This plugin generates a binary trace compatible with the excellent uftrace: https://github.com/namhyung/uftrace
In short, it tracks all function calls performed during execution, based on frame pointer analysis. A big advantage over "uftrace record" is that it works in system mode, allowing to trace a full system execution, which was the original goal. It works as well in user mode, but uftrace itself already does this. It's implemented for aarch64 only (with the intent to add x86_64 later). Let's start with concrete examples of the result. First, in system mode, booting a stack using TF-A + U-boot + Linux: - Two first stages of boot sequence in Arm Trusted Firmware (EL3 and S-EL1) https://fileserver.linaro.org/s/kkxBS552W7nYESX/preview - Stat and open syscalls in kernel https://fileserver.linaro.org/s/dXe4MfraKg2F476/preview - Poweroff sequence (from kernel back to firmware, NS-EL2 to EL3) https://fileserver.linaro.org/s/oR2PtyGKJrqnfRf/preview Full trace is available here: https://fileserver.linaro.org/s/WsemLboPEzo24nw/download/aarch64_boot.json.gz You can download and open it on https://ui.perfetto.dev/ to explore it. Second, in user mode, tracing qemu-aarch64 (itself) running git --help: - Loading program and its interpreter https://fileserver.linaro.org/s/fie8JgX76yyL5cq/preview - TB creation https://fileserver.linaro.org/s/GXY6NKMw5EeRCew/preview Full trace is available here: https://fileserver.linaro.org/s/N8X8fnZ5yGRZLsT/download/qemu_aarch64_git_help.json.gz If you had curiosity and now you're ready to give some attention, most of the details you want to read are included in the documentation patch (final one). Overhead is around x2 (sampling only) to x10-x15 (precise), and long traces can be directly filtered with uftrace if needed. The series is splitted in: - implementing the plugin - adding useful options (especially sampling and privilege level tracing) - add a companion script to symbolize traces generated - add documentation with examples I hope this plugin can help people trying to understand what happens out of the user space, and get a better grasp of how firmwares, bootloader, and kernel interact behind the curtain. v2 -- - trace active stacks on exit - do not erase map generated in system_emulation - add documentation to generate restricted visual traces around specific events of execution v3 -- - fix missing include unistd.h (build failed on MacOS only) Pierrick Bouvier (6): contrib/plugins/uftrace: new uftrace plugin contrib/plugins/uftrace: add trace-sample option contrib/plugins/uftrace: add trace-privilege-level option contrib/plugins/uftrace: add timestamp-based-on-real-time option contrib/plugins/uftrace_symbols.py contrib/plugins/uftrace: add documentation docs/about/emulation.rst | 207 +++++++ contrib/plugins/uftrace.c | 920 +++++++++++++++++++++++++++++ contrib/plugins/meson.build | 3 +- contrib/plugins/uftrace_symbols.py | 152 +++++ 4 files changed, 1281 insertions(+), 1 deletion(-) create mode 100644 contrib/plugins/uftrace.c create mode 100755 contrib/plugins/uftrace_symbols.py -- 2.47.2
