Files
Leo YanandNamhyung Kim a9e99b860f perf cs-etm: Filter synthesized branch samples
The itrace 'c' and 'r' options request synthesized branch events for
calls and returns only. For perf script the default itrace options are
"--itrace=ce", so CS ETM should emit call branches and error events by
default.

CS ETM currently synthesizes a branch sample for every decoded taken
branch whenever branch synthesis is enabled. This produces redundant
jump and conditional branch samples.

Add a branch filter derived from the itrace calls and returns options.
When neither option is set, keep the existing behavior and synthesize all
branch samples. When calls or returns are requested, emit only branch
samples whose flags match the selected branch type, while preserving trace
begin/end markers.

Also update test_arm_coresight_disasm.sh and arm-cs-trace-disasm.py
to use the --itrace=b option for generating branch samples.

Before:

  perf script -F,+flags

  callchain_test    6114 [005] 331519.825214:          1 branches:   tr strt jmp                           0 [unknown] ([unknown]) => ffff8000803a3a68 perf_report_aux_output_id+0x50 ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   call                   ffff8000803a3a74 perf_report_aux_output_id+0x5c ([kernel.kallsyms]) => ffff8000817f4d88 memset+0x0 ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   jmp                    ffff8000817f4d8c memset+0x4 ([kernel.kallsyms]) => ffff8000817f4c00 __pi_memset_generic+0x0 ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   jcc                    ffff8000817f4c1c __pi_memset_generic+0x1c ([kernel.kallsyms]) => ffff8000817f4c44 __pi_memset_generic+0x44 ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   jcc                    ffff8000817f4c4c __pi_memset_generic+0x4c ([kernel.kallsyms]) => ffff8000817f4c5c __pi_memset_generic+0x5c ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   jcc                    ffff8000817f4c5c __pi_memset_generic+0x5c ([kernel.kallsyms]) => ffff8000817f4cf0 __pi_memset_generic+0xf0 ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   jcc                    ffff8000817f4d30 __pi_memset_generic+0x130 ([kernel.kallsyms]) => ffff8000817f4d68 __pi_memset_generic+0x168 ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   jcc                    ffff8000817f4d78 __pi_memset_generic+0x178 ([kernel.kallsyms]) => ffff8000817f4d6c __pi_memset_generic+0x16c ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   jcc                    ffff8000817f4d78 __pi_memset_generic+0x178 ([kernel.kallsyms]) => ffff8000817f4d6c __pi_memset_generic+0x16c ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   jcc                    ffff8000817f4d78 __pi_memset_generic+0x178 ([kernel.kallsyms]) => ffff8000817f4d6c __pi_memset_generic+0x16c ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   return                 ffff8000817f4d84 __pi_memset_generic+0x184 ([kernel.kallsyms]) => ffff8000803a3a78 perf_report_aux_output_id+0x60 ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   jcc                    ffff8000803a3a98 perf_report_aux_output_id+0x80 ([kernel.kallsyms]) => ffff8000803a3b04 perf_report_aux_output_id+0xec ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   call                   ffff8000803a3b1c perf_report_aux_output_id+0x104 ([kernel.kallsyms]) => ffff8000803a38f8 __perf_event_header__init_id+0x0 ([kernel.kallsyms])

After:

  callchain_test    6114 [005] 331519.825214:          1 branches:   tr strt jmp                           0 [unknown] ([unknown]) => ffff8000803a3a68 perf_report_aux_output_id+0x50 ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   call                   ffff8000803a3a74 perf_report_aux_output_id+0x5c ([kernel.kallsyms]) => ffff8000817f4d88 memset+0x0 ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   call                   ffff8000803a3b1c perf_report_aux_output_id+0x104 ([kernel.kallsyms]) => ffff8000803a38f8 __perf_event_header__init_id+0x0 ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   call                   ffff8000803a39c0 __perf_event_header__init_id+0xc8 ([kernel.kallsyms]) => ffff800080105258 __task_pid_nr_ns+0x0 ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   call                   ffff80008010528c __task_pid_nr_ns+0x34 ([kernel.kallsyms]) => ffff8000801d5610 __rcu_read_lock+0x0 ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   call                   ffff8000801052b0 __task_pid_nr_ns+0x58 ([kernel.kallsyms]) => ffff800080192078 lock_acquire+0x0 ([kernel.kallsyms])
  callchain_test    6114 [005] 331519.825214:          1 branches:   call                   ffff8000801923f4 lock_acquire+0x37c ([kernel.kallsyms]) => ffff8000801d6da0 rcu_is_watching+0x0 ([kernel.kallsyms])

Fixes: b12235b113 ("perf tools: Add mechanic to synthesise CoreSight trace packets")
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: James Clark <james.clark@linaro.org>
Signed-off-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
2026-07-03 16:51:59 -07:00
..
2025-03-24 09:38:20 -07:00