1 // SPDX-License-Identifier: GPL-2.0-only
2 // Copyright (C) 2019-2020 Arm Ltd.
5 #include <linux/kasan-checks.h>
10 /* Looks dumb, but generates nice-ish code */
11 static u64 accumulate(u64 sum, u64 data)  in accumulate()  argument
13 	__uint128_t tmp = (__uint128_t)sum + data;  in accumulate()
18  * We over-read the buffer and this makes KASAN unhappy. Instead, disable
23 	unsigned int offset, shift, sum;  in do_csum()  local
25 	u64 data, sum64 = 0;  in do_csum()  local
34 	 * should absolutely not be pointing to anything read-sensitive. We do,  in do_csum()
37 	 * compensate with an explicit check up-front.  in do_csum()
40 	ptr = (u64 *)(buff - offset);  in do_csum()
41 	len = len + offset - 8;  in do_csum()
48 	shift = offset * 8;  in do_csum()
49 	data = *ptr++;  in do_csum()
51 	data = (data >> shift) << shift;  in do_csum()
53 	data = (data << shift) >> shift;  in do_csum()
70 		len -= 64;  in do_csum()
91 		sum64 = accumulate(sum64, data);  in do_csum()
94 		len -= 16;  in do_csum()
98 		data = tmp >> 64;  in do_csum()
101 		data = tmp;  in do_csum()
106 		sum64 = accumulate(sum64, data);  in do_csum()
107 		data = *ptr;  in do_csum()
108 		len -= 8;  in do_csum()
111 	 * Tail: zero any over-read bytes similarly to the head, again  in do_csum()
114 	shift = len * -8;  in do_csum()
116 	data = (data << shift) >> shift;  in do_csum()
118 	data = (data >> shift) << shift;  in do_csum()
120 	sum64 = accumulate(sum64, data);  in do_csum()
139 	src = *(const __uint128_t *)saddr->s6_addr;  in csum_ipv6_magic()
140 	dst = *(const __uint128_t *)daddr->s6_addr;  in csum_ipv6_magic()