Re: [PATCH v3 13/18] arm64: __clean_dcache_area_poc to take end parameter instead of size

From: Mark Rutland <mark.rutland@arm.com>
To: Fuad Tabba <tabba@google.com>
Cc: linux-arm-kernel@lists.infradead.org, will@kernel.org,
	catalin.marinas@arm.com, maz@kernel.org, ardb@kernel.org,
	james.morse@arm.com, alexandru.elisei@arm.com,
	suzuki.poulose@arm.com, robin.murphy@arm.com
Subject: Re: [PATCH v3 13/18] arm64: __clean_dcache_area_poc to take end parameter instead of size
Date: Thu, 20 May 2021 17:16:31 +0100	[thread overview]
Message-ID: <20210520161631.GR17233@C02TD0UTHF1T.local> (raw)
In-Reply-To: <20210520124406.2731873-14-tabba@google.com>

On Thu, May 20, 2021 at 01:44:01PM +0100, Fuad Tabba wrote:
> To be consistent with other functions with similar names and
> functionality in cacheflush.h, cache.S, and cachetlb.rst, change
> to specify the range in terms of start and end, as opposed to
> start and size.
> 
> Because the code is shared with __dma_clean_area, it changes the
> parameters for that as well. However, __dma_clean_area is local to
> cache.S, so no other users are affected.
> 
> No functional change intended.
> 
> Reported-by: Will Deacon <will@kernel.org>
> Signed-off-by: Fuad Tabba <tabba@google.com>

One minor comment below, with that addressed:

Acked-by: Mark Rutland <mark.rutland@arm.com>

Mark.

> ---
>  arch/arm64/include/asm/cacheflush.h |  2 +-
>  arch/arm64/kernel/efi-entry.S       |  5 +++--
>  arch/arm64/mm/cache.S               | 16 +++++++---------
>  3 files changed, 11 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
> index 695f88864784..3255878d6f30 100644
> --- a/arch/arm64/include/asm/cacheflush.h
> +++ b/arch/arm64/include/asm/cacheflush.h
> @@ -60,7 +60,7 @@ extern void __flush_icache_range(unsigned long start, unsigned long end);
>  extern void invalidate_icache_range(unsigned long start, unsigned long end);
>  extern void __flush_dcache_area(unsigned long start, unsigned long end);
>  extern void __inval_dcache_area(unsigned long start, unsigned long end);
> -extern void __clean_dcache_area_poc(void *addr, size_t len);
> +extern void __clean_dcache_area_poc(unsigned long start, unsigned long end);
>  extern void __clean_dcache_area_pop(void *addr, size_t len);
>  extern void __clean_dcache_area_pou(void *addr, size_t len);
>  extern long __flush_cache_user_range(unsigned long start, unsigned long end);
> diff --git a/arch/arm64/kernel/efi-entry.S b/arch/arm64/kernel/efi-entry.S
> index 0073b24b5d25..72e6a580290a 100644
> --- a/arch/arm64/kernel/efi-entry.S
> +++ b/arch/arm64/kernel/efi-entry.S
> @@ -28,6 +28,7 @@ SYM_CODE_START(efi_enter_kernel)
>  	 * stale icache entries from before relocation.
>  	 */
>  	ldr	w1, =kernel_size
> +	add	x1, x0, x1
>  	bl	__clean_dcache_area_poc
>  	ic	ialluis
>  
> @@ -36,7 +37,7 @@ SYM_CODE_START(efi_enter_kernel)
>  	 * so that we can safely disable the MMU and caches.
>  	 */
>  	adr	x0, 0f
> -	ldr	w1, 3f
> +	adr	x1, 3f
>  	bl	__clean_dcache_area_poc
>  0:
>  	/* Turn off Dcache and MMU */
> @@ -65,4 +66,4 @@ SYM_CODE_START(efi_enter_kernel)
>  	mov	x3, xzr
>  	br	x19
>  SYM_CODE_END(efi_enter_kernel)
> -3:	.long	. - 0b
> +3:

Now that we're using this label for code rather than data, could we
please move this before the SYM_CODE_END()? It looks a bit out-of-place
sitting after the function now that it has no associated data, and it
shouldn't have a functional impact either way.

Mark.

> diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S
> index 35abc8d77c4e..9a9c44bb26d2 100644
> --- a/arch/arm64/mm/cache.S
> +++ b/arch/arm64/mm/cache.S
> @@ -178,24 +178,23 @@ SYM_FUNC_END_PI(__inval_dcache_area)
>  SYM_FUNC_END(__dma_inv_area)
>  
>  /*
> - *	__clean_dcache_area_poc(kaddr, size)
> + *	__clean_dcache_area_poc(start, end)
>   *
> - * 	Ensure that any D-cache lines for the interval [kaddr, kaddr+size)
> + * 	Ensure that any D-cache lines for the interval [start, end)
>   * 	are cleaned to the PoC.
>   *
> - *	- kaddr   - kernel address
> - *	- size    - size in question
> + *	- start   - virtual start address of region
> + *	- end     - virtual end address of region
>   */
>  SYM_FUNC_START_LOCAL(__dma_clean_area)
>  SYM_FUNC_START_PI(__clean_dcache_area_poc)
>  	/* FALLTHROUGH */
>  
>  /*
> - *	__dma_clean_area(start, size)
> + *	__dma_clean_area(start, end)
>   *	- start   - virtual start address of region
> - *	- size    - size in question
> + *	- end     - virtual end address of region
>   */
> -	add	x1, x0, x1
>  	dcache_by_line_op cvac, sy, x0, x1, x2, x3
>  	ret
>  SYM_FUNC_END_PI(__clean_dcache_area_poc)
> @@ -211,10 +210,10 @@ SYM_FUNC_END(__dma_clean_area)
>   *	- size    - size in question
>   */
>  SYM_FUNC_START_PI(__clean_dcache_area_pop)
> +	add	x1, x0, x1
>  	alternative_if_not ARM64_HAS_DCPOP
>  	b	__clean_dcache_area_poc
>  	alternative_else_nop_endif
> -	add	x1, x0, x1
>  	dcache_by_line_op cvap, sy, x0, x1, x2, x3
>  	ret
>  SYM_FUNC_END_PI(__clean_dcache_area_pop)
> @@ -243,7 +242,6 @@ SYM_FUNC_START_PI(__dma_map_area)
>  	add	x1, x0, x1
>  	cmp	w2, #DMA_FROM_DEVICE
>  	b.eq	__dma_inv_area
> -	sub	x1, x1, x0
>  	b	__dma_clean_area
>  SYM_FUNC_END_PI(__dma_map_area)
>  
> -- 
> 2.31.1.751.gd2f1c929bd-goog
> 

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