[ISSUE] trace_id of ETM will be invalid when there are more than 48 CPUs on chip

[Mike Leach]

Hi

On Mon, 16 May 2022 at 04:51, liuqi (BA) <liuqi115 at huawei.com> wrote:
>
> Hi all,
>
> My colleague Junhao He noticed this issue when tracing CPU48 on
> Kunpeng920 platform, log as follows:
>
> [root at localhost ~]# perf record -e cs_etm/@sink_smb1/ -C 48 -o perf.data
> taskset -c 48 uname -a
> [root at localhost ~]# perf report -D --stdio -i perf.data > perf_48.log
> 0x270 [0xc8]: failed to process type: 70 [Invalid argument]
> Error:
> failed to process sample
> [root at localhost ~]# perf -v
> perf version 5.17.rc4.gdeea22e4af29
> [root at localhost ~]# ldd /usr/bin/perf | grep opencsd
>          libopencsd_c_api.so.1 => /root/lib/libopencsd_c_api.so.1
>          libopencsd.so.1 => /root/lib/libopencsd.so.1
>
> As (CORESIGHT_ETM_PMU_SEED + (cpu * 2)) is used in
> coresight_get_trace_id() to cacualate trace_id, if there are more than
> 48 CPUs on chip, we will have some ETM device which trace id is
> invalid(trace_id = 0 or trace_id > 0x6F). In this situation, we cannot
> parse trace data using perf tool.
>
> Perhaps we should make trace_id in the range of 1 to 0x6F in
> coresight_get_trace_id()? But there also might be parsing problem if
> duplicate trace ID is used during collection.
>
> Any response will be highly appreciated.
>
> Thanks,
> Qi

Addressed by patchset here:

[PATCH 00/10] coresight: Add new API to allocate trace source ID values
https://lists.linaro.org/archives/list/coresight@lists.linaro.org/thread/BJEO7KMX723YZWVTPWAY7F3GWSVTO644/

Version 2 of this patchset is to be published in due course.

Regards

Mike

-- 
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK