Subject: [PATCH v1 2/3] perf cs-etm: Add callchain to instruction sample

From: Leo Yan <[email-masked]>
Date: Fri, 30 Aug 2019 14:24:20 +0800

Firstly, this patch adds support for the thread stack; when every branch
packet is coming we will push or pop the stack based on the sample
flags.

Secondly, based on the thread stack we can synthesize call chain for the
instruction sample, this can be used by itrace option '--itrace=g'.

Signed-off-by: Leo Yan <[email-masked]>
---
 tools/perf/util/cs-etm.c | 74 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 73 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 882a0718033d..ad573d3bd305 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -17,6 +17,7 @@
 #include <stdlib.h>
 
 #include "auxtrace.h"
+#include "callchain.h"
 #include "color.h"
 #include "cs-etm.h"
 #include "cs-etm-decoder/cs-etm-decoder.h"
@@ -69,6 +70,7 @@ struct cs_etm_traceid_queue {
 	size_t last_branch_pos;
 	union perf_event *event_buf;
 	struct thread *thread;
+	struct ip_callchain *chain;
 	struct branch_stack *last_branch;
 	struct branch_stack *last_branch_rb;
 	struct cs_etm_packet *prev_packet;
@@ -246,6 +248,16 @@ static int cs_etm__init_traceid_queue(struct cs_etm_queue *etmq,
 	if (!tidq->prev_packet)
 		goto out_free;
 
+	if (etm->synth_opts.callchain) {
+		size_t sz = sizeof(struct ip_callchain);
+
+		/* Add 1 to callchain_sz for callchain context */
+		sz += (etm->synth_opts.callchain_sz + 1) * sizeof(u64);
+		tidq->chain = zalloc(sz);
+		if (!tidq->chain)
+			goto out_free;
+	}
+
 	if (etm->synth_opts.last_branch) {
 		size_t sz = sizeof(struct branch_stack);
 
@@ -270,6 +282,7 @@ static int cs_etm__init_traceid_queue(struct cs_etm_queue *etmq,
 	zfree(&tidq->last_branch);
 	zfree(&tidq->prev_packet);
 	zfree(&tidq->packet);
+	zfree(&tidq->chain);
 out:
 	return rc;
 }
@@ -541,6 +554,7 @@ static void cs_etm__free_traceid_queues(struct cs_etm_queue *etmq)
 		zfree(&tidq->last_branch_rb);
 		zfree(&tidq->prev_packet);
 		zfree(&tidq->packet);
+		zfree(&tidq->chain);
 		zfree(&tidq);
 
 		/*
@@ -1121,6 +1135,41 @@ static void cs_etm__copy_insn(struct cs_etm_queue *etmq,
 			   sample->insn_len, (void *)sample->insn);
 }
 
+static void cs_etm__add_stack_event(struct cs_etm_queue *etmq,
+				    struct cs_etm_traceid_queue *tidq)
+{
+	struct cs_etm_auxtrace *etm = etmq->etm;
+	u8 trace_chan_id = tidq->trace_chan_id;
+	int insn_len;
+	u64 from_ip, to_ip;
+
+	if (etm->synth_opts.callchain || etm->synth_opts.thread_stack) {
+
+		from_ip = cs_etm__last_executed_instr(tidq->prev_packet);
+		to_ip = cs_etm__first_executed_instr(tidq->packet);
+
+		/*
+		 * T32 instruction size might be 32-bit or 16-bit, decide by
+		 * calling cs_etm__t32_instr_size().
+		 */
+		if (tidq->prev_packet->isa == CS_ETM_ISA_T32)
+			insn_len = cs_etm__t32_instr_size(etmq, trace_chan_id,
+							  from_ip);
+		/* Otherwise, A64 and A32 instruction size are always 32-bit. */
+		else
+			insn_len = 4;
+
+		thread_stack__event(tidq->thread, tidq->prev_packet->cpu,
+				    tidq->prev_packet->flags,
+				    from_ip, to_ip, insn_len,
+				    etmq->buffer->buffer_nr);
+	} else {
+		thread_stack__set_trace_nr(tidq->thread,
+					   tidq->prev_packet->cpu,
+					   etmq->buffer->buffer_nr);
+	}
+}
+
 static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
 					    struct cs_etm_traceid_queue *tidq,
 					    u64 addr, u64 period)
@@ -1146,6 +1195,14 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
 
 	cs_etm__copy_insn(etmq, tidq->trace_chan_id, tidq->packet, &sample);
 
+	if (etm->synth_opts.callchain) {
+		thread_stack__sample(tidq->thread, tidq->packet->cpu,
+				     tidq->chain,
+				     etm->synth_opts.callchain_sz + 1,
+				     sample.ip, etm->kernel_start);
+		sample.callchain = tidq->chain;
+	}
+
 	if (etm->synth_opts.last_branch) {
 		cs_etm__copy_last_branch_rb(etmq, tidq);
 		sample.branch_stack = tidq->last_branch;
@@ -1329,6 +1386,8 @@ static int cs_etm__synth_events(struct cs_etm_auxtrace *etm,
 		attr.sample_type &= ~(u64)PERF_SAMPLE_ADDR;
 	}
 
+	if (etm->synth_opts.callchain)
+		attr.sample_type |= PERF_SAMPLE_CALLCHAIN;
 	if (etm->synth_opts.last_branch)
 		attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
 
@@ -1397,6 +1456,9 @@ static int cs_etm__sample(struct cs_etm_queue *etmq,
 		tidq->period_instructions = instrs_over;
 	}
 
+	if (tidq->prev_packet->last_instr_taken_branch)
+		cs_etm__add_stack_event(etmq, tidq);
+
 	if (etm->sample_branches) {
 		bool generate_sample = false;
 
@@ -2596,7 +2658,17 @@ int cs_etm__process_auxtrace_info(union perf_event *event,
 	} else {
 		itrace_synth_opts__set_default(&etm->synth_opts,
 				session->itrace_synth_opts->default_no_sample);
-		etm->synth_opts.callchain = false;
+
+		etm->synth_opts.thread_stack =
+				session->itrace_synth_opts->thread_stack;
+	}
+
+	if (etm->synth_opts.callchain && !symbol_conf.use_callchain) {
+		symbol_conf.use_callchain = true;
+		if (callchain_register_param(&callchain_param) < 0) {
+			symbol_conf.use_callchain = false;
+			etm->synth_opts.callchain = false;
+		}
 	}
 
 	err = cs_etm__synth_events(etm, session);
-- 
2.17.1

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