On Mon, Dec 10, 2018 at 04:53:01PM +0800, Leo Yan wrote: > The exception packet appears as one element with 'elem_type' == > OCSD_GEN_TRC_ELEM_EXCEPTION or OCSD_GEN_TRC_ELEM_EXCEPTION_RET, > which present for exception entry and exit respectively. The decoder > set packet fields 'packet->exc' and 'packet->exc_ret' to indicate the > exception packets; but exception packets don't have dedicated sample > type and shares the same sample type CS_ETM_RANGE with normal > instruction packets. > > As result, the exception packets are taken as normal instruction packets > and this introduces confusion to mix different packet types. > Furthermore, these instruction range packets will be processed for > branch sample only when 'packet->last_instr_taken_branch' is true, > otherwise they will be omitted, this can introduce mess for exception > and exception returning due we don't have complete address range info > for context switching. > > To process exception packets properly, this patch introduce two new > sample type: CS_ETM_EXCEPTION and CS_ETM_EXCEPTION_RET; for these two > kind packets, they will be handled by cs_etm__exception(). The func > cs_etm__exception() forces to set previous CS_ETM_RANGE packet flag > 'prev_packet->last_instr_taken_branch' to true, this matches well with > the program flow when the exception is trapped from user space to kernel > space, no matter if the most recent flow has branch taken or not; this > is also safe for returning to user space after exception handling. > > After exception packets have their own sample type, the packet fields > 'packet->exc' and 'packet->exc_ret' aren't needed anymore, so remove > them. > > Cc: Mathieu Poirier <[email protected]> > Cc: Mike Leach <[email protected]> > Cc: Robert Walker <[email protected]> > Signed-off-by: Leo Yan <[email protected]> > --- > tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 26 +++++++++++++++++------ > tools/perf/util/cs-etm-decoder/cs-etm-decoder.h | 4 ++-- > tools/perf/util/cs-etm.c | 28 > +++++++++++++++++++++++++ > 3 files changed, 50 insertions(+), 8 deletions(-) > > diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c > b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c > index bcb5c98..6d89d0e 100644 > --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c > +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c > @@ -291,8 +291,6 @@ static void cs_etm_decoder__clear_buffer(struct > cs_etm_decoder *decoder) > decoder->packet_buffer[i].instr_count = 0; > decoder->packet_buffer[i].last_instr_taken_branch = false; > decoder->packet_buffer[i].last_instr_size = 0; > - decoder->packet_buffer[i].exc = false; > - decoder->packet_buffer[i].exc_ret = false; > decoder->packet_buffer[i].cpu = INT_MIN; > } > } > @@ -320,8 +318,6 @@ cs_etm_decoder__buffer_packet(struct cs_etm_decoder > *decoder, > > decoder->packet_buffer[et].sample_type = sample_type; > decoder->packet_buffer[et].isa = CS_ETM_ISA_UNKNOWN; > - decoder->packet_buffer[et].exc = false; > - decoder->packet_buffer[et].exc_ret = false; > decoder->packet_buffer[et].cpu = *((int *)inode->priv); > decoder->packet_buffer[et].start_addr = CS_ETM_INVAL_ADDR; > decoder->packet_buffer[et].end_addr = CS_ETM_INVAL_ADDR; > @@ -398,6 +394,22 @@ cs_etm_decoder__buffer_discontinuity(struct > cs_etm_decoder *decoder, > CS_ETM_DISCONTINUITY); > } > > +static ocsd_datapath_resp_t > +cs_etm_decoder__buffer_exception(struct cs_etm_decoder *decoder, > + const uint8_t trace_chan_id) > +{ > + return cs_etm_decoder__buffer_packet(decoder, trace_chan_id, > + CS_ETM_EXCEPTION); > +} > + > +static ocsd_datapath_resp_t > +cs_etm_decoder__buffer_exception_ret(struct cs_etm_decoder *decoder, > + const uint8_t trace_chan_id) > +{ > + return cs_etm_decoder__buffer_packet(decoder, trace_chan_id, > + CS_ETM_EXCEPTION_RET); > +} > + > static ocsd_datapath_resp_t cs_etm_decoder__gen_trace_elem_printer( > const void *context, > const ocsd_trc_index_t indx __maybe_unused, > @@ -426,10 +438,12 @@ static ocsd_datapath_resp_t > cs_etm_decoder__gen_trace_elem_printer( > trace_chan_id); > break; > case OCSD_GEN_TRC_ELEM_EXCEPTION: > - decoder->packet_buffer[decoder->tail].exc = true; > + resp = cs_etm_decoder__buffer_exception(decoder, > + trace_chan_id); > break; > case OCSD_GEN_TRC_ELEM_EXCEPTION_RET: > - decoder->packet_buffer[decoder->tail].exc_ret = true; > + resp = cs_etm_decoder__buffer_exception_ret(decoder, > + trace_chan_id); > break; > case OCSD_GEN_TRC_ELEM_PE_CONTEXT: > case OCSD_GEN_TRC_ELEM_ADDR_NACC: > diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h > b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h > index a272317..a6407d4 100644 > --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h > +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h > @@ -26,6 +26,8 @@ enum cs_etm_sample_type { > CS_ETM_EMPTY, > CS_ETM_RANGE, > CS_ETM_DISCONTINUITY, > + CS_ETM_EXCEPTION, > + CS_ETM_EXCEPTION_RET, > }; > > enum cs_etm_isa { > @@ -43,8 +45,6 @@ struct cs_etm_packet { > u32 instr_count; > u8 last_instr_taken_branch; > u8 last_instr_size; > - u8 exc; > - u8 exc_ret; > int cpu; > }; > > diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c > index cea3158..27a374d 100644 > --- a/tools/perf/util/cs-etm.c > +++ b/tools/perf/util/cs-etm.c > @@ -1000,6 +1000,25 @@ static int cs_etm__sample(struct cs_etm_queue *etmq) > return 0; > } > > +static int cs_etm__exception(struct cs_etm_queue *etmq) > +{ > + /* > + * When the exception packet is inserted, whether the last instruction > + * in previous range packet is taken branch or not, we need to force > + * to set 'prev_packet->last_instr_taken_branch' to true. This ensures > + * to generate branch sample for the instruction range before the > + * exception is trapped to kernel or before the exception returning. > + * > + * The exception packet includes the dummy address values, so don't > + * swap PACKET with PREV_PACKET. This keeps PREV_PACKET to be useful > + * for generating instruction and branch samples. > + */ > + if (etmq->prev_packet->sample_type == CS_ETM_RANGE) > + etmq->prev_packet->last_instr_taken_branch = true; > + > + return 0; > +} > + > static int cs_etm__flush(struct cs_etm_queue *etmq) > { > int err = 0; > @@ -1148,6 +1167,15 @@ static int cs_etm__run_decoder(struct cs_etm_queue > *etmq) > */ > cs_etm__sample(etmq); > break; > + case CS_ETM_EXCEPTION: > + case CS_ETM_EXCEPTION_RET: > + /* > + * If the exception packet is coming, > + * make sure the previous instruction > + * range packet to be handled properly. > + */ > + cs_etm__exception(etmq); > + break; > case CS_ETM_DISCONTINUITY: > /* > * Discontinuity in trace, flush > -- > 2.7.4 >
Reviewed-by: Mathieu Poirier <[email protected]>
