1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __ASM_ARM_WORD_AT_A_TIME_H
3 #define __ASM_ARM_WORD_AT_A_TIME_H
4
5 #ifndef __ARMEB__
6
7 /*
8 * Little-endian word-at-a-time zero byte handling.
9 * Heavily based on the x86 algorithm.
10 */
11 #include <linux/bitops.h>
12 #include <linux/wordpart.h>
13
14 struct word_at_a_time {
15 const unsigned long one_bits, high_bits;
16 };
17
18 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
19
20 static inline unsigned long has_zero(unsigned long a, unsigned long *bits,
21 const struct word_at_a_time *c)
22 {
23 unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
24 *bits = mask;
25 return mask;
26 }
27
28 #define prep_zero_mask(a, bits, c) (bits)
29
30 static inline unsigned long create_zero_mask(unsigned long bits)
31 {
32 bits = (bits - 1) & ~bits;
33 return bits >> 7;
34 }
35
36 static inline unsigned long find_zero(unsigned long mask)
37 {
38 unsigned long ret;
39
40 #if __LINUX_ARM_ARCH__ >= 5
41 /* We have clz available. */
42 ret = fls(mask) >> 3;
43 #else
44 /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
45 ret = (0x0ff0001 + mask) >> 23;
46 /* Fix the 1 for 00 case */
47 ret &= mask;
48 #endif
49
50 return ret;
51 }
52
53 #define zero_bytemask(mask) (mask)
54
55 #else /* __ARMEB__ */
56 #include <asm-generic/word-at-a-time.h>
57 #endif
58
59 #ifdef CONFIG_DCACHE_WORD_ACCESS
60
61 /*
62 * Load an unaligned word from kernel space.
63 *
64 * In the (very unlikely) case of the word being a page-crosser
65 * and the next page not being mapped, take the exception and
66 * return zeroes in the non-existing part.
67 */
68 static inline unsigned long load_unaligned_zeropad(const void *addr)
69 {
70 unsigned long ret, offset;
71
72 /* Load word from unaligned pointer addr */
73 asm(
74 "1: ldr %0, [%2]\n"
75 "2:\n"
76 " .pushsection .text.fixup,\"ax\"\n"
77 " .align 2\n"
78 "3: and %1, %2, #0x3\n"
79 " bic %2, %2, #0x3\n"
80 " ldr %0, [%2]\n"
81 " lsl %1, %1, #0x3\n"
82 #ifndef __ARMEB__
83 " lsr %0, %0, %1\n"
84 #else
85 " lsl %0, %0, %1\n"
86 #endif
87 " b 2b\n"
88 " .popsection\n"
89 " .pushsection __ex_table,\"a\"\n"
90 " .align 3\n"
91 " .long 1b, 3b\n"
92 " .popsection"
93 : "=&r" (ret), "=&r" (offset)
94 : "r" (addr), "Qo" (*(unsigned long *)addr));
95
96 return ret;
97 }
98
99 #endif /* DCACHE_WORD_ACCESS */
100 #endif /* __ASM_ARM_WORD_AT_A_TIME_H */
101
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