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
has_zero(unsigned long a,unsigned long * bits,const struct word_at_a_time * c)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
create_zero_mask(unsigned long bits)29 static inline unsigned long create_zero_mask(unsigned long bits)
30 {
31 bits = (bits - 1) & ~bits;
32 return bits >> 7;
33 }
34
find_zero(unsigned long mask)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 */
load_unaligned_zeropad(const void * addr)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