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Message-ID: <50a7ea0b-017d-481b-8057-1ca06be289e7@linaro.org>
Date: Thu, 13 Feb 2025 13:20:28 +0000
From: James Clark <james.clark@...aro.org>
To: Mike Leach <mike.leach@...aro.org>
Cc: lcherian@...vell.com, coresight@...ts.linaro.org,
Suzuki K Poulose <suzuki.poulose@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Alexandre Torgue <alexandre.torgue@...s.st.com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-stm32@...md-mailman.stormreply.com
Subject: Re: [PATCH 5/7] coresight: Clear self hosted claim tag on probe
On 12/02/2025 6:24 pm, Mike Leach wrote:
> Hi James,
>
> On Tue, 11 Feb 2025 at 10:40, James Clark <james.clark@...aro.org> wrote:
>>
>> This can be left behind from a crashed kernel after a kexec so clear it
>> when probing each device. Similarly to
>> coresight_disclaim_device_unlocked(), only clear it if it's already set
>> to avoid races with an external debugger.
>>
>> We need a csdev_access struct in etm_init_arch_data() so just replace
>> the iomem pointer with a full csdev_access struct. This means all usages
>> need to be updated to go through csa->base.
>>
>> Signed-off-by: James Clark <james.clark@...aro.org>
>> ---
>> drivers/hwtracing/coresight/coresight-catu.c | 1 +
>> drivers/hwtracing/coresight/coresight-core.c | 48 +++++++++++++++----
>> .../hwtracing/coresight/coresight-cti-core.c | 2 +
>> drivers/hwtracing/coresight/coresight-etb10.c | 2 +
>> drivers/hwtracing/coresight/coresight-etm.h | 6 +--
>> .../coresight/coresight-etm3x-core.c | 28 +++++------
>> .../coresight/coresight-etm3x-sysfs.c | 8 ++--
>> .../coresight/coresight-etm4x-core.c | 2 +
>> .../hwtracing/coresight/coresight-funnel.c | 2 +
>> .../coresight/coresight-replicator.c | 1 +
>> .../hwtracing/coresight/coresight-tmc-core.c | 1 +
>> include/linux/coresight.h | 3 ++
>> 12 files changed, 73 insertions(+), 31 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-catu.c b/drivers/hwtracing/coresight/coresight-catu.c
>> index d9259c0b6e64..575c2d247a90 100644
>> --- a/drivers/hwtracing/coresight/coresight-catu.c
>> +++ b/drivers/hwtracing/coresight/coresight-catu.c
>> @@ -558,6 +558,7 @@ static int __catu_probe(struct device *dev, struct resource *res)
>> catu_desc.subtype.helper_subtype = CORESIGHT_DEV_SUBTYPE_HELPER_CATU;
>> catu_desc.ops = &catu_ops;
>>
>> + coresight_reset_claim(&catu_desc.access);
>> drvdata->csdev = coresight_register(&catu_desc);
>> if (IS_ERR(drvdata->csdev))
>> ret = PTR_ERR(drvdata->csdev);
>> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
>> index 7fe5d5d432c4..97f33ffad05e 100644
>> --- a/drivers/hwtracing/coresight/coresight-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-core.c
>> @@ -212,20 +212,48 @@ int coresight_claim_device(struct coresight_device *csdev)
>> EXPORT_SYMBOL_GPL(coresight_claim_device);
>>
>> /*
>> - * coresight_disclaim_device_unlocked : Clear the claim tag for the device.
>> + * Clear the claim tag for the device.
>> + * Returns an error if the device wasn't already claimed.
>> + */
>> +int coresight_reset_claim(struct csdev_access *csa)
>
> Given the iusue being fixed - i.e. previous sessions having residual
> claims - and the fact that this funtion is only ever called from
> device initialisation as far as I can tell,
> would this be better to be called coresight_init_claim() and return /
> log an error only if the device _was_ actually claimed.
>
> As it stands it seems to return an error if the device was not claimed
> - which on initialisation is the correct state!
>
> Since the retrun code is ignored by all of the callees, the rerun
> could be dropped and a warning issued withing this function if the
> claim needed clearing.
>
This is only to reuse code with coresight_disclaim_device_unlocked()
which does use the return code. I can drop the return code from here but
then we'd have to have two functions that do the same thing. One used on
probe and the other used on disable.
>> +{
>> + int ret;
>> +
>> + CS_UNLOCK(csa->base);
>> + ret = coresight_reset_claim_unlocked(csa);
>> + CS_LOCK(csa->base);
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(coresight_reset_claim);
>> +
>> +/*
>> + * Clear the claim tag for the device. Called with CS_UNLOCKed for the component.
>> + * Returns an error if the device wasn't already claimed.
>> + */
>> +int coresight_reset_claim_unlocked(struct csdev_access *csa)
>
> Given the comment and the function - this could be named
> "coresight_clear_claim_unlocked()"
>
I suppose we could rename it. It might cause some confusion with
coresight_clear_self_claim_tag() though. I deliberately picked 'reset'
because of when it was used on probe. Whereas 'clearing' is some
existing function that only clears a bit without any extra logic. That
kind of leaves it structured like this:
clear: lowest level, only mechanical clear of the bit
reset: clear if set, no warning
disclaim: clear if set, warn if not set
>
> Regards
>
> Mike
>
>> +{
>> + if (coresight_read_claim_tags(csa) == CORESIGHT_CLAIM_SELF_HOSTED) {
>> + coresight_clear_self_claim_tag(csa);
>> + return 0;
>> + }
>> +
>> + return -EINVAL;
>> +}
>> +EXPORT_SYMBOL_GPL(coresight_reset_claim_unlocked);
>> +
>> +/*
>> + * coresight_disclaim_device_unlocked : Clear the claim tag for the device
>> + * and warn if the device wasn't already claimed.
>> * Called with CS_UNLOCKed for the component.
>> */
>> void coresight_disclaim_device_unlocked(struct csdev_access *csa)
>> {
>> - if (coresight_read_claim_tags(csa) == CORESIGHT_CLAIM_SELF_HOSTED)
>> - coresight_clear_self_claim_tag(csa);
>> - else
>> - /*
>> - * The external agent may have not honoured our claim
>> - * and has manipulated it. Or something else has seriously
>> - * gone wrong in our driver.
>> - */
>> - WARN_ON_ONCE(1);
>> + /*
>> + * Warn if the external agent hasn't honoured our claim
>> + * and has manipulated it. Or something else has seriously
>> + * gone wrong in our driver.
>> + */
>> + WARN_ON_ONCE(coresight_reset_claim_unlocked(csa));
>> }
>> EXPORT_SYMBOL_GPL(coresight_disclaim_device_unlocked);
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-cti-core.c b/drivers/hwtracing/coresight/coresight-cti-core.c
>> index 073f67a41af9..389a72362f0c 100644
>> --- a/drivers/hwtracing/coresight/coresight-cti-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-cti-core.c
>> @@ -931,6 +931,8 @@ static int cti_probe(struct amba_device *adev, const struct amba_id *id)
>> cti_desc.ops = &cti_ops;
>> cti_desc.groups = drvdata->ctidev.con_groups;
>> cti_desc.dev = dev;
>> +
>> + coresight_reset_claim(&cti_desc.access);
>> drvdata->csdev = coresight_register(&cti_desc);
>> if (IS_ERR(drvdata->csdev)) {
>> ret = PTR_ERR(drvdata->csdev);
>> diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
>> index d8bc3e776c88..b598b2c0c9bb 100644
>> --- a/drivers/hwtracing/coresight/coresight-etb10.c
>> +++ b/drivers/hwtracing/coresight/coresight-etb10.c
>> @@ -772,6 +772,8 @@ static int etb_probe(struct amba_device *adev, const struct amba_id *id)
>> desc.pdata = pdata;
>> desc.dev = dev;
>> desc.groups = coresight_etb_groups;
>> +
>> + coresight_reset_claim(&desc.access);
>> drvdata->csdev = coresight_register(&desc);
>> if (IS_ERR(drvdata->csdev))
>> return PTR_ERR(drvdata->csdev);
>> diff --git a/drivers/hwtracing/coresight/coresight-etm.h b/drivers/hwtracing/coresight/coresight-etm.h
>> index e02c3ea972c9..a89736309c27 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm.h
>> +++ b/drivers/hwtracing/coresight/coresight-etm.h
>> @@ -229,7 +229,7 @@ struct etm_config {
>> * @config: structure holding configuration parameters.
>> */
>> struct etm_drvdata {
>> - void __iomem *base;
>> + struct csdev_access csa;
>> struct clk *atclk;
>> struct coresight_device *csdev;
>> spinlock_t spinlock;
>> @@ -260,7 +260,7 @@ static inline void etm_writel(struct etm_drvdata *drvdata,
>> "invalid CP14 access to ETM reg: %#x", off);
>> }
>> } else {
>> - writel_relaxed(val, drvdata->base + off);
>> + writel_relaxed(val, drvdata->csa.base + off);
>> }
>> }
>>
>> @@ -274,7 +274,7 @@ static inline unsigned int etm_readl(struct etm_drvdata *drvdata, u32 off)
>> "invalid CP14 access to ETM reg: %#x", off);
>> }
>> } else {
>> - val = readl_relaxed(drvdata->base + off);
>> + val = readl_relaxed(drvdata->csa.base + off);
>> }
>>
>> return val;
>> diff --git a/drivers/hwtracing/coresight/coresight-etm3x-core.c b/drivers/hwtracing/coresight/coresight-etm3x-core.c
>> index 509f53b69e42..0b010683b883 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm3x-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c
>> @@ -86,9 +86,9 @@ static void etm_set_pwrup(struct etm_drvdata *drvdata)
>> {
>> u32 etmpdcr;
>>
>> - etmpdcr = readl_relaxed(drvdata->base + ETMPDCR);
>> + etmpdcr = readl_relaxed(drvdata->csa.base + ETMPDCR);
>> etmpdcr |= ETMPDCR_PWD_UP;
>> - writel_relaxed(etmpdcr, drvdata->base + ETMPDCR);
>> + writel_relaxed(etmpdcr, drvdata->csa.base + ETMPDCR);
>> /* Ensure pwrup completes before subsequent cp14 accesses */
>> mb();
>> isb();
>> @@ -101,9 +101,9 @@ static void etm_clr_pwrup(struct etm_drvdata *drvdata)
>> /* Ensure pending cp14 accesses complete before clearing pwrup */
>> mb();
>> isb();
>> - etmpdcr = readl_relaxed(drvdata->base + ETMPDCR);
>> + etmpdcr = readl_relaxed(drvdata->csa.base + ETMPDCR);
>> etmpdcr &= ~ETMPDCR_PWD_UP;
>> - writel_relaxed(etmpdcr, drvdata->base + ETMPDCR);
>> + writel_relaxed(etmpdcr, drvdata->csa.base + ETMPDCR);
>> }
>>
>> /**
>> @@ -365,7 +365,7 @@ static int etm_enable_hw(struct etm_drvdata *drvdata)
>> struct etm_config *config = &drvdata->config;
>> struct coresight_device *csdev = drvdata->csdev;
>>
>> - CS_UNLOCK(drvdata->base);
>> + CS_UNLOCK(drvdata->csa.base);
>>
>> rc = coresight_claim_device_unlocked(csdev);
>> if (rc)
>> @@ -427,7 +427,7 @@ static int etm_enable_hw(struct etm_drvdata *drvdata)
>> etm_clr_prog(drvdata);
>>
>> done:
>> - CS_LOCK(drvdata->base);
>> + CS_LOCK(drvdata->csa.base);
>>
>> dev_dbg(&drvdata->csdev->dev, "cpu: %d enable smp call done: %d\n",
>> drvdata->cpu, rc);
>> @@ -589,7 +589,7 @@ static void etm_disable_hw(void *info)
>> struct etm_config *config = &drvdata->config;
>> struct coresight_device *csdev = drvdata->csdev;
>>
>> - CS_UNLOCK(drvdata->base);
>> + CS_UNLOCK(drvdata->csa.base);
>> etm_set_prog(drvdata);
>>
>> /* Read back sequencer and counters for post trace analysis */
>> @@ -601,7 +601,7 @@ static void etm_disable_hw(void *info)
>> etm_set_pwrdwn(drvdata);
>> coresight_disclaim_device_unlocked(&csdev->access);
>>
>> - CS_LOCK(drvdata->base);
>> + CS_LOCK(drvdata->csa.base);
>>
>> dev_dbg(&drvdata->csdev->dev,
>> "cpu: %d disable smp call done\n", drvdata->cpu);
>> @@ -614,7 +614,7 @@ static void etm_disable_perf(struct coresight_device *csdev)
>> if (WARN_ON_ONCE(drvdata->cpu != smp_processor_id()))
>> return;
>>
>> - CS_UNLOCK(drvdata->base);
>> + CS_UNLOCK(drvdata->csa.base);
>>
>> /* Setting the prog bit disables tracing immediately */
>> etm_set_prog(drvdata);
>> @@ -626,7 +626,7 @@ static void etm_disable_perf(struct coresight_device *csdev)
>> etm_set_pwrdwn(drvdata);
>> coresight_disclaim_device_unlocked(&csdev->access);
>>
>> - CS_LOCK(drvdata->base);
>> + CS_LOCK(drvdata->csa.base);
>>
>> /*
>> * perf will release trace ids when _free_aux()
>> @@ -772,7 +772,7 @@ static void etm_init_arch_data(void *info)
>> /* Make sure all registers are accessible */
>> etm_os_unlock(drvdata);
>>
>> - CS_UNLOCK(drvdata->base);
>> + CS_UNLOCK(drvdata->csa.base);
>>
>> /* First dummy read */
>> (void)etm_readl(drvdata, ETMPDSR);
>> @@ -803,9 +803,10 @@ static void etm_init_arch_data(void *info)
>> drvdata->nr_ext_out = BMVAL(etmccr, 20, 22);
>> drvdata->nr_ctxid_cmp = BMVAL(etmccr, 24, 25);
>>
>> + coresight_reset_claim_unlocked(&drvdata->csa);
>> etm_set_pwrdwn(drvdata);
>> etm_clr_pwrup(drvdata);
>> - CS_LOCK(drvdata->base);
>> + CS_LOCK(drvdata->csa.base);
>> }
>>
>> static int __init etm_hp_setup(void)
>> @@ -866,8 +867,7 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
>> if (IS_ERR(base))
>> return PTR_ERR(base);
>>
>> - drvdata->base = base;
>> - desc.access = CSDEV_ACCESS_IOMEM(base);
>> + desc.access = drvdata->csa = CSDEV_ACCESS_IOMEM(base);
>>
>> spin_lock_init(&drvdata->spinlock);
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
>> index 68c644be9813..af566b62785c 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
>> +++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
>> @@ -50,11 +50,11 @@ static ssize_t etmsr_show(struct device *dev,
>>
>> pm_runtime_get_sync(dev->parent);
>> spin_lock_irqsave(&drvdata->spinlock, flags);
>> - CS_UNLOCK(drvdata->base);
>> + CS_UNLOCK(drvdata->csa.base);
>>
>> val = etm_readl(drvdata, ETMSR);
>>
>> - CS_LOCK(drvdata->base);
>> + CS_LOCK(drvdata->csa.base);
>> spin_unlock_irqrestore(&drvdata->spinlock, flags);
>> pm_runtime_put(dev->parent);
>>
>> @@ -949,9 +949,9 @@ static ssize_t seq_curr_state_show(struct device *dev,
>> pm_runtime_get_sync(dev->parent);
>> spin_lock_irqsave(&drvdata->spinlock, flags);
>>
>> - CS_UNLOCK(drvdata->base);
>> + CS_UNLOCK(drvdata->csa.base);
>> val = (etm_readl(drvdata, ETMSQR) & ETM_SQR_MASK);
>> - CS_LOCK(drvdata->base);
>> + CS_LOCK(drvdata->csa.base);
>>
>> spin_unlock_irqrestore(&drvdata->spinlock, flags);
>> pm_runtime_put(dev->parent);
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> index 45b30a4b3eba..3609bb74c4ec 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> @@ -1337,6 +1337,8 @@ static void etm4_init_arch_data(void *info)
>> drvdata->nrseqstate = FIELD_GET(TRCIDR5_NUMSEQSTATE_MASK, etmidr5);
>> /* NUMCNTR, bits[30:28] number of counters available for tracing */
>> drvdata->nr_cntr = FIELD_GET(TRCIDR5_NUMCNTR_MASK, etmidr5);
>> +
>> + coresight_reset_claim_unlocked(csa);
>> etm4_cs_lock(drvdata, csa);
>> cpu_detect_trace_filtering(drvdata);
>> }
>> diff --git a/drivers/hwtracing/coresight/coresight-funnel.c b/drivers/hwtracing/coresight/coresight-funnel.c
>> index e986922d555b..be2a47636ef3 100644
>> --- a/drivers/hwtracing/coresight/coresight-funnel.c
>> +++ b/drivers/hwtracing/coresight/coresight-funnel.c
>> @@ -255,6 +255,7 @@ static int funnel_probe(struct device *dev, struct resource *res)
>> drvdata->base = base;
>> desc.groups = coresight_funnel_groups;
>> desc.access = CSDEV_ACCESS_IOMEM(base);
>> + coresight_reset_claim(&desc.access);
>> }
>>
>> dev_set_drvdata(dev, drvdata);
>> @@ -272,6 +273,7 @@ static int funnel_probe(struct device *dev, struct resource *res)
>> desc.ops = &funnel_cs_ops;
>> desc.pdata = pdata;
>> desc.dev = dev;
>> +
>> drvdata->csdev = coresight_register(&desc);
>> if (IS_ERR(drvdata->csdev)) {
>> ret = PTR_ERR(drvdata->csdev);
>> diff --git a/drivers/hwtracing/coresight/coresight-replicator.c b/drivers/hwtracing/coresight/coresight-replicator.c
>> index 5d42a9a8c460..679a36effbe8 100644
>> --- a/drivers/hwtracing/coresight/coresight-replicator.c
>> +++ b/drivers/hwtracing/coresight/coresight-replicator.c
>> @@ -284,6 +284,7 @@ static int replicator_probe(struct device *dev, struct resource *res)
>> desc.pdata = dev->platform_data;
>> desc.dev = dev;
>>
>> + coresight_reset_claim(&desc.access);
>> drvdata->csdev = coresight_register(&desc);
>> if (IS_ERR(drvdata->csdev)) {
>> ret = PTR_ERR(drvdata->csdev);
>> diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
>> index e9876252a789..5ac4e3c706ac 100644
>> --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
>> @@ -558,6 +558,7 @@ static int __tmc_probe(struct device *dev, struct resource *res)
>> dev->platform_data = pdata;
>> desc.pdata = pdata;
>>
>> + coresight_reset_claim(&desc.access);
>> drvdata->csdev = coresight_register(&desc);
>> if (IS_ERR(drvdata->csdev)) {
>> ret = PTR_ERR(drvdata->csdev);
>> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
>> index 937931d107e0..11808aee9d1d 100644
>> --- a/include/linux/coresight.h
>> +++ b/include/linux/coresight.h
>> @@ -655,6 +655,9 @@ extern int coresight_claim_device_unlocked(struct coresight_device *csdev);
>>
>> extern void coresight_disclaim_device(struct csdev_access *csa);
>> extern void coresight_disclaim_device_unlocked(struct csdev_access *csa);
>> +int coresight_reset_claim_unlocked(struct csdev_access *csa);
>> +int coresight_reset_claim(struct csdev_access *csa);
>> +
>> extern char *coresight_alloc_device_name(struct coresight_dev_list *devs,
>> struct device *dev);
>>
>> --
>> 2.34.1
>>
>
>
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