Re: [PATCH v3 3/6] perf cs-etm: Support thread stack

Mathieu Poirier
2019-10-11T17:54:20Z

On Sat, Oct 05, 2019 at 05:16:11PM +0800, Leo Yan wrote:
> Since Arm CoreSight doesn't support thread stack, the decoding cannot
> display symbols with indented spaces to reflect the stack depth.
>
> This patch adds support thread stack for Arm CoreSight, this allows
> 'perf script' to display properly for option '-F,+callindent'.
>
> Before:
>
> # perf script -F,+callindent
> main 2808 1 branches: coresight_test1 ffff8634f5c8 coresight_test1+0x3c (/root/coresight_test/libcstest.so)
> main 2808 1 branches: printf@plt aaaaba8d37ec main+0x28 (/root/coresight_test/main)
> main 2808 1 branches: printf@plt aaaaba8d36bc printf@plt+0xc (/root/coresight_test/main)
> main 2808 1 branches: _init aaaaba8d3650 _init+0x30 (/root/coresight_test/main)
> main 2808 1 branches: _dl_fixup ffff86373b4c _dl_runtime_resolve+0x40 (/lib/aarch64-linux-gnu/ld-2.28.so)
> main 2808 1 branches: _dl_lookup_symbol_x ffff8636e078 _dl_fixup+0xb8 (/lib/aarch64-linux-gnu/ld-2.28.so)
> [...]
>
> After:
>
> # perf script -F,+callindent
> main 2808 1 branches: coresight_test1 ffff8634f5c8 coresight_test1+0x3c (/root/coresight_test/libcstest.so)
> main 2808 1 branches: printf@plt aaaaba8d37ec main+0x28 (/root/coresight_test/main)
> main 2808 1 branches: printf@plt aaaaba8d36bc printf@plt+0xc (/root/coresight_test/main)
> main 2808 1 branches: _init aaaaba8d3650 _init+0x30 (/root/coresight_test/main)
> main 2808 1 branches: _dl_fixup ffff86373b4c _dl_runtime_resolve+0x40 (/lib/aarch64-linux-gnu/ld-2.28.s
> main 2808 1 branches: _dl_lookup_symbol_x ffff8636e078 _dl_fixup+0xb8 (/lib/aarch64-linux-gnu/ld-2.28.so)
> [...]
>
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
> ---
> tools/perf/util/cs-etm.c | 44 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 44 insertions(+)
>
> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> index 58ceba7b91d5..780abbfd1833 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -1117,6 +1117,45 @@ static void cs_etm__copy_insn(struct cs_etm_queue *etmq,
> sample->insn_len, (void *)sample->insn);
> }
>
> +static void cs_etm__add_stack_event(struct cs_etm_queue *etmq,
> + struct cs_etm_traceid_queue *tidq)
> +{
> + struct cs_etm_auxtrace *etm = etmq->etm;
> + u8 trace_chan_id = tidq->trace_chan_id;
> + int insn_len;
> + u64 from_ip, to_ip;
> +
> + if (etm->synth_opts.thread_stack) {
> + from_ip = cs_etm__last_executed_instr(tidq->prev_packet);
> + to_ip = cs_etm__first_executed_instr(tidq->packet);
> +
> + insn_len = cs_etm__instr_size(etmq, trace_chan_id,
> + tidq->prev_packet->isa, from_ip);
> +
> + /*
> + * Create thread stacks by keeping track of calls and returns;
> + * any call pushes thread stack, return pops the stack, and
> + * flush stack when the trace is discontinuous.
> + */
> + thread_stack__event(tidq->thread, tidq->prev_packet->cpu,
> + tidq->prev_packet->flags,
> + from_ip, to_ip, insn_len,
> + etmq->buffer->buffer_nr);

Details are a little fuzzy in my head but I'm pretty sure
we want trace_chan_id here.

> + } else {
> + /*
> + * The thread stack can be output via thread_stack__process();
> + * thus the detailed information about paired calls and returns
> + * will be facilitated by Python script for the db-export.
> + *
> + * Need to set trace buffer number and flush thread stack if the
> + * trace buffer number has been alternate.
> + */
> + thread_stack__set_trace_nr(tidq->thread,
> + tidq->prev_packet->cpu,
> + etmq->buffer->buffer_nr);

Same here.

> + }
> +}
> +
> static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
> struct cs_etm_traceid_queue *tidq,
> u64 addr, u64 period)
> @@ -1393,6 +1432,9 @@ static int cs_etm__sample(struct cs_etm_queue *etmq,
> tidq->period_instructions = instrs_over;
> }
>
> + if (tidq->prev_packet->last_instr_taken_branch)
> + cs_etm__add_stack_event(etmq, tidq);
> +
> if (etm->sample_branches) {
> bool generate_sample = false;
>
> @@ -2593,6 +2635,8 @@ int cs_etm__process_auxtrace_info(union perf_event *event,
> itrace_synth_opts__set_default(&etm->synth_opts,
> session->itrace_synth_opts->default_no_sample);
> etm->synth_opts.callchain = false;
> + etm->synth_opts.thread_stack =
> + session->itrace_synth_opts->thread_stack;
> }
>
> err = cs_etm__synth_events(etm, session);
> --
> 2.17.1