From: David Laight <David.Laight@ACULAB.COM>
To: "'Laurent Dufour'" <ldufour@linux.vnet.ibm.com>,
        "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jslaby@suse.cz>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] powerpc/hvsi: Fix endianness issues in the HVSI driver
Thread-Topic: [PATCH] powerpc/hvsi: Fix endianness issues in the HVSI driver
Thread-Index: AQHQy3OWhkkc2JuBs0KGkILRUzV70Z36H7pQ
Date: Mon, 3 Aug 2015 11:00:18 +0000
Message-ID: <063D6719AE5E284EB5DD2968C1650D6D1CB71D3E@AcuExch.aculab.com>
References: <1438334990-11765-1-git-send-email-ldufour@linux.vnet.ibm.com>
In-Reply-To: <1438334990-11765-1-git-send-email-ldufour@linux.vnet.ibm.com>
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From: Laurent Dufour
> Sent: 31 July 2015 10:30
> This patch fixes several endianness issues detected when running the HVSI
> driver in little endian mode.
> 
> These issues are raised in little endian mode because the data exchanged in
> memory between the kernel and the hypervisor has to be in big endian
> format.
...
> diff --git a/drivers/tty/hvc/hvsi.c b/drivers/tty/hvc/hvsi.c
> index 41901997c0d6..a75146f600cb 100644
> --- a/drivers/tty/hvc/hvsi.c
> +++ b/drivers/tty/hvc/hvsi.c
> @@ -240,9 +240,9 @@ static void hvsi_recv_control(struct hvsi_struct *hp, uint8_t *packet,
>  {
>  	struct hvsi_control *header = (struct hvsi_control *)packet;
> 
> -	switch (header->verb) {
> +	switch (be16_to_cpu(header->verb)) {
>  		case VSV_MODEM_CTL_UPDATE:
> -			if ((header->word & HVSI_TSCD) == 0) {
> +			if ((be32_to_cpu(header->word) & HVSI_TSCD) == 0) {

It is generally best to byteswap constants.

	David

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