Re: [PATCH v2 14/20] arm64: Add helpers for checking CPU MIDR against a range

[Dave Martin]

On Wed, Jan 31, 2018 at 06:28:01PM +0000, Suzuki K Poulose wrote:
> Add helpers for checking if the given CPU midr falls in a range
> of variants/revisions for a given model.
> 
> Cc: Dave Martin <dave.martin@xxxxxxx>
> Cc: Will Deacon <will.deacon@xxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>

Reviewed-by: Dave Martin <Dave.Martin@xxxxxxx>

> ---
>  arch/arm64/include/asm/cpufeature.h |  7 ++-----
>  arch/arm64/include/asm/cputype.h    | 38 +++++++++++++++++++++++++++++++++++++
>  arch/arm64/kernel/cpu_errata.c      | 16 +++++-----------
>  3 files changed, 45 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> index 42292a0b93a4..0cfe42c3225c 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -10,6 +10,7 @@
>  #define __ASM_CPUFEATURE_H
>  
>  #include <asm/cpucaps.h>
> +#include <asm/cputype.h>
>  #include <asm/fpsimd.h>
>  #include <asm/hwcap.h>
>  #include <asm/sigcontext.h>
> @@ -279,11 +280,7 @@ struct arm64_cpu_capabilities {
>  	 */
>  	void (*cpu_enable)(const struct arm64_cpu_capabilities *cap);
>  	union {
> -		struct {	/* To be used for erratum handling only */
> -			u32 midr_model;
> -			u32 midr_range_min, midr_range_max;
> -		};
> -
> +		struct midr_range midr_range;	/* To be used for erratum handling only */
>  		struct {	/* Feature register checking */
>  			u32 sys_reg;
>  			u8 field_pos;
> diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h
> index 2f8d39ed9c2e..26bc5b302060 100644
> --- a/arch/arm64/include/asm/cputype.h
> +++ b/arch/arm64/include/asm/cputype.h
> @@ -115,6 +115,44 @@
>  
>  #define read_cpuid(reg)			read_sysreg_s(SYS_ ## reg)
>  
> +/*
> + * Represent a range of MIDR values for a given CPU model and a
> + * range of variant/revision values.
> + *
> + * @model	- CPU model as defined by MIDR_CPU_MODEL
> + * @rv_min	- Minimum value for the revision/variant as defined by
> + *		  MIDR_CPU_VAR_REV
> + * @rv_max	- Maximum value for the variant/revision for the range.
> + */
> +struct midr_range {
> +	u32 model;
> +	u32 rv_min;
> +	u32 rv_max;
> +};
> +
> +#define MIDR_RANGE(m, v_min, r_min, v_max, r_max)		\
> +	{							\
> +		.model = m,					\
> +		.rv_min = MIDR_CPU_VAR_REV(v_min, r_min),	\
> +		.rv_max = MIDR_CPU_VAR_REV(v_max, r_max),	\
> +	}
> +
> +#define MIDR_ALL_VERSIONS(m) MIDR_RANGE(m, 0, 0, 0xf, 0xf)
> +
> +static inline bool is_midr_in_range(u32 midr, struct midr_range const *range)
> +{
> +	return MIDR_IS_CPU_MODEL_RANGE(midr, range->model,
> +				 range->rv_min, range->rv_max);
> +}
> +
> +static inline bool is_midr_in_range_list(u32 midr, struct midr_range const *ranges)
> +{
> +	while (ranges->model)
> +		if (is_midr_in_range(midr, ranges++))
> +			return true;
> +	return false;
> +}
> +
>  /*
>   * The CPU ID never changes at run time, so we might as well tell the
>   * compiler that it's constant.  Use this function to read the CPU ID
> diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
> index 4351d48b0b0f..bc3f7dce42ba 100644
> --- a/arch/arm64/kernel/cpu_errata.c
> +++ b/arch/arm64/kernel/cpu_errata.c
> @@ -25,9 +25,7 @@ static bool __maybe_unused
>  is_affected_midr_range(const struct arm64_cpu_capabilities *entry, int scope)
>  {
>  	WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible());
> -	return MIDR_IS_CPU_MODEL_RANGE(read_cpuid_id(), entry->midr_model,
> -				       entry->midr_range_min,
> -				       entry->midr_range_max);
> +	return is_midr_in_range(read_cpuid_id(), &entry->midr_range);
>  }
>  
>  static bool __maybe_unused
> @@ -41,7 +39,7 @@ is_kryo_midr(const struct arm64_cpu_capabilities *entry, int scope)
>  	model &= MIDR_IMPLEMENTOR_MASK | (0xf00 << MIDR_PARTNUM_SHIFT) |
>  		 MIDR_ARCHITECTURE_MASK;
>  
> -	return model == entry->midr_model;
> +	return model == entry->midr_range.model;
>  }
>  
>  static bool
> @@ -176,15 +174,11 @@ static void qcom_enable_link_stack_sanitization(
>  
>  #define CAP_MIDR_RANGE(model, v_min, r_min, v_max, r_max)	\
>  	.matches = is_affected_midr_range,			\
> -	.midr_model = model,					\
> -	.midr_range_min = MIDR_CPU_VAR_REV(v_min, r_min),	\
> -	.midr_range_max = MIDR_CPU_VAR_REV(v_max, r_max)
> +	.midr_range = MIDR_RANGE(model, v_min, r_min, v_max, r_max)
>  
>  #define CAP_MIDR_ALL_VERSIONS(model)					\
>  	.matches = is_affected_midr_range,				\
> -	.midr_model = model,						\
> -	.midr_range_min = MIDR_CPU_VAR_REV(0, 0),			\
> -	.midr_range_max = (MIDR_VARIANT_MASK | MIDR_REVISION_MASK)
> +	.midr_range = MIDR_ALL_VERSIONS(model)
>  
>  #define ERRATA_MIDR_RANGE(model, v_min, r_min, v_max, r_max)		\
>  	.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,				\
> @@ -315,7 +309,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
>  		.desc = "Qualcomm Technologies Kryo erratum 1003",
>  		.capability = ARM64_WORKAROUND_QCOM_FALKOR_E1003,
>  		.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,
> -		.midr_model = MIDR_QCOM_KRYO,
> +		.midr_range.model = MIDR_QCOM_KRYO,
>  		.matches = is_kryo_midr,
>  	},
>  #endif
> -- 
> 2.14.3
> 
> 
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