[PATCH v3] ARM: zImage: perform cache maintenance after relocating code (was: ARM: zImage: add DSB and ISB barriers after relocating code)

[Nicolas Pitre]

On Mon, 11 Aug 2014, Marc Carino wrote:

> The zImage loader will relocate the kernel image if it determines that
> decompression will overwrite its current location. Since the act of relocation
> is a form of code self-modification, we need to ensure that the CPU fetches
> the updated instruction stream.
> 
> Instead of conditionally executing cache maintenance, this commit ensures that
> cache maintenance is performed in all cases. Besides ensuring coherency with
> the caches and main memory, performing cache maintenance ensures that any
> potentially stale instructions are flushed from the instruction pipeline.
> 
> Signed-off-by: Marc Carino <marc.ceeeee at gmail.com>

Acked-by: Nicolas Pitre <nico at linaro.org>


> ---
>  arch/arm/boot/compressed/head.S | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index 3a8b32d..8a39054 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -395,8 +395,7 @@ dtb_check_done:
>  		add	sp, sp, r6
>  #endif
>  
> -		tst	r4, #1
> -		bleq	cache_clean_flush
> +		bl	cache_clean_flush
>  
>  		adr	r0, BSYM(restart)
>  		add	r0, r0, r6
> -- 
> 1.8.1.3
> 
>