Re: [PATCH V4 03/11] coresight: tmc: Extract device properties from AMBA pid based table lookup
From: Anshuman Khandual
Date: Tue Feb 13 2024 - 22:36:21 EST
On 2/13/24 16:02, Suzuki K Poulose wrote:
> On 13/02/2024 03:13, Anshuman Khandual wrote:
>>
>>
>> On 2/12/24 17:43, Suzuki K Poulose wrote:
>>> On 23/01/2024 05:46, Anshuman Khandual wrote:
>>>> This extracts device properties from AMBA pid based table lookup. This also
>>>> defers tmc_etr_setup_caps() after the coresight device has been initialized
>>>> so that PID value can be read.
>>>>
>>>> Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
>>>> Cc: Mike Leach <mike.leach@xxxxxxxxxx>
>>>> Cc: James Clark <james.clark@xxxxxxx>
>>>> Cc: coresight@xxxxxxxxxxxxxxxx
>>>> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
>>>> Cc: linux-kernel@xxxxxxxxxxxxxxx
>>>> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
>>>> ---
>>>> .../hwtracing/coresight/coresight-tmc-core.c | 19 +++++++++++++------
>>>> 1 file changed, 13 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
>>>> index 7ec5365e2b64..e71db3099a29 100644
>>>> --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
>>>> +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
>>>> @@ -370,16 +370,24 @@ static inline bool tmc_etr_has_non_secure_access(struct tmc_drvdata *drvdata)
>>>> return (auth & TMC_AUTH_NSID_MASK) == 0x3;
>>>> }
>>>> +#define TMC_AMBA_MASK 0xfffff
>>>> +
>>>> +static const struct amba_id tmc_ids[];
>>>> +
>>>> /* Detect and initialise the capabilities of a TMC ETR */
>>>> -static int tmc_etr_setup_caps(struct device *parent, u32 devid, void *dev_caps)
>>>> +static int tmc_etr_setup_caps(struct device *parent, u32 devid)
>>>> {
>>>> int rc;
>>>> - u32 dma_mask = 0;
>>>> + u32 tmc_pid, dma_mask = 0;
>>>> struct tmc_drvdata *drvdata = dev_get_drvdata(parent);
>>>> + void *dev_caps;
>>>> if (!tmc_etr_has_non_secure_access(drvdata))
>>>> return -EACCES;
>>>> + tmc_pid = coresight_get_pid(&drvdata->csdev->access) & TMC_AMBA_MASK;
>>>> + dev_caps = coresight_get_uci_data_from_amba(tmc_ids, tmc_pid);
>>>> +
>>>> /* Set the unadvertised capabilities */
>>>> tmc_etr_init_caps(drvdata, (u32)(unsigned long)dev_caps);
>>>> @@ -497,10 +505,6 @@ static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
>>>> desc.type = CORESIGHT_DEV_TYPE_SINK;
>>>> desc.subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_SYSMEM;
>>>> desc.ops = &tmc_etr_cs_ops;
>>>> - ret = tmc_etr_setup_caps(dev, devid,
>>>> - coresight_get_uci_data(id));
>>>> - if (ret)
>>>> - goto out;
>>>> idr_init(&drvdata->idr);
>>>> mutex_init(&drvdata->idr_mutex);
>>>> dev_list = &etr_devs;
>>>> @@ -539,6 +543,9 @@ static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
>>>> goto out;
>>>> }
>>>> + if (drvdata->config_type == TMC_CONFIG_TYPE_ETR)
>>>> + ret = tmc_etr_setup_caps(dev, devid);
>>>> +
>>>
>>> With this change, we silently accept an ETR that may only have "SECURE" access only and crash later while we try to enable tracing. You could
>>> pass in the "access" (which is already in 'desc.access' in the original
>>> call site and deal with it ?
>>
>> Just wondering, if something like the following will help ? A failed tmc_etr_setup_caps()
>> because of failed tmc_etr_has_non_secure_access(), will unregister the coresight device
>> before returning.
>>
>> --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
>> @@ -538,8 +538,13 @@ static int __tmc_probe(struct device *dev, struct resource *res)
>> goto out;
>> }
>> - if (drvdata->config_type == TMC_CONFIG_TYPE_ETR)
>> + if (drvdata->config_type == TMC_CONFIG_TYPE_ETR) {
>> ret = tmc_etr_setup_caps(dev, devid);
>> + if (ret) {
>> + coresight_unregister(drvdata->csdev);
>> + goto out;
>> + }
>> + }
>
> Why do we move the tmc_etr_setup_caps() in the first place ? We could retain where that was and pass "desc.access" parameter rather than registering the csdev and then relying csdev->access ?
Agreed, and after implementing the changes suggested above, the entire patch
will look something like the following. Please do confirm if this looks good
enough.
--- a/drivers/hwtracing/coresight/coresight-tmc-core.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
@@ -370,16 +370,25 @@ static inline bool tmc_etr_has_non_secure_access(struct tmc_drvdata *drvdata)
return (auth & TMC_AUTH_NSID_MASK) == 0x3;
}
+#define TMC_AMBA_MASK 0xfffff
+
+static const struct amba_id tmc_ids[];
+
/* Detect and initialise the capabilities of a TMC ETR */
-static int tmc_etr_setup_caps(struct device *parent, u32 devid, void *dev_caps)
+static int tmc_etr_setup_caps(struct device *parent, u32 devid,
+ struct csdev_access *access)
{
int rc;
- u32 dma_mask = 0;
+ u32 tmc_pid, dma_mask = 0;
struct tmc_drvdata *drvdata = dev_get_drvdata(parent);
+ void *dev_caps;
if (!tmc_etr_has_non_secure_access(drvdata))
return -EACCES;
+ tmc_pid = coresight_get_pid(access) & TMC_AMBA_MASK;
+ dev_caps = coresight_get_uci_data_from_amba(tmc_ids, tmc_pid);
+
/* Set the unadvertised capabilities */
tmc_etr_init_caps(drvdata, (u32)(unsigned long)dev_caps);
@@ -497,8 +506,7 @@ static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
desc.type = CORESIGHT_DEV_TYPE_SINK;
desc.subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_SYSMEM;
desc.ops = &tmc_etr_cs_ops;
- ret = tmc_etr_setup_caps(dev, devid,
- coresight_get_uci_data(id));
+ ret = tmc_etr_setup_caps(dev, devid, &desc.access);
if (ret)
goto out;
idr_init(&drvdata->idr);