On Tue, 17 Oct 2017 13:48:34 +0530
"Naveen N. Rao" <naveen.n....@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 <mhira...@kernel.org>
I'll update the document too.
Thanks,
>
> Reported-by: Michael Ellerman <m...@ellerman.id.au>
> Signed-off-by: Naveen N. Rao <naveen.n....@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 <mhira...@kernel.org>
