[U-Boot] [PATCH 1/3] mtd: onenand: Fix unaligned access

[Marek Vasut]

On Thursday, December 26, 2013 at 01:01:24 AM, Marek Vasut wrote:
> Fix unaligned access in OneNAND core. The problem is that the ffchars[]
> array is an array of "unsigned char", but in onenand_write_ops_nolock()
> can be passed to the memcpy_16() function. The memcpy_16() function will
> treat the buffer as an array of "unsigned short", thus triggering
> unaligned access if the compiler decided ffchars[] to be not aligned.
> 
> I managed to trigger the problem with regular ELDK 5.4 GCC compiler.
> 
> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Albert Aribaud <albert.u.boot at aribaud.net>
> Cc: Scott Wood <scottwood at freescale.com>
> Cc: Tom Rini <trini at ti.com>
> ---
>  drivers/mtd/onenand/onenand_base.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/onenand/onenand_base.c
> b/drivers/mtd/onenand/onenand_base.c index 979e4af..e33e8d3 100644
> --- a/drivers/mtd/onenand/onenand_base.c
> +++ b/drivers/mtd/onenand/onenand_base.c
> @@ -91,7 +91,13 @@ static struct nand_ecclayout onenand_oob_32 = {
>  	.oobfree	= { {2, 3}, {14, 2}, {18, 3}, {30, 2} }
>  };
> 
> -static const unsigned char ffchars[] = {
> +/*
> + * Warning! This array is used with the memcpy_16() function, thus
> + * it must be aligned to 2 bytes. GCC can make this array unaligned
> + * as the array is made of unsigned char, which memcpy16() doesn't
> + * like and will cause unaligned access.
> + */
> +static const unsigned char __aligned(2) ffchars[] = {
>  	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
>  	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,	/* 16 */
>  	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

Lukasz, can you please review this one?

Best regards,
Marek Vasut