[PATCH v4 4/5] perf cs-etm: Add helper cs_etm__get_pid_fmt()

[Leo Yan]

This patch adds helper function cs_etm__get_pid_fmt(), by passing
parameter "traceID", it returns the PID format.

Signed-off-by: Leo Yan <leo....@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poir...@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poul...@arm.com>
---
 tools/perf/util/cs-etm.c | 42 ++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/cs-etm.h |  1 +
 2 files changed, 43 insertions(+)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index a2a369e2fbb6..b9c1d329a7f1 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -7,6 +7,7 @@
  */
 
 #include <linux/bitops.h>
+#include <linux/coresight-pmu.h>
 #include <linux/err.h>
 #include <linux/kernel.h>
 #include <linux/log2.h>
@@ -156,6 +157,47 @@ int cs_etm__get_cpu(u8 trace_chan_id, int *cpu)
        return 0;
 }
 
+/*
+ * The returned PID format is presented by two bits:
+ *
+ *   Bit ETM_OPT_CTXTID: CONTEXTIDR or CONTEXTIDR_EL1 is traced;
+ *   Bit ETM_OPT_CTXTID2: CONTEXTIDR_EL2 is traced.
+ *
+ * It's possible that the two bits ETM_OPT_CTXTID and ETM_OPT_CTXTID2
+ * are enabled at the same time when the session runs on an EL2 kernel.
+ * This means the CONTEXTIDR_EL1 and CONTEXTIDR_EL2 both will be
+ * recorded in the trace data, the tool will selectively use
+ * CONTEXTIDR_EL2 as PID.
+ */
+int cs_etm__get_pid_fmt(u8 trace_chan_id, u64 *pid_fmt)
+{
+       struct int_node *inode;
+       u64 *metadata, val;
+
+       inode = intlist__find(traceid_list, trace_chan_id);
+       if (!inode)
+               return -EINVAL;
+
+       metadata = inode->priv;
+
+       if (metadata[CS_ETM_MAGIC] == __perf_cs_etmv3_magic) {
+               val = metadata[CS_ETM_ETMCR];
+               /* CONTEXTIDR is traced */
+               if (val & BIT(ETM_OPT_CTXTID))
+                       *pid_fmt = BIT(ETM_OPT_CTXTID);
+       } else {
+               val = metadata[CS_ETMV4_TRCCONFIGR];
+               /* CONTEXTIDR_EL2 is traced */
+               if (val & (BIT(ETM4_CFG_BIT_VMID) | BIT(ETM4_CFG_BIT_VMID_OPT)))
+                       *pid_fmt = BIT(ETM_OPT_CTXTID2);
+               /* CONTEXTIDR_EL1 is traced */
+               else if (val & BIT(ETM4_CFG_BIT_CTXTID))
+                       *pid_fmt = BIT(ETM_OPT_CTXTID);
+       }
+
+       return 0;
+}
+
 void cs_etm__etmq_set_traceid_queue_timestamp(struct cs_etm_queue *etmq,
                                              u8 trace_chan_id)
 {
diff --git a/tools/perf/util/cs-etm.h b/tools/perf/util/cs-etm.h
index 4ad925d6d799..7cc3bba0017d 100644
--- a/tools/perf/util/cs-etm.h
+++ b/tools/perf/util/cs-etm.h
@@ -173,6 +173,7 @@ struct cs_etm_packet_queue {
 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);
+int cs_etm__get_pid_fmt(u8 trace_chan_id, u64 *pid_fmt);
 int cs_etm__etmq_set_tid(struct cs_etm_queue *etmq,
                         pid_t tid, u8 trace_chan_id);
 bool cs_etm__etmq_is_timeless(struct cs_etm_queue *etmq);
-- 
2.25.1