[PATCH v2 6/7] perf cs-etm: Detect pid in VMID for kernel running at EL2

[Leo Yan]

From: Suzuki K Poulose <suzuki.poul...@arm.com>

The PID of the task could be traced as VMID when the kernel is running
at EL2.  Teach the decoder to look for VMID when the CONTEXTIDR (Arm32)
or CONTEXTIDR_EL1 (Arm64) is invalid but we have a valid VMID.

Cc: Mike Leach <mike.le...@linaro.org>
Cc: Mathieu Poirier <mathieu.poir...@linaro.org>
Cc: Al Grant <al.gr...@arm.com>
Co-developed-by: Leo Yan <leo....@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poul...@arm.com>
Signed-off-by: Leo Yan <leo....@linaro.org>
---
 .../perf/util/cs-etm-decoder/cs-etm-decoder.c | 32 ++++++++++++++++---
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c 
b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
index 3f4bc4050477..fb2a163ff74e 100644
--- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
+++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
@@ -6,6 +6,7 @@
  * Author: Mathieu Poirier <mathieu.poir...@linaro.org>
  */
 
+#include <linux/coresight-pmu.h>
 #include <linux/err.h>
 #include <linux/list.h>
 #include <linux/zalloc.h>
@@ -491,13 +492,36 @@ cs_etm_decoder__set_tid(struct cs_etm_queue *etmq,
                        const ocsd_generic_trace_elem *elem,
                        const uint8_t trace_chan_id)
 {
-       pid_t tid;
+       pid_t tid = -1;
+       u64 pid_fmt;
+       int ret;
 
-       /* Ignore PE_CONTEXT packets that don't have a valid contextID */
-       if (!elem->context.ctxt_id_valid)
+       ret = cs_etm__get_pid_fmt(trace_chan_id, &pid_fmt);
+       if (ret)
+               return OCSD_RESP_FATAL_SYS_ERR;
+
+       /*
+        * Process the PE_CONTEXT packets if we have a valid contextID or VMID.
+        * If the kernel is running at EL2, the PID is traced in CONTEXTIDR_EL2
+        * as VMID, Bit ETM_OPT_CTXTID2 is set in this case.
+        */
+       switch (pid_fmt) {
+       case BIT(ETM_OPT_CTXTID):
+               if (elem->context.ctxt_id_valid)
+                       tid = elem->context.context_id;
+               break;
+       case BIT(ETM_OPT_CTXTID2) | BIT(ETM_OPT_CTXTID):
+       case BIT(ETM_OPT_CTXTID2):
+               if (elem->context.vmid_valid)
+                       tid = elem->context.vmid;
+               break;
+       default:
+               break;
+       }
+
+       if (tid == -1)
                return OCSD_RESP_CONT;
 
-       tid =  elem->context.context_id;
        if (cs_etm__etmq_set_tid(etmq, tid, trace_chan_id))
                return OCSD_RESP_FATAL_SYS_ERR;
 
-- 
2.25.1