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SubjectRe: [PATCH v7 05/10] coresight: syscfg: Add API to activate and enable configurations
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On 25/06/2021 15:37, Mike Leach wrote:
> HI Branislav, Mathieu,
>
> I have started to look into this as a top priority.
>
> However, when I enable the CONFIG_DEBUG_ option my board fails to boot
> at all. (Dragonboard DB410c), so the resolution make take a little
> time.
>
> At this point I am assuming that the mutex will need to be replaced by
> a spinlock - so a re-design + v8 set may well be required.

Or may be a refcount on the "config" instance may work too ?
i.e, when the config is loaded onto a device, a refcount could be
taken on the config and dropped on unload.

Whoever drops it to zero could release it.

Thoughts ?

Suzuki


>
> Regards
>
> Mike
>
> On Mon, 14 Jun 2021 at 18:03, Mathieu Poirier
> <mathieu.poirier@linaro.org> wrote:
>>
>> Hi Branislav,
>>
>> On Thu, 10 Jun 2021 at 05:05, Branislav Rankov <branislav.rankov@arm.com> wrote:
>>>
>>>
>>> On 4/14/21 8:18 PM, Mike Leach wrote:
>>>> Configurations are first activated, then when any coresight device is
>>>> enabled, the active configurations are checked and any matching
>>>> one is enabled.
>>>>
>>>> This patch provides the activation / enable API.
>>>>
>>>> Signed-off-by: Mike Leach <mike.leach@linaro.org>
>>>> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
>>>> ---
>>>> .../hwtracing/coresight/coresight-config.h | 2 +
>>>> .../hwtracing/coresight/coresight-syscfg.c | 172 ++++++++++++++++++
>>>> .../hwtracing/coresight/coresight-syscfg.h | 8 +
>>>> include/linux/coresight.h | 2 +
>>>> 4 files changed, 184 insertions(+)
>>>>
>>>> diff --git a/drivers/hwtracing/coresight/coresight-config.h b/drivers/hwtracing/coresight/coresight-config.h
>>>> index 0667581822c1..25eb6c632692 100644
>>>> --- a/drivers/hwtracing/coresight/coresight-config.h
>>>> +++ b/drivers/hwtracing/coresight/coresight-config.h
>>>> @@ -127,6 +127,7 @@ struct cscfg_feature_desc {
>>>> * @nr_total_params: Sum of all parameters declared by used features
>>>> * @presets: Array of preset values.
>>>> * @event_ea: Extended attribute for perf event value
>>>> + * @active_cnt: ref count for activate on this configuration.
>>>> *
>>>> */
>>>> struct cscfg_config_desc {
>>>> @@ -139,6 +140,7 @@ struct cscfg_config_desc {
>>>> int nr_total_params;
>>>> const u64 *presets; /* nr_presets * nr_total_params */
>>>> struct dev_ext_attribute *event_ea;
>>>> + atomic_t active_cnt;
>>>> };
>>>>
>>>> /**
>>>> diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
>>>> index e35f8c0ac2f8..b234e45c153f 100644
>>>> --- a/drivers/hwtracing/coresight/coresight-syscfg.c
>>>> +++ b/drivers/hwtracing/coresight/coresight-syscfg.c
>>>> @@ -283,6 +283,7 @@ static int cscfg_load_config(struct cscfg_config_desc *config_desc)
>>>> return err;
>>>>
>>>> list_add(&config_desc->item, &cscfg_mgr->config_desc_list);
>>>> + atomic_set(&config_desc->active_cnt, 0);
>>>> return 0;
>>>> }
>>>>
>>>> @@ -468,6 +469,176 @@ void cscfg_unregister_csdev(struct coresight_device *csdev)
>>>> }
>>>> EXPORT_SYMBOL_GPL(cscfg_unregister_csdev);
>>>>
>>>> +/**
>>>> + * cscfg_csdev_reset_feats - reset features for a CoreSight device.
>>>> + *
>>>> + * Resets all parameters and register values for any features loaded
>>>> + * into @csdev to their default values.
>>>> + *
>>>> + * @csdev: The CoreSight device.
>>>> + */
>>>> +void cscfg_csdev_reset_feats(struct coresight_device *csdev)
>>>> +{
>>>> + struct cscfg_feature_csdev *feat_csdev;
>>>> +
>>>> + mutex_lock(&cscfg_csdev_mutex);
>>>> + if (list_empty(&csdev->feature_csdev_list))
>>>> + goto unlock_exit;
>>>> +
>>>> + list_for_each_entry(feat_csdev, &csdev->feature_csdev_list, node)
>>>> + cscfg_reset_feat(feat_csdev);
>>>> +
>>>> +unlock_exit:
>>>> + mutex_unlock(&cscfg_csdev_mutex);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(cscfg_csdev_reset_feats);
>>>> +
>>>> +/**
>>>> + * cscfg_activate_config - Mark a configuration descriptor as active.
>>>> + *
>>>> + * This will be seen when csdev devices are enabled in the system.
>>>> + * Only activated configurations can be enabled on individual devices.
>>>> + * Activation protects the configuration from alteration or removal while
>>>> + * active.
>>>> + *
>>>> + * Selection by hash value - generated from the configuration name when it
>>>> + * was loaded and added to the cs_etm/configurations file system for selection
>>>> + * by perf.
>>>> + *
>>>> + * Increments the configuration descriptor active count and the global active
>>>> + * count.
>>>> + *
>>>> + * @cfg_hash: Hash value of the selected configuration name.
>>>> + */
>>>> +int cscfg_activate_config(unsigned long cfg_hash)
>>>> +{
>>>> + struct cscfg_config_desc *config_desc;
>>>> + int err = -EINVAL;
>>>> +
>>>> + mutex_lock(&cscfg_mutex);
>>>> +
>>>> + list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) {
>>>> + if ((unsigned long)config_desc->event_ea->var == cfg_hash) {
>>>> + /*
>>>> + * increment the global active count - control changes to
>>>> + * active configurations
>>>> + */
>>>> + atomic_inc(&cscfg_mgr->sys_active_cnt);
>>>> +
>>>> + /*
>>>> + * mark the descriptor as active so enable config on a
>>>> + * device instance will use it
>>>> + */
>>>> + atomic_inc(&config_desc->active_cnt);
>>>> +
>>>> + err = 0;
>>>> + dev_dbg(cscfg_device(), "Activate config %s.\n", config_desc->name);
>>>> + break;
>>>> + }
>>>> + }
>>>> + mutex_unlock(&cscfg_mutex);
>>>> +
>>>> + return err;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(cscfg_activate_config);
>>>> +
>>>> +/**
>>>> + * cscfg_deactivate_config - Mark a config descriptor as inactive.
>>>> + *
>>>> + * Decrement the configuration and global active counts.
>>>> + *
>>>> + * @cfg_hash: Hash value of the selected configuration name.
>>>> + */
>>>> +void cscfg_deactivate_config(unsigned long cfg_hash)
>>>> +{
>>>> + struct cscfg_config_desc *config_desc;
>>>> +
>>>> + mutex_lock(&cscfg_mutex);
>>>> +
>>>> + list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) {
>>>> + if ((unsigned long)config_desc->event_ea->var == cfg_hash) {
>>>> + atomic_dec(&config_desc->active_cnt);
>>>> + atomic_dec(&cscfg_mgr->sys_active_cnt);
>>>> + dev_dbg(cscfg_device(), "Deactivate config %s.\n", config_desc->name);
>>>> + break;
>>>> + }
>>>> + }
>>>> + mutex_unlock(&cscfg_mutex);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(cscfg_deactivate_config);
>>>> +
>>>> +/**
>>>> + * cscfg_csdev_enable_active_config - Enable matching active configuration for device.
>>>> + *
>>>> + * Enables the configuration selected by @cfg_hash if the configuration is supported
>>>> + * on the device and has been activated.
>>>> + *
>>>> + * If active and supported the CoreSight device @csdev will be programmed with the
>>>> + * configuration, using @preset parameters.
>>>> + *
>>>> + * Should be called before driver hardware enable for the requested device, prior to
>>>> + * programming and enabling the physical hardware.
>>>> + *
>>>> + * @csdev: CoreSight device to program.
>>>> + * @cfg_hash: Selector for the configuration.
>>>> + * @preset: Preset parameter values to use, 0 for current / default values.
>>>> + */
>>>> +int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
>>>> + unsigned long cfg_hash, int preset)
>>>> +{
>>>> + struct cscfg_config_csdev *config_csdev_active = NULL, *config_csdev_item;
>>>> + const struct cscfg_config_desc *config_desc;
>>>> + int err = 0;
>>>> +
>>>> + /* quickly check global count */
>>>> + if (!atomic_read(&cscfg_mgr->sys_active_cnt))
>>>> + return 0;
>>>> +
>>>> + mutex_lock(&cscfg_csdev_mutex);
>>>> + list_for_each_entry(config_csdev_item, &csdev->config_csdev_list, node) {
>>>> + config_desc = config_csdev_item->config_desc;
>>>> + if ((atomic_read(&config_desc->active_cnt)) &&
>>>> + ((unsigned long)config_desc->event_ea->var == cfg_hash)) {
>>>> + config_csdev_active = config_csdev_item;
>>>> + break;
>>>> + }
>>>> + }
>>>> + if (config_csdev_active) {
>>>> + err = cscfg_csdev_enable_config(config_csdev_active, preset);
>>>> + if (!err)
>>>> + csdev->active_cscfg_ctxt = (void *)config_csdev_active;
>>>> + }
>>>> + mutex_unlock(&cscfg_csdev_mutex);
>>>> + return err;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(cscfg_csdev_enable_active_config);
>>>> +
>>>> +/**
>>>> + * cscfg_csdev_disable_active_config - disable an active config on the device.
>>>> + *
>>>> + * Disables the active configuration on the CoreSight device @csdev.
>>>> + * Disable will save the values of any registers marked in the configurations
>>>> + * as save on disable.
>>>> + *
>>>> + * Should be called after driver hardware disable for the requested device,
>>>> + * after disabling the physical hardware and reading back registers.
>>>> + *
>>>> + * @csdev: The CoreSight device.
>>>> + */
>>>> +void cscfg_csdev_disable_active_config(struct coresight_device *csdev)
>>>> +{
>>>> + struct cscfg_config_csdev *config_csdev;
>>>> +
>>>> + mutex_lock(&cscfg_csdev_mutex);
>>>
>>> This line seems to cause a bug report when the kernel is compiled with CONFIG_DEBUG_ATOMIC_SLEEP=y
>>>
>>> I have tested this by applying the series to 5.10 kernel on Dragonboard 845c.
>>>
>>> It only happens when strobing is used.
>>
>> Thanks for reporting this. Unfortunately Mike is away and likely
>> won't be able to look at this in time for the merge window. As such I
>> backed out the complex configuration feature from the next branch but
>> that code is still available on next-complex-configuration.
>>
>> Thanks,
>> Mathieu
>>
>>>
>>> The report is this:
>>>
>>> [13431.885395] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:283
>>> [13431.893919] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 3525, name: perf
>>> [13431.901882] CPU: 0 PID: 3525 Comm: perf Tainted: G W 5.10.0-rc5-17282-g923b456a55fb #124
>>> [13431.911436] Hardware name: Thundercomm Dragonboard 845c (DT)
>>> [13431.917450] Call trace:
>>> [13431.919938] dump_backtrace+0x0/0x1a0
>>> [13431.923644] show_stack+0x18/0x68
>>> [13431.927008] dump_stack+0xd0/0x12c
>>> [13431.930444] ___might_sleep+0xf0/0x130
>>> [13431.934228] __might_sleep+0x54/0x90
>>> [13431.937945] mutex_lock+0x28/0x80
>>> [13431.941468] cscfg_csdev_disable_active_config+0x24/0x50
>>> [13431.946952] etm4_disable+0xf0/0x100
>>> [13431.950571] etm_event_stop+0xb8/0x130
>>> [13431.954380] etm_event_del+0x14/0x20
>>> [13431.958008] event_sched_out.isra.0+0x84/0x1c8
>>> [13431.962496] group_sched_out.part.0+0x44/0xc8
>>> [13431.967010] __perf_event_disable+0xe4/0x198
>>> [13431.971549] event_function+0x8c/0xe8
>>> [13431.975256] remote_function+0x64/0x78
>>> [13431.979161] generic_exec_single+0xa0/0x100
>>> [13431.983876] smp_call_function_single+0x158/0x1d8
>>> [13431.988629] event_function_call+0x128/0x138
>>> [13431.992942] _perf_event_disable+0x48/0x70
>>> [13431.997082] perf_event_for_each_child+0x3c/0x90
>>> [13432.001751] _perf_ioctl+0x198/0x4a8
>>> [13432.005359] perf_ioctl+0x4c/0x78
>>> [13432.008715] __arm64_sys_ioctl+0xa8/0xf0
>>> [13432.012835] el0_svc_common.constprop.0+0x78/0x1a0
>>> [13432.017767] do_el0_svc+0x24/0x90
>>> [13432.021616] el0_sync_handler+0x160/0x168
>>> [13432.025670] el0_sync+0x174/0x180
>>>
>>>
>>>> + config_csdev = (struct cscfg_config_csdev *)csdev->active_cscfg_ctxt;
>>>> + if (config_csdev) {
>>>> + cscfg_csdev_disable_config(config_csdev);
>>>> + csdev->active_cscfg_ctxt = NULL;
>>>> + }
>>>> + mutex_unlock(&cscfg_csdev_mutex);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(cscfg_csdev_disable_active_config);
>>>> +
>>>> /* Initialise system configuration management device. */
>>>>
>>>> struct device *cscfg_device(void)
>>>> @@ -536,6 +707,7 @@ int __init cscfg_init(void)
>>>> INIT_LIST_HEAD(&cscfg_mgr->csdev_desc_list);
>>>> INIT_LIST_HEAD(&cscfg_mgr->feat_desc_list);
>>>> INIT_LIST_HEAD(&cscfg_mgr->config_desc_list);
>>>> + atomic_set(&cscfg_mgr->sys_active_cnt, 0);
>>>>
>>>> dev_info(cscfg_device(), "CoreSight Configuration manager initialised");
>>>> return 0;
>>>> diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h
>>>> index 5bcae3b374c6..a52775890670 100644
>>>> --- a/drivers/hwtracing/coresight/coresight-syscfg.h
>>>> +++ b/drivers/hwtracing/coresight/coresight-syscfg.h
>>>> @@ -24,12 +24,14 @@
>>>> * @csdev_desc_list: List of coresight devices registered with the configuration manager.
>>>> * @feat_desc_list: List of feature descriptors to load into registered devices.
>>>> * @config_desc_list: List of system configuration descriptors to load into registered devices.
>>>> + * @sys_active_cnt: Total number of active config descriptor references.
>>>> */
>>>> struct cscfg_manager {
>>>> struct device dev;
>>>> struct list_head csdev_desc_list;
>>>> struct list_head feat_desc_list;
>>>> struct list_head config_desc_list;
>>>> + atomic_t sys_active_cnt;
>>>> };
>>>>
>>>> /* get reference to dev in cscfg_manager */
>>>> @@ -61,5 +63,11 @@ int cscfg_load_config_sets(struct cscfg_config_desc **cfg_descs,
>>>> int cscfg_register_csdev(struct coresight_device *csdev, u32 match_flags,
>>>> struct cscfg_csdev_feat_ops *ops);
>>>> void cscfg_unregister_csdev(struct coresight_device *csdev);
>>>> +int cscfg_activate_config(unsigned long cfg_hash);
>>>> +void cscfg_deactivate_config(unsigned long cfg_hash);
>>>> +void cscfg_csdev_reset_feats(struct coresight_device *csdev);
>>>> +int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
>>>> + unsigned long cfg_hash, int preset);
>>>> +void cscfg_csdev_disable_active_config(struct coresight_device *csdev);
>>>>
>>>> #endif /* CORESIGHT_SYSCFG_H */
>>>> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
>>>> index 6fb516e1b22e..a348049ee08b 100644
>>>> --- a/include/linux/coresight.h
>>>> +++ b/include/linux/coresight.h
>>>> @@ -222,6 +222,7 @@ struct coresight_sysfs_link {
>>>> * @has_conns_grp: Have added a "connections" group for sysfs links.
>>>> * @feature_csdev_list: List of complex feature programming added to the device.
>>>> * @config_csdev_list: List of system configurations added to the device.
>>>> + * @active_cscfg_ctxt: Context information for current active system configuration.
>>>> */
>>>> struct coresight_device {
>>>> struct coresight_platform_data *pdata;
>>>> @@ -246,6 +247,7 @@ struct coresight_device {
>>>> /* system configuration and feature lists */
>>>> struct list_head feature_csdev_list;
>>>> struct list_head config_csdev_list;
>>>> + void *active_cscfg_ctxt;
>>>> };
>>>>
>>>> /*
>>>>
>
>
>

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