[PATCH v2 04/14] perf cs-etm: Centralize packet ISA initialization
From: Leo Yan
Date: Wed Sep 23 2026 - 11:38:34 EST
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@xxxxxxx>
---
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