ARM: kernel/sleep.S: fix Thumb2 compilation issues

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>

On Fri, Mar 18, 2011 at 11:00:02PM -0400, Nicolas Pitre wrote:
> 
> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
> 
> diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
> index bfad698..6398ead 100644
> --- a/arch/arm/kernel/sleep.S
> +++ b/arch/arm/kernel/sleep.S
> @@ -119,11 +119,19 @@ ENTRY(cpu_resume)
>  #else
>  	ldr	r0, sleep_save_sp	@ stack phys addr
>  #endif
> -	msr	cpsr_c, #PSR_I_BIT | PSR_F_BIT | SVC_MODE @ set SVC, irqs off
> +	setmode	PSR_I_BIT | PSR_F_BIT | SVC_MODE, r1  @ set SVC, irqs off
>  #ifdef MULTI_CPU
> -	ldmia	r0!, {r1, sp, lr, pc}	@ load v:p, stack, return fn, resume fn
> +	@ load v:p, stack, return fn, resume fn
> +  ARM(	ldmia	r0!, {r1, sp, lr, pc}	)
> +THUMB(	ldmia	r0!, {r1, r2, r3, r4}	)
> +THUMB(	mov	sp, r2			)
> +THUMB(	mov	lr, r3			)
> +THUMB(	bx	r4			)
>  #else
> -	ldmia	r0!, {r1, sp, lr}	@ load v:p, stack, return fn
> +	@ load v:p, stack, return fn
> +  ARM(	ldmia	r0!, {r1, sp, lr}	)
> +THUMB(	ldmia	r0!, {r1, r2, lr}	)
> +THUMB(	mov	sp, r2			)
>  	b	cpu_do_resume
>  #endif
>  ENDPROC(cpu_resume)

As far as I can determine from the context, r1-r4 are not live at
this point, so the suggested change looks sound.

Reviewed-by: Dave Martin <dave.martin@linaro.org>

I haven't watched the generic suspend/resume discussion too
closely; how would I go about testing this?

Cheers
---Dave

On Fri, Mar 18, 2011 at 11:00:02PM -0400, Nicolas Pitre wrote:
> 
> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
> 
> diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
> index bfad698..6398ead 100644
> --- a/arch/arm/kernel/sleep.S
> +++ b/arch/arm/kernel/sleep.S
> @@ -119,11 +119,19 @@ ENTRY(cpu_resume)
>  #else
>  	ldr	r0, sleep_save_sp	@ stack phys addr
>  #endif
> -	msr	cpsr_c, #PSR_I_BIT | PSR_F_BIT | SVC_MODE @ set SVC, irqs off
> +	setmode	PSR_I_BIT | PSR_F_BIT | SVC_MODE, r1  @ set SVC, irqs off
>  #ifdef MULTI_CPU
> -	ldmia	r0!, {r1, sp, lr, pc}	@ load v:p, stack, return fn, resume fn
> +	@ load v:p, stack, return fn, resume fn
> +  ARM(	ldmia	r0!, {r1, sp, lr, pc}	)
> +THUMB(	ldmia	r0!, {r1, r2, r3, r4}	)
> +THUMB(	mov	sp, r2			)
> +THUMB(	mov	lr, r3			)
> +THUMB(	bx	r4			)
>  #else
> -	ldmia	r0!, {r1, sp, lr}	@ load v:p, stack, return fn
> +	@ load v:p, stack, return fn
> +  ARM(	ldmia	r0!, {r1, sp, lr}	)
> +THUMB(	ldmia	r0!, {r1, r2, lr}	)
> +THUMB(	mov	sp, r2			)
>  	b	cpu_do_resume
>  #endif
>  ENDPROC(cpu_resume)

Do we know whether boot loaders support calling the resume path in Thumb
mode, and is the necessary setup in place for telling boot loaders that
they are to call the resume path in Thumb mode?

On Sat, 26 Mar 2011, Russell King - ARM Linux wrote:

> On Fri, Mar 18, 2011 at 11:00:02PM -0400, Nicolas Pitre wrote:
> > 
> > Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
> > 
> > diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
> > index bfad698..6398ead 100644
> > --- a/arch/arm/kernel/sleep.S
> > +++ b/arch/arm/kernel/sleep.S
> > @@ -119,11 +119,19 @@ ENTRY(cpu_resume)
> >  #else
> >  	ldr	r0, sleep_save_sp	@ stack phys addr
> >  #endif
> > -	msr	cpsr_c, #PSR_I_BIT | PSR_F_BIT | SVC_MODE @ set SVC, irqs off
> > +	setmode	PSR_I_BIT | PSR_F_BIT | SVC_MODE, r1  @ set SVC, irqs off
> >  #ifdef MULTI_CPU
> > -	ldmia	r0!, {r1, sp, lr, pc}	@ load v:p, stack, return fn, resume fn
> > +	@ load v:p, stack, return fn, resume fn
> > +  ARM(	ldmia	r0!, {r1, sp, lr, pc}	)
> > +THUMB(	ldmia	r0!, {r1, r2, r3, r4}	)
> > +THUMB(	mov	sp, r2			)
> > +THUMB(	mov	lr, r3			)
> > +THUMB(	bx	r4			)
> >  #else
> > -	ldmia	r0!, {r1, sp, lr}	@ load v:p, stack, return fn
> > +	@ load v:p, stack, return fn
> > +  ARM(	ldmia	r0!, {r1, sp, lr}	)
> > +THUMB(	ldmia	r0!, {r1, r2, lr}	)
> > +THUMB(	mov	sp, r2			)
> >  	b	cpu_do_resume
> >  #endif
> >  ENDPROC(cpu_resume)
> 
> Do we know whether boot loaders support calling the resume path in Thumb
> mode, and is the necessary setup in place for telling boot loaders that
> they are to call the resume path in Thumb mode?

Hard to tell for sure without testing.  But in theory, if the bootloader 
is passed the value of the cpu_resume symbol, even after going through 
virt_to_phys(), then bit 0 should be set indicating Thumb mode and 
therefore it ought to work correctly by simply loading that value into 
the pc (not true for ARMv6T2 but we don't support any of those).


Nicolas