[PATCH] aarch64: fix strcpy and strnlen for big-endian

[Szabolcs Nagy]

The 05/15/2020 10:12, Lexi Shao wrote:
> This patch fixes the optimized implementation of strcpy and strnlen
> on a big-endian arm64 machine.
> 
> The optimized method uses neon, which can process 128bit with one
> instruction. On a big-endian machine, the bit order should be reversed
> for the whole 128-bits double word. But with instuction
> 	rev64	datav.16b, datav.16b
> it reverses 64bits in the two halves rather than reverseing 128bits.
> There is no such instruction as rev128 to reverse the 128bits, but we
> can fix this by loading the data registers accordingly.
> 
> Fixes 0237b61526e7("aarch64: Optimized implementation of strcpy") and
> 2911cb68ed3d("aarch64: Optimized implementation of strnlen").
> 
> Signed-off-by: Lexi Shao <shaolexi@huawei.com>

Please add the bug reference to the title i.e.
append [BZ #25824]

note the patch was corrupted below you might want
to check if it's something on your side. (in this
case i could fix it because it was in the context)

with those fixed it's ok to commit,

Reviewed-by: Szabolcs Nagy  <szabolcs.nagy@arm.com>

if you don't have commit rights then i can commit
this for you.

> ---
>  sysdeps/aarch64/strcpy.S  | 5 +++++
>  sysdeps/aarch64/strnlen.S | 5 +++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/sysdeps/aarch64/strcpy.S b/sysdeps/aarch64/strcpy.S
> index 52c21c9..08859dd 100644
> --- a/sysdeps/aarch64/strcpy.S
> +++ b/sysdeps/aarch64/strcpy.S
> @@ -234,8 +234,13 @@ L(entry_no_page_cross):
>  #endif
>  	/* ���loc */
corrupt: ^^^^^^^^^

>  	cmeq	datav.16b, datav.16b, #0
> +#ifdef __AARCH64EB__
> +	mov	data1, datav.d[1]
> +	mov	data2, datav.d[0]
> +#else
>  	mov	data1, datav.d[0]
>  	mov	data2, datav.d[1]
> +#endif
>  	cmp	data1, 0
>  	csel	data1, data1, data2, ne
>  	mov	pos, 8
> diff --git a/sysdeps/aarch64/strnlen.S b/sysdeps/aarch64/strnlen.S
> index 5981247..086a5c7 100644
> --- a/sysdeps/aarch64/strnlen.S
> +++ b/sysdeps/aarch64/strnlen.S
> @@ -154,8 +154,13 @@ L(loop_end):
>  	   byte.  */
>  
>  	cmeq	datav.16b, datav.16b, #0
> +#ifdef __AARCH64EB__
> +	mov	data1, datav.d[1]
> +	mov	data2, datav.d[0]
> +#else
>  	mov	data1, datav.d[0]
>  	mov	data2, datav.d[1]
> +#endif
>  	cmp	data1, 0
>  	csel	data1, data1, data2, ne
>  	sub	len, src, srcin
> -- 
> 2.12.3
>