On Thu, Nov 08, 2018 at 04:51:52PM +0800, leo.yan@linaro.org wrote:
Hi Jiri,
On Wed, Nov 07, 2018 at 03:10:06PM +0100, Jiri Olsa wrote:
On Fri, Nov 02, 2018 at 10:55:16AM +0800, leo.yan@linaro.org wrote:
Hi all,
Now I found that if use the command 'perf script' for Arm CoreSight trace data, it fails to parse kernel symbols if we don't specify kernel vmlinux file. So when we don't specify kernel symbol files then perf tool will roll back to use /proc/kallsyms for kernel symbols parsing, as result it will run into below flow:
yep, AFAIK if there's no vmlinux found we fallback to /proc/kallsyms
thread__find_addr_map(thread, cpumode, MAP__FUNCTION, address, &al); map__load(al.map); dso__data_read_offset(al.map->dso, machine, offset, buffer, size); `-> data_read_offset()
so what is the actual error you see in the perf script? unresolved samples? could you please describe your config and workload?
So at my side the error is the CoreSight trace decoder fails to generate samples if the sample has kernel address, thus the decoder doesn't generate any kernel sample if use kallsyms as dso.
For more detailed info is: the CoreSight decoder needs firstly to get dso related info by calling dso__data_read_offset() [1], if we use kallsyms then this function always returns failure then this leads the docoder to discard all kernel samples.
I haven't checked on this code for some time but AFAICS before you call dso__data_read_offset you need to check dso->data.status != DSO_DATA_STATUS_ERROR
map__load call ahead should take care on setting this and find the source of the data
check the intel_pt code (intel_pt_walk_next_insn) or for example grab_bb in perf script
I guess you need to have either vmlinux or kcore in place to get some data out of it
jirka