From: Pablo Neira Ayuso
> Sent: 08 January 2016 14:02
> From: Florian Westphal <fw@xxxxxxxxx>
>
> Needed to convert the (64bit) conntrack counters to BE ordering.
>
...
> switch (priv->size) {
> + case 8: {
> + u64 src64;
> +
> + switch (priv->op) {
> + case NFT_BYTEORDER_NTOH:
> + for (i = 0; i < priv->len / 8; i++) {
> + src64 = get_unaligned_be64(&src[i]);
> + src64 = be64_to_cpu((__force __be64)src64);
> + put_unaligned_be64(src64, &dst[i]);
> + }
> + break;
> + case NFT_BYTEORDER_HTON:
> + for (i = 0; i < priv->len / 8; i++) {
> + src64 = get_unaligned_be64(&src[i]);
> + src64 = (__force u64)cpu_to_be64(src64);
> + put_unaligned_be64(src64, &dst[i]);
> + }
> + break;
> + }
> + break;
That is horrid.
On a little-endian system you are byteswapping the data 3 times.
Image the code on a cpu that doesn't support misaligned transfers
and doesn't have a byteswap instruction.
David
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