perf cs-etm: Set sample flags for exception packet

The exception taken and returning are typical flow for instruction jump
but it needs to be handled with exception packets. This patch is to set
sample flags for exception packet.

Since the exception packet contains the exception number, according to
the exception number this patch makes decision for belonging to which
exception types.

The decoder have defined different exception number for ETMv3 and ETMv4
separately, hence this patch needs firstly decide the ETM version by
using the metadata magic number, and this patch adds helper function
cs_etm__get_magic() for easily getting magic number.

Based on different ETM version, the exception packet contains the
exception number, according to the exception number this patch makes
decision for the exception belonging to which exception types.

In this patch, it introduces helper function cs_etm__is_svc_instr(); for
ETMv4 CS_ETMV4_EXC_CALL covers SVC, SMC and HVC cases in the single
exception number, thus need to use cs_etm__is_svc_instr() to decide an
exception taken for system call.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Robert Walker <robert.walker@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Suzuki K Poulouse <suzuki.poulose@arm.com>
Cc: coresight ml <coresight@lists.linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20190129122842.32041-8-leo.yan@linaro.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>