diff mbox series

[v2,01/10] coresight: etm4x: Save restore TRFCR_EL1

Message ID 20210723124611.3828908-2-suzuki.poulose@arm.com (mailing list archive)
State New, archived
Headers show
Series coresight: TRBE and Self-Hosted trace fixes | expand

Commit Message

Suzuki K Poulose July 23, 2021, 12:46 p.m. UTC 
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>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
Changes since v1:
 - Moved the TRFCR helpers in to a new header file
---
 .../coresight/coresight-etm4x-core.c          | 43 +++++++++++++------
 drivers/hwtracing/coresight/coresight-etm4x.h |  2 +
 .../coresight/coresight-self-hosted-trace.h   | 25 +++++++++++
 3 files changed, 58 insertions(+), 12 deletions(-)
 create mode 100644 drivers/hwtracing/coresight/coresight-self-hosted-trace.h

Comments

Anshuman Khandual July 30, 2021, 3:05 a.m. UTC | #1 
On 7/23/21 6:16 PM, Suzuki K Poulose wrote:
> 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>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
> Changes since v1:
>  - Moved the TRFCR helpers in to a new header file
> ---
>  .../coresight/coresight-etm4x-core.c          | 43 +++++++++++++------
>  drivers/hwtracing/coresight/coresight-etm4x.h |  2 +
>  .../coresight/coresight-self-hosted-trace.h   | 25 +++++++++++
>  3 files changed, 58 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 da27cd4a3c38..3e548dac9b05 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);
> @@ -985,7 +986,7 @@ 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..53b35a28075e
> --- /dev/null
> +++ b/drivers/hwtracing/coresight/coresight-self-hosted-trace.h
> @@ -0,0 +1,25 @@
> +/* 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 */
> 

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
diff mbox series

Patch

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index da27cd4a3c38..3e548dac9b05 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);
@@ -985,7 +986,7 @@  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..53b35a28075e
--- /dev/null
+++ b/drivers/hwtracing/coresight/coresight-self-hosted-trace.h
@@ -0,0 +1,25 @@ 
+/* 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 */