1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Copyright (C) 2013 ARM Ltd.
4 */
5 #ifndef __ASM_WORD_AT_A_TIME_H
6 #define __ASM_WORD_AT_A_TIME_H
7
8 #include <linux/uaccess.h>
9
10 #ifndef __AARCH64EB__
11
12 #include <linux/bitops.h>
13 #include <linux/wordpart.h>
14
15 struct word_at_a_time {
16 const unsigned long one_bits, high_bits;
17 };
18
19 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
20
21 static inline unsigned long has_zero(unsigned long a, unsigned long *bits,
22 const struct word_at_a_time *c)
23 {
24 unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
25 *bits = mask;
26 return mask;
27 }
28
29 #define prep_zero_mask(a, bits, c) (bits)
30 #define create_zero_mask(bits) (bits)
31 #define find_zero(bits) (__ffs(bits) >> 3)
32
33 static inline unsigned long zero_bytemask(unsigned long bits)
34 {
35 bits = (bits - 1) & ~bits;
36 return bits >> 7;
37 }
38
39 #else /* __AARCH64EB__ */
40 #include <asm-generic/word-at-a-time.h>
41 #endif
42
43 /*
44 * Load an unaligned word from kernel space.
45 *
46 * In the (very unlikely) case of the word being a page-crosser
47 * and the next page not being mapped, take the exception and
48 * return zeroes in the non-existing part.
49 */
50 static inline unsigned long load_unaligned_zeropad(const void *addr)
51 {
52 unsigned long ret;
53
54 __mte_enable_tco_async();
55
56 /* Load word from unaligned pointer addr */
57 asm(
58 "1: ldr %0, %2\n"
59 "2:\n"
60 _ASM_EXTABLE_LOAD_UNALIGNED_ZEROPAD(1b, 2b, %0, %1)
61 : "=&r" (ret)
62 : "r" (addr), "Q" (*(unsigned long *)addr));
63
64 __mte_disable_tco_async();
65
66 return ret;
67 }
68
69 #endif /* __ASM_WORD_AT_A_TIME_H */
70
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