On 2/4/21 3:47 AM, Leo Yan wrote:
On Tue, Feb 02, 2021 at 11:19:22PM +0000, Suzuki Kuruppassery Poulose wrote:
On 2/2/21 4:38 PM, Leo Yan wrote:
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>
---
tools/perf/util/cs-etm.c | 43 ++++++++++++++++++++++++++++++++++++++++
tools/perf/util/cs-etm.h | 1 +
2 files changed, 44 insertions(+)
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index a2a369e2fbb6..8194ddbd01e5 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 +157,48 @@ 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 these two bits are set together, this means the tracing
+ * contains PIDs for both CONTEXTIDR_EL1 and CONTEXTIDR_EL2.
This is a bit confusing. If both the bits are set, the session
was run on an EL2 kernel. Thus, the PID is always in CONTEXTIDR_EL2.
Sorry for confusion. I'd like to rephrase as:
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];
+
+ *pid_fmt = 0;
+
+ /* 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 */
+ if (val & BIT(ETM4_CFG_BIT_CTXTID))
I haven't looked at how this gets used. But, Shouldn't this be :
else if (val & BIT(ETM4_CFG_BIT_CTXTID)) ?
Actually it's deliberately to set both bits ETM_OPT_CTXTID2 and
ETM_OPT_CTXTID if user has enable configs "contextid1" and
"contextid2". So this is exactly the reversed flow in the
function cs_etmv4_get_config().
The point is, we don't care if the user selected both options. What we
care is, where can we find the PID. CONTEXTIDR_EL1 or CONTEXTIDR_EL2.
As such, get_pid_fmt simply should make that decision and pass it on.
So, if the CONTEXTIDR_EL2 is selected (which can only be done successfully
on an EL2 kernel), thats our pid.
So we should return the format for the PID here. i.e
ETM_OPT_CTXTID2 OR ETM_OPT_CTXTID. But not both.
Cheers
Suzuki
