This series adds Linux RISC-V trace support via the generic hardware trace (gtrace) framework [1]. The RISC-V trace encoder, funnel, ATB bridge, and timestamp components are implemented as gtrace components, and the CoreSight funnel and TMC (ETB/ETF/ETR) are likewise re-implemented as gtrace components so that they can be composed with the RISC-V components into a single trace path.
This work supersedes the earlier CoreSight-based RFC [2]. Instead of forcing the RISC-V trace IP to conform to the CoreSight device, this series shifts the topology onto the gtrace framework to achieve cleaner architectural decoupling and shared data paths.
The series includes:
- gtrace sysfs support, exposing per-component attributes (control, features, and timestamp) for configuration and validation - gtrace component drivers for the RISC-V trace encoder, funnel, ATB bridge, and timestamp components - gtrace component drivers for the CoreSight dynamic funnel and TMC (ETB/ETF/ETR), built on top of the CoreSight platform core APIs (CLAIM/device registration) re-implemented as gtrace components - perf PMU support: gtrace event format attributes, per-event configuration parsing, and an AUX flag marking CoreSight-formatted trace data - perf tooling: a Nexus (N-Trace) decoder and a gtrace AUX decoder that synthesizes branch samples, including machine-mode instruction access
Verification on K3 SoC: The device tree follows [1], with only the compatible properties changed for the gtrace components.
# perf list pmu gtrace// [Kernel PMU event]
# perf record -e gtrace// --per-thread uname [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 1.946 MB perf.data ]
# perf script uname 767863 1 branches: ffffffff80d18b04 gtrace_poll_bit+0x34 ([kernel.kallsyms]) => ffffffff80d18b12 gtrace_poll_bit+0x42 ([kernel.kallsyms]) uname 767863 1 branches: ffffffff80d18b4e gtrace_poll_bit+0x7e ([kernel.kallsyms]) => ffffffff80d18b6c gtrace_poll_bit+0x9c ([kernel.kallsyms]) uname 767863 1 branches: ffffffff80d1c17a rvtrace_encoder_start+0x112 ([kernel.kallsyms]) => ffffffff80d1c196 rvtrace_encoder_start+0x12e ([kernel.kallsyms]) uname 767863 1 branches: ffffffff80d18782 gtrace_path_start+0xbe ([kernel.kallsyms]) => ffffffff80d18702 gtrace_path_start+0x3e ([kernel.kallsyms]) uname 767863 1 branches: ffffffff80d18712 gtrace_path_start+0x4e ([kernel.kallsyms]) => ffffffff80d18724 gtrace_path_start+0x60 ([kernel.kallsyms]) ...
In per-cpu mode, correlating trace data with the running task requires the encoder to emit a context ID. This depends on writing the task PID to the RISC-V scontext CSR on context switch [3].
[1] https://lore.kernel.org/all/20260810152223.3946743-1-mayuresh.chitale@oss.qu... [2] https://lore.kernel.org/all/20260414034153.3272485-1-liangzhen@linux.spacemi... [3] https://lore.kernel.org/all/20240329-dev-maxh-lin-452-6-9-v1-0-1534f93b94a7@...
Zane Leung (24): gtrace: Move connection release into component unregister gtrace: Initial implementation of gtrace sysfs framework gtrace: Drop trace format field and helper function gtrace: Add RISC-V trace encoder sysfs support gtrace: Introduce some PMU format attributes gtrace: Replace owner PID with perf_event pointer in gtrace_path gtrace: Parse RISC-V Trace encoder config from perf event gtrace: add perf symlink support for gtrace components gtrace: Add port-level start/stop driver callbacks gtrace: Add RISC-V trace funnel driver gtrace: Add RISC-V trace timestamp support gtrace: Add RISC-V trace ATB bridge driver gtrace: Add CoreSight platform core APIs gtrace: Add CoreSight funnel driver gtrace: Only copy AUX data from the path sink perf: Flag whether gtrace AUX data carries CoreSight framing gtrace: Unify default sink selection across CPUs in perf setup gtrace: Add sink-specific buffer alloc/free callbacks gtrace: Add setup_sysfs_buf callback to setup sysfs sink buffer gtrace: Add CoreSight TMC driver support perf tools: riscv: making gtrace PMU listable perf tools: Add Nexus RISC-V Trace decoder perf tools: gtrace: Record and parse trace encoder metadata perf tools: gtrace: Add AUX trace decoder and branch sample synthesis
.../hwtracing/coresight/coresight-tmc-etf.c | 1 - drivers/hwtracing/gtrace/Kconfig | 70 + drivers/hwtracing/gtrace/Makefile | 12 +- drivers/hwtracing/gtrace/coresight-funnel.c | 430 ++++ drivers/hwtracing/gtrace/coresight-platform.c | 279 +++ drivers/hwtracing/gtrace/coresight-tmc-core.c | 1111 ++++++++++ drivers/hwtracing/gtrace/coresight-tmc-etf.c | 573 +++++ drivers/hwtracing/gtrace/coresight-tmc-etr.c | 1888 +++++++++++++++++ drivers/hwtracing/gtrace/coresight-tmc.h | 469 ++++ drivers/hwtracing/gtrace/coresight.h | 212 ++ drivers/hwtracing/gtrace/gtrace-core.c | 165 +- drivers/hwtracing/gtrace/gtrace-perf.c | 122 +- drivers/hwtracing/gtrace/gtrace-sysfs.c | 452 ++++ drivers/hwtracing/gtrace/rvtrace-atbbridge.c | 153 ++ ...trace-encoder.c => rvtrace-encoder-core.c} | 182 +- .../hwtracing/gtrace/rvtrace-encoder-sysfs.c | 323 +++ drivers/hwtracing/gtrace/rvtrace-encoder.h | 61 + drivers/hwtracing/gtrace/rvtrace-funnel.c | 220 ++ drivers/hwtracing/gtrace/rvtrace-funnel.h | 29 + drivers/hwtracing/gtrace/rvtrace-platform.c | 26 +- drivers/hwtracing/gtrace/rvtrace-ramsink.c | 11 +- drivers/hwtracing/gtrace/rvtrace-timestamp.c | 336 +++ drivers/hwtracing/gtrace/rvtrace-timestamp.h | 44 + drivers/hwtracing/gtrace/rvtrace.h | 5 + include/linux/gtrace.h | 161 +- include/uapi/linux/perf_event.h | 1 + tools/arch/riscv/include/asm/insn.h | 645 ++++++ tools/include/uapi/linux/perf_event.h | 1 + tools/perf/arch/riscv/util/Build | 1 + tools/perf/arch/riscv/util/auxtrace.c | 203 +- tools/perf/arch/riscv/util/pmu.c | 19 + tools/perf/builtin-script.c | 4 + tools/perf/util/Build | 1 + tools/perf/util/gtrace-decoder.c | 1283 ++++++++++- tools/perf/util/gtrace.h | 30 +- tools/perf/util/rvtrace-decoder/Build | 2 + .../util/rvtrace-decoder/rvtrace-decoder.c | 423 ++++ .../util/rvtrace-decoder/rvtrace-decoder.h | 122 ++ .../rvtrace-decoder/rvtrace-ntrace-decoder.c | 910 ++++++++ .../rvtrace-decoder/rvtrace-ntrace-decoder.h | 124 ++ tools/perf/util/symbol_conf.h | 2 + 41 files changed, 10926 insertions(+), 180 deletions(-) create mode 100644 drivers/hwtracing/gtrace/coresight-funnel.c create mode 100644 drivers/hwtracing/gtrace/coresight-platform.c create mode 100644 drivers/hwtracing/gtrace/coresight-tmc-core.c create mode 100644 drivers/hwtracing/gtrace/coresight-tmc-etf.c create mode 100644 drivers/hwtracing/gtrace/coresight-tmc-etr.c create mode 100644 drivers/hwtracing/gtrace/coresight-tmc.h create mode 100644 drivers/hwtracing/gtrace/coresight.h create mode 100644 drivers/hwtracing/gtrace/gtrace-sysfs.c create mode 100644 drivers/hwtracing/gtrace/rvtrace-atbbridge.c rename drivers/hwtracing/gtrace/{rvtrace-encoder.c => rvtrace-encoder-core.c} (55%) create mode 100644 drivers/hwtracing/gtrace/rvtrace-encoder-sysfs.c create mode 100644 drivers/hwtracing/gtrace/rvtrace-encoder.h create mode 100644 drivers/hwtracing/gtrace/rvtrace-funnel.c create mode 100644 drivers/hwtracing/gtrace/rvtrace-funnel.h create mode 100644 drivers/hwtracing/gtrace/rvtrace-timestamp.c create mode 100644 drivers/hwtracing/gtrace/rvtrace-timestamp.h create mode 100644 tools/arch/riscv/include/asm/insn.h create mode 100644 tools/perf/arch/riscv/util/pmu.c create mode 100644 tools/perf/util/rvtrace-decoder/Build create mode 100644 tools/perf/util/rvtrace-decoder/rvtrace-decoder.c create mode 100644 tools/perf/util/rvtrace-decoder/rvtrace-decoder.h create mode 100644 tools/perf/util/rvtrace-decoder/rvtrace-ntrace-decoder.c create mode 100644 tools/perf/util/rvtrace-decoder/rvtrace-ntrace-decoder.h