libbpf: Add support for dynamic tracepoints #8350
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Dynamic tracepoints can be created using debugfs, perf or similar tools.
For example:
$ perf probe -a 'tcp_listendrop sk'
This command creates a new tracepoint under debugfs:
$ ls /sys/kernel/debug/tracing/events/probe/tcp_listendrop/
enable filter format hist id trigger
Notably, the probed function tcp_listendrop() is an inlined kernel function.
Although this dynamic tracepoint appears as a tracepoint, it is internally
implemented as a kprobe. Therefore, if we want to attach a bpf prog to
it, the bpf prog must be loaded as a kprobe prog.
The primary motivation for adding support for dynamic tracepoints is to
simplify tracing of inlined kernel functions using BPF tools, such as
bpftrace. By leveraging tools like perf, users can create a dynamic
tracepoint for an inlined kernel function and then attach a BPF program to
it.
To achieve this, a new section, SEC("kprobe/SUBSYSTEM/PROBE"), has been
introduced.
Suggested-by: Jiri Olsa <[email protected]>
Signed-off-by: Yafang Shao <[email protected]>
Cc: Daniel Xu <[email protected]>
The result is as follows, $ tools/testing/selftests/bpf/test_progs --name=dynamic_tp #85 dynamic_tp:OK Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Yafang Shao <[email protected]>
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Upstream branch: be339dd |
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=924589 expired. Closing PR. |
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Pull request for series with
subject: libbpf: Add support for dynamic tracepoints
version: 2
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=924589