linux-kernel - [PATCH 4/6] perf cs-etm: Support PID tracing in config

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Message-Id: <20210224164835.3497311-5-mathieu.poirier@linaro.org>
Date:   Wed, 24 Feb 2021 09:48:33 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     acme@...nel.org
Cc:     mike.leach@...aro.org, leo.yan@...aro.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 4/6] perf cs-etm: Support PID tracing in config

From: Suzuki K Poulose <suzuki.poulose@....com>

If the kernel is running at EL2, the pid of a task is exposed via VMID
instead of the CONTEXTID.  Add support for this in the perf tool.

This patch respects user setting if user has specified any configs
from "contextid", "contextid1" or "contextid2"; otherwise, it
dynamically sets config based on PMU format "contextid".

Cc: Mike Leach <mike.leach@...aro.org>
Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Al Grant <al.grant@....com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
Co-developed-by: Leo Yan <leo.yan@...aro.org>
Signed-off-by: Leo Yan <leo.yan@...aro.org>
Reviewed-by: Mike Leach <mike.leach@...aro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>
Link: https://lore.kernel.org/r/20210213113220.292229-4-leo.yan@linaro.org
---
 tools/include/linux/coresight-pmu.h |  3 ++
 tools/perf/arch/arm/util/cs-etm.c   | 61 +++++++++++++++++++++++------
 2 files changed, 52 insertions(+), 12 deletions(-)

diff --git a/tools/include/linux/coresight-pmu.h b/tools/include/linux/coresight-pmu.h
index 5dc47cfdcf07..4ac5c081af93 100644
--- a/tools/include/linux/coresight-pmu.h
+++ b/tools/include/linux/coresight-pmu.h
@@ -20,14 +20,17 @@
  */
 #define ETM_OPT_CYCACC		12
 #define ETM_OPT_CTXTID		14
+#define ETM_OPT_CTXTID2		15
 #define ETM_OPT_TS		28
 #define ETM_OPT_RETSTK		29
 
 /* ETMv4 CONFIGR programming bits for the ETM OPTs */
 #define ETM4_CFG_BIT_CYCACC	4
 #define ETM4_CFG_BIT_CTXTID	6
+#define ETM4_CFG_BIT_VMID	7
 #define ETM4_CFG_BIT_TS		11
 #define ETM4_CFG_BIT_RETSTK	12
+#define ETM4_CFG_BIT_VMID_OPT	15
 
 static inline int coresight_get_trace_id(int cpu)
 {
diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c
index 5b2bb7fc5ee1..911c7f2b3581 100644
--- a/tools/perf/arch/arm/util/cs-etm.c
+++ b/tools/perf/arch/arm/util/cs-etm.c
@@ -67,6 +67,7 @@ static int cs_etm_set_context_id(struct auxtrace_record *itr,
 	char path[PATH_MAX];
 	int err = -EINVAL;
 	u32 val;
+	u64 contextid;
 
 	ptr = container_of(itr, struct cs_etm_recording, itr);
 	cs_etm_pmu = ptr->cs_etm_pmu;
@@ -86,25 +87,59 @@ static int cs_etm_set_context_id(struct auxtrace_record *itr,
 		goto out;
 	}
 
+	/* User has configured for PID tracing, respects it. */
+	contextid = evsel->core.attr.config &
+			(BIT(ETM_OPT_CTXTID) | BIT(ETM_OPT_CTXTID2));
+
 	/*
-	 * TRCIDR2.CIDSIZE, bit [9-5], indicates whether contextID tracing
-	 * is supported:
-	 *  0b00000 Context ID tracing is not supported.
-	 *  0b00100 Maximum of 32-bit Context ID size.
-	 *  All other values are reserved.
+	 * If user doesn't configure the contextid format, parse PMU format and
+	 * enable PID tracing according to the "contextid" format bits:
+	 *
+	 *   If bit ETM_OPT_CTXTID is set, trace CONTEXTIDR_EL1;
+	 *   If bit ETM_OPT_CTXTID2 is set, trace CONTEXTIDR_EL2.
 	 */
-	val = BMVAL(val, 5, 9);
-	if (!val || val != 0x4) {
-		err = -EINVAL;
-		goto out;
+	if (!contextid)
+		contextid = perf_pmu__format_bits(&cs_etm_pmu->format,
+						  "contextid");
+
+	if (contextid & BIT(ETM_OPT_CTXTID)) {
+		/*
+		 * TRCIDR2.CIDSIZE, bit [9-5], indicates whether contextID
+		 * tracing is supported:
+		 *  0b00000 Context ID tracing is not supported.
+		 *  0b00100 Maximum of 32-bit Context ID size.
+		 *  All other values are reserved.
+		 */
+		val = BMVAL(val, 5, 9);
+		if (!val || val != 0x4) {
+			pr_err("%s: CONTEXTIDR_EL1 isn't supported\n",
+			       CORESIGHT_ETM_PMU_NAME);
+			err = -EINVAL;
+			goto out;
+		}
+	}
+
+	if (contextid & BIT(ETM_OPT_CTXTID2)) {
+		/*
+		 * TRCIDR2.VMIDOPT[30:29] != 0 and
+		 * TRCIDR2.VMIDSIZE[14:10] == 0b00100 (32bit virtual contextid)
+		 * We can't support CONTEXTIDR in VMID if the size of the
+		 * virtual context id is < 32bit.
+		 * Any value of VMIDSIZE >= 4 (i.e, > 32bit) is fine for us.
+		 */
+		if (!BMVAL(val, 29, 30) || BMVAL(val, 10, 14) < 4) {
+			pr_err("%s: CONTEXTIDR_EL2 isn't supported\n",
+			       CORESIGHT_ETM_PMU_NAME);
+			err = -EINVAL;
+			goto out;
+		}
 	}
 
 	/* All good, let the kernel know */
-	evsel->core.attr.config |= (1 << ETM_OPT_CTXTID);
+	evsel->core.attr.config |= contextid;
 	err = 0;
 
 out:
-
 	return err;
 }
 
@@ -485,7 +520,9 @@ static u64 cs_etmv4_get_config(struct auxtrace_record *itr)
 		config |= BIT(ETM4_CFG_BIT_TS);
 	if (config_opts & BIT(ETM_OPT_RETSTK))
 		config |= BIT(ETM4_CFG_BIT_RETSTK);
-
+	if (config_opts & BIT(ETM_OPT_CTXTID2))
+		config |= BIT(ETM4_CFG_BIT_VMID) |
+			  BIT(ETM4_CFG_BIT_VMID_OPT);
 	return config;
 }
 
-- 
2.25.1