Re: [PATCH v3 10/18] arm64: __inval_dcache_area to take end parameter instead of size

[Mark Rutland <mark.rutland@arm.com>]

On Thu, May 20, 2021 at 01:43:58PM +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_inv_area, it changes the
> parameters for that as well. However, __dma_inv_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>

All the conversions below look correct to me, and judging by a grep of
the kernel tree there are no stale callers. I see the ADD->SUB dance in
__dma_map_area() will be undone in a subsequent patch. So:

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

Mark.

> ---
>  arch/arm64/include/asm/cacheflush.h |  2 +-
>  arch/arm64/kernel/head.S            |  5 +----
>  arch/arm64/mm/cache.S               | 16 +++++++++-------
>  arch/arm64/mm/flush.c               |  2 +-
>  4 files changed, 12 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
> index a586afa84172..157234706817 100644
> --- a/arch/arm64/include/asm/cacheflush.h
> +++ b/arch/arm64/include/asm/cacheflush.h
> @@ -59,7 +59,7 @@
>  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(void *addr, size_t len);
> -extern void __inval_dcache_area(void *addr, size_t len);
> +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_pop(void *addr, size_t len);
>  extern void __clean_dcache_area_pou(void *addr, size_t len);
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index 96873dfa67fd..8df0ac8d9123 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -117,7 +117,7 @@ SYM_CODE_START_LOCAL(preserve_boot_args)
>  	dmb	sy				// needed before dc ivac with
>  						// MMU off
>  
> -	mov	x1, #0x20			// 4 x 8 bytes
> +	add	x1, x0, #0x20			// 4 x 8 bytes
>  	b	__inval_dcache_area		// tail call
>  SYM_CODE_END(preserve_boot_args)
>  
> @@ -268,7 +268,6 @@ SYM_FUNC_START_LOCAL(__create_page_tables)
>  	 */
>  	adrp	x0, init_pg_dir
>  	adrp	x1, init_pg_end
> -	sub	x1, x1, x0
>  	bl	__inval_dcache_area
>  
>  	/*
> @@ -382,12 +381,10 @@ SYM_FUNC_START_LOCAL(__create_page_tables)
>  
>  	adrp	x0, idmap_pg_dir
>  	adrp	x1, idmap_pg_end
> -	sub	x1, x1, x0
>  	bl	__inval_dcache_area
>  
>  	adrp	x0, init_pg_dir
>  	adrp	x1, init_pg_end
> -	sub	x1, x1, x0
>  	bl	__inval_dcache_area
>  
>  	ret	x28
> diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S
> index 80da4b8718b6..5170d9ab450a 100644
> --- a/arch/arm64/mm/cache.S
> +++ b/arch/arm64/mm/cache.S
> @@ -138,25 +138,24 @@ alternative_else_nop_endif
>  SYM_FUNC_END(__clean_dcache_area_pou)
>  
>  /*
> - *	__inval_dcache_area(kaddr, size)
> + *	__inval_dcache_area(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 invalidated. Any partial lines at the ends of the interval are
>   *	also cleaned to PoC to prevent data loss.
>   *
> - *	- kaddr   - kernel address
> - *	- size    - size in question
> + *	- start   - kernel start address of region
> + *	- end     - kernel end address of region
>   */
>  SYM_FUNC_START_LOCAL(__dma_inv_area)
>  SYM_FUNC_START_PI(__inval_dcache_area)
>  	/* FALLTHROUGH */
>  
>  /*
> - *	__dma_inv_area(start, size)
> + *	__dma_inv_area(start, end)
>   *	- start   - virtual start address of region
> - *	- size    - size in question
> + *	- end     - virtual end address of region
>   */
> -	add	x1, x1, x0
>  	dcache_line_size x2, x3
>  	sub	x3, x2, #1
>  	tst	x1, x3				// end cache line aligned?
> @@ -237,8 +236,10 @@ SYM_FUNC_END_PI(__dma_flush_area)
>   *	- dir	- DMA direction
>   */
>  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)
>  
> @@ -249,6 +250,7 @@ SYM_FUNC_END_PI(__dma_map_area)
>   *	- dir	- DMA direction
>   */
>  SYM_FUNC_START_PI(__dma_unmap_area)
> +	add	x1, x0, x1
>  	cmp	w2, #DMA_TO_DEVICE
>  	b.ne	__dma_inv_area
>  	ret
> diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c
> index ac485163a4a7..4e3505c2bea6 100644
> --- a/arch/arm64/mm/flush.c
> +++ b/arch/arm64/mm/flush.c
> @@ -88,7 +88,7 @@ EXPORT_SYMBOL_GPL(arch_wb_cache_pmem);
>  
>  void arch_invalidate_pmem(void *addr, size_t size)
>  {
> -	__inval_dcache_area(addr, size);
> +	__inval_dcache_area((unsigned long)addr, (unsigned long)addr + size);
>  }
>  EXPORT_SYMBOL_GPL(arch_invalidate_pmem);
>  #endif
> -- 
> 2.31.1.751.gd2f1c929bd-goog
> 

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