perf cs-etm: Update ETM metadata format

The current fixed metadata version format (version 0), means that adding
metadata parameter items renders files from a previous version of perf
unreadable. Per CPU parameters appear in a fixed order, but there is no
field to indicate the number of ETM parameters per CPU.

This patch updates the per CPU parameter blocks to include a NR_PARAMs
value which indicates the number of parameters in the block.

The header version is incremented to 1. Fixed ordering is retained,
new ETM parameters are added to the end of the list.

The reader code is updated to be able to read current version 0 files,
For version 1, the reader will read the number of parameters in the
per CPU block. This allows the reader to process older or newer files
that may have different numbers of parameters than in use at the
time perf was built.

Signed-off-by: Mike Leach <mike.leach@linaro.org>
Reviewed-by: Leo Yan <leo.yan@linaro.org>
Tested-by: Leo Yan <leo.yan@linaro.org>
Link: https://lore.kernel.org/r/20210202214040.32349-1-mike.leach@linaro.org
Link: https://lore.kernel.org/r/20210224164835.3497311-2-mathieu.poirier@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 25 insertions, 5 deletions

diff --git a/tools/perf/util/cs-etm.h b/tools/perf/util/cs-etm.h
index 4ad925d6d799..e153d02df0de 100644
--- a/tools/perf/util/cs-etm.h
+++ b/tools/perf/util/cs-etm.h
@@ -17,23 +17,37 @@ struct perf_session;
  */
 enum {
 	/* Starting with 0x0 */
-	CS_HEADER_VERSION_0,
+	CS_HEADER_VERSION,
 	/* PMU->type (32 bit), total # of CPUs (32 bit) */
 	CS_PMU_TYPE_CPUS,
 	CS_ETM_SNAPSHOT,
-	CS_HEADER_VERSION_0_MAX,
+	CS_HEADER_VERSION_MAX,
 };
 
+/*
+ * Update the version for new format.
+ *
+ * New version 1 format adds a param count to the per cpu metadata.
+ * This allows easy adding of new metadata parameters.
+ * Requires that new params always added after current ones.
+ * Also allows client reader to handle file versions that are different by
+ * checking the number of params in the file vs the number expected.
+ */
+#define CS_HEADER_CURRENT_VERSION 1
+
 /* Beginning of header common to both ETMv3 and V4 */
 enum {
 	CS_ETM_MAGIC,
 	CS_ETM_CPU,
+	/* Number of trace config params in following ETM specific block */
+	CS_ETM_NR_TRC_PARAMS,
+	CS_ETM_COMMON_BLK_MAX_V1,
 };
 
 /* ETMv3/PTM metadata */
 enum {
 	/* Dynamic, configurable parameters */
-	CS_ETM_ETMCR = CS_ETM_CPU + 1,
+	CS_ETM_ETMCR = CS_ETM_COMMON_BLK_MAX_V1,
 	CS_ETM_ETMTRACEIDR,
 	/* RO, taken from sysFS */
 	CS_ETM_ETMCCER,
@@ -41,10 +55,13 @@ enum {
 	CS_ETM_PRIV_MAX,
 };
 
+/* define fixed version 0 length - allow new format reader to read old files. */
+#define CS_ETM_NR_TRC_PARAMS_V0 (CS_ETM_ETMIDR - CS_ETM_ETMCR + 1)
+
 /* ETMv4 metadata */
 enum {
 	/* Dynamic, configurable parameters */
-	CS_ETMV4_TRCCONFIGR = CS_ETM_CPU + 1,
+	CS_ETMV4_TRCCONFIGR = CS_ETM_COMMON_BLK_MAX_V1,
 	CS_ETMV4_TRCTRACEIDR,
 	/* RO, taken from sysFS */
 	CS_ETMV4_TRCIDR0,
@@ -55,6 +72,9 @@ enum {
 	CS_ETMV4_PRIV_MAX,
 };
 
+/* define fixed version 0 length - allow new format reader to read old files. */
+#define CS_ETMV4_NR_TRC_PARAMS_V0 (CS_ETMV4_TRCAUTHSTATUS - CS_ETMV4_TRCCONFIGR + 1)
+
 /*
  * ETMv3 exception encoding number:
  * See Embedded Trace Macrocell spcification (ARM IHI 0014Q)
@@ -162,7 +182,7 @@ struct cs_etm_packet_queue {
 
 #define BMVAL(val, lsb, msb)	((val & GENMASK(msb, lsb)) >> lsb)
 
-#define CS_ETM_HEADER_SIZE (CS_HEADER_VERSION_0_MAX * sizeof(u64))
+#define CS_ETM_HEADER_SIZE (CS_HEADER_VERSION_MAX * sizeof(u64))
 
 #define __perf_cs_etmv3_magic 0x3030303030303030ULL
 #define __perf_cs_etmv4_magic 0x4040404040404040ULL