| Message ID | 1513392177-10298-1-git-send-email-josef@toxicpanda.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | trace: reenable preemption if we modify the ip | expand |
On 12/16/2017 03:42 AM, Josef Bacik wrote: > From: Josef Bacik <jbacik@fb.com> > > Things got moved around between the original bpf_override_return patches > and the final version, and now the ftrace kprobe dispatcher assumes if > you modified the ip that you also enabled preemption. Make a comment of > this and enable preemption, this fixes the lockdep splat that happened > when using this feature. > > Signed-off-by: Josef Bacik <jbacik@fb.com> Applied to bpf-next with Fixes tag, thanks Josef.
On Fri, 15 Dec 2017 21:42:57 -0500 Josef Bacik <josef@toxicpanda.com> wrote: > From: Josef Bacik <jbacik@fb.com> > > Things got moved around between the original bpf_override_return patches > and the final version, and now the ftrace kprobe dispatcher assumes if > you modified the ip that you also enabled preemption. Make a comment of > this and enable preemption, this fixes the lockdep splat that happened > when using this feature. > > Signed-off-by: Josef Bacik <jbacik@fb.com> > --- > kernel/trace/trace_kprobe.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index 5db849809a56..91f4b57dab82 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -1322,8 +1322,15 @@ static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs) > if (tk->tp.flags & TP_FLAG_TRACE) > kprobe_trace_func(tk, regs); > #ifdef CONFIG_PERF_EVENTS > - if (tk->tp.flags & TP_FLAG_PROFILE) > + if (tk->tp.flags & TP_FLAG_PROFILE) { > ret = kprobe_perf_func(tk, regs); > + /* > + * The ftrace kprobe handler leaves it up to us to re-enable > + * preemption here before returning if we've modified the ip. > + */ > + if (ret) > + preempt_enable_no_resched(); Where is reset_current_kprobe()? Since kprobes still expects this modification is used by jprobes, we need to call it in caller-side. Thank you, > + } > #endif > return ret; > } > -- > 2.7.5 >
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 5db849809a56..91f4b57dab82 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -1322,8 +1322,15 @@ static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs) if (tk->tp.flags & TP_FLAG_TRACE) kprobe_trace_func(tk, regs); #ifdef CONFIG_PERF_EVENTS - if (tk->tp.flags & TP_FLAG_PROFILE) + if (tk->tp.flags & TP_FLAG_PROFILE) { ret = kprobe_perf_func(tk, regs); + /* + * The ftrace kprobe handler leaves it up to us to re-enable + * preemption here before returning if we've modified the ip. + */ + if (ret) + preempt_enable_no_resched(); + } #endif return ret; }