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
14struct 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
20static 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
30static inline unsigned long create_zero_mask(unsigned long bits)
31{
32	bits = (bits - 1) & ~bits;
33	return bits >> 7;
34}
35
36static 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 */
68static 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