tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * iovec manipulation routines.
3 *
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
9 *
10 * Fixes:
11 * Andrew Lunn : Errors in iovec copying.
12 * Pedro Roque : Added memcpy_fromiovecend and
13 * csum_..._fromiovecend.
14 * Andi Kleen : fixed error handling for 2.1
15 * Alexey Kuznetsov: 2.1 optimisations
16 * Andi Kleen : Fix csum*fromiovecend for IPv6.
17 */
18
19#include <linux/errno.h>
20#include <linux/module.h>
21#include <linux/kernel.h>
22#include <linux/mm.h>
23#include <linux/net.h>
24#include <linux/in6.h>
25#include <asm/uaccess.h>
26#include <asm/byteorder.h>
27#include <net/checksum.h>
28#include <net/sock.h>
29
30/*
31 * And now for the all-in-one: copy and checksum from a user iovec
32 * directly to a datagram
33 * Calls to csum_partial but the last must be in 32 bit chunks
34 *
35 * ip_build_xmit must ensure that when fragmenting only the last
36 * call to this function will be unaligned also.
37 */
38int csum_partial_copy_fromiovecend(unsigned char *kdata, struct iovec *iov,
39 int offset, unsigned int len, __wsum *csump)
40{
41 __wsum csum = *csump;
42 int partial_cnt = 0, err = 0;
43
44 /* Skip over the finished iovecs */
45 while (offset >= iov->iov_len) {
46 offset -= iov->iov_len;
47 iov++;
48 }
49
50 while (len > 0) {
51 u8 __user *base = iov->iov_base + offset;
52 int copy = min_t(unsigned int, len, iov->iov_len - offset);
53
54 offset = 0;
55
56 /* There is a remnant from previous iov. */
57 if (partial_cnt) {
58 int par_len = 4 - partial_cnt;
59
60 /* iov component is too short ... */
61 if (par_len > copy) {
62 if (copy_from_user(kdata, base, copy))
63 goto out_fault;
64 kdata += copy;
65 base += copy;
66 partial_cnt += copy;
67 len -= copy;
68 iov++;
69 if (len)
70 continue;
71 *csump = csum_partial(kdata - partial_cnt,
72 partial_cnt, csum);
73 goto out;
74 }
75 if (copy_from_user(kdata, base, par_len))
76 goto out_fault;
77 csum = csum_partial(kdata - partial_cnt, 4, csum);
78 kdata += par_len;
79 base += par_len;
80 copy -= par_len;
81 len -= par_len;
82 partial_cnt = 0;
83 }
84
85 if (len > copy) {
86 partial_cnt = copy % 4;
87 if (partial_cnt) {
88 copy -= partial_cnt;
89 if (copy_from_user(kdata + copy, base + copy,
90 partial_cnt))
91 goto out_fault;
92 }
93 }
94
95 if (copy) {
96 csum = csum_and_copy_from_user(base, kdata, copy,
97 csum, &err);
98 if (err)
99 goto out;
100 }
101 len -= copy + partial_cnt;
102 kdata += copy + partial_cnt;
103 iov++;
104 }
105 *csump = csum;
106out:
107 return err;
108
109out_fault:
110 err = -EFAULT;
111 goto out;
112}
113EXPORT_SYMBOL(csum_partial_copy_fromiovecend);
114
115unsigned long iov_pages(const struct iovec *iov, int offset,
116 unsigned long nr_segs)
117{
118 unsigned long seg, base;
119 int pages = 0, len, size;
120
121 while (nr_segs && (offset >= iov->iov_len)) {
122 offset -= iov->iov_len;
123 ++iov;
124 --nr_segs;
125 }
126
127 for (seg = 0; seg < nr_segs; seg++) {
128 base = (unsigned long)iov[seg].iov_base + offset;
129 len = iov[seg].iov_len - offset;
130 size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT;
131 pages += size;
132 offset = 0;
133 }
134
135 return pages;
136}
137EXPORT_SYMBOL(iov_pages);