Consider using TCG plugins

[XVilka]

The support for tracing with TCG plugin has expanded greatly since this project was started:

• https://www.qemu.org/docs/master/devel/tcg-plugins.html
• https://gitlab.com/qemu-project/qemu/-/tree/master/contrib/plugins

See, for example, https://gitlab.com/qemu-project/qemu/-/blob/master/contrib/plugins/execlog.c

Switching to the plugins system would alleviate the need of hard work rebasing it for supporting newer QEMU versions.
It's one of the problems that PANDA struggles with:

• Move to TCG-Plugin based model panda-re/panda#1383
• Update to modern QEMU! panda-re/panda#570 (comment)
• https://lore.kernel.org/qemu-devel/20221213213757.4123265-1-fasano@mit.edu/

[XVilka]

Blocked by:

• QEMU GitLab: Allow TCG plugins to receive registers' value
• QEMU GitLab: Allow TCG plugins to get memory value

[XVilka]

There is now patch series in QEMU targeting the registers access: https://lore.kernel.org/qemu-devel/20230816145155.21049-1-akihiko.odaki@daynix.com/T/#md4f5cc5eecdd2cb5b0672d760dc811c32aa68ba3

cc @akihikodaki

[XVilka]

https://lore.kernel.org/qemu-devel/20240706191335.878142-1-pierrick.bouvier@linaro.org/ should close the last missing piece of the puzzle - the memory contents API for TCG plugins.

[XVilka]

Ok, now both APIs are merged - registers and memory. Finally it could be migrated to the TCG-plugin based tracing, without modifying the QEMU itself:

• https://gitlab.com/qemu-project/qemu/-/blob/master/contrib/plugins/execlog.c?ref_type=heads
• https://gitlab.com/qemu-project/qemu/-/blob/master/tests/tcg/plugins/mem.c?ref_type=heads
• https://gitlab.com/qemu-project/qemu/-/blob/master/tests/tcg/plugins/syscall.c?ref_type=heads

cc @wargio @DMaroo @Rot127

[Rot127]

Let's wait until the next release of QEMU.

[XVilka]

Let's wait until the next release of QEMU.

It's out: https://wiki.qemu.org/ChangeLog/9.2