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Subject[PATCH v4 5/5] perf cs-etm: Detect pid in VMID for kernel running at EL2
Date
From: Suzuki K Poulose <suzuki.poulose@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.leach@linaro.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Al Grant <al.grant@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Co-developed-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
.../perf/util/cs-etm-decoder/cs-etm-decoder.c | 38 +++++++++++++++++--
1 file changed, 34 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..4052c9ce6e2f 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.poirier@linaro.org>
*/

+#include <linux/coresight-pmu.h>
#include <linux/err.h>
#include <linux/list.h>
#include <linux/zalloc.h>
@@ -491,13 +492,42 @@ 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;
+ static u64 pid_fmt;
+ int ret;

- /* Ignore PE_CONTEXT packets that don't have a valid contextID */
- if (!elem->context.ctxt_id_valid)
+ /*
+ * As all the ETMs run at the same exception level, the system should
+ * have the same PID format crossing CPUs. So cache the PID format
+ * and reuse it for sequential decoding.
+ */
+ if (!pid_fmt) {
+ 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):
+ 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
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