[PATCH v2 04/14] perf cs-etm: Centralize packet ISA initialization
Leo Yan
leo.yan at arm.com
Wed Sep 23 08:21:44 PDT 2026
Exception packets need their own ISA so the frontend can generate samples
directly from them. Currently, ISA initialization is limited to instruction
range packets.
Move ISA initialization into cs_etm_decoder__buffer_packet() and use a
common helper to obtain it from the OpenCSD element. Populate the ISA for
instruction ranges, context updates and exceptions, leaving it unknown
for other element types.
Assisted-by: Codex:gpt-6
Signed-off-by: Leo Yan <leo.yan at arm.com>
---
tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 69 +++++++++++++++----------
1 file changed, 41 insertions(+), 28 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 35ca1a23e12735416d0d412a949595efc5bfe50a..469aba5e596a791289c5bcece132aba7b0baf6c3 100644
--- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
+++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
@@ -368,9 +368,38 @@ cs_etm_decoder__reset_timestamp(struct cs_etm_packet_queue *packet_queue)
packet_queue->instr_count = 0;
}
+static enum cs_etm_isa
+cs_etm_decoder__get_isa(const ocsd_generic_trace_elem *elem)
+{
+ /*
+ * OpenCSD preserves ISA and context between output elements, including
+ * exceptions after a context change with no intervening range.
+ */
+ if (elem->elem_type != OCSD_GEN_TRC_ELEM_PE_CONTEXT &&
+ elem->elem_type != OCSD_GEN_TRC_ELEM_INSTR_RANGE &&
+ elem->elem_type != OCSD_GEN_TRC_ELEM_EXCEPTION)
+ return CS_ETM_ISA_UNKNOWN;
+
+ switch (elem->isa) {
+ case ocsd_isa_aarch64:
+ return CS_ETM_ISA_A64;
+ case ocsd_isa_arm:
+ return CS_ETM_ISA_A32;
+ case ocsd_isa_thumb2:
+ return CS_ETM_ISA_T32;
+ case ocsd_isa_tee:
+ case ocsd_isa_jazelle:
+ case ocsd_isa_custom:
+ case ocsd_isa_unknown:
+ default:
+ return CS_ETM_ISA_UNKNOWN;
+ }
+}
+
static ocsd_datapath_resp_t
cs_etm_decoder__buffer_packet(struct cs_etm_queue *etmq,
struct cs_etm_packet_queue *packet_queue,
+ const ocsd_generic_trace_elem *elem,
const u8 trace_chan_id,
enum cs_etm_sample_type sample_type)
{
@@ -389,7 +418,7 @@ cs_etm_decoder__buffer_packet(struct cs_etm_queue *etmq,
packet_queue->packet_count++;
packet_queue->packet_buffer[et].sample_type = sample_type;
- packet_queue->packet_buffer[et].isa = CS_ETM_ISA_UNKNOWN;
+ packet_queue->packet_buffer[et].isa = cs_etm_decoder__get_isa(elem);
packet_queue->packet_buffer[et].cpu = cpu;
packet_queue->packet_buffer[et].start_addr = CS_ETM_INVAL_ADDR;
packet_queue->packet_buffer[et].end_addr = CS_ETM_INVAL_ADDR;
@@ -420,31 +449,13 @@ cs_etm_decoder__buffer_range(struct cs_etm_queue *etmq,
int ret = 0;
struct cs_etm_packet *packet;
- ret = cs_etm_decoder__buffer_packet(etmq, packet_queue, trace_chan_id,
- CS_ETM_RANGE);
+ ret = cs_etm_decoder__buffer_packet(etmq, packet_queue, elem,
+ trace_chan_id, CS_ETM_RANGE);
if (ret != OCSD_RESP_CONT && ret != OCSD_RESP_WAIT)
return ret;
packet = &packet_queue->packet_buffer[packet_queue->tail];
- switch (elem->isa) {
- case ocsd_isa_aarch64:
- packet->isa = CS_ETM_ISA_A64;
- break;
- case ocsd_isa_arm:
- packet->isa = CS_ETM_ISA_A32;
- break;
- case ocsd_isa_thumb2:
- packet->isa = CS_ETM_ISA_T32;
- break;
- case ocsd_isa_tee:
- case ocsd_isa_jazelle:
- case ocsd_isa_custom:
- case ocsd_isa_unknown:
- default:
- packet->isa = CS_ETM_ISA_UNKNOWN;
- }
-
packet->start_addr = elem->st_addr;
packet->end_addr = elem->en_addr;
packet->instr_count = elem->num_instr_range;
@@ -483,6 +494,7 @@ cs_etm_decoder__buffer_range(struct cs_etm_queue *etmq,
static ocsd_datapath_resp_t
cs_etm_decoder__buffer_discontinuity(struct cs_etm_queue *etmq,
struct cs_etm_packet_queue *queue,
+ const ocsd_generic_trace_elem *elem,
const uint8_t trace_chan_id)
{
/*
@@ -490,7 +502,7 @@ cs_etm_decoder__buffer_discontinuity(struct cs_etm_queue *etmq,
* reset time statistics.
*/
cs_etm_decoder__reset_timestamp(queue);
- return cs_etm_decoder__buffer_packet(etmq, queue, trace_chan_id,
+ return cs_etm_decoder__buffer_packet(etmq, queue, elem, trace_chan_id,
CS_ETM_DISCONTINUITY);
}
@@ -502,7 +514,7 @@ cs_etm_decoder__buffer_exception(struct cs_etm_queue *etmq,
{ int ret = 0;
struct cs_etm_packet *packet;
- ret = cs_etm_decoder__buffer_packet(etmq, queue, trace_chan_id,
+ ret = cs_etm_decoder__buffer_packet(etmq, queue, elem, trace_chan_id,
CS_ETM_EXCEPTION);
if (ret != OCSD_RESP_CONT && ret != OCSD_RESP_WAIT)
return ret;
@@ -516,9 +528,10 @@ cs_etm_decoder__buffer_exception(struct cs_etm_queue *etmq,
static ocsd_datapath_resp_t
cs_etm_decoder__buffer_exception_ret(struct cs_etm_queue *etmq,
struct cs_etm_packet_queue *queue,
+ const ocsd_generic_trace_elem *elem,
const uint8_t trace_chan_id)
{
- return cs_etm_decoder__buffer_packet(etmq, queue, trace_chan_id,
+ return cs_etm_decoder__buffer_packet(etmq, queue, elem, trace_chan_id,
CS_ETM_EXCEPTION_RET);
}
@@ -555,8 +568,8 @@ cs_etm_decoder__set_tid(struct cs_etm_queue *etmq,
elem->context.exception_level, tid))
return OCSD_RESP_FATAL_SYS_ERR;
- ret = cs_etm_decoder__buffer_packet(etmq, packet_queue, trace_chan_id,
- CS_ETM_CONTEXT);
+ ret = cs_etm_decoder__buffer_packet(etmq, packet_queue, elem,
+ trace_chan_id, CS_ETM_CONTEXT);
if (ret != OCSD_RESP_CONT && ret != OCSD_RESP_WAIT)
return ret;
@@ -597,7 +610,7 @@ static ocsd_datapath_resp_t cs_etm_decoder__gen_trace_elem_printer(
type == OCSD_GEN_TRC_ELEM_TRACE_ON ||
type == OCSD_GEN_TRC_ELEM_ADDR_NACC)
resp = cs_etm_decoder__buffer_discontinuity(etmq, packet_queue,
- trace_chan_id);
+ elem, trace_chan_id);
else if (type == OCSD_GEN_TRC_ELEM_INSTR_RANGE)
resp = cs_etm_decoder__buffer_range(etmq, packet_queue, elem,
trace_chan_id);
@@ -606,7 +619,7 @@ static ocsd_datapath_resp_t cs_etm_decoder__gen_trace_elem_printer(
trace_chan_id);
else if (type == OCSD_GEN_TRC_ELEM_EXCEPTION_RET)
resp = cs_etm_decoder__buffer_exception_ret(etmq, packet_queue,
- trace_chan_id);
+ elem, trace_chan_id);
else if (type == OCSD_GEN_TRC_ELEM_TIMESTAMP)
resp = cs_etm_decoder__do_hard_timestamp(etmq, elem,
trace_chan_id,
--
2.34.1
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