[PATCH 09/23] perf cs-etm: Swap packets for instruction samples

[PATCH 09/23] perf cs-etm: Swap packets for instruction samples

[Arnaldo Carvalho de Melo]

From: Leo Yan <leo.yan@linaro.org>

If use option '--itrace=iNNN' with Arm CoreSight trace data, perf tool
fails inject instruction samples; the root cause is the packets are only
swapped for branch samples and last branches but not for instruction
samples, so the new coming packets cannot be properly handled for only
synthesizing instruction samples.

To fix this issue, this patch refactors the code with a new function
cs_etm__packet_swap() which is used to swap packets and adds the
condition for instruction samples.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Walker <robert.walker@arm.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: coresight ml <coresight@lists.linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lore.kernel.org/lkml/20200219021811.20067-2-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/cs-etm.c | 39 +++++++++++++++++++--------------------
 1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index b3b3fe3ea345..294b09cfb034 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -363,6 +363,23 @@ struct cs_etm_packet_queue
 	return NULL;
 }
 
+static void cs_etm__packet_swap(struct cs_etm_auxtrace *etm,
+				struct cs_etm_traceid_queue *tidq)
+{
+	struct cs_etm_packet *tmp;
+
+	if (etm->sample_branches || etm->synth_opts.last_branch ||
+	    etm->sample_instructions) {
+		/*
+		 * Swap PACKET with PREV_PACKET: PACKET becomes PREV_PACKET for
+		 * the next incoming packet.
+		 */
+		tmp = tidq->packet;
+		tidq->packet = tidq->prev_packet;
+		tidq->prev_packet = tmp;
+	}
+}
+
 static void cs_etm__packet_dump(const char *pkt_string)
 {
 	const char *color = PERF_COLOR_BLUE;
@@ -1342,7 +1359,6 @@ static int cs_etm__sample(struct cs_etm_queue *etmq,
 			  struct cs_etm_traceid_queue *tidq)
 {
 	struct cs_etm_auxtrace *etm = etmq->etm;
-	struct cs_etm_packet *tmp;
 	int ret;
 	u8 trace_chan_id = tidq->trace_chan_id;
 	u64 instrs_executed = tidq->packet->instr_count;
@@ -1406,15 +1422,7 @@ static int cs_etm__sample(struct cs_etm_queue *etmq,
 		}
 	}
 
-	if (etm->sample_branches || etm->synth_opts.last_branch) {
-		/*
-		 * Swap PACKET with PREV_PACKET: PACKET becomes PREV_PACKET for
-		 * the next incoming packet.
-		 */
-		tmp = tidq->packet;
-		tidq->packet = tidq->prev_packet;
-		tidq->prev_packet = tmp;
-	}
+	cs_etm__packet_swap(etm, tidq);
 
 	return 0;
 }
@@ -1443,7 +1451,6 @@ static int cs_etm__flush(struct cs_etm_queue *etmq,
 {
 	int err = 0;
 	struct cs_etm_auxtrace *etm = etmq->etm;
-	struct cs_etm_packet *tmp;
 
 	/* Handle start tracing packet */
 	if (tidq->prev_packet->sample_type == CS_ETM_EMPTY)
@@ -1478,15 +1485,7 @@ static int cs_etm__flush(struct cs_etm_queue *etmq,
 	}
 
 swap_packet:
-	if (etm->sample_branches || etm->synth_opts.last_branch) {
-		/*
-		 * Swap PACKET with PREV_PACKET: PACKET becomes PREV_PACKET for
-		 * the next incoming packet.
-		 */
-		tmp = tidq->packet;
-		tidq->packet = tidq->prev_packet;
-		tidq->prev_packet = tmp;
-	}
+	cs_etm__packet_swap(etm, tidq);
 
 	return err;
 }
-- 
2.21.1


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[PATCH 10/23] perf cs-etm: Continuously record last branch

[Arnaldo Carvalho de Melo]

From: Leo Yan <leo.yan@linaro.org>

Every time synthesize instruction sample, the last branch recording will
be reset.  This is fine if the instruction period is big enough, for
example if use the option '--itrace=i100000', the last branch array is
reset for every sample with 100000 instructions per period; before
generate the next instruction sample, there has the sufficient packets
coming to fill the last branch array.

On the other hand, if set a very small period, the packets will be
significantly reduced between two continuous instruction samples, thus
the last branch array is almost empty for new instruction sample by
frequently resetting.

To allow the last branches to work properly for any instruction periods,
this patch avoids to reset the last branch for every instruction sample
and only reset it when flush the trace data.  The last branches will be
reset only for two cases, one is for trace starting, another case is for
discontinuous trace; other cases can keep recording last branches for
continuous instruction samples.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Walker <robert.walker@arm.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: coresight ml <coresight@lists.linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lore.kernel.org/lkml/20200219021811.20067-3-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/cs-etm.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 294b09cfb034..2c4156c5ed09 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1170,9 +1170,6 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
 			"CS ETM Trace: failed to deliver instruction event, error %d\n",
 			ret);
 
-	if (etm->synth_opts.last_branch)
-		cs_etm__reset_last_branch_rb(tidq);
-
 	return ret;
 }
 
@@ -1487,6 +1484,10 @@ static int cs_etm__flush(struct cs_etm_queue *etmq,
 swap_packet:
 	cs_etm__packet_swap(etm, tidq);
 
+	/* Reset last branches after flush the trace */
+	if (etm->synth_opts.last_branch)
+		cs_etm__reset_last_branch_rb(tidq);
+
 	return err;
 }
 
-- 
2.21.1


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[PATCH 11/23] perf cs-etm: Correct synthesizing instruction samples

[Arnaldo Carvalho de Melo]

From: Leo Yan <leo.yan@linaro.org>

When 'etm->instructions_sample_period' is less than
'tidq->period_instructions', the function cs_etm__sample() cannot handle
this case properly with its logic.

Let's see below flow as an example:

- If we set itrace option '--itrace=i4', then function cs_etm__sample()
  has variables with initialized values:

  tidq->period_instructions = 0
  etm->instructions_sample_period = 4

- When the first packet is coming:

  packet->instr_count = 10; the number of instructions executed in this
  packet is 10, thus update period_instructions as below:

  tidq->period_instructions = 0 + 10 = 10
  instrs_over = 10 - 4 = 6
  offset = 10 - 6 - 1 = 3
  tidq->period_instructions = instrs_over = 6

- When the second packet is coming:

  packet->instr_count = 10; in the second pass, assume 10 instructions
  in the trace sample again:

  tidq->period_instructions = 6 + 10 = 16
  instrs_over = 16 - 4 = 12
  offset = 10 - 12 - 1 = -3  -> the negative value
  tidq->period_instructions = instrs_over = 12

So after handle these two packets, there have below issues:

The first issue is that cs_etm__instr_addr() returns the address within
the current trace sample of the instruction related to offset, so the
offset is supposed to be always unsigned value.  But in fact, function
cs_etm__sample() might calculate a negative offset value (in handling
the second packet, the offset is -3) and pass to cs_etm__instr_addr()
with u64 type with a big positive integer.

The second issue is it only synthesizes 2 samples for sample period = 4.
In theory, every packet has 10 instructions so the two packets have
total 20 instructions, 20 instructions should generate 5 samples
(4 x 5 = 20).  This is because cs_etm__sample() only calls once
cs_etm__synth_instruction_sample() to generate instruction sample per
range packet.

This patch fixes the logic in function cs_etm__sample(); the basic
idea for handling coming packet is:

- To synthesize the first instruction sample, it combines the left
  instructions from the previous packet and the head of the new
  packet; then generate continuous samples with sample period;
- At the tail of the new packet, if it has the rest instructions,
  these instructions will be left for the sequential sample.

Suggested-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Walker <robert.walker@arm.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: coresight ml <coresight@lists.linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lore.kernel.org/lkml/20200219021811.20067-4-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/cs-etm.c | 87 ++++++++++++++++++++++++++++++++--------
 1 file changed, 70 insertions(+), 17 deletions(-)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 2c4156c5ed09..1ddcc67e13dd 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1358,9 +1358,12 @@ static int cs_etm__sample(struct cs_etm_queue *etmq,
 	struct cs_etm_auxtrace *etm = etmq->etm;
 	int ret;
 	u8 trace_chan_id = tidq->trace_chan_id;
-	u64 instrs_executed = tidq->packet->instr_count;
+	u64 instrs_prev;
 
-	tidq->period_instructions += instrs_executed;
+	/* Get instructions remainder from previous packet */
+	instrs_prev = tidq->period_instructions;
+
+	tidq->period_instructions += tidq->packet->instr_count;
 
 	/*
 	 * Record a branch when the last instruction in
@@ -1378,26 +1381,76 @@ static int cs_etm__sample(struct cs_etm_queue *etmq,
 		 * TODO: allow period to be defined in cycles and clock time
 		 */
 
-		/* Get number of instructions executed after the sample point */
-		u64 instrs_over = tidq->period_instructions -
-			etm->instructions_sample_period;
+		/*
+		 * Below diagram demonstrates the instruction samples
+		 * generation flows:
+		 *
+		 *    Instrs     Instrs       Instrs       Instrs
+		 *   Sample(n)  Sample(n+1)  Sample(n+2)  Sample(n+3)
+		 *    |            |            |            |
+		 *    V            V            V            V
+		 *   --------------------------------------------------
+		 *            ^                                  ^
+		 *            |                                  |
+		 *         Period                             Period
+		 *    instructions(Pi)                   instructions(Pi')
+		 *
+		 *            |                                  |
+		 *            \---------------- -----------------/
+		 *                             V
+		 *                 tidq->packet->instr_count
+		 *
+		 * Instrs Sample(n...) are the synthesised samples occurring
+		 * every etm->instructions_sample_period instructions - as
+		 * defined on the perf command line.  Sample(n) is being the
+		 * last sample before the current etm packet, n+1 to n+3
+		 * samples are generated from the current etm packet.
+		 *
+		 * tidq->packet->instr_count represents the number of
+		 * instructions in the current etm packet.
+		 *
+		 * Period instructions (Pi) contains the the number of
+		 * instructions executed after the sample point(n) from the
+		 * previous etm packet.  This will always be less than
+		 * etm->instructions_sample_period.
+		 *
+		 * When generate new samples, it combines with two parts
+		 * instructions, one is the tail of the old packet and another
+		 * is the head of the new coming packet, to generate
+		 * sample(n+1); sample(n+2) and sample(n+3) consume the
+		 * instructions with sample period.  After sample(n+3), the rest
+		 * instructions will be used by later packet and it is assigned
+		 * to tidq->period_instructions for next round calculation.
+		 */
 
 		/*
-		 * Calculate the address of the sampled instruction (-1 as
-		 * sample is reported as though instruction has just been
-		 * executed, but PC has not advanced to next instruction)
+		 * Get the initial offset into the current packet instructions;
+		 * entry conditions ensure that instrs_prev is less than
+		 * etm->instructions_sample_period.
 		 */
-		u64 offset = (instrs_executed - instrs_over - 1);
-		u64 addr = cs_etm__instr_addr(etmq, trace_chan_id,
-					      tidq->packet, offset);
+		u64 offset = etm->instructions_sample_period - instrs_prev;
+		u64 addr;
 
-		ret = cs_etm__synth_instruction_sample(
-			etmq, tidq, addr, etm->instructions_sample_period);
-		if (ret)
-			return ret;
+		while (tidq->period_instructions >=
+				etm->instructions_sample_period) {
+			/*
+			 * Calculate the address of the sampled instruction (-1
+			 * as sample is reported as though instruction has just
+			 * been executed, but PC has not advanced to next
+			 * instruction)
+			 */
+			addr = cs_etm__instr_addr(etmq, trace_chan_id,
+						  tidq->packet, offset - 1);
+			ret = cs_etm__synth_instruction_sample(
+				etmq, tidq, addr,
+				etm->instructions_sample_period);
+			if (ret)
+				return ret;
 
-		/* Carry remaining instructions into next sample period */
-		tidq->period_instructions = instrs_over;
+			offset += etm->instructions_sample_period;
+			tidq->period_instructions -=
+				etm->instructions_sample_period;
+		}
 	}
 
 	if (etm->sample_branches) {
-- 
2.21.1


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[PATCH 12/23] perf cs-etm: Optimize copying last branches

[Arnaldo Carvalho de Melo]

From: Leo Yan <leo.yan@linaro.org>

If an instruction range packet can generate multiple instruction
samples, these samples share the same last branches; it's not necessary
to copy the same last branches repeatedly for these samples within the
same packet.

This patch moves out the last branches copying from function
cs_etm__synth_instruction_sample(), and execute it prior to generating
instruction samples.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Walker <robert.walker@arm.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: coresight ml <coresight@lists.linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lore.kernel.org/lkml/20200219021811.20067-5-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/cs-etm.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 1ddcc67e13dd..87d9943177bc 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1151,10 +1151,8 @@ 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.last_branch) {
-		cs_etm__copy_last_branch_rb(etmq, tidq);
+	if (etm->synth_opts.last_branch)
 		sample.branch_stack = tidq->last_branch;
-	}
 
 	if (etm->synth_opts.inject) {
 		ret = cs_etm__inject_event(event, &sample,
@@ -1431,6 +1429,10 @@ static int cs_etm__sample(struct cs_etm_queue *etmq,
 		u64 offset = etm->instructions_sample_period - instrs_prev;
 		u64 addr;
 
+		/* Prepare last branches for instruction sample */
+		if (etm->synth_opts.last_branch)
+			cs_etm__copy_last_branch_rb(etmq, tidq);
+
 		while (tidq->period_instructions >=
 				etm->instructions_sample_period) {
 			/*
@@ -1508,6 +1510,11 @@ static int cs_etm__flush(struct cs_etm_queue *etmq,
 
 	if (etmq->etm->synth_opts.last_branch &&
 	    tidq->prev_packet->sample_type == CS_ETM_RANGE) {
+		u64 addr;
+
+		/* Prepare last branches for instruction sample */
+		cs_etm__copy_last_branch_rb(etmq, tidq);
+
 		/*
 		 * Generate a last branch event for the branches left in the
 		 * circular buffer at the end of the trace.
@@ -1515,7 +1522,7 @@ static int cs_etm__flush(struct cs_etm_queue *etmq,
 		 * Use the address of the end of the last reported execution
 		 * range
 		 */
-		u64 addr = cs_etm__last_executed_instr(tidq->prev_packet);
+		addr = cs_etm__last_executed_instr(tidq->prev_packet);
 
 		err = cs_etm__synth_instruction_sample(
 			etmq, tidq, addr,
@@ -1560,11 +1567,16 @@ static int cs_etm__end_block(struct cs_etm_queue *etmq,
 	 */
 	if (etmq->etm->synth_opts.last_branch &&
 	    tidq->prev_packet->sample_type == CS_ETM_RANGE) {
+		u64 addr;
+
+		/* Prepare last branches for instruction sample */
+		cs_etm__copy_last_branch_rb(etmq, tidq);
+
 		/*
 		 * Use the address of the end of the last reported execution
 		 * range.
 		 */
-		u64 addr = cs_etm__last_executed_instr(tidq->prev_packet);
+		addr = cs_etm__last_executed_instr(tidq->prev_packet);
 
 		err = cs_etm__synth_instruction_sample(
 			etmq, tidq, addr,
-- 
2.21.1


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[PATCH 13/23] perf cs-etm: Fix unsigned variable comparison to zero

[Arnaldo Carvalho de Melo]

From: Leo Yan <leo.yan@linaro.org>

The variable 'offset' in function cs_etm__sample() is u64 type, it's not
appropriate to check it with 'while (offset > 0)'; this patch changes to
'while (offset)'.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Walker <robert.walker@arm.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: coresight ml <coresight@lists.linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lore.kernel.org/lkml/20200219021811.20067-6-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/cs-etm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 87d9943177bc..62d2f9b9ce1b 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -962,7 +962,7 @@ static inline u64 cs_etm__instr_addr(struct cs_etm_queue *etmq,
 	if (packet->isa == CS_ETM_ISA_T32) {
 		u64 addr = packet->start_addr;
 
-		while (offset > 0) {
+		while (offset) {
 			addr += cs_etm__t32_instr_size(etmq,
 						       trace_chan_id, addr);
 			offset--;
-- 
2.21.1


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