe_instance(); > } > -- > 2.14.2 >
-- Masami Hiramatsu <mhiramat@kernel.org>
| |