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Message-ID: <CAJ9a7Visv1tbR06RFZH435Q1UNCdqz+Mh0wGbsPPoYmnkVOzgA@mail.gmail.com>
Date: Wed, 12 Feb 2025 18:24:08 +0000
From: Mike Leach <mike.leach@...aro.org>
To: James Clark <james.clark@...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
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.
> +{
> + 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()"
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
>
--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK
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