tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1/*
2 * Copyright (C) 2013 ARM Ltd.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program. If not, see <http://www.gnu.org/licenses/>.
15 */
16#ifndef __ASM_WORD_AT_A_TIME_H
17#define __ASM_WORD_AT_A_TIME_H
18
19#include <linux/uaccess.h>
20
21#ifndef __AARCH64EB__
22
23#include <linux/kernel.h>
24
25struct word_at_a_time {
26 const unsigned long one_bits, high_bits;
27};
28
29#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
30
31static inline unsigned long has_zero(unsigned long a, unsigned long *bits,
32 const struct word_at_a_time *c)
33{
34 unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
35 *bits = mask;
36 return mask;
37}
38
39#define prep_zero_mask(a, bits, c) (bits)
40
41static inline unsigned long create_zero_mask(unsigned long bits)
42{
43 bits = (bits - 1) & ~bits;
44 return bits >> 7;
45}
46
47static inline unsigned long find_zero(unsigned long mask)
48{
49 return fls64(mask) >> 3;
50}
51
52#define zero_bytemask(mask) (mask)
53
54#else /* __AARCH64EB__ */
55#include <asm-generic/word-at-a-time.h>
56#endif
57
58/*
59 * Load an unaligned word from kernel space.
60 *
61 * In the (very unlikely) case of the word being a page-crosser
62 * and the next page not being mapped, take the exception and
63 * return zeroes in the non-existing part.
64 */
65static inline unsigned long load_unaligned_zeropad(const void *addr)
66{
67 unsigned long ret, offset;
68
69 /* Load word from unaligned pointer addr */
70 asm(
71 "1: ldr %0, %3\n"
72 "2:\n"
73 " .pushsection .fixup,\"ax\"\n"
74 " .align 2\n"
75 "3: and %1, %2, #0x7\n"
76 " bic %2, %2, #0x7\n"
77 " ldr %0, [%2]\n"
78 " lsl %1, %1, #0x3\n"
79#ifndef __AARCH64EB__
80 " lsr %0, %0, %1\n"
81#else
82 " lsl %0, %0, %1\n"
83#endif
84 " b 2b\n"
85 " .popsection\n"
86 _ASM_EXTABLE(1b, 3b)
87 : "=&r" (ret), "=&r" (offset)
88 : "r" (addr), "Q" (*(unsigned long *)addr));
89
90 return ret;
91}
92
93#endif /* __ASM_WORD_AT_A_TIME_H */