Subject: Patch "perf cs-etm: Change tuple from traceID-CPU# to traceID-metadata" has been added to the 4.19-stable tree

From: <[email-masked]>
Date: Sun, 27 Dec 2020 12:42:30 +0100

This is a note to let you know that I've just added the patch titled

    perf cs-etm: Change tuple from traceID-CPU# to traceID-metadata

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     perf-cs-etm-change-tuple-from-traceid-cpu-to-traceid-metadata.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <[email-masked]> know about it.

>From 95c6fe970a0160cb770c5dce9f80311b42d030c0 Mon Sep 17 00:00:00 2001
From: Leo Yan <[email-masked]>
Date: Tue, 29 Jan 2019 20:28:39 +0800
Subject: perf cs-etm: Change tuple from traceID-CPU# to traceID-metadata

From: Leo Yan <[email-masked]>

commit 95c6fe970a0160cb770c5dce9f80311b42d030c0 upstream.

If packet processing wants to know the packet is bound with which ETM
version, it needs to access metadata to decide that based on metadata
magic number; but we cannot simply to use CPU logic ID number as index
to access metadata sequential array, especially when system have
hotplugged off CPUs, the metadata array are only allocated for online
CPUs but not offline CPUs, so the CPU logic number doesn't match with
its index in the array.

This patch is to change tuple from traceID-CPU# to traceID-metadata,
thus it can use the tuple to retrieve metadata pointer according to
traceID.

For safe accessing metadata fields, this patch provides helper function
cs_etm__get_cpu() which is used to return CPU number according to
traceID; cs_etm_decoder__buffer_packet() is the first consumer for this
helper function.

Signed-off-by: Leo Yan <[email-masked]>
Reviewed-by: Mathieu Poirier <[email-masked]>
Cc: Alexander Shishkin <[email-masked]>
Cc: Jiri Olsa <[email-masked]>
Cc: Mike Leach <[email-masked]>
Cc: Namhyung Kim <[email-masked]>
Cc: Robert Walker <[email-masked]>
Cc: Suzuki K Poulouse <[email-masked]>
Cc: coresight ml <[email-masked]>
Cc: [email-masked]
Link: http://lkml.kernel.org/r/[email-masked]
Signed-off-by: Arnaldo Carvalho de Melo <[email-masked]>
[Salvatore Bonaccorso: Adjust for context changes in
tools/perf/util/cs-etm-decoder/cs-etm-decoder.c]
Signed-off-by: Salvatore Bonaccorso <[email-masked]>
Signed-off-by: Greg Kroah-Hartman <[email-masked]>
---
 tools/perf/util/cs-etm-decoder/cs-etm-decoder.c |    8 ++-----
 tools/perf/util/cs-etm.c                        |   26 ++++++++++++++++++------
 tools/perf/util/cs-etm.h                        |    9 +++++++-
 3 files changed, 31 insertions(+), 12 deletions(-)

--- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
+++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
@@ -278,14 +278,12 @@ cs_etm_decoder__buffer_packet(struct cs_
 			      enum cs_etm_sample_type sample_type)
 {
 	u32 et = 0;
-	struct int_node *inode = NULL;
+	int cpu;
 
 	if (decoder->packet_count >= MAX_BUFFER - 1)
 		return OCSD_RESP_FATAL_SYS_ERR;
 
-	/* Search the RB tree for the cpu associated with this traceID */
-	inode = intlist__find(traceid_list, trace_chan_id);
-	if (!inode)
+	if (cs_etm__get_cpu(trace_chan_id, &cpu) < 0)
 		return OCSD_RESP_FATAL_SYS_ERR;
 
 	et = decoder->tail;
@@ -296,7 +294,7 @@ cs_etm_decoder__buffer_packet(struct cs_
 	decoder->packet_buffer[et].sample_type = sample_type;
 	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].cpu = cpu;
 	decoder->packet_buffer[et].start_addr = CS_ETM_INVAL_ADDR;
 	decoder->packet_buffer[et].end_addr = CS_ETM_INVAL_ADDR;
 
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -91,6 +91,20 @@ static int cs_etm__update_queues(struct
 static int cs_etm__process_timeless_queues(struct cs_etm_auxtrace *etm,
 					   pid_t tid, u64 time_);
 
+int cs_etm__get_cpu(u8 trace_chan_id, int *cpu)
+{
+	struct int_node *inode;
+	u64 *metadata;
+
+	inode = intlist__find(traceid_list, trace_chan_id);
+	if (!inode)
+		return -EINVAL;
+
+	metadata = inode->priv;
+	*cpu = (int)metadata[CS_ETM_CPU];
+	return 0;
+}
+
 static void cs_etm__packet_dump(const char *pkt_string)
 {
 	const char *color = PERF_COLOR_BLUE;
@@ -230,7 +244,7 @@ static void cs_etm__free(struct perf_ses
 	cs_etm__free_events(session);
 	session->auxtrace = NULL;
 
-	/* First remove all traceID/CPU# nodes for the RB tree */
+	/* First remove all traceID/metadata nodes for the RB tree */
 	intlist__for_each_entry_safe(inode, tmp, traceid_list)
 		intlist__remove(traceid_list, inode);
 	/* Then the RB tree itself */
@@ -1316,9 +1330,9 @@ int cs_etm__process_auxtrace_info(union
 				    0xffffffff);
 
 	/*
-	 * Create an RB tree for traceID-CPU# tuple. Since the conversion has
-	 * to be made for each packet that gets decoded, optimizing access in
-	 * anything other than a sequential array is worth doing.
+	 * Create an RB tree for traceID-metadata tuple.  Since the conversion
+	 * has to be made for each packet that gets decoded, optimizing access
+	 * in anything other than a sequential array is worth doing.
 	 */
 	traceid_list = intlist__new(NULL);
 	if (!traceid_list) {
@@ -1384,8 +1398,8 @@ int cs_etm__process_auxtrace_info(union
 			err = -EINVAL;
 			goto err_free_metadata;
 		}
-		/* All good, associate the traceID with the CPU# */
-		inode->priv = &metadata[j][CS_ETM_CPU];
+		/* All good, associate the traceID with the metadata pointer */
+		inode->priv = metadata[j];
 	}
 
 	/*
--- a/tools/perf/util/cs-etm.h
+++ b/tools/perf/util/cs-etm.h
@@ -53,7 +53,7 @@ enum {
 	CS_ETMV4_PRIV_MAX,
 };
 
-/* RB tree for quick conversion between traceID and CPUs */
+/* RB tree for quick conversion between traceID and metadata pointers */
 struct intlist *traceid_list;
 
 #define KiB(x) ((x) * 1024)
@@ -69,6 +69,7 @@ static const u64 __perf_cs_etmv4_magic
 #ifdef HAVE_CSTRACE_SUPPORT
 int cs_etm__process_auxtrace_info(union perf_event *event,
 				  struct perf_session *session);
+int cs_etm__get_cpu(u8 trace_chan_id, int *cpu);
 #else
 static inline int
 cs_etm__process_auxtrace_info(union perf_event *event __maybe_unused,
@@ -76,6 +77,12 @@ cs_etm__process_auxtrace_info(union perf
 {
 	return -1;
 }
+
+static inline int cs_etm__get_cpu(u8 trace_chan_id __maybe_unused,
+				  int *cpu __maybe_unused)
+{
+	return -1;
+}
 #endif
 
 #endif

Patches currently in stable-queue which might be from [email-masked] are

queue-4.19/perf-cs-etm-change-tuple-from-traceid-cpu-to-traceid-metadata.patch
queue-4.19/perf-cs-etm-move-definition-of-traceid_list-global-variable-from-header-file.patch

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