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

Mathieu Poirier
2020-08-13T19:46:41Z

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");
> --
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> a Linux Foundation Collaborative Project