[PATCH v5] perf: Support for Arm A32/T32 instruction sets in CoreSight trace

[Robert Walker]

This patch adds support for generating instruction samples from trace of
AArch32 programs using the A32 and T32 instruction sets.

T32 has variable 2 or 4 byte instruction size, so the conversion between
addresses and instruction counts requires extra information from the trace
decoder, requiring version 0.10.0 of OpenCSD.  A check for the OpenCSD
library version has been added to the feature check for OpenCSD.

Signed-off-by: Robert Walker <robert.walker@xxxxxxx>
---

Changes since v4:
 Formatting of comment block

 tools/build/feature/test-libopencsd.c           |  8 +++
 tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 29 ++++++++++
 tools/perf/util/cs-etm-decoder/cs-etm-decoder.h | 10 ++++
 tools/perf/util/cs-etm.c                        | 70 +++++++++++--------------
 4 files changed, 78 insertions(+), 39 deletions(-)

diff --git a/tools/build/feature/test-libopencsd.c b/tools/build/feature/test-libopencsd.c
index 5ff1246..d68eb4f 100644
--- a/tools/build/feature/test-libopencsd.c
+++ b/tools/build/feature/test-libopencsd.c
@@ -1,6 +1,14 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <opencsd/c_api/opencsd_c_api.h>
 
+/*
+ * Check OpenCSD library version is sufficient to provide required features
+ */
+#define OCSD_MIN_VER ((0 << 16) | (10 << 8) | (0))
+#if !defined(OCSD_VER_NUM) || (OCSD_VER_NUM < OCSD_MIN_VER)
+#error "OpenCSD >= 0.10.0 is required"
+#endif
+
 int main(void)
 {
 	(void)ocsd_get_version();
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 938def6..5efb616 100644
--- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
+++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
@@ -263,9 +263,12 @@ static void cs_etm_decoder__clear_buffer(struct cs_etm_decoder *decoder)
 	decoder->tail = 0;
 	decoder->packet_count = 0;
 	for (i = 0; i < MAX_BUFFER; i++) {
+		decoder->packet_buffer[i].isa = CS_ETM_ISA_UNKNOWN;
 		decoder->packet_buffer[i].start_addr = CS_ETM_INVAL_ADDR;
 		decoder->packet_buffer[i].end_addr = CS_ETM_INVAL_ADDR;
+		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;
@@ -294,11 +297,15 @@ cs_etm_decoder__buffer_packet(struct cs_etm_decoder *decoder,
 	decoder->packet_count++;
 
 	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;
+	decoder->packet_buffer[et].instr_count = 0;
+	decoder->packet_buffer[et].last_instr_taken_branch = false;
+	decoder->packet_buffer[et].last_instr_size = 0;
 
 	if (decoder->packet_count == MAX_BUFFER - 1)
 		return OCSD_RESP_WAIT;
@@ -321,8 +328,28 @@ cs_etm_decoder__buffer_range(struct cs_etm_decoder *decoder,
 
 	packet = &decoder->packet_buffer[decoder->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;
+
 	switch (elem->last_i_type) {
 	case OCSD_INSTR_BR:
 	case OCSD_INSTR_BR_INDIRECT:
@@ -336,6 +363,8 @@ cs_etm_decoder__buffer_range(struct cs_etm_decoder *decoder,
 		break;
 	}
 
+	packet->last_instr_size = elem->last_instr_sz;
+
 	return ret;
 }
 
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 612b575..9351bd1 100644
--- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
+++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
@@ -28,11 +28,21 @@ enum cs_etm_sample_type {
 	CS_ETM_TRACE_ON = 1 << 1,
 };
 
+enum cs_etm_isa {
+	CS_ETM_ISA_UNKNOWN,
+	CS_ETM_ISA_A64,
+	CS_ETM_ISA_A32,
+	CS_ETM_ISA_T32,
+};
+
 struct cs_etm_packet {
 	enum cs_etm_sample_type sample_type;
+	enum cs_etm_isa isa;
 	u64 start_addr;
 	u64 end_addr;
+	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 73430b7..48ad217 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -31,14 +31,6 @@
 
 #define MAX_TIMESTAMP (~0ULL)
 
-/*
- * A64 instructions are always 4 bytes
- *
- * Only A64 is supported, so can use this constant for converting between
- * addresses and instruction counts, calculting offsets etc
- */
-#define A64_INSTR_SIZE 4
-
 struct cs_etm_auxtrace {
 	struct auxtrace auxtrace;
 	struct auxtrace_queues queues;
@@ -510,21 +502,17 @@ static inline void cs_etm__reset_last_branch_rb(struct cs_etm_queue *etmq)
 	etmq->last_branch_rb->nr = 0;
 }
 
-static inline u64 cs_etm__last_executed_instr(struct cs_etm_packet *packet)
-{
-	/* Returns 0 for the CS_ETM_TRACE_ON packet */
-	if (packet->sample_type == CS_ETM_TRACE_ON)
-		return 0;
+static inline int cs_etm__t32_instr_size(struct cs_etm_queue *etmq,
+					 u64 addr) {
+	u8 instrBytes[2];
 
+	cs_etm__mem_access(etmq, addr, ARRAY_SIZE(instrBytes), instrBytes);
 	/*
-	 * The packet records the execution range with an exclusive end address
-	 *
-	 * A64 instructions are constant size, so the last executed
-	 * instruction is A64_INSTR_SIZE before the end address
-	 * Will need to do instruction level decode for T32 instructions as
-	 * they can be variable size (not yet supported).
+	 * T32 instruction size is indicated by bits[15:11] of the first
+	 * 16-bit word of the instruction: 0b11101, 0b11110 and 0b11111
+	 * denote a 32-bit instruction.
 	 */
-	return packet->end_addr - A64_INSTR_SIZE;
+	return ((instrBytes[1] & 0xF8) >= 0xE8) ? 4 : 2;
 }
 
 static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet)
@@ -536,27 +524,32 @@ static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet)
 	return packet->start_addr;
 }
 
-static inline u64 cs_etm__instr_count(const struct cs_etm_packet *packet)
+static inline
+u64 cs_etm__last_executed_instr(const struct cs_etm_packet *packet)
 {
-	/*
-	 * Only A64 instructions are currently supported, so can get
-	 * instruction count by dividing.
-	 * Will need to do instruction level decode for T32 instructions as
-	 * they can be variable size (not yet supported).
-	 */
-	return (packet->end_addr - packet->start_addr) / A64_INSTR_SIZE;
+	/* Returns 0 for the CS_ETM_TRACE_ON packet */
+	if (packet->sample_type == CS_ETM_TRACE_ON)
+		return 0;
+
+	return packet->end_addr - packet->last_instr_size;
 }
 
-static inline u64 cs_etm__instr_addr(const struct cs_etm_packet *packet,
+static inline u64 cs_etm__instr_addr(struct cs_etm_queue *etmq,
+				     const struct cs_etm_packet *packet,
 				     u64 offset)
 {
-	/*
-	 * Only A64 instructions are currently supported, so can get
-	 * instruction address by muliplying.
-	 * Will need to do instruction level decode for T32 instructions as
-	 * they can be variable size (not yet supported).
-	 */
-	return packet->start_addr + offset * A64_INSTR_SIZE;
+	if (packet->isa == CS_ETM_ISA_T32) {
+		u64 addr = packet->start_addr;
+
+		while (offset > 0) {
+			addr += cs_etm__t32_instr_size(etmq, addr);
+			offset--;
+		}
+		return addr;
+	}
+
+	/* Assume a 4 byte instruction size (A32/A64) */
+	return packet->start_addr + offset * 4;
 }
 
 static void cs_etm__update_last_branch_rb(struct cs_etm_queue *etmq)
@@ -888,9 +881,8 @@ static int cs_etm__sample(struct cs_etm_queue *etmq)
 	struct cs_etm_auxtrace *etm = etmq->etm;
 	struct cs_etm_packet *tmp;
 	int ret;
-	u64 instrs_executed;
+	u64 instrs_executed = etmq->packet->instr_count;
 
-	instrs_executed = cs_etm__instr_count(etmq->packet);
 	etmq->period_instructions += instrs_executed;
 
 	/*
@@ -920,7 +912,7 @@ static int cs_etm__sample(struct cs_etm_queue *etmq)
 		 * executed, but PC has not advanced to next instruction)
 		 */
 		u64 offset = (instrs_executed - instrs_over - 1);
-		u64 addr = cs_etm__instr_addr(etmq->packet, offset);
+		u64 addr = cs_etm__instr_addr(etmq, etmq->packet, offset);
 
 		ret = cs_etm__synth_instruction_sample(
 			etmq, addr, etm->instructions_sample_period);
-- 
2.7.4