perf cs-etm: Enable itrace option 'T'

Prior to Armv8.4, the feature FEAT_TRF is not supported by Arm CPUs.
Consequently, the sysfs node 'ts_source' will not be set as 1 by the
CoreSight ETM driver.  On the other hand, the perf tool relies on the
'ts_source' node to determine whether the kernel timestamp is traced.
Since the 'ts_source' is not set for Arm CPUs prior to Armv8.4,
platforms in this case cannot utilize the traced timestamp as the kernel
time.

This patch enables the 'T' itrace option, which forcibly utilizes the
traced timestamp as the kernel time.  If users are aware that their
working platform's Arm CoreSight shares the same counter with the kernel
time, they can specify 'T' option to decode the traced timestamp as the
kernel time.

An usage example is:

  # perf record -e cs_etm// -- test_program
  # perf script --itrace=i10ibT
  # perf report --itrace=i10ibT

Reviewed-by: James Clark <[email protected]>
Signed-off-by: Leo Yan <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: John Garry <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Mike Leach <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Suzuki Poulouse <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

0 files changed, 0 insertions, 0 deletions