[PATCH] arm64/kernel: kaslr: drop special Image placement logic

[Steve Capper]

On Wed, Jan 17, 2018 at 04:11:27PM +0000, Ard Biesheuvel wrote:
> Now that the early kernel mapping logic can tolerate placements of
> Image that cross swapper table boundaries, we can remove the logic
> that adjusts the offset if the dice roll produced an offset that
> puts the kernel right on top of one.

Reviewed-by: Steve Capper <steve.capper at arm.com>

> 
> Cc: Steve Capper <steve.capper at arm.com>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> ---
>  arch/arm64/kernel/kaslr.c | 15 ---------------
>  1 file changed, 15 deletions(-)
> 
> diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
> index 47080c49cc7e..e3d5cbe2167b 100644
> --- a/arch/arm64/kernel/kaslr.c
> +++ b/arch/arm64/kernel/kaslr.c
> @@ -128,21 +128,6 @@ u64 __init kaslr_early_init(u64 dt_phys)
>  	/* use the top 16 bits to randomize the linear region */
>  	memstart_offset_seed = seed >> 48;
>  
> -	/*
> -	 * The kernel Image should not extend across a 1GB/32MB/512MB alignment
> -	 * boundary (for 4KB/16KB/64KB granule kernels, respectively). If this
> -	 * happens, round down the KASLR offset by (1 << SWAPPER_TABLE_SHIFT).
> -	 *
> -	 * NOTE: The references to _text and _end below will already take the
> -	 *       modulo offset (the physical displacement modulo 2 MB) into
> -	 *       account, given that the physical placement is controlled by
> -	 *       the loader, and will not change as a result of the virtual
> -	 *       mapping we choose.
> -	 */
> -	if ((((u64)_text + offset) >> SWAPPER_TABLE_SHIFT) !=
> -	    (((u64)_end + offset) >> SWAPPER_TABLE_SHIFT))
> -		offset = round_down(offset, 1 << SWAPPER_TABLE_SHIFT);
> -
>  	if (IS_ENABLED(CONFIG_KASAN))
>  		/*
>  		 * KASAN does not expect the module region to intersect the
> -- 
> 2.11.0
>