1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Copyright (C) 2012 Regents of the University of California
4 *
5 * Derived from arch/x86/include/asm/word-at-a-time.h
6 */
7
8 #ifndef _ASM_RISCV_WORD_AT_A_TIME_H
9 #define _ASM_RISCV_WORD_AT_A_TIME_H
10
11
12 #include <asm/asm-extable.h>
13 #include <linux/bitops.h>
14 #include <linux/wordpart.h>
15
16 struct word_at_a_time {
17 const unsigned long one_bits, high_bits;
18 };
19
20 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
21
22 static inline unsigned long has_zero(unsigned long val,
23 unsigned long *bits, const struct word_at_a_time *c)
24 {
25 unsigned long mask = ((val - c->one_bits) & ~val) & c->high_bits;
26 *bits = mask;
27 return mask;
28 }
29
30 static inline unsigned long prep_zero_mask(unsigned long val,
31 unsigned long bits, const struct word_at_a_time *c)
32 {
33 return bits;
34 }
35
36 static inline unsigned long create_zero_mask(unsigned long bits)
37 {
38 bits = (bits - 1) & ~bits;
39 return bits >> 7;
40 }
41
42 static inline unsigned long find_zero(unsigned long mask)
43 {
44 return fls64(mask) >> 3;
45 }
46
47 /* The mask we created is directly usable as a bytemask */
48 #define zero_bytemask(mask) (mask)
49
50 #ifdef CONFIG_DCACHE_WORD_ACCESS
51
52 /*
53 * Load an unaligned word from kernel space.
54 *
55 * In the (very unlikely) case of the word being a page-crosser
56 * and the next page not being mapped, take the exception and
57 * return zeroes in the non-existing part.
58 */
59 static inline unsigned long load_unaligned_zeropad(const void *addr)
60 {
61 unsigned long ret;
62
63 /* Load word from unaligned pointer addr */
64 asm(
65 "1: " REG_L " %0, %2\n"
66 "2:\n"
67 _ASM_EXTABLE_LOAD_UNALIGNED_ZEROPAD(1b, 2b, %0, %1)
68 : "=&r" (ret)
69 : "r" (addr), "m" (*(unsigned long *)addr));
70
71 return ret;
72 }
73
74 #endif /* CONFIG_DCACHE_WORD_ACCESS */
75
76 #endif /* _ASM_RISCV_WORD_AT_A_TIME_H */
77
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