[PATCH] arm64: vdso: minor ABI fix for clock_getres

[Will Deacon]

On Tue, Feb 24, 2015 at 11:21:07PM +0000, Nathan Lynch wrote:
> The vdso implementation of clock_getres currently returns 0 (success)
> whenever a null timespec is provided by the caller, regardless of the
> clock id supplied.
> 
> This behavior is incorrect.  It should fall back to syscall when an
> unrecognized clock id is passed, even when the timespec argument is
> null.  This ensures that clock_getres always returns an error for
> invalid clock ids.
> 
> Signed-off-by: Nathan Lynch <nathan_lynch at mentor.com>
> ---
>  arch/arm64/kernel/vdso/gettimeofday.S | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)

Acked-by: Will Deacon <will.deacon at arm.com>

Thanks, Nathan.

Will

> diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S
> index fe652ffd34c2..efa79e8d4196 100644
> --- a/arch/arm64/kernel/vdso/gettimeofday.S
> +++ b/arch/arm64/kernel/vdso/gettimeofday.S
> @@ -174,8 +174,6 @@ ENDPROC(__kernel_clock_gettime)
>  /* int __kernel_clock_getres(clockid_t clock_id, struct timespec *res); */
>  ENTRY(__kernel_clock_getres)
>  	.cfi_startproc
> -	cbz	w1, 3f
> -
>  	cmp	w0, #CLOCK_REALTIME
>  	ccmp	w0, #CLOCK_MONOTONIC, #0x4, ne
>  	b.ne	1f
> @@ -188,6 +186,7 @@ ENTRY(__kernel_clock_getres)
>  	b.ne	4f
>  	ldr	x2, 6f
>  2:
> +	cbz	w1, 3f
>  	stp	xzr, x2, [x1]
>  
>  3:	/* res == NULL. */
> -- 
> 1.9.3
> 
>