Re: [PATCH v8 10/24] coresight: etm4x: allow etm4x to be built as a module

[Mathieu Poirier <mathieu.poirier@linaro.org>]

On Fri, Aug 07, 2020 at 07:11:39PM +0800, Tingwei Zhang wrote:
> From: Kim Phillips <kim.phillips@arm.com>
> 
> Allow to build coresight-etm4x as a module, for ease of development.
> 
> - Kconfig becomes a tristate, to allow =m
> - append -core to source file name to allow module to
>   be called coresight-etm4x by the Makefile
> - add an etm4_remove function, for module unload
> - add a MODULE_DEVICE_TABLE for autoloading on boot
> - protect etmdrvdata[] with mutex lock from racing
>   between module unload and CPU hotplug
> 
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Cc: Leo Yan <leo.yan@linaro.org>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: Randy Dunlap <rdunlap@infradead.org>
> Cc: Suzuki K Poulose <Suzuki.Poulose@arm.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Russell King <linux@armlinux.org.uk>
> Signed-off-by: Kim Phillips <kim.phillips@arm.com>
> Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
> Tested-by: Mike Leach <mike.leach@linaro.org>
> ---
>  drivers/hwtracing/coresight/Kconfig           |   5 +-
>  drivers/hwtracing/coresight/Makefile          |   4 +-
>  ...resight-etm4x.c => coresight-etm4x-core.c} | 118 +++++++++++++-----
>  3 files changed, 92 insertions(+), 35 deletions(-)
>  rename drivers/hwtracing/coresight/{coresight-etm4x.c => coresight-etm4x-core.c} (95%)
> 
> diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
> index 8fd9fd139cf3..d6e107bbd30b 100644
> --- a/drivers/hwtracing/coresight/Kconfig
> +++ b/drivers/hwtracing/coresight/Kconfig
> @@ -78,7 +78,7 @@ config CORESIGHT_SOURCE_ETM3X
>  	  module will be called coresight-etm3x.
>  
>  config CORESIGHT_SOURCE_ETM4X
> -	bool "CoreSight Embedded Trace Macrocell 4.x driver"
> +	tristate "CoreSight Embedded Trace Macrocell 4.x driver"
>  	depends on ARM64
>  	select CORESIGHT_LINKS_AND_SINKS
>  	select PID_IN_CONTEXTIDR
> @@ -88,6 +88,9 @@ config CORESIGHT_SOURCE_ETM4X
>  	  for instruction level tracing. Depending on the implemented version
>  	  data tracing may also be available.
>  
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called coresight-etm4x.
> +
>  config CORESIGHT_STM
>  	tristate "CoreSight System Trace Macrocell driver"
>  	depends on (ARM && !(CPU_32v3 || CPU_32v4 || CPU_32v4T)) || ARM64
> diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
> index d619cfd0abd8..271dc255454f 100644
> --- a/drivers/hwtracing/coresight/Makefile
> +++ b/drivers/hwtracing/coresight/Makefile
> @@ -14,8 +14,8 @@ obj-$(CONFIG_CORESIGHT_LINKS_AND_SINKS) += coresight-funnel.o \
>  obj-$(CONFIG_CORESIGHT_SOURCE_ETM3X) += coresight-etm3x.o
>  coresight-etm3x-y := coresight-etm3x-core.o coresight-etm-cp14.o \
>  					coresight-etm3x-sysfs.o
> -obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o \
> -					coresight-etm4x-sysfs.o
> +obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o
> +coresight-etm4x-y := coresight-etm4x-core.o coresight-etm4x-sysfs.o
>  obj-$(CONFIG_CORESIGHT_STM) += coresight-stm.o
>  obj-$(CONFIG_CORESIGHT_CPU_DEBUG) += coresight-cpu-debug.o
>  obj-$(CONFIG_CORESIGHT_CATU) += coresight-catu.o
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> similarity index 95%
> rename from drivers/hwtracing/coresight/coresight-etm4x.c
> rename to drivers/hwtracing/coresight/coresight-etm4x-core.c
> index fddfd93b9a7b..ae9847e194a3 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -48,6 +48,7 @@ module_param(pm_save_enable, int, 0444);
>  MODULE_PARM_DESC(pm_save_enable,
>  	"Save/restore state on power down: 1 = never, 2 = self-hosted");
>  
> +static DEFINE_PER_CPU(struct mutex, etmdrvdata_lock);
>  static struct etmv4_drvdata *etmdrvdata[NR_CPUS];
>  static void etm4_set_default_config(struct etmv4_config *config);
>  static int etm4_set_event_filters(struct etmv4_drvdata *drvdata,
> @@ -1089,18 +1090,25 @@ void etm4_config_trace_mode(struct etmv4_config *config)
>  
>  static int etm4_online_cpu(unsigned int cpu)
>  {
> -	if (!etmdrvdata[cpu])
> +	mutex_lock(&per_cpu(etmdrvdata_lock, cpu));
> +	if (!etmdrvdata[cpu]) {
> +		mutex_unlock(&per_cpu(etmdrvdata_lock, cpu));
>  		return 0;
> +	}
>  
>  	if (etmdrvdata[cpu]->boot_enable && !etmdrvdata[cpu]->sticky_enable)
>  		coresight_enable(etmdrvdata[cpu]->csdev);
> +	mutex_unlock(&per_cpu(etmdrvdata_lock, cpu));
>  	return 0;
>  }
>  
>  static int etm4_starting_cpu(unsigned int cpu)
>  {
> -	if (!etmdrvdata[cpu])
> +	mutex_lock(&per_cpu(etmdrvdata_lock, cpu));
> +	if (!etmdrvdata[cpu]) {
> +		mutex_unlock(&per_cpu(etmdrvdata_lock, cpu));
>  		return 0;
> +	}
>  
>  	spin_lock(&etmdrvdata[cpu]->spinlock);
>  	if (!etmdrvdata[cpu]->os_unlock)
> @@ -1109,18 +1117,23 @@ static int etm4_starting_cpu(unsigned int cpu)
>  	if (local_read(&etmdrvdata[cpu]->mode))
>  		etm4_enable_hw(etmdrvdata[cpu]);
>  	spin_unlock(&etmdrvdata[cpu]->spinlock);
> +	mutex_unlock(&per_cpu(etmdrvdata_lock, cpu));
>  	return 0;
>  }
>  
>  static int etm4_dying_cpu(unsigned int cpu)
>  {
> -	if (!etmdrvdata[cpu])
> +	mutex_lock(&per_cpu(etmdrvdata_lock, cpu));
> +	if (!etmdrvdata[cpu]) {
> +		mutex_unlock(&per_cpu(etmdrvdata_lock, cpu));
>  		return 0;
> +	}
>  
>  	spin_lock(&etmdrvdata[cpu]->spinlock);
>  	if (local_read(&etmdrvdata[cpu]->mode))
>  		etm4_disable_hw(etmdrvdata[cpu]);
>  	spin_unlock(&etmdrvdata[cpu]->spinlock);
> +	mutex_unlock(&per_cpu(etmdrvdata_lock, cpu));
>  	return 0;
>  }
>  
> @@ -1360,24 +1373,30 @@ static int etm4_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
>  {
>  	struct etmv4_drvdata *drvdata;
>  	unsigned int cpu = smp_processor_id();
> +	int ret = NOTIFY_OK;
>  
> +	mutex_lock(&per_cpu(etmdrvdata_lock, cpu));
>  	if (!etmdrvdata[cpu])
> -		return NOTIFY_OK;
> +		goto out;
>  
>  	drvdata = etmdrvdata[cpu];
>  
>  	if (!drvdata->save_state)
> -		return NOTIFY_OK;
> +		goto out;
>  
> -	if (WARN_ON_ONCE(drvdata->cpu != cpu))
> -		return NOTIFY_BAD;
> +	if (WARN_ON_ONCE(drvdata->cpu != cpu)) {
> +		ret = NOTIFY_BAD;
> +		goto out;
> +	}
>  
>  	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)) {
> +				ret = NOTIFY_BAD;
> +				goto out;
> +			}
>  		break;
>  	case CPU_PM_EXIT:
>  		/* fallthrough */
> @@ -1386,10 +1405,12 @@ static int etm4_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
>  			etm4_cpu_restore(drvdata);
>  		break;
>  	default:
> -		return NOTIFY_DONE;
> +		goto out;
>  	}
>  
> -	return NOTIFY_OK;
> +out:
> +	mutex_unlock(&per_cpu(etmdrvdata_lock, cpu));
> +	return ret;
>  }
>  
>  static struct notifier_block etm4_cpu_pm_nb = {
> @@ -1430,7 +1451,7 @@ static int __init etm4_pm_setup(void)
>  	return ret;
>  }
>  
> -static void __init etm4_pm_clear(void)
> +static void etm4_pm_clear(void)
>  {
>  	cpu_pm_unregister_notifier(&etm4_cpu_pm_nb);
>  	cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);
> @@ -1487,25 +1508,20 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
>  	if (!desc.name)
>  		return -ENOMEM;
>  
> -	etmdrvdata[drvdata->cpu] = drvdata;
> -
>  	if (smp_call_function_single(drvdata->cpu,
>  				etm4_init_arch_data,  drvdata, 1))
>  		dev_err(dev, "ETM arch init failed\n");
>  
> -	if (etm4_arch_supported(drvdata->arch) == false) {
> -		ret = -EINVAL;
> -		goto err_arch_supported;
> -	}
> +	if (etm4_arch_supported(drvdata->arch) == false)
> +		return -EINVAL;
>  
>  	etm4_init_trace_id(drvdata);
>  	etm4_set_default(&drvdata->config);
>  
>  	pdata = coresight_get_platform_data(dev);
> -	if (IS_ERR(pdata)) {
> -		ret = PTR_ERR(pdata);
> -		goto err_arch_supported;
> -	}
> +	if (IS_ERR(pdata))
> +		return PTR_ERR(pdata);
> +
>  	adev->dev.platform_data = pdata;
>  
>  	desc.type = CORESIGHT_DEV_TYPE_SOURCE;
> @@ -1515,17 +1531,19 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
>  	desc.dev = dev;
>  	desc.groups = coresight_etmv4_groups;
>  	drvdata->csdev = coresight_register(&desc);
> -	if (IS_ERR(drvdata->csdev)) {
> -		ret = PTR_ERR(drvdata->csdev);
> -		goto err_arch_supported;
> -	}
> +	if (IS_ERR(drvdata->csdev))
> +		return PTR_ERR(drvdata->csdev);
>  
>  	ret = etm_perf_symlink(drvdata->csdev, true);
>  	if (ret) {
>  		coresight_unregister(drvdata->csdev);
> -		goto err_arch_supported;
> +		return ret;
>  	}
>  
> +	mutex_lock(&per_cpu(etmdrvdata_lock, drvdata->cpu));
> +	etmdrvdata[drvdata->cpu] = drvdata;
> +	mutex_unlock(&per_cpu(etmdrvdata_lock, drvdata->cpu));
> +
>  	pm_runtime_put(&adev->dev);
>  	dev_info(&drvdata->csdev->dev, "CPU%d: ETM v%d.%d initialized\n",
>  		 drvdata->cpu, drvdata->arch >> 4, drvdata->arch & 0xf);
> @@ -1536,10 +1554,6 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
>  	}
>  
>  	return 0;
> -
> -err_arch_supported:
> -	etmdrvdata[drvdata->cpu] = NULL;
> -	return ret;
>  }
>  
>  static struct amba_cs_uci_id uci_id_etm4[] = {
> @@ -1551,6 +1565,22 @@ static struct amba_cs_uci_id uci_id_etm4[] = {
>  	}
>  };
>  
> +static int __exit etm4_remove(struct amba_device *adev)
> +{
> +	struct etmv4_drvdata *drvdata = dev_get_drvdata(&adev->dev);
> +
> +	etm_perf_symlink(drvdata->csdev, false);
> +
> +	mutex_lock(&per_cpu(etmdrvdata_lock, drvdata->cpu));
> +	etmdrvdata[drvdata->cpu] = NULL;
> +	mutex_unlock(&per_cpu(etmdrvdata_lock, drvdata->cpu));
> +
> +	coresight_unregister(drvdata->csdev);
> +
> +	return 0;
> +}
> +
> +

Extra line

>  static const struct amba_id etm4_ids[] = {
>  	CS_AMBA_ID(0x000bb95d),			/* Cortex-A53 */
>  	CS_AMBA_ID(0x000bb95e),			/* Cortex-A57 */
> @@ -1568,18 +1598,26 @@ static const struct amba_id etm4_ids[] = {
>  	{},
>  };
>  
> +MODULE_DEVICE_TABLE(amba, etm4_ids);
> +
>  static struct amba_driver etm4x_driver = {
>  	.drv = {
>  		.name   = "coresight-etm4x",
> +		.owner  = THIS_MODULE,
>  		.suppress_bind_attrs = true,
>  	},
>  	.probe		= etm4_probe,
> +	.remove         = etm4_remove,
>  	.id_table	= etm4_ids,
>  };
>  
>  static int __init etm4x_init(void)
>  {
>  	int ret;
> +	int cpu;
> +
> +	for_each_possible_cpu(cpu)
> +		mutex_init(&per_cpu(etmdrvdata_lock, cpu));
>  
>  	ret = etm4_pm_setup();
>  
> @@ -1595,4 +1633,20 @@ static int __init etm4x_init(void)
>  
>  	return ret;
>  }
> -device_initcall(etm4x_init);
> +
> +static void __exit etm4x_exit(void)
> +{
> +	int cpu;
> +
> +	amba_driver_unregister(&etm4x_driver);
> +	etm4_pm_clear();
> +	for_each_possible_cpu(cpu)
> +		mutex_destroy(&per_cpu(etmdrvdata_lock, cpu));
> +}
> +module_init(etm4x_init);
> +module_exit(etm4x_exit);
> +
> +MODULE_AUTHOR("Pratik Patel <pratikp@codeaurora.org>");
> +MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>");
> +MODULE_DESCRIPTION("Arm CoreSight Program Flow Trace v4 driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
> 

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