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: 9802d86585
("bpf: add a bpf_override_function helper")
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
parent
4a29c0db69
commit
46df3d209d
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@ -1322,8 +1322,15 @@ static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs)
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if (tk->tp.flags & TP_FLAG_TRACE)
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kprobe_trace_func(tk, regs);
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#ifdef CONFIG_PERF_EVENTS
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if (tk->tp.flags & TP_FLAG_PROFILE)
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if (tk->tp.flags & TP_FLAG_PROFILE) {
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ret = kprobe_perf_func(tk, regs);
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/*
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* The ftrace kprobe handler leaves it up to us to re-enable
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* preemption here before returning if we've modified the ip.
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*/
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if (ret)
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preempt_enable_no_resched();
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}
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#endif
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return ret;
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}
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