Re: [PATCH v3 09/15] coresight: etm4x: Cleanup TRCVICTLR register accesses

James Clark
2022-03-28T10:41:03Z

On 23/03/2022 15:59, Mathieu Poirier wrote:
> Hi James,
>
> On Fri, Mar 04, 2022 at 05:19:06PM +0000, James Clark wrote:
>> This is a no-op change for style and consistency and has no effect on
>> the binary output by the compiler. In sysreg.h fields are defined as
>> the register name followed by the field name and then _MASK. This
>> allows for grepping for fields by name rather than using magic numbers.
>>
>> Signed-off-by: James Clark <james.clark@arm.com>
>> ---
>> .../coresight/coresight-etm4x-core.c | 10 +++---
>> .../coresight/coresight-etm4x-sysfs.c | 36 +++++++++----------
>> drivers/hwtracing/coresight/coresight-etm4x.h | 22 +++++-------
>> 3 files changed, 31 insertions(+), 37 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> index 445e2057d5ed..88353f8ba414 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> @@ -1206,7 +1206,7 @@ static void etm4_init_arch_data(void *info)
>>
>> static inline u32 etm4_get_victlr_access_type(struct etmv4_config *config)
>> {
>> - return etm4_get_access_type(config) << TRCVICTLR_EXLEVEL_SHIFT;
>> + return etm4_get_access_type(config) << __bf_shf(TRCVICTLR_EXLEVEL_MASK);
>> }
>>
>> /* Set ELx trace filter access in the TRCVICTLR register */
>> @@ -1232,7 +1232,7 @@ static void etm4_set_default_config(struct etmv4_config *config)
>> config->ts_ctrl = 0x0;
>>
>> /* TRCVICTLR::EVENT = 0x01, select the always on logic */
>> - config->vinst_ctrl = BIT(0);
>> + config->vinst_ctrl = FIELD_PREP(TRCVICTLR_EVENT_MASK, 0x01);
>>
>> /* TRCVICTLR::EXLEVEL_NS:EXLEVELS: Set kernel / user filtering */
>> etm4_set_victlr_access(config);
>> @@ -1341,7 +1341,7 @@ static void etm4_set_default_filter(struct etmv4_config *config)
>> * TRCVICTLR::SSSTATUS == 1, the start-stop logic is
>> * in the started state
>> */
>> - config->vinst_ctrl |= BIT(9);
>> + config->vinst_ctrl |= TRCVICTLR_SSSTATUS;
>> config->mode |= ETM_MODE_VIEWINST_STARTSTOP;
>>
>> /* No start-stop filtering for ViewInst */
>> @@ -1445,7 +1445,7 @@ static int etm4_set_event_filters(struct etmv4_drvdata *drvdata,
>> * TRCVICTLR::SSSTATUS == 1, the start-stop logic is
>> * in the started state
>> */
>> - config->vinst_ctrl |= BIT(9);
>> + config->vinst_ctrl |= TRCVICTLR_SSSTATUS;
>>
>> /* No start-stop filtering for ViewInst */
>> config->vissctlr = 0x0;
>> @@ -1473,7 +1473,7 @@ static int etm4_set_event_filters(struct etmv4_drvdata *drvdata,
>> * etm4_disable_perf().
>> */
>> if (filters->ssstatus)
>> - config->vinst_ctrl |= BIT(9);
>> + config->vinst_ctrl |= TRCVICTLR_SSSTATUS;
>>
>> /* No include/exclude filtering for ViewInst */
>> config->viiectlr = 0x0;
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
>> index cd24590ea38a..b3b1b92909cc 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
>> @@ -206,11 +206,11 @@ static ssize_t reset_store(struct device *dev,
>> * started state. ARM recommends start-stop logic is set before
>> * each trace run.
>> */
>> - config->vinst_ctrl = BIT(0);
>> + config->vinst_ctrl = FIELD_PREP(TRCVICTLR_EVENT_MASK, 0x01);
>> if (drvdata->nr_addr_cmp > 0) {
>> config->mode |= ETM_MODE_VIEWINST_STARTSTOP;
>> /* SSSTATUS, bit[9] */
>> - config->vinst_ctrl |= BIT(9);
>> + config->vinst_ctrl |= TRCVICTLR_SSSTATUS;
>> }
>>
>> /* No address range filtering for ViewInst */
>> @@ -416,22 +416,22 @@ static ssize_t mode_store(struct device *dev,
>>
>> /* bit[9] Start/stop logic control bit */
>> if (config->mode & ETM_MODE_VIEWINST_STARTSTOP)
>> - config->vinst_ctrl |= BIT(9);
>> + config->vinst_ctrl |= TRCVICTLR_SSSTATUS;
>> else
>> - config->vinst_ctrl &= ~BIT(9);
>> + config->vinst_ctrl &= ~TRCVICTLR_SSSTATUS;
>>
>> /* bit[10], Whether a trace unit must trace a Reset exception */
>> if (config->mode & ETM_MODE_TRACE_RESET)
>> - config->vinst_ctrl |= BIT(10);
>> + config->vinst_ctrl |= TRCVICTLR_TRCRESET;
>> else
>> - config->vinst_ctrl &= ~BIT(10);
>> + config->vinst_ctrl &= ~TRCVICTLR_TRCRESET;
>>
>> /* bit[11], Whether a trace unit must trace a system error exception */
>> if ((config->mode & ETM_MODE_TRACE_ERR) &&
>> (drvdata->trc_error == true))
>> - config->vinst_ctrl |= BIT(11);
>> + config->vinst_ctrl |= TRCVICTLR_TRCERR;
>> else
>> - config->vinst_ctrl &= ~BIT(11);
>> + config->vinst_ctrl &= ~TRCVICTLR_TRCERR;
>>
>> if (config->mode & (ETM_MODE_EXCL_KERN | ETM_MODE_EXCL_USER))
>> etm4_config_trace_mode(config);
>> @@ -723,7 +723,7 @@ static ssize_t event_vinst_show(struct device *dev,
>> struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
>> struct etmv4_config *config = &drvdata->config;
>>
>> - val = config->vinst_ctrl & ETMv4_EVENT_MASK;
>> + val = FIELD_GET(TRCVICTLR_EVENT_MASK, config->vinst_ctrl);
>> return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
>> }
>>
>> @@ -739,9 +739,9 @@ static ssize_t event_vinst_store(struct device *dev,
>> return -EINVAL;
>>
>> spin_lock(&drvdata->spinlock);
>> - val &= ETMv4_EVENT_MASK;
>> - config->vinst_ctrl &= ~ETMv4_EVENT_MASK;
>> - config->vinst_ctrl |= val;
>> + val &= TRCVICTLR_EVENT_MASK >> __bf_shf(TRCVICTLR_EVENT_MASK);
>
> Not sure why the right-shifting operation is needed since the mask starts at bit
> 0. Please consider fixing _if_ you end up respinning this.

Yes you're right it doesn't need shifting. I suppose I did it that way so that when
reading the code it's obvious that 'val' is a value starting at bit 0, rather than
the original state of the register shifted to some arbitrary position.

Someone reading the code wouldn't know that TRCVICTLR_EVENT_MASK starts at 0,
so without the explicit shift they might think excluding it was a mistake. It also
makes it consistent with other uses of masks that don't start at 0.

James

>
> Thanks,
> Mathieu
>
>> + config->vinst_ctrl &= ~TRCVICTLR_EVENT_MASK;
>> + config->vinst_ctrl |= FIELD_PREP(TRCVICTLR_EVENT_MASK, val);
>> spin_unlock(&drvdata->spinlock);
>> return size;
>> }
>> @@ -755,7 +755,7 @@ static ssize_t s_exlevel_vinst_show(struct device *dev,
>> struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
>> struct etmv4_config *config = &drvdata->config;
>>
>> - val = (config->vinst_ctrl & TRCVICTLR_EXLEVEL_S_MASK) >> TRCVICTLR_EXLEVEL_S_SHIFT;
>> + val = FIELD_GET(TRCVICTLR_EXLEVEL_S_MASK, config->vinst_ctrl);
>> return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
>> }
>>
>> @@ -772,10 +772,10 @@ static ssize_t s_exlevel_vinst_store(struct device *dev,
>>
>> spin_lock(&drvdata->spinlock);
>> /* clear all EXLEVEL_S bits */
>> - config->vinst_ctrl &= ~(TRCVICTLR_EXLEVEL_S_MASK);
>> + config->vinst_ctrl &= ~TRCVICTLR_EXLEVEL_S_MASK;
>> /* enable instruction tracing for corresponding exception level */
>> val &= drvdata->s_ex_level;
>> - config->vinst_ctrl |= (val << TRCVICTLR_EXLEVEL_S_SHIFT);
>> + config->vinst_ctrl |= val << __bf_shf(TRCVICTLR_EXLEVEL_S_MASK);
>> spin_unlock(&drvdata->spinlock);
>> return size;
>> }
>> @@ -790,7 +790,7 @@ static ssize_t ns_exlevel_vinst_show(struct device *dev,
>> struct etmv4_config *config = &drvdata->config;
>>
>> /* EXLEVEL_NS, bits[23:20] */
>> - val = (config->vinst_ctrl & TRCVICTLR_EXLEVEL_NS_MASK) >> TRCVICTLR_EXLEVEL_NS_SHIFT;
>> + val = FIELD_GET(TRCVICTLR_EXLEVEL_NS_MASK, config->vinst_ctrl);
>> return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
>> }
>>
>> @@ -807,10 +807,10 @@ static ssize_t ns_exlevel_vinst_store(struct device *dev,
>>
>> spin_lock(&drvdata->spinlock);
>> /* clear EXLEVEL_NS bits */
>> - config->vinst_ctrl &= ~(TRCVICTLR_EXLEVEL_NS_MASK);
>> + config->vinst_ctrl &= ~TRCVICTLR_EXLEVEL_NS_MASK;
>> /* enable instruction tracing for corresponding exception level */
>> val &= drvdata->ns_ex_level;
>> - config->vinst_ctrl |= (val << TRCVICTLR_EXLEVEL_NS_SHIFT);
>> + config->vinst_ctrl |= val << __bf_shf(TRCVICTLR_EXLEVEL_NS_MASK);
>> spin_unlock(&drvdata->spinlock);
>> return size;
>> }
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
>> index 36934056a5dc..9cacc38b1890 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
>> @@ -200,6 +200,14 @@
>> #define TRCSTALLCTLR_INSTPRIORITY BIT(10)
>> #define TRCSTALLCTLR_NOOVERFLOW BIT(13)
>>
>> +#define TRCVICTLR_EVENT_MASK GENMASK(7, 0)
>> +#define TRCVICTLR_SSSTATUS BIT(9)
>> +#define TRCVICTLR_TRCRESET BIT(10)
>> +#define TRCVICTLR_TRCERR BIT(11)
>> +#define TRCVICTLR_EXLEVEL_MASK GENMASK(22, 16)
>> +#define TRCVICTLR_EXLEVEL_S_MASK GENMASK(19, 16)
>> +#define TRCVICTLR_EXLEVEL_NS_MASK GENMASK(22, 20)
>> +
>> /*
>> * System instructions to access ETM registers.
>> * See ETMv4.4 spec ARM IHI0064F section 4.3.6 System instructions
>> @@ -700,23 +708,9 @@
>> #define ETM_EXLEVEL_NS_OS BIT(5) /* NonSecure EL1 */
>> #define ETM_EXLEVEL_NS_HYP BIT(6) /* NonSecure EL2 */
>>
>> -#define ETM_EXLEVEL_MASK (GENMASK(6, 0))
>> -#define ETM_EXLEVEL_S_MASK (GENMASK(3, 0))
>> -#define ETM_EXLEVEL_NS_MASK (GENMASK(6, 4))
>> -
>> /* access level controls in TRCACATRn */
>> #define TRCACATR_EXLEVEL_SHIFT 8
>>
>> -/* access level control in TRCVICTLR */
>> -#define TRCVICTLR_EXLEVEL_SHIFT 16
>> -#define TRCVICTLR_EXLEVEL_S_SHIFT 16
>> -#define TRCVICTLR_EXLEVEL_NS_SHIFT 20
>> -
>> -/* secure / non secure masks - TRCVICTLR, IDR3 */
>> -#define TRCVICTLR_EXLEVEL_MASK (ETM_EXLEVEL_MASK << TRCVICTLR_EXLEVEL_SHIFT)
>> -#define TRCVICTLR_EXLEVEL_S_MASK (ETM_EXLEVEL_S_MASK << TRCVICTLR_EXLEVEL_SHIFT)
>> -#define TRCVICTLR_EXLEVEL_NS_MASK (ETM_EXLEVEL_NS_MASK << TRCVICTLR_EXLEVEL_SHIFT)
>> -
>> #define ETM_TRCIDR1_ARCH_MAJOR_SHIFT 8
>> #define ETM_TRCIDR1_ARCH_MAJOR_MASK (0xfU << ETM_TRCIDR1_ARCH_MAJOR_SHIFT)
>> #define ETM_TRCIDR1_ARCH_MAJOR(x) \
>> --
>> 2.28.0
>>