diff options
| author | Josef Bacik <jbacik@fb.com> | 2017-12-15 21:42:57 -0500 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2017-12-17 20:47:32 +0100 |
| commit | 46df3d209db080395a98fc0875bd05e45e8f44e0 (patch) | |
| tree | f9a0fcd0e875ddaa5bf6317a2937d568e8417d07 /kernel/trace | |
| parent | 4a29c0db69e58b20cd7a2efce997627c6b376244 (diff) | |
| download | lwn-46df3d209db080395a98fc0875bd05e45e8f44e0.tar.gz lwn-46df3d209db080395a98fc0875bd05e45e8f44e0.zip | |
trace: reenable preemption if we modify the ip
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.
Fixes: 9802d86585db ("bpf: add a bpf_override_function helper")
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace_kprobe.c | 9 |
1 files changed, 8 insertions, 1 deletions
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; } |