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@linaro.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@linaro.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