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