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From 7150eac72ee0c2c7da03f53a90a871c3d6d4e538 Mon Sep 17 00:00:00 2001
From: Suzuki K Poulose <suzuki.poulose@arm.com>
Date: Tue, 14 Sep 2021 11:26:32 +0100
Subject: [PATCH 1/2] coresight: etm4x: Save restore TRFCR_EL1
When the CPU enters a low power mode, the TRFCR_EL1 contents could be
reset. Thus we need to save/restore the TRFCR_EL1 along with the ETM4x
registers to allow the tracing.
The TRFCR related helpers are in a new header file, as we need to use
them for TRBE in the later patches.
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20210914102641.1852544-2-suzuki.poulose@arm.com
[Fixed cosmetic details]
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Upstream-Status: Backport [https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=937d3f58cacf377cab7c32e475e1ffa91d611dce]
Signed-off-by: Davidson K <davidson.kumaresan@arm.com>
---
.../coresight/coresight-etm4x-core.c | 43 +++++++++++++------
drivers/hwtracing/coresight/coresight-etm4x.h | 2 +
.../coresight/coresight-self-hosted-trace.h | 24 +++++++++++
3 files changed, 57 insertions(+), 12 deletions(-)
create mode 100644 drivers/hwtracing/coresight/coresight-self-hosted-trace.h
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 90827077d2f9..b78080d169f8 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -39,6 +39,7 @@
#include "coresight-etm4x.h"
#include "coresight-etm-perf.h"
+#include "coresight-self-hosted-trace.h"
static int boot_enable;
module_param(boot_enable, int, 0444);
@@ -990,7 +991,7 @@ static void cpu_enable_tracing(struct etmv4_drvdata *drvdata)
if (is_kernel_in_hyp_mode())
trfcr |= TRFCR_EL2_CX;
- write_sysreg_s(trfcr, SYS_TRFCR_EL1);
+ write_trfcr(trfcr);
}
static void etm4_init_arch_data(void *info)
@@ -1528,7 +1529,7 @@ static void etm4_init_trace_id(struct etmv4_drvdata *drvdata)
drvdata->trcid = coresight_get_trace_id(drvdata->cpu);
}
-static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
+static int __etm4_cpu_save(struct etmv4_drvdata *drvdata)
{
int i, ret = 0;
struct etmv4_save_state *state;
@@ -1667,7 +1668,23 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
return ret;
}
-static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
+static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
+{
+ int ret = 0;
+
+ /* Save the TRFCR irrespective of whether the ETM is ON */
+ if (drvdata->trfc)
+ drvdata->save_trfcr = read_trfcr();
+ /*
+ * Save and restore the ETM Trace registers only if
+ * the ETM is active.
+ */
+ if (local_read(&drvdata->mode) && drvdata->save_state)
+ ret = __etm4_cpu_save(drvdata);
+ return ret;
+}
+
+static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata)
{
int i;
struct etmv4_save_state *state = drvdata->save_state;
@@ -1763,6 +1780,14 @@ static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
etm4_cs_lock(drvdata, csa);
}
+static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
+{
+ if (drvdata->trfc)
+ write_trfcr(drvdata->save_trfcr);
+ if (drvdata->state_needs_restore)
+ __etm4_cpu_restore(drvdata);
+}
+
static int etm4_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
void *v)
{
@@ -1774,23 +1799,17 @@ static int etm4_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
drvdata = etmdrvdata[cpu];
- if (!drvdata->save_state)
- return NOTIFY_OK;
-
if (WARN_ON_ONCE(drvdata->cpu != cpu))
return NOTIFY_BAD;
switch (cmd) {
case CPU_PM_ENTER:
- /* save the state if self-hosted coresight is in use */
- if (local_read(&drvdata->mode))
- if (etm4_cpu_save(drvdata))
- return NOTIFY_BAD;
+ if (etm4_cpu_save(drvdata))
+ return NOTIFY_BAD;
break;
case CPU_PM_EXIT:
case CPU_PM_ENTER_FAILED:
- if (drvdata->state_needs_restore)
- etm4_cpu_restore(drvdata);
+ etm4_cpu_restore(drvdata);
break;
default:
return NOTIFY_DONE;
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index e5b79bdb9851..82cba16b73a6 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -921,6 +921,7 @@ struct etmv4_save_state {
* @lpoverride: If the implementation can support low-power state over.
* @trfc: If the implementation supports Arm v8.4 trace filter controls.
* @config: structure holding configuration parameters.
+ * @save_trfcr: Saved TRFCR_EL1 register during a CPU PM event.
* @save_state: State to be preserved across power loss
* @state_needs_restore: True when there is context to restore after PM exit
* @skip_power_up: Indicates if an implementation can skip powering up
@@ -973,6 +974,7 @@ struct etmv4_drvdata {
bool lpoverride;
bool trfc;
struct etmv4_config config;
+ u64 save_trfcr;
struct etmv4_save_state *save_state;
bool state_needs_restore;
bool skip_power_up;
diff --git a/drivers/hwtracing/coresight/coresight-self-hosted-trace.h b/drivers/hwtracing/coresight/coresight-self-hosted-trace.h
new file mode 100644
index 000000000000..303d71911870
--- /dev/null
+++ b/drivers/hwtracing/coresight/coresight-self-hosted-trace.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Arm v8 Self-Hosted trace support.
+ *
+ * Copyright (C) 2021 ARM Ltd.
+ */
+
+#ifndef __CORESIGHT_SELF_HOSTED_TRACE_H
+#define __CORESIGHT_SELF_HOSTED_TRACE_H
+
+#include <asm/sysreg.h>
+
+static inline u64 read_trfcr(void)
+{
+ return read_sysreg_s(SYS_TRFCR_EL1);
+}
+
+static inline void write_trfcr(u64 val)
+{
+ write_sysreg_s(val, SYS_TRFCR_EL1);
+ isb();
+}
+
+#endif /* __CORESIGHT_SELF_HOSTED_TRACE_H */
--
2.34.1
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