[RFC PATCH 00/12] Add Linux RISC-V trace support via CoreSight

14 Apr 2026


      From: liangzhen zhen.liang@spacemit.com
This series adds Linux RISC-V trace support via CoreSight, implementing RISC-V
trace drivers within the CoreSight framework and integrating them with perf tools.
The K3 SoC contains RISC-V Encoder, Funnel, ATB, CoreSight Funnel, and CoreSight TMC
components, which can be directly leveraged through the existing CoreSight infrastructure.
Linux RISC-V trace support form Anup Patel:
(https://patchwork.kernel.org/project/linux-riscv/cover/20260225062448.402794...)
which currently lacks ATB component support and guidance on reusing CoreSight components.
The series includes:
- RISC-V trace driver implementation within the CoreSight framework
- RISC-V Trace Encoder, Funnel, and ATB Bridge drivers as CoreSight devices
- RISC-V trace PMU record capabilities and parsing events in perf.
- RISC-V Nexus Trace decoder for perf tools
Any comments or suggestions are welcome.
Verification on K3 SoC:
To verify this patch series on K3 hardware, the following device tree are required:
1. RISC-V Trace Encoder node (8)
2. RISC-V ATB Bridge node (8)
3. RISC-V Trace Funnel node (2)
3. CoreSight Funnel configuration for RISC-V (1)
4. CoreSight TMC configuration for trace buffer (1)
/{
        dummy_clk: apb-pclk {
                compatible = "fixed-clock";
                #clock-cells = <0x0>;
                clock-output-names = "clk14mhz";
                clock-frequency = <14000000>;
        };
soc: soc {
                #address-cells = <2>;
                #size-cells = <2>;
encoder0: encoder@d9002000 {
                        compatible = "riscv,trace-encoder";
                        reg = <0x0 0xd9002000 0x0 0x1000>;
                        cpus = <&cpu_0>;
                        out-ports {
                                port {
                                        cluster0_encoder0_out_port: endpoint {
                                                remote-endpoint = <&cluster0_bridge0_in_port>;
                                        };
                                };
                        };
                };
bridge0: bridge@d9003000 {
                        compatible = "riscv,trace-atbbridge";
                        reg = <0x0 0xd9003000 0x0 0x1000>;
                        cpus = <&cpu_0>;
                        out-ports {
                                port {
                                        cluster0_bridge0_out_port: endpoint {
                                                remote-endpoint = <&cluster0_funnel_in_port0>;
                                        };
                                };
                        };
                        in-ports {
                                port {
                                        cluster0_bridge0_in_port: endpoint {
                                                remote-endpoint = <&cluster0_encoder0_out_port>;
                                        };
                                };
                        };
                };
...
cluster0_funnel: funnel@d9000000 {
                        compatible = "riscv,trace-funnel";
                        reg = <0x0 0xd9000000 0x0 0x1000>;
                        cpus = <&cpu_0>, <&cpu_1>, <&cpu_2>, <&cpu_3>;
                        riscv,timestamp-present;
                        out-ports {
                                port {
                                        cluster0_funnel_out_port: endpoint {
                                                remote-endpoint = <&main_funnel_in_port0>;
                                        };
                                };
                        };
                        in-ports {
                                #address-cells = <1>;
                                #size-cells = <0>;
port@0 {
                                        reg = <0>;
                                        cluster0_funnel_in_port0: endpoint {
                                                remote-endpoint = <&cluster0_bridge0_out_port>;
                                        };
                                };
port@1 {
                                        reg = <1>;
                                        cluster0_funnel_in_port1: endpoint {
                                                remote-endpoint = <&cluster0_bridge1_out_port>;
                                        };
                                };
port@2 {
                                        reg = <2>;
                                        cluster0_funnel_in_port2: endpoint {
                                                remote-endpoint = <&cluster0_bridge2_out_port>;
                                        };
                                };
port@3 {
                                        reg = <3>;
                                        cluster0_funnel_in_port3: endpoint {
                                                remote-endpoint = <&cluster0_bridge3_out_port>;
                                        };
                                };
                        };
                };
cluster1_funnel: funnel@d9010000 {
                        compatible = "riscv,trace-funnel";
                        reg = <0x0 0xd9010000 0x0 0x1000>;
                        cpus = <&cpu_4>, <&cpu_5>, <&cpu_6>, <&cpu_7>;
                        riscv,timestamp-present;
                        out-ports {
                                port {
                                        cluster1_funnel_out_port: endpoint {
                                                remote-endpoint = <&main_funnel_in_port1>;
                                        };
                                };
                        };
                        in-ports {
                                #address-cells = <1>;
                                #size-cells = <0>;
port@0 {
                                        reg = <0>;
                                        cluster1_funnel_in_port0: endpoint {
                                                remote-endpoint = <&cluster1_bridge0_out_port>;
                                        };
                                };
port@1 {
                                        reg = <1>;
                                        cluster1_funnel_in_port1: endpoint {
                                                remote-endpoint = <&cluster1_bridge1_out_port>;
                                        };
                                };
port@2 {
                                        reg = <2>;
                                        cluster1_funnel_in_port2: endpoint {
                                                remote-endpoint = <&cluster1_bridge2_out_port>;
                                        };
                                };
port@3 {
                                        reg = <3>;
                                        cluster1_funnel_in_port3: endpoint {
                                                remote-endpoint = <&cluster1_bridge3_out_port>;
                                        };
                                };
                        };
                };
main_funnel: funnel@d9042000 {
                        compatible = "arm,coresight-dynamic-funnel", "arm,primecell";
                        reg = <0x0 0xd9042000 0x0 0x1000>;
                        clocks = <&dummy_clk>;
                        clock-names = "apb_pclk";
                        out-ports {
                                port {
                                        main_funnel_out_port: endpoint {
                                                remote-endpoint = <&etf_in_port>;
                                        };
                                };
                        };
                        in-ports {
                                #address-cells = <1>;
                                #size-cells = <0>;
port@0 {
                                        reg = <0>;
                                        main_funnel_in_port0: endpoint {
                                                remote-endpoint = <&cluster0_funnel_out_port>;
                                        };
                                };
port@1 {
                                        reg = <1>;
                                        main_funnel_in_port1: endpoint {
                                                remote-endpoint = <&cluster1_funnel_out_port>;
                                        };
                                };
                        };
                };
etf: etf@d9043000 {
                        compatible = "arm,coresight-tmc", "arm,primecell";
                        reg = <0x0 0xd9043000 0x0 0x1000>;
                        clocks = <&dummy_clk>;
                        clock-names = "apb_pclk";
                        out-ports {
                                port {
                                        etf_out_port: endpoint {
                                                remote-endpoint = <&etr_in_port>;
                                        };
                                };
                        };
                        in-ports {
                                port {
                                        etf_in_port: endpoint {
                                                remote-endpoint = <&main_funnel_out_port>;
                                        };
                                };
                        };
                };
etr: etr@d9044000 {
                        compatible = "arm,coresight-tmc", "arm,primecell";
                        reg = <0x0 0xd9044000 0x0 0x1000>;
                        clocks = <&dummy_clk>;
                        clock-names = "apb_pclk";
                        arm,scatter-gather;
                        in-ports {
                                port {
                                        etr_in_port: endpoint {
                                                remote-endpoint = <&etf_out_port>;
                                        };
                                };
                        };
                };
        };
};
Verification case:
~ # perf list pmu
  rvtrace//                                          [Kernel PMU event]
~ # perf record -e rvtrace/@tmc_etr0/ --per-thread uname
Linux
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.191 MB perf.data ]
~ # perf script
           uname     137 [003]          1           branches:  ffffffff80931470 rvtrace_poll_bit+0x38 ([kernel.kallsyms]) => ffffffff80931492 rvtrace_poll_bit+0x5a ([kernel.kallsyms])
           uname     137 [003]          1           branches:  ffffffff809328a6 encoder_enable_hw+0x252 ([kernel.kallsyms]) => ffffffff809328ba encoder_enable_hw+0x266 ([kernel.kallsyms])
           uname     137 [003]          1           branches:  ffffffff80932c4a encoder_enable+0x82 ([kernel.kallsyms]) => ffffffff80932c36 encoder_enable+0x6e ([kernel.kallsyms])
           uname     137 [003]          1           branches:  ffffffff80928198 etm_event_start+0xf0 ([kernel.kallsyms]) => ffffffff809281aa etm_event_start+0x102 ([kernel.kallsyms])
           uname     137 [003]          1           branches:  ffffffff809281e6 etm_event_start+0x13e ([kernel.kallsyms]) => ffffffff8092755e coresight_get_sink_id+0x16 ([kernel.kallsyms])
           uname     137 [003]          1           branches:  ffffffff8092820e etm_event_start+0x166 ([kernel.kallsyms]) => ffffffff80928226 etm_event_start+0x17e ([kernel.kallsyms])
           uname     137 [003]          1           branches:  ffffffff801c3bb4 perf_report_aux_output_id+0x0 ([kernel.kallsyms]) => ffffffff801c3bd6 perf_report_aux_output_id+0x22 ([kernel.kallsyms])
           uname     137 [003]          1           branches:  ffffffff801c3c5a perf_report_aux_output_id+0xa6 ([kernel.kallsyms]) => ffffffff801c3bf0 perf_report_aux_output_id+0x3c ([kernel.kallsyms])
           uname     137 [003]          1           branches:  ffffffff801c3c40 perf_report_aux_output_id+0x8c ([kernel.kallsyms]) => ffffffff801c3aea __perf_event_header__init_id+0x2a ([kernel.kallsyms])
           uname     137 [003]          1           branches:  ffffffff801c3b42 __perf_event_header__init_id+0x82 ([kernel.kallsyms]) => ffffffff801c3b4a __perf_event_header__init_id+0x8a ([kernel.kallsyms])
           uname     137 [003]          1           branches:  ffffffff801c3bb0 __perf_event_header__init_id+0xf0 ([kernel.kallsyms]) => ffffffff801c3b58 __perf_event_header__init_id+0x98 ([kernel.kallsyms])
           uname     137 [003]          1           branches:  ffffffff8004c658 __task_pid_nr_ns+0x0 ([kernel.kallsyms]) => ffffffff8004c696 __task_pid_nr_ns+0x3e ([kernel.kallsyms])
           uname     137 [003]          1           branches:  ffffffff8004c71e __task_pid_nr_ns+0xc6 ([kernel.kallsyms]) => ffffffff8004c6a4 __task_pid_nr_ns+0x4c ([kernel.kallsyms])
           uname     137 [003]          1           branches:  ffffffff8004c6e4 __task_pid_nr_ns+0x8c ([kernel.kallsyms]) => ffffffff8004c6e4 __task_pid_nr_ns+0x8c ([kernel.kallsyms])
...
liangzhen (12):
  coresight: Add RISC-V support to CoreSight tracing
  coresight: Initial implementation of RISC-V trace driver
  coresight: Add RISC-V Trace Encoder driver
  coresight: Add RISC-V Trace Funnel driver
  coresight: Add RISC-V Trace ATB Bridge driver
  coresight rvtrace: Add timestamp component support for encoder and
    funnel
  coresight: Add RISC-V PMU name support
  perf tools: riscv: making rvtrace PMU listable
  perf tools: Add RISC-V trace PMU record capabilities
  perf tools: Add Nexus RISC-V Trace decoder
  perf symbols: Add RISC-V PLT entry sizes
  perf tools: Integrate RISC-V trace decoder into auxtrace
drivers/hwtracing/Kconfig                     |    2 +
 drivers/hwtracing/coresight/Kconfig           |   46 +-
 drivers/hwtracing/coresight/Makefile          |    6 +
 drivers/hwtracing/coresight/coresight-core.c  |    8 +
 .../hwtracing/coresight/coresight-etm-perf.c  |    1 -
 .../hwtracing/coresight/coresight-etm-perf.h  |   21 +
 .../hwtracing/coresight/coresight-platform.c  |    1 -
 .../hwtracing/coresight/coresight-tmc-etf.c   |    4 +
 .../hwtracing/coresight/coresight-tmc-etr.c   |    4 +
 .../hwtracing/coresight/rvtrace-atbbridge.c   |  239 +++
 drivers/hwtracing/coresight/rvtrace-core.c    |  135 ++
 .../coresight/rvtrace-encoder-core.c          |  562 +++++++
 .../coresight/rvtrace-encoder-sysfs.c         |  363 +++++
 drivers/hwtracing/coresight/rvtrace-encoder.h |  151 ++
 drivers/hwtracing/coresight/rvtrace-funnel.c  |  337 ++++
 drivers/hwtracing/coresight/rvtrace-funnel.h  |   39 +
 .../hwtracing/coresight/rvtrace-timestamp.c   |  278 ++++
 .../hwtracing/coresight/rvtrace-timestamp.h   |   64 +
 include/linux/coresight-pmu.h                 |    4 +
 include/linux/rvtrace.h                       |  116 ++
 tools/arch/riscv/include/asm/insn.h           |  645 ++++++++
 tools/perf/arch/riscv/util/Build              |    2 +
 tools/perf/arch/riscv/util/auxtrace.c         |  490 ++++++
 tools/perf/arch/riscv/util/pmu.c              |   20 +
 tools/perf/util/Build                         |    3 +
 tools/perf/util/auxtrace.c                    |    4 +
 tools/perf/util/auxtrace.h                    |    1 +
 tools/perf/util/nexus-rv-decoder/Build        |    1 +
 .../util/nexus-rv-decoder/nexus-rv-decoder.c  | 1364 +++++++++++++++++
 .../util/nexus-rv-decoder/nexus-rv-decoder.h  |  139 ++
 .../perf/util/nexus-rv-decoder/nexus-rv-msg.h |  190 +++
 tools/perf/util/rvtrace-decoder.c             | 1039 +++++++++++++
 tools/perf/util/rvtrace.h                     |   40 +
 tools/perf/util/symbol-elf.c                  |    4 +
 34 files changed, 6320 insertions(+), 3 deletions(-)
 create mode 100644 drivers/hwtracing/coresight/rvtrace-atbbridge.c
 create mode 100644 drivers/hwtracing/coresight/rvtrace-core.c
 create mode 100644 drivers/hwtracing/coresight/rvtrace-encoder-core.c
 create mode 100644 drivers/hwtracing/coresight/rvtrace-encoder-sysfs.c
 create mode 100644 drivers/hwtracing/coresight/rvtrace-encoder.h
 create mode 100644 drivers/hwtracing/coresight/rvtrace-funnel.c
 create mode 100644 drivers/hwtracing/coresight/rvtrace-funnel.h
 create mode 100644 drivers/hwtracing/coresight/rvtrace-timestamp.c
 create mode 100644 drivers/hwtracing/coresight/rvtrace-timestamp.h
 create mode 100644 include/linux/rvtrace.h
 create mode 100644 tools/arch/riscv/include/asm/insn.h
 create mode 100644 tools/perf/arch/riscv/util/auxtrace.c
 create mode 100644 tools/perf/arch/riscv/util/pmu.c
 create mode 100644 tools/perf/util/nexus-rv-decoder/Build
 create mode 100644 tools/perf/util/nexus-rv-decoder/nexus-rv-decoder.c
 create mode 100644 tools/perf/util/nexus-rv-decoder/nexus-rv-decoder.h
 create mode 100644 tools/perf/util/nexus-rv-decoder/nexus-rv-msg.h
 create mode 100644 tools/perf/util/rvtrace-decoder.c
 create mode 100644 tools/perf/util/rvtrace.h
-- 
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[RFC PATCH 00/12] Add Linux RISC-V trace support via CoreSight