Messages in this thread | | | Date | Mon, 12 Feb 2024 06:26:14 +0000 | From | Al Viro <> | Subject | Re: [PATCH v6 2/2] lib: checksum: Use aligned accesses for ip_fast_csum and csum_ipv6_magic tests |
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On Wed, Feb 07, 2024 at 04:22:51PM -0800, Charlie Jenkins wrote: > + struct csum_ipv6_magic_data { > + const struct in6_addr saddr; > + const struct in6_addr daddr; > + unsigned int len; > + __wsum csum; > + unsigned char proto; > + } data, *data_ptr;
Huh?
> + int num_tests = MAX_LEN / WORD_ALIGNMENT - sizeof(struct csum_ipv6_magic_data); > + > + for (int i = 0; i < num_tests; i++) { > + data_ptr = (struct csum_ipv6_magic_data *)(random_buf + (i * WORD_ALIGNMENT)); > + > + cpu_to_be32_array((__be32 *)&data.saddr, (const u32 *)&data_ptr->saddr, > + sizeof_field(struct csum_ipv6_magic_data, saddr) / 4); > + cpu_to_be32_array((__be32 *)&data.daddr, (const u32 *)&data_ptr->daddr, > + sizeof_field(struct csum_ipv6_magic_data, daddr) / 4); > + data.len = data_ptr->len; > + data.csum = (__force __wsum)htonl((__force u32)data_ptr->csum);
What are those cpu_to_be32() about? Checksum calculations *DO* *NOT* involve any endianness conversions. At any point.
Replace those assignments with memcpy() and be done with that - that will take care of unaligned accesses.
Result will have host-independent memory representation. The only place where you might want to play with byteswaps (only 16-bit ones) is if you initialized the array of expected results with u16 constants. That will have opposite memory representations on l-e and b-e, so you'll need to byteswap to compare with what you get from function. Alternatively, make it an array of bytes and do sum16 = csum_ipv6_magic(saddr, daddr, len, proto, csum); if (memcmp(sum16, expected_csum_ipv6_magic + i * 2, 2)) complain
That's it.
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