[FR] Support for lua / nginx-lua profiling

[sharang]

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• [x] I had searched in the issues and found no similar feature requirement.

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[sharang]

1. 获得 lua 虚拟机结构体字段偏移量。不同版本可能有区别。

   参考代码：

   • deepflow/agent/crates/trace-utils/src/unwind/python.rs at a166226a6aa58669b88868c86ab2eca3571df7af ·

2. 在进程中寻找 lua 函数调用栈内存地址

   参考代码：

   • deepflow/agent/crates/trace-utils/src/unwind/python.rs at a166226a6aa58669b88868c86ab2eca3571df7af ·

3. 将 1 和 2 通过 bpf table 传给 ebpf 程序

   参考代码：

   • https://github.com/deepflowio/deepflow/blob/a166226a6aa58669b88868c86ab2eca3571df7af/agent/src/ebpf/user/unwind_tracer.c#L297

   相关函数：

   • unwind_process_exec：进程启动时添加 lua 所需记录
   • unwind_process_exit：进程退出时清理记录

4. ebpf 程序中进行栈回溯，获取 lua 栈（可能还有符号信息）并发送给用户程序

   参考代码：

   • 入口：https://github.com/deepflowio/deepflow/blob/a166226a6aa58669b88868c86ab2eca3571df7af/agent/src/ebpf/kernel/perf_profiler.bpf.c#L550
   • Python 回溯：deepflow/agent/src/ebpf/kernel/perf_profiler.bpf.c at a166226a6aa58669b88868c86ab2eca3571df7af · dee

5. 将栈中地址翻译成符号

   参考代码（intpstack 相关）：

   • https://github.com/deepflowio/deepflow/blob/57fd682018e120dbeb13927503fe0381496b84c6/agent/src/ebpf/user/profile/stringifier.c#L665

[sharang]

• @woodgear

[sharang]

@rvql

[rvql]

相关代码的位置可以参考这个提交 https://github.com/deepflowio/deepflow/commit/b7dec55ec627140edc62fc15aba5dbb1b558360c