Re: [PATCH v2 6/7] perf cs-etm: Detect pid in VMID for kernel running at EL2
From: Suzuki K Poulose
Date: Thu Feb 04 2021 - 05:58:13 EST
On 2/4/21 4:00 AM, Leo Yan wrote:
On Tue, Feb 02, 2021 at 11:29:47PM +0000, Suzuki Kuruppassery Poulose wrote:
On 2/2/21 4:38 PM, Leo Yan wrote:
From: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
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@xxxxxxxxxx>
Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Al Grant <al.grant@xxxxxxx>
Co-developed-by: Leo Yan <leo.yan@xxxxxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
---
.../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.poirier@xxxxxxxxxx>
*/
+#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)
Is this something we can cache in this function ? e.g,
static u64 pid_fmt;
if (!pid_pfmt)
ret = cs_etm__get_pid_fmt(trace_chan_id, &pid_fmt);
As all the ETMs will be running at the same exception level.
Sorry that I let you repeated your comments again.
To be honest, I considered this after read your comment in the previous
series, but I thought it's possible that multiple CPUs have different
PID format, especially for big.LITTLE arch. After read your suggestion
again, I think my concern is not valid, even for big.LITTLE, all CPUs
should run on the same kernel exception level.
So will follow up your suggestion to cache "pid_fmt".
No problem.
+ 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):
I would rather fix the cs_etm__get_pid_fmt() to return either of these
as commented. i.e, ETM_OPT_CTXTID or ETM_OPT_CTXTID2. Thus we don't
need the this case.
I explained why I set both bits for ETM_OPT_CTXTID and ETM_OPT_CTXTID2
in the patch 05/07. Could you take a look for it?
I have responded to the comment in the patch.
With the above two addressed:
Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Thanks
Suzuki