[PATCH 12/19] coresight: etm4x: Cleanup secure exception level masks

[Suzuki K Poulose]

On 09/18/2020 04:35 PM, Mike Leach wrote:
> On Fri, 11 Sep 2020 at 09:41, Suzuki K Poulose <suzuki.poulose at arm.com> wrote:
>>
>> We rely on the ETM architecture version to decide whether
>> Secure EL2 is available on the CPU for excluding the level
>> for address comparators and viewinst main control register.
>> We must instead use the TRCDIDR3.EXLEVEL_S field to detect
>> the supported levels.
>>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose at arm.com>
>> ---
>>   drivers/hwtracing/coresight/coresight-etm4x.c | 13 +++----------
>>   drivers/hwtracing/coresight/coresight-etm4x.h |  6 ++++--
>>   2 files changed, 7 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
>> index 7feb57108bdc..439e9da41006 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x.c
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x.c
>> @@ -758,7 +758,6 @@ static void etm4_init_arch_data(void *info)
>>           * TRCARCHMAJ, bits[11:8] architecture major versin number
>>           */
>>          drvdata->arch = BMVAL(etmidr1, 4, 11);
>> -       drvdata->config.arch = drvdata->arch;
>>
>>          /* maximum size of resources */
>>          etmidr2 = etm4x_relaxed_read32(&csa, TRCIDR2);
>> @@ -774,6 +773,7 @@ static void etm4_init_arch_data(void *info)
>>          drvdata->ccitmin = BMVAL(etmidr3, 0, 11);
>>          /* EXLEVEL_S, bits[19:16] Secure state instruction tracing */
>>          drvdata->s_ex_level = BMVAL(etmidr3, 16, 19);
>> +       drvdata->config.s_ex_level = drvdata->s_ex_level;
>>          /* EXLEVEL_NS, bits[23:20] Non-secure state instruction tracing */
>>          drvdata->ns_ex_level = BMVAL(etmidr3, 20, 23);
>>
>> @@ -935,16 +935,9 @@ static u64 etm4_get_ns_access_type(struct etmv4_config *config)
>>   static u64 etm4_get_access_type(struct etmv4_config *config)
>>   {
>>          u64 access_type = etm4_get_ns_access_type(config);
>> -       u64 s_hyp = (config->arch & 0x0f) >= 0x4 ? ETM_EXLEVEL_S_HYP : 0;
>>
>> -       /*
>> -        * EXLEVEL_S, bits[11:8], don't trace anything happening
>> -        * in secure state.
>> -        */
>> -       access_type |= (ETM_EXLEVEL_S_APP       |
>> -                       ETM_EXLEVEL_S_OS        |
>> -                       s_hyp                   |
>> -                       ETM_EXLEVEL_S_MON);
>> +       /* All supported secure ELs are excluded */
>> +       access_type |= (u64)config->s_ex_level << TRCACATR_EXLEVEL_SHIFT;
>>
> 
> What is the << TRCACATR_EXLEVEL_SHIFT doing here?

The config->s_ex_level is the EXLVEL mask from the TRCIDR3 shifted to bit 0, as above.
We need to make sure that we use the mask in the correct position for TRCACATR register.
Basically, we simply exclude all the secure levels supported by the ETM.

> 
>>          return access_type;
>>   }
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
>> index efd903688edd..407ad6647f36 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
>> @@ -522,6 +522,8 @@
>>   /* PowerDown Control Register bits */
>>   #define TRCPDCR_PU                     BIT(3)
>>
>> +#define TRCACATR_EXLEVEL_SHIFT         8
>> +
>>   /* secure state access levels - TRCACATRn */
>>   #define ETM_EXLEVEL_S_APP              BIT(8)
>>   #define ETM_EXLEVEL_S_OS               BIT(9)
>> @@ -604,7 +606,7 @@
>>    * @vmid_mask0:        VM ID comparator mask for comparator 0-3.
>>    * @vmid_mask1:        VM ID comparator mask for comparator 4-7.
>>    * @ext_inp:   External input selection.
>> - * @arch:      ETM architecture version (for arch dependent config).
>> + * @s_ex_level: Secure ELs where tracing is supported.
>>    */
>>   struct etmv4_config {
>>          u32                             mode;
>> @@ -648,7 +650,7 @@ struct etmv4_config {
>>          u32                             vmid_mask0;
>>          u32                             vmid_mask1;
>>          u32                             ext_inp;
>> -       u8                              arch;
>> +       u8                              s_ex_level;
>>   };
>>
>>   /**
>> --
>> 2.24.1
>>
> 
> Perhaps this patch could be combined with the next patch as it
> operates on the same set of flags.
> 

I agree that they both deal with the same set of masks. However, functionally
they have separate purposes.

1) This patch disconnects the usage of drvdata->arch field to determine
the secure exception level mask. This is more of a correctness, as a given
v4.4 implementation may not have a Secure EL2.

2) The next patch cleans up the way we define and use all the exception level
masks, both secure and non-secure.

I understand that the subjects are quite similar. I could try to fix the
subject for this one to make (1) more explicit. This way it is more easier
to review.

Suzuki