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