word-at-a-time.h

 1/* SPDX-License-Identifier: GPL-2.0 */
 2#ifndef _ASM_WORD_AT_A_TIME_H
 3#define _ASM_WORD_AT_A_TIME_H
 4
 5#include <linux/bitops.h>
 6#include <linux/wordpart.h>
 7#include <asm/asm-extable.h>
 8#include <asm/bitsperlong.h>
 9
10struct word_at_a_time {
11	const unsigned long bits;
12};
13
14#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x7f) }
15
16static inline unsigned long prep_zero_mask(unsigned long val, unsigned long data, const struct word_at_a_time *c)
17{
18	return data;
19}
20
21static inline unsigned long create_zero_mask(unsigned long data)
22{
23	return __fls(data);
24}
25
26static inline unsigned long find_zero(unsigned long data)
27{
28	return (data ^ (BITS_PER_LONG - 1)) >> 3;
29}
30
31static inline unsigned long has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)
32{
33	unsigned long mask = (val & c->bits) + c->bits;
34
35	*data = ~(mask | val | c->bits);
36	return *data;
37}
38
39static inline unsigned long zero_bytemask(unsigned long data)
40{
41	return ~1UL << data;
42}
43
44/*
45 * Load an unaligned word from kernel space.
46 *
47 * In the (very unlikely) case of the word being a page-crosser
48 * and the next page not being mapped, take the exception and
49 * return zeroes in the non-existing part.
50 */
51static inline unsigned long load_unaligned_zeropad(const void *addr)
52{
53	unsigned long data;
54
55	asm_inline volatile(
56		"0:	lg	%[data],0(%[addr])\n"
57		"1:	nopr	%%r7\n"
58		EX_TABLE_ZEROPAD(0b, 1b, %[data], %[addr])
59		EX_TABLE_ZEROPAD(1b, 1b, %[data], %[addr])
60		: [data] "=d" (data)
61		: [addr] "a" (addr), "m" (*(unsigned long *)addr));
62	return data;
63}
64
65#endif /* _ASM_WORD_AT_A_TIME_H */