1 /*
2  * Copyright (C) 2013 ARM Ltd.
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11  * GNU General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public License
14  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
15  */
16 #ifndef __ASM_WORD_AT_A_TIME_H
17 #define __ASM_WORD_AT_A_TIME_H
18 
19 #include <linux/uaccess.h>
20 
21 #ifndef __AARCH64EB__
22 
23 #include <linux/kernel.h>
24 
25 struct word_at_a_time {
26 	const unsigned long one_bits, high_bits;
27 };
28 
29 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
30 
31 static inline unsigned long has_zero(unsigned long a, unsigned long *bits,
32 				     const struct word_at_a_time *c)
33 {
34 	unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
35 	*bits = mask;
36 	return mask;
37 }
38 
39 #define prep_zero_mask(a, bits, c) (bits)
40 
41 static inline unsigned long create_zero_mask(unsigned long bits)
42 {
43 	bits = (bits - 1) & ~bits;
44 	return bits >> 7;
45 }
46 
47 static inline unsigned long find_zero(unsigned long mask)
48 {
49 	return fls64(mask) >> 3;
50 }
51 
52 #define zero_bytemask(mask) (mask)
53 
54 #else	/* __AARCH64EB__ */
55 #include <asm-generic/word-at-a-time.h>
56 #endif
57 
58 /*
59  * Load an unaligned word from kernel space.
60  *
61  * In the (very unlikely) case of the word being a page-crosser
62  * and the next page not being mapped, take the exception and
63  * return zeroes in the non-existing part.
64  */
65 static inline unsigned long load_unaligned_zeropad(const void *addr)
66 {
67 	unsigned long ret, offset;
68 
69 	/* Load word from unaligned pointer addr */
70 	asm(
71 	"1:	ldr	%0, %3\n"
72 	"2:\n"
73 	"	.pushsection .fixup,\"ax\"\n"
74 	"	.align 2\n"
75 	"3:	and	%1, %2, #0x7\n"
76 	"	bic	%2, %2, #0x7\n"
77 	"	ldr	%0, [%2]\n"
78 	"	lsl	%1, %1, #0x3\n"
79 #ifndef __AARCH64EB__
80 	"	lsr	%0, %0, %1\n"
81 #else
82 	"	lsl	%0, %0, %1\n"
83 #endif
84 	"	b	2b\n"
85 	"	.popsection\n"
86 	_ASM_EXTABLE(1b, 3b)
87 	: "=&r" (ret), "=&r" (offset)
88 	: "r" (addr), "Q" (*(unsigned long *)addr));
89 
90 	return ret;
91 }
92 
93 #endif /* __ASM_WORD_AT_A_TIME_H */
94