linux-kernel - Re: [PATCH 6/8] arm64: Introduce raw_{d,i}cache_line

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Message-ID: <57AA032F.6050704@arm.com>
Date:	Tue, 09 Aug 2016 17:22:07 +0100
From:	James Morse <james.morse@....com>
To:	Suzuki K Poulose <suzuki.poulose@....com>
CC:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	catalin.marinas@....com, mark.rutland@....com, will.deacon@....com,
	Geoff Levand <geoff@...radead.org>
Subject: Re: [PATCH 6/8] arm64: Introduce raw_{d,i}cache_line_size

Hi Suzuki,

Sorry this fell through the cracks...

On 08/07/16 12:37, Suzuki K Poulose wrote:
> On systems with mismatched i/d cache min line sizes, we need to use
> the smallest size possible across all CPUs. This will be done by fetching
> the system wide safe value from CPU feature infrastructure.
> However the some special users(e.g kexec, hibernate) would need the line
> size on the CPU (rather than the system wide), when the system wide
> feature may not be accessible. Provide another helper which will fetch
> cache line size on the current CPU.

> diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
> index d5025c6..a4bb3f5 100644
> --- a/arch/arm64/include/asm/assembler.h
> +++ b/arch/arm64/include/asm/assembler.h
> @@ -218,9 +218,10 @@ lr	.req	x30		// link register
>  	.endm
>  
>  /*
> - * dcache_line_size - get the minimum D-cache line size from the CTR register.
> + * raw_dcache_line_size - get the minimum D-cache line size on this CPU
> + * from the CTR register.
>   */
> -	.macro	dcache_line_size, reg, tmp
> +	.macro	raw_dcache_line_size, reg, tmp
>  	mrs	\tmp, ctr_el0			// read CTR
>  	ubfm	\tmp, \tmp, #16, #19		// cache line size encoding
>  	mov	\reg, #4			// bytes per word
> @@ -228,9 +229,17 @@ lr	.req	x30		// link register
>  	.endm
>  
>  /*
> - * icache_line_size - get the minimum I-cache line size from the CTR register.
> + * dcache_line_size - get the safe D-cache line size across all CPUs
>   */
> -	.macro	icache_line_size, reg, tmp
> +	.macro	dcache_line_size, reg, tmp
> +	raw_dcache_line_size	\reg, \tmp
> +	.endm
> +
> +/*
> + * raw_icache_line_size - get the minimum I-cache line size on this CPU
> + * from the CTR register.
> + */
> +	.macro	raw_icache_line_size, reg, tmp
>  	mrs	\tmp, ctr_el0			// read CTR
>  	and	\tmp, \tmp, #0xf		// cache line size encoding
>  	mov	\reg, #4			// bytes per word
> @@ -238,6 +247,13 @@ lr	.req	x30		// link register
>  	.endm
>  
>  /*
> + * icache_line_size - get the safe I-cache line size across all CPUs
> + */
> +	.macro	icache_line_size, reg, tmp
> +	raw_icache_line_size	\reg, \tmp
> +	.endm
> +
> +/*
>   * tcr_set_idmap_t0sz - update TCR.T0SZ so that we can load the ID map
>   */
>  	.macro	tcr_set_idmap_t0sz, valreg, tmpreg
> diff --git a/arch/arm64/kernel/hibernate-asm.S b/arch/arm64/kernel/hibernate-asm.S
> index 46f29b6..4ebc6a1 100644
> --- a/arch/arm64/kernel/hibernate-asm.S
> +++ b/arch/arm64/kernel/hibernate-asm.S
> @@ -96,7 +96,7 @@ ENTRY(swsusp_arch_suspend_exit)
>  
>  	add	x1, x10, #PAGE_SIZE
>  	/* Clean the copied page to PoU - based on flush_icache_range() */
> -	dcache_line_size x2, x3
> +	raw_dcache_line_size x2, x3
>  	sub	x3, x2, #1
>  	bic	x4, x10, x3
>  2:	dc	cvau, x4	/* clean D line / unified line */


Looks like no-change to me!

If you think you need it:
Acked-by: James Morse <james.morse@....com>


Thanks,

James