QEMU uftrace plugin

[p-b-o]

Hi,

I wanted to share that QEMU now has a uftrace plugin (see source here).
It tracks current function via frame pointer analysis and supports x64 and aarch64 architectures.

The plugin generates a binary trace compatible with uftrace (similar to uftrace record), and allows to trace execution, in both user and system modes. System mode execution is particularly useful, as you can see visually what's executed in your firmwares, bootloader, and kernel, all at once.

One thing I would like to add is a link to executed source code, embedded in perfetto trace. Depending on the quality of the result, I'll send a pull request to uftrace to add this to dump command.

As an example, this is a trace of stat and open syscalls from kernel perspective:

Many thanks to uftrace developers and @namhyung for making this freely available.
I can't imagine all the bugs I would have need to fix before being able to display anything out of this.

Regards,
Pierrick

[namhyung]

Awesome! Thanks for your contribution!

I'd be happy to review your PR. Please let me know if you have something to improve.

[p-b-o]

I'll probably add an option to uftrace dump taking the template as parameter (something like --src 'this.bin|https://url/{file}:{line}', but if you have a better idea, I would be happy to hear it.

[namhyung]

I prefer something general to be applied to other dump formats. And we also have --srcline option, can you reuse it?

[p-b-o]

That's a good idea. I took a look, it should be easy to generate a .dbg file with (absolute) locations of each symbol. From there, dump can be extended to support --srcline as well and report this, similar to replay command. Finally, I can use a simple sed on the final json to get urls to source online, without having to deal with that in uftrace.

[p-b-o]

I just noticed this has been implemented recently (81fe3b9), great!

[honggyukim]

Amazing! Thanks very much for your work! I'm not familiar with qemu plugin but I will try to use it when I have some time.

[p-b-o]

As a complement to this, and to ease navigating huge traces, I implemented a web viewer for it.
It uses pre-generated partial perfetto traces (1 second / trace), and link them to console output.
This allows to visualize any trace independently of their size.

https://once-upon-a-boot.github.io/

[namhyung]

Fantastic! I've played with it and really enjoyed it. Thanks for sharing the amazing work!!