Subject: Re: [PATCH v4 14/25] coresight: etm4x: Clean up exception level masks

From: Mathieu Poirier <[email-masked]>
Date: Mon, 30 Nov 2020 14:45:13 -0700

On Thu, Nov 19, 2020 at 04:45:36PM +0000, Suzuki K Poulose wrote:
> etm4_get_access_type() calculates the exception level bits
> for use in address comparator registers. This is also used
> by the TRCVICTLR register by shifting to the required position.
> 
> This patch cleans up the logic to make etm4_get_access_type()
> calcualte a generic mask which can be used by all users by
> shifting to their field.
> 
> No functional changes intended.
> 
> Signed-off-by: Suzuki K Poulose <[email-masked]>
> ---
> Changes since v3:
>   - Fix errors in victlr ns_mask setting.
> Changes since v2:
>   - Fix the duplicate shift. More commentary
> ---
>  .../coresight/coresight-etm4x-core.c          | 47 +++++++++----------
>  .../coresight/coresight-etm4x-sysfs.c         | 12 ++---
>  drivers/hwtracing/coresight/coresight-etm4x.h | 47 ++++++++++++-------
>  3 files changed, 60 insertions(+), 46 deletions(-)
> 

Reviewed-by: Mathieu Poirier <[email-masked]>

> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index a1f294703c43..2342e72c5016 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -861,20 +861,16 @@ static void etm4_init_arch_data(void *info)
>  	etm4_cs_lock(drvdata, csa);
>  }
>  
> +static inline u32 etm4_get_victlr_access_type(struct etmv4_config *config)
> +{
> +	return etm4_get_access_type(config) << TRCVICTLR_EXLEVEL_SHIFT;
> +}
> +
>  /* Set ELx trace filter access in the TRCVICTLR register */
>  static void etm4_set_victlr_access(struct etmv4_config *config)
>  {
> -	u64 access_type;
> -
> -	config->vinst_ctrl &= ~(ETM_EXLEVEL_S_VICTLR_MASK | ETM_EXLEVEL_NS_VICTLR_MASK);
> -
> -	/*
> -	 * TRCVICTLR::EXLEVEL_NS:EXLEVELS: Set kernel / user filtering
> -	 * bits in vinst_ctrl, same bit pattern as TRCACATRn values returned by
> -	 * etm4_get_access_type() but with a relative shift in this register.
> -	 */
> -	access_type = etm4_get_access_type(config) << ETM_EXLEVEL_LSHIFT_TRCVICTLR;
> -	config->vinst_ctrl |= (u32)access_type;
> +	config->vinst_ctrl &= ~TRCVICTLR_EXLEVEL_MASK;
> +	config->vinst_ctrl |= etm4_get_victlr_access_type(config);
>  }
>  
>  static void etm4_set_default_config(struct etmv4_config *config)
> @@ -904,12 +900,9 @@ static u64 etm4_get_ns_access_type(struct etmv4_config *config)
>  	u64 access_type = 0;
>  
>  	/*
> -	 * EXLEVEL_NS, bits[15:12]
> -	 * The Exception levels are:
> -	 *   Bit[12] Exception level 0 - Application
> -	 *   Bit[13] Exception level 1 - OS
> -	 *   Bit[14] Exception level 2 - Hypervisor
> -	 *   Bit[15] Never implemented
> +	 * EXLEVEL_NS, for NonSecure Exception levels.
> +	 * The mask here is a generic value and must be
> +	 * shifted to the corresponding field for the registers
>  	 */
>  	if (!is_kernel_in_hyp_mode()) {
>  		/* Stay away from hypervisor mode for non-VHE */
> @@ -926,20 +919,26 @@ static u64 etm4_get_ns_access_type(struct etmv4_config *config)
>  	return access_type;
>  }
>  
> +/*
> + * Construct the exception level masks for a given config.
> + * This must be shifted to the corresponding register field
> + * for usage.
> + */
>  static u64 etm4_get_access_type(struct etmv4_config *config)
>  {
> -	u64 access_type = etm4_get_ns_access_type(config);
> -
> -	/* All supported secure ELs are excluded */
> -	access_type |= (u64)config->s_ex_level << TRCACATR_EXLEVEL_SHIFT;
> +	/* All Secure exception levels are excluded from the trace */
> +	return etm4_get_ns_access_type(config) | (u64)config->s_ex_level;
> +}
>  
> -	return access_type;
> +static u64 etm4_get_comparator_access_type(struct etmv4_config *config)
> +{
> +	return etm4_get_access_type(config) << TRCACATR_EXLEVEL_SHIFT;
>  }
>  
>  static void etm4_set_comparator_filter(struct etmv4_config *config,
>  				       u64 start, u64 stop, int comparator)
>  {
> -	u64 access_type = etm4_get_access_type(config);
> +	u64 access_type = etm4_get_comparator_access_type(config);
>  
>  	/* First half of default address comparator */
>  	config->addr_val[comparator] = start;
> @@ -974,7 +973,7 @@ static void etm4_set_start_stop_filter(struct etmv4_config *config,
>  				       enum etm_addr_type type)
>  {
>  	int shift;
> -	u64 access_type = etm4_get_access_type(config);
> +	u64 access_type = etm4_get_comparator_access_type(config);
>  
>  	/* Configure the comparator */
>  	config->addr_val[comparator] = address;
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> index fce9df16bfb5..009818675928 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> @@ -743,7 +743,7 @@ 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 & ETM_EXLEVEL_S_VICTLR_MASK) >> 16;
> +	val = (config->vinst_ctrl & TRCVICTLR_EXLEVEL_S_MASK) >> TRCVICTLR_EXLEVEL_S_SHIFT;
>  	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
>  }
>  
> @@ -760,10 +760,10 @@ static ssize_t s_exlevel_vinst_store(struct device *dev,
>  
>  	spin_lock(&drvdata->spinlock);
>  	/* clear all EXLEVEL_S bits  */
> -	config->vinst_ctrl &= ~(ETM_EXLEVEL_S_VICTLR_MASK);
> +	config->vinst_ctrl &= ~(TRCVICTLR_EXLEVEL_S_MASK);
>  	/* enable instruction tracing for corresponding exception level */
>  	val &= drvdata->s_ex_level;
> -	config->vinst_ctrl |= (val << 16);
> +	config->vinst_ctrl |= (val << TRCVICTLR_EXLEVEL_S_SHIFT);
>  	spin_unlock(&drvdata->spinlock);
>  	return size;
>  }
> @@ -778,7 +778,7 @@ 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 & ETM_EXLEVEL_NS_VICTLR_MASK) >> 20;
> +	val = (config->vinst_ctrl & TRCVICTLR_EXLEVEL_NS_MASK) >> TRCVICTLR_EXLEVEL_NS_SHIFT;
>  	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
>  }
>  
> @@ -795,10 +795,10 @@ static ssize_t ns_exlevel_vinst_store(struct device *dev,
>  
>  	spin_lock(&drvdata->spinlock);
>  	/* clear EXLEVEL_NS bits  */
> -	config->vinst_ctrl &= ~(ETM_EXLEVEL_NS_VICTLR_MASK);
> +	config->vinst_ctrl &= ~(TRCVICTLR_EXLEVEL_NS_MASK);
>  	/* enable instruction tracing for corresponding exception level */
>  	val &= drvdata->ns_ex_level;
> -	config->vinst_ctrl |= (val << 20);
> +	config->vinst_ctrl |= (val << TRCVICTLR_EXLEVEL_NS_SHIFT);
>  	spin_unlock(&drvdata->spinlock);
>  	return size;
>  }
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
> index 94ead0cd98df..173ea7445c29 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
> @@ -551,24 +551,39 @@
>  
>  #define TRCACATR_EXLEVEL_SHIFT		8
>  
> -/* secure state access levels - TRCACATRn */
> -#define ETM_EXLEVEL_S_APP		BIT(8)
> -#define ETM_EXLEVEL_S_OS		BIT(9)
> -#define ETM_EXLEVEL_S_HYP		BIT(10)
> -#define ETM_EXLEVEL_S_MON		BIT(11)
> -/* non-secure state access levels - TRCACATRn */
> -#define ETM_EXLEVEL_NS_APP		BIT(12)
> -#define ETM_EXLEVEL_NS_OS		BIT(13)
> -#define ETM_EXLEVEL_NS_HYP		BIT(14)
> -#define ETM_EXLEVEL_NS_NA		BIT(15)
> -
> -/* access level control in TRCVICTLR - same bits as TRCACATRn but shifted */
> -#define ETM_EXLEVEL_LSHIFT_TRCVICTLR	8
> +/*
> + * Exception level mask for Secure and Non-Secure ELs.
> + * ETM defines the bits for EL control (e.g, TRVICTLR, TRCACTRn).
> + * The Secure and Non-Secure ELs are always to gether.
> + * Non-secure EL3 is never implemented.
> + * We use the following generic mask as they appear in different
> + * registers and this can be shifted for the appropriate
> + * fields.
> + */
> +#define ETM_EXLEVEL_S_APP		BIT(0)	/* Secure EL0		*/
> +#define ETM_EXLEVEL_S_OS		BIT(1)	/* Secure EL1		*/
> +#define ETM_EXLEVEL_S_HYP		BIT(2)	/* Secure EL2		*/
> +#define ETM_EXLEVEL_S_MON		BIT(3)	/* Secure EL3/Monitor	*/
> +#define ETM_EXLEVEL_NS_APP		BIT(4)	/* NonSecure EL0	*/
> +#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 ETM_EXLEVEL_S_VICTLR_MASK	GENMASK(19, 16)
> -/* NS MON (EL3) mode never implemented */
> -#define ETM_EXLEVEL_NS_VICTLR_MASK	GENMASK(22, 20)
> +#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)
>  
>  /* Interpretation of resource numbers change at ETM v4.3 architecture */
>  #define ETM4X_ARCH_4V3	0x43
> -- 
> 2.24.1
> 

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