[PATCH 2/2] ARM: kexec: Fix crash_setup_regs() for ARMv7 and CONFIG_THUMB2_KERNEL

[Mika Westerberg]

Hi,

On Tue, Nov 16, 2010 at 01:12:21PM +0000, Dave Martin wrote:
>  * Fix kexec build failure with CONFIG_THUMB2_KERNEL.
> 
>  * Avoids deprecated/forbidden sp and pc usage in for ARMv7 onwards,
> retaining compatibility with older architecture versions.
> 
>  * The pc value saved to newregs is now aligned on a predictable
> instruction boundary.
> 
> (stmia { ... pc } or str pc has implementation-defined results
> in most versions of the ARM architecutre, and is prohibited
> (unpredictable) in Thumb-2.)
> 
>  * Switch to named inline asm arguments (else I get readily confused ...)
> 
> The resulting code should be compatible with all architecture versions >= v3,
> with or without CONFIG_THUMB2_KERNEL.
> 
> Applies cleanly on v2.6.37-rc1.

Quickly tested this and seems to work. So FWIW:

Acked-by: Mika Westerberg <mika.westerberg at iki.fi>

> 
> Signed-off-by: Dave Martin <dave.martin at linaro.org>
> Acked-by: Catalin Marinas <catalin.marinas at arm.com>
> Reviewed-by: Will Deacon <will.deacon at arm.com>
> ---
>  arch/arm/include/asm/kexec.h |   18 ++++++++++++++----
>  1 files changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/include/asm/kexec.h b/arch/arm/include/asm/kexec.h
> index b37e02c..c0094d8 100644
> --- a/arch/arm/include/asm/kexec.h
> +++ b/arch/arm/include/asm/kexec.h
> @@ -33,10 +33,20 @@ static inline void crash_setup_regs(struct pt_regs *newregs,
>  	if (oldregs) {
>  		memcpy(newregs, oldregs, sizeof(*newregs));
>  	} else {
> -		__asm__ __volatile__ ("stmia %0, {r0 - r15}"
> -				      : : "r" (&newregs->ARM_r0) : "memory");
> -		__asm__ __volatile__ ("mrs %0, cpsr"
> -				      : "=r" (newregs->ARM_cpsr));
> +		__asm__ __volatile__ (
> +			"stmia	%[regs_base], {r0-r12}\n\t"
> +			"mov	%[_ARM_sp], sp\n\t"
> +			"str	lr, %[_ARM_lr]\n\t"
> +			"adr	%[_ARM_pc], 1f\n\t"
> +			"mrs	%[_ARM_cpsr], cpsr\n\t"
> +		"1:"
> +			: [_ARM_pc] "=r" (newregs->ARM_pc),
> +			  [_ARM_cpsr] "=r" (newregs->ARM_cpsr),
> +			  [_ARM_sp] "=r" (newregs->ARM_sp),
> +			  [_ARM_lr] "=o" (newregs->ARM_lr)
> +			: [regs_base] "r" (&newregs->ARM_r0)
> +			: "memory"
> +		);
>  	}
>  }
>  
> -- 
> 1.7.1