Re: [PATCH 2/2] RISC-V: alternative: Remove feature_probe_func

[Conor Dooley]

Hey Evan,

On Fri, Jun 23, 2023 at 03:20:16PM -0700, Evan Green wrote:
> Now that we're testing unaligned memory copy and making that
> determination generically, there are no more users of the vendor
> feature_probe_func(). While I think it's probably going to need to come
> back, there are no users right now, so let's remove it until it's
> needed.

How come this is done as a separate patch, rather than delete the dead
code as part of the probe addition? Ease of review?

Change itself seems fine to me though, so
Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>

Cheers,
Conor.

> 
> Signed-off-by: Evan Green <evan@xxxxxxxxxxxx>
> 
> ---
> 
>  arch/riscv/errata/thead/errata.c     |  8 --------
>  arch/riscv/include/asm/alternative.h |  5 -----
>  arch/riscv/kernel/alternative.c      | 19 -------------------
>  arch/riscv/kernel/smpboot.c          |  1 -
>  4 files changed, 33 deletions(-)
> 
> diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
> index c259dc925ec1..bf42857c977f 100644
> --- a/arch/riscv/errata/thead/errata.c
> +++ b/arch/riscv/errata/thead/errata.c
> @@ -117,11 +117,3 @@ void thead_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
>  	if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
>  		local_flush_icache_all();
>  }
> -
> -void thead_feature_probe_func(unsigned int cpu,
> -			      unsigned long archid,
> -			      unsigned long impid)
> -{
> -	if ((archid == 0) && (impid == 0))
> -		per_cpu(misaligned_access_speed, cpu) = RISCV_HWPROBE_MISALIGNED_FAST;
> -}
> diff --git a/arch/riscv/include/asm/alternative.h b/arch/riscv/include/asm/alternative.h
> index 6a41537826a7..58ccd2f8cab7 100644
> --- a/arch/riscv/include/asm/alternative.h
> +++ b/arch/riscv/include/asm/alternative.h
> @@ -30,7 +30,6 @@
>  #define ALT_OLD_PTR(a)			__ALT_PTR(a, old_offset)
>  #define ALT_ALT_PTR(a)			__ALT_PTR(a, alt_offset)
>  
> -void probe_vendor_features(unsigned int cpu);
>  void __init apply_boot_alternatives(void);
>  void __init apply_early_boot_alternatives(void);
>  void apply_module_alternatives(void *start, size_t length);
> @@ -53,15 +52,11 @@ void thead_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
>  			     unsigned long archid, unsigned long impid,
>  			     unsigned int stage);
>  
> -void thead_feature_probe_func(unsigned int cpu, unsigned long archid,
> -			      unsigned long impid);
> -
>  void riscv_cpufeature_patch_func(struct alt_entry *begin, struct alt_entry *end,
>  				 unsigned int stage);
>  
>  #else /* CONFIG_RISCV_ALTERNATIVE */
>  
> -static inline void probe_vendor_features(unsigned int cpu) { }
>  static inline void apply_boot_alternatives(void) { }
>  static inline void apply_early_boot_alternatives(void) { }
>  static inline void apply_module_alternatives(void *start, size_t length) { }
> diff --git a/arch/riscv/kernel/alternative.c b/arch/riscv/kernel/alternative.c
> index 6b75788c18e6..85056153fa23 100644
> --- a/arch/riscv/kernel/alternative.c
> +++ b/arch/riscv/kernel/alternative.c
> @@ -27,8 +27,6 @@ struct cpu_manufacturer_info_t {
>  	void (*patch_func)(struct alt_entry *begin, struct alt_entry *end,
>  				  unsigned long archid, unsigned long impid,
>  				  unsigned int stage);
> -	void (*feature_probe_func)(unsigned int cpu, unsigned long archid,
> -				   unsigned long impid);
>  };
>  
>  static void riscv_fill_cpu_mfr_info(struct cpu_manufacturer_info_t *cpu_mfr_info)
> @@ -43,7 +41,6 @@ static void riscv_fill_cpu_mfr_info(struct cpu_manufacturer_info_t *cpu_mfr_info
>  	cpu_mfr_info->imp_id = sbi_get_mimpid();
>  #endif
>  
> -	cpu_mfr_info->feature_probe_func = NULL;
>  	switch (cpu_mfr_info->vendor_id) {
>  #ifdef CONFIG_ERRATA_SIFIVE
>  	case SIFIVE_VENDOR_ID:
> @@ -53,7 +50,6 @@ static void riscv_fill_cpu_mfr_info(struct cpu_manufacturer_info_t *cpu_mfr_info
>  #ifdef CONFIG_ERRATA_THEAD
>  	case THEAD_VENDOR_ID:
>  		cpu_mfr_info->patch_func = thead_errata_patch_func;
> -		cpu_mfr_info->feature_probe_func = thead_feature_probe_func;
>  		break;
>  #endif
>  	default:
> @@ -143,20 +139,6 @@ void riscv_alternative_fix_offsets(void *alt_ptr, unsigned int len,
>  	}
>  }
>  
> -/* Called on each CPU as it starts */
> -void probe_vendor_features(unsigned int cpu)
> -{
> -	struct cpu_manufacturer_info_t cpu_mfr_info;
> -
> -	riscv_fill_cpu_mfr_info(&cpu_mfr_info);
> -	if (!cpu_mfr_info.feature_probe_func)
> -		return;
> -
> -	cpu_mfr_info.feature_probe_func(cpu,
> -					cpu_mfr_info.arch_id,
> -					cpu_mfr_info.imp_id);
> -}
> -
>  /*
>   * This is called very early in the boot process (directly after we run
>   * a feature detect on the boot CPU). No need to worry about other CPUs
> @@ -211,7 +193,6 @@ void __init apply_boot_alternatives(void)
>  	/* If called on non-boot cpu things could go wrong */
>  	WARN_ON(smp_processor_id() != 0);
>  
> -	probe_vendor_features(0);
>  	_apply_alternatives((struct alt_entry *)__alt_start,
>  			    (struct alt_entry *)__alt_end,
>  			    RISCV_ALTERNATIVES_BOOT);
> diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
> index e34a71b4786b..054f2d4474d0 100644
> --- a/arch/riscv/kernel/smpboot.c
> +++ b/arch/riscv/kernel/smpboot.c
> @@ -246,7 +246,6 @@ asmlinkage __visible void smp_callin(void)
>  	numa_add_cpu(curr_cpuid);
>  	set_cpu_online(curr_cpuid, 1);
>  	check_misaligned_access(curr_cpuid);
> -	probe_vendor_features(curr_cpuid);
>  
>  	if (has_vector()) {
>  		if (riscv_v_setup_vsize())
> -- 
> 2.34.1
>

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