[PATCH 1/2] arm64: add macro to handle large immediates

[Ard Biesheuvel]

On 6 January 2016 at 12:05, Mark Rutland <mark.rutland at arm.com> wrote:
> Sometimes we want to be able to load values greater than 0xff into a
> register, without placing said values in a literal pool. Arranging for
> the value to be split up across a number of movz and movk instructions
> is tedious and error-prone.
>
> Following the example of {adr,str,ldr}_l, this patch adds a new mov_l
> macro which can be used to load immediate values of up to 64 bits into a
> register.
>
> Signed-off-by: Mark Rutland <mark.rutland at arm.com>
> Cc: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> Cc: Catalin Marinas <catalin.marinas at arm.com>
> Cc: Marc Zyngier <marc.zyngier at arm.com>
> Cc: Will Deacon <will.deacon at arm.com>
> ---
>  arch/arm64/include/asm/assembler.h | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>
> diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
> index 12eff92..64fd0a2 100644
> --- a/arch/arm64/include/asm/assembler.h
> +++ b/arch/arm64/include/asm/assembler.h
> @@ -193,6 +193,19 @@ lr .req    x30             // link register
>         str     \src, [\tmp, :lo12:\sym]
>         .endm
>
> +       /*
> +        * Move a large immediate up to 64-bits.
> +        *
> +        * @dst: destination register (64 bit wide)
> +        * @val: value
> +        */
> +       .macro  mov_l, dst, val
> +       movz    \dst, :abs_g0_nc:\val
> +       movk    \dst, :abs_g1_nc:\val
> +       movk    \dst, :abs_g2_nc:\val
> +       movk    \dst, :abs_g3:\val
> +       .endm
> +

Ack for the general idea, but for correctness, you should pair the
movk instructions with the _nc relocations (i.e., keep movz first, but
invert the order of the relocs)