Re: [PATCH net-next] net: enetc: use get/put_unaligned() for mac address handling

[Michael Walle]

Am 2021-06-04 14:44, schrieb Heiner Kallweit:
> On 04.06.2021 14:30, Michael Walle wrote:
> > The supplied buffer for the MAC address might not be aligned. Thus
> > doing a 32bit (or 16bit) access could be on an unaligned address. For
> > now, enetc is only used on aarch64 which can do unaligned accesses, 
> > thus
> > there is no error. In any case, be correct and use the 
> > get/put_unaligned()
> > helpers.
> >
> > Signed-off-by: Michael Walle <michael@xxxxxxxx>
> > ---
> >  drivers/net/ethernet/freescale/enetc/enetc_pf.c | 9 +++++----
> >  1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/freescale/enetc/enetc_pf.c 
> > b/drivers/net/ethernet/freescale/enetc/enetc_pf.c
> > index 31274325159a..a96d2acb5e11 100644
> > --- a/drivers/net/ethernet/freescale/enetc/enetc_pf.c
> > +++ b/drivers/net/ethernet/freescale/enetc/enetc_pf.c
> > @@ -1,6 +1,7 @@
> >  // SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
> >  /* Copyright 2017-2019 NXP */
> >
> > +#include <asm/unaligned.h>
> >  #include <linux/mdio.h>
> >  #include <linux/module.h>
> >  #include <linux/fsl/enetc_mdio.h>
> > @@ -17,15 +18,15 @@ static void enetc_pf_get_primary_mac_addr(struct 
> > enetc_hw *hw, int si, u8 *addr)
> >  	u32 upper = __raw_readl(hw->port + ENETC_PSIPMAR0(si));
> >  	u16 lower = __raw_readw(hw->port + ENETC_PSIPMAR1(si));
> >
> > -	*(u32 *)addr = upper;
> > -	*(u16 *)(addr + 4) = lower;
> > +	put_unaligned(upper, (u32 *)addr);
> > +	put_unaligned(lower, (u16 *)(addr + 4));
>
> I think you want to write little endian, therefore on a BE platform
> this code may be wrong. Better use put_unaligned_le32?
> By using these versions of the unaligned helpers you could also
> remove the pointer cast.

I wasn't sure about the endianness. Might be the case, that on BE
platforms, the endianess of the register will swap too. (OTOH I
could use aarch64 with BE..)

But I'm fine with changing it. I'd presume this being the only
platform for now it doesn't really matter.

-michael