[PATCH 1/3] ARM: move cpu_resume() to .text section

[Nicolas Pitre]

On Tue, 24 Mar 2015, Ard Biesheuvel wrote:

> Move cpu_resume() to the .text section where it belongs. Change
> the adr reference to sleep_save_sp to an explicit PC relative
> reference so sleep_save_sp itself can remain in .data.
> 
> This helps prevent linker failure on large kernels, as the code
> in the .data section may be too far away to be in range for normal
> b/bl instructions.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>

I'm mystified.  I'm sure I did convert this code away from .data at some 
point.  Oh well...

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

> ---
>  arch/arm/kernel/sleep.S | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
> index 31041b4a3f53..fb64c96cd801 100644
> --- a/arch/arm/kernel/sleep.S
> +++ b/arch/arm/kernel/sleep.S
> @@ -116,14 +116,7 @@ cpu_resume_after_mmu:
>  	ldmfd	sp!, {r4 - r11, pc}
>  ENDPROC(cpu_resume_after_mmu)
>  
> -/*
> - * Note: Yes, part of the following code is located into the .data section.
> - *       This is to allow sleep_save_sp to be accessed with a relative load
> - *       while we can't rely on any MMU translation.  We could have put
> - *       sleep_save_sp in the .text section as well, but some setups might
> - *       insist on it to be truly read-only.
> - */
> -	.data
> +	.text
>  	.align
>  ENTRY(cpu_resume)
>  ARM_BE8(setend be)			@ ensure we are in BE mode
> @@ -145,6 +138,8 @@ ARM_BE8(setend be)			@ ensure we are in BE mode
>  	compute_mpidr_hash	r1, r4, r5, r6, r0, r3
>  1:
>  	adr	r0, _sleep_save_sp
> +	ldr	r2, [r0]
> +	add	r0, r0, r2
>  	ldr	r0, [r0, #SLEEP_SAVE_SP_PHYS]
>  	ldr	r0, [r0, r1, lsl #2]
>  
> @@ -156,10 +151,12 @@ THUMB(	bx	r3			)
>  ENDPROC(cpu_resume)
>  
>  	.align 2
> +_sleep_save_sp:
> +	.long	sleep_save_sp - .
>  mpidr_hash_ptr:
>  	.long	mpidr_hash - .			@ mpidr_hash struct offset
>  
> +	.data
>  	.type	sleep_save_sp, #object
>  ENTRY(sleep_save_sp)
> -_sleep_save_sp:
>  	.space	SLEEP_SAVE_SP_SZ		@ struct sleep_save_sp
> -- 
> 1.8.3.2
> 
>