[PATCH v2 6/9] arm64: call __enable_mmu as an ordinary function for secondary/resume

[Mark Rutland]

On Wed, Aug 24, 2016 at 04:36:03PM +0200, Ard Biesheuvel wrote:
> This updates the secondary and cpu_resume call sites to simply call
> __enable_mmu as an ordinary function, with a bl instruction. This
> requires the callers to be covered by .idmap.text.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> ---
>  arch/arm64/kernel/head.S  | 14 ++++++--------
>  arch/arm64/kernel/sleep.S | 10 +++-------
>  2 files changed, 9 insertions(+), 15 deletions(-)

Can we please fold this with patch 5?

>From my PoV the combined diff is simpler to follow, and by doing so we
avoid a few temporary issues (misleading comment above __enable_mmu, fun
and games with the lr) that the series is generally cleaning up.

>From a quick look at __idmap_text_{start,end}, we have plenty of
headroom in the idmap page, so moving a few more things in there is fine
by me.

FWIW, With the two patches folded:

Reviewed-by: Mark Rutland <mark.rutland at arm.com>

Thanks,
Mark.

> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index 3e08e51578d5..c112c153821e 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -634,6 +634,7 @@ ENTRY(__boot_cpu_mode)
>  	 * This provides a "holding pen" for platforms to hold all secondary
>  	 * cores are held until we're ready for them to initialise.
>  	 */
> +	.pushsection	".idmap.text", "ax"
>  ENTRY(secondary_holding_pen)
>  	bl	el2_setup			// Drop to EL1, w0=cpu_boot_mode
>  	bl	set_cpu_boot_mode_flag
> @@ -663,10 +664,12 @@ secondary_startup:
>  	 * Common entry point for secondary CPUs.
>  	 */
>  	bl	__cpu_setup			// initialise processor
> -
> -	adr_l	lr, __secondary_switch		// address to jump to after enabling the MMU
> -	b	__enable_mmu
> +	bl	__enable_mmu
> +	ldr	x8, =__secondary_switched
> +	br	x8
>  ENDPROC(secondary_startup)
> +	.ltorg
> +	.popsection
>  
>  __secondary_switched:
>  	adr_l	x5, vectors
> @@ -812,8 +815,3 @@ __primary_switch:
>  	ldr	x8, =__primary_switched
>  	br	x8
>  ENDPROC(__primary_switch)
> -
> -__secondary_switch:
> -	ldr	x8, =__secondary_switched
> -	br	x8
> -ENDPROC(__secondary_switch)
> diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
> index 4bce95cd656a..1d4aba6fcc7a 100644
> --- a/arch/arm64/kernel/sleep.S
> +++ b/arch/arm64/kernel/sleep.S
> @@ -95,19 +95,15 @@ ENTRY(__cpu_suspend_enter)
>  	ret
>  ENDPROC(__cpu_suspend_enter)
>  
> +	.pushsection	".idmap.text", "ax"
>  ENTRY(cpu_resume)
>  	bl	el2_setup		// if in EL2 drop to EL1 cleanly
>  	bl	__cpu_setup
>  	/* enable the MMU early - so we can access sleep_save_stash by va */
> -	adr_l	lr, _resume_switched	/* __enable_mmu will branch here */
> -	b	__enable_mmu
> -ENDPROC(cpu_resume)
> -
> -	.pushsection	".idmap.text", "ax"
> -_resume_switched:
> +	bl	__enable_mmu
>  	ldr	x8, =_cpu_resume
>  	br	x8
> -ENDPROC(_resume_switched)
> +ENDPROC(cpu_resume)
>  	.ltorg
>  	.popsection
>  
> -- 
> 2.7.4
>