linux-kernel - Re: [PATCH AUTOSEL 4.9 10/15] ARM: split out processor lookup

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Date:   Fri, 23 Nov 2018 00:04:42 +0000
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Sasha Levin <sashal@...nel.org>
Cc:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 4.9 10/15] ARM: split out processor lookup

Sorry, I meant this patch, not patch 11.

On Thu, Nov 22, 2018 at 02:56:16PM -0500, Sasha Levin wrote:
> From: Russell King <rmk+kernel@...linux.org.uk>
> 
> [ Upstream commit 65987a8553061515b5851b472081aedb9837a391 ]
> 
> Split out the lookup of the processor type and associated error handling
> from the rest of setup_processor() - we will need to use this in the
> secondary CPU bringup path for big.Little Spectre variant 2 mitigation.
> 
> Reviewed-by: Julien Thierry <julien.thierry@....com>
> Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  arch/arm/include/asm/cputype.h |  1 +
>  arch/arm/kernel/setup.c        | 31 +++++++++++++++++++------------
>  2 files changed, 20 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/arm/include/asm/cputype.h b/arch/arm/include/asm/cputype.h
> index b62eaeb147aa..65db1376f09a 100644
> --- a/arch/arm/include/asm/cputype.h
> +++ b/arch/arm/include/asm/cputype.h
> @@ -98,6 +98,7 @@
>  #define ARM_CPU_PART_SCORPION		0x510002d0
>  
>  extern unsigned int processor_id;
> +struct proc_info_list *lookup_processor(u32 midr);
>  
>  #ifdef CONFIG_CPU_CP15
>  #define read_cpuid(reg)							\
> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index f4e54503afa9..8d5c3a118abe 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -667,22 +667,29 @@ static void __init smp_build_mpidr_hash(void)
>  }
>  #endif
>  
> -static void __init setup_processor(void)
> +/*
> + * locate processor in the list of supported processor types.  The linker
> + * builds this table for us from the entries in arch/arm/mm/proc-*.S
> + */
> +struct proc_info_list *lookup_processor(u32 midr)
>  {
> -	struct proc_info_list *list;
> +	struct proc_info_list *list = lookup_processor_type(midr);
>  
> -	/*
> -	 * locate processor in the list of supported processor
> -	 * types.  The linker builds this table for us from the
> -	 * entries in arch/arm/mm/proc-*.S
> -	 */
> -	list = lookup_processor_type(read_cpuid_id());
>  	if (!list) {
> -		pr_err("CPU configuration botched (ID %08x), unable to continue.\n",
> -		       read_cpuid_id());
> -		while (1);
> +		pr_err("CPU%u: configuration botched (ID %08x), CPU halted\n",
> +		       smp_processor_id(), midr);
> +		while (1)
> +		/* can't use cpu_relax() here as it may require MMU setup */;
>  	}
>  
> +	return list;
> +}
> +
> +static void __init setup_processor(void)
> +{
> +	unsigned int midr = read_cpuid_id();
> +	struct proc_info_list *list = lookup_processor(midr);
> +
>  	cpu_name = list->cpu_name;
>  	__cpu_architecture = __get_cpu_architecture();
>  
> @@ -700,7 +707,7 @@ static void __init setup_processor(void)
>  #endif
>  
>  	pr_info("CPU: %s [%08x] revision %d (ARMv%s), cr=%08lx\n",
> -		cpu_name, read_cpuid_id(), read_cpuid_id() & 15,
> +		list->cpu_name, midr, midr & 15,
>  		proc_arch[cpu_architecture()], get_cr());
>  
>  	snprintf(init_utsname()->machine, __NEW_UTS_LEN + 1, "%s%c",
> -- 
> 2.17.1
> 

-- 
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