I and other people in the University of Tokyo, where I research processor design, found TCG plugins are very useful for processor design exploration.
The feature we find missing is the capability to read registers from plugins. In this series, I propose to add such a capability by reusing gdbstub code. The reuse of gdbstub code ensures the long-term stability of the TCG plugin interface for register access without incurring a burden to maintain yet another interface for register access. This process to add TCG plugin involves four major changes. The first one is to add GDBFeature structure that represents a GDB feature, which usually includes registers. GDBFeature can be generated from static XML files or dynamically generated by architecture-specific code. In fact, this is a refactoring independent of the feature this series adds, and potentially it's benefitial even without the plugin feature. The plugin feature will utilize this new structure to describe registers exposed to plugins. The second one is to make gdb_read_register/gdb_write_register usable outside of gdbstub context. The third one is to actually make registers readable for plugins. The last one is to allow to implement a QEMU plugin in C++. A plugin that I'll describe later is written in C++. The below is a summary of patches: Patch 01 fixes a bug in execlog plugin. Patch [02, 13] introduces GDBFeature. Patch [14, 17] adds information useful for plugins to GDBFeature. Patch [18, 20] makes registers readable outside of gdbstub context. Patch [21, 23] adds the feature to read registers from plugins. Patch [24, 25] makes it possible to write plugins in C++. The execlog plugin will have new options to demonstrate the new feature. I also have a plugin that uses this new feature to generate execution traces for Sniper processor simulator, which is available at: https://github.com/shioya-lab/sniper/tree/akihikodaki/bb V2 -> V3: Added patch "hw/core/cpu: Return static value with gdb_arch_name()" Added patch "gdbstub: Dynamically allocate target.xml buffer" (Alex Bennée) Added patch "gdbstub: Introduce GDBFeatureBuilder" (Alex Bennée) Dropped Reviewed-by tags for "target/*: Use GDBFeature for dynamic XML" Changed gdb_find_static_feature() to abort on failure (Alex Bennée) Changed the execlog plugin to log the register value only when changed (Alex Bennée) Dropped 0x prefixes for register value logs for conciseness V1 -> V2: Added SPDX-License-Identifier: GPL-2.0-or-later (Philippe Mathieu-Daudé) Split long lines. (Philippe Mathieu-Daudé) Renamed gdb_features to gdb_static_features (Philippe Mathieu-Daudé) Dropped RFC. Akihiko Odaki (25): contrib/plugins: Use GRWLock in execlog gdbstub: Introduce GDBFeature structure gdbstub: Add num_regs member to GDBFeature gdbstub: Introduce gdb_find_static_feature() target/arm: Move the reference to arm-core.xml hw/core/cpu: Replace gdb_core_xml_file with gdb_core_feature gdbstub: Introduce GDBFeatureBuilder target/arm: Use GDBFeature for dynamic XML target/ppc: Use GDBFeature for dynamic XML target/riscv: Use GDBFeature for dynamic XML gdbstub: Use GDBFeature for gdb_register_coprocessor gdbstub: Use GDBFeature for GDBRegisterState hw/core/cpu: Return static value with gdb_arch_name() gdbstub: Dynamically allocate target.xml buffer gdbstub: Simplify XML lookup hw/core/cpu: Remove gdb_get_dynamic_xml member gdbstub: Add members to identify registers to GDBFeature hw/core/cpu: Add a parameter to gdb_read_register/gdb_write_register gdbstub: Hide gdb_has_xml gdbstub: Expose functions to read registers cpu: Call plugin hooks only when ready plugins: Allow to read registers contrib/plugins: Allow to log registers plugins: Support C++ contrib/plugins: Add cc plugin MAINTAINERS | 2 +- docs/devel/tcg-plugins.rst | 18 ++- configure | 15 ++- meson.build | 2 +- gdbstub/internals.h | 10 +- include/exec/gdbstub.h | 51 +++++++-- include/hw/core/cpu.h | 17 ++- include/qemu/qemu-plugin.h | 69 +++++++++++- target/alpha/cpu.h | 6 +- target/arm/cpu.h | 37 +++---- target/arm/internals.h | 2 +- target/avr/cpu.h | 6 +- target/cris/cpu.h | 9 +- target/hexagon/internal.h | 6 +- target/hppa/cpu.h | 6 +- target/i386/cpu.h | 6 +- target/loongarch/internals.h | 6 +- target/m68k/cpu.h | 6 +- target/microblaze/cpu.h | 6 +- target/mips/internal.h | 6 +- target/openrisc/cpu.h | 6 +- target/ppc/cpu-qom.h | 3 +- target/ppc/cpu.h | 15 ++- target/ppc/internal.h | 2 +- target/riscv/cpu.h | 10 +- target/rx/cpu.h | 6 +- target/s390x/cpu.h | 2 - target/s390x/s390x-internal.h | 6 +- target/sh4/cpu.h | 6 +- target/sparc/cpu.h | 6 +- target/tricore/cpu.h | 6 +- target/xtensa/cpu.h | 6 +- contrib/plugins/execlog.c | 150 +++++++++++++++++++------ cpu.c | 11 -- gdbstub/gdbstub.c | 203 ++++++++++++++++++++++++---------- gdbstub/softmmu.c | 2 +- hw/core/cpu-common.c | 16 ++- plugins/api.c | 40 +++++++ stubs/gdbstub.c | 6 +- target/alpha/gdbstub.c | 6 +- target/arm/cpu.c | 12 +- target/arm/cpu64.c | 8 +- target/arm/gdbstub.c | 184 +++++++++++++----------------- target/arm/gdbstub64.c | 96 +++++++--------- target/arm/tcg/cpu32.c | 3 +- target/avr/cpu.c | 4 +- target/avr/gdbstub.c | 6 +- target/cris/gdbstub.c | 9 +- target/hexagon/cpu.c | 5 +- target/hexagon/gdbstub.c | 6 +- target/hppa/gdbstub.c | 6 +- target/i386/cpu.c | 13 +-- target/i386/gdbstub.c | 10 +- target/loongarch/cpu.c | 8 +- target/loongarch/gdbstub.c | 8 +- target/m68k/cpu.c | 7 +- target/m68k/gdbstub.c | 6 +- target/m68k/helper.c | 6 +- target/microblaze/cpu.c | 9 +- target/microblaze/gdbstub.c | 6 +- target/mips/gdbstub.c | 6 +- target/nios2/cpu.c | 6 +- target/openrisc/gdbstub.c | 6 +- target/ppc/cpu_init.c | 9 +- target/ppc/gdbstub.c | 90 ++++++--------- target/riscv/cpu.c | 27 ++--- target/riscv/gdbstub.c | 95 +++++++--------- target/rx/cpu.c | 4 +- target/rx/gdbstub.c | 6 +- target/s390x/cpu.c | 8 +- target/s390x/gdbstub.c | 34 ++---- target/sh4/gdbstub.c | 6 +- target/sparc/gdbstub.c | 6 +- target/tricore/cpu.c | 4 +- target/tricore/gdbstub.c | 6 +- target/xtensa/gdbstub.c | 6 +- contrib/plugins/Makefile | 5 + contrib/plugins/cc.cc | 17 +++ plugins/qemu-plugins.symbols | 2 + scripts/feature_to_c.py | 102 +++++++++++++++++ scripts/feature_to_c.sh | 69 ------------ tests/tcg/Makefile.target | 3 + 82 files changed, 1045 insertions(+), 678 deletions(-) create mode 100644 contrib/plugins/cc.cc create mode 100755 scripts/feature_to_c.py delete mode 100644 scripts/feature_to_c.sh -- 2.41.0
