1/* SPDX-License-Identifier: GPL-2.0 */
 2#ifndef __ASM_GENERIC_GETORDER_H
 3#define __ASM_GENERIC_GETORDER_H
 4
 5#ifndef __ASSEMBLY__
 6
 7#include <linux/compiler.h>
 8#include <linux/log2.h>
 9
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
10/**
11 * get_order - Determine the allocation order of a memory size
12 * @size: The size for which to get the order
13 *
14 * Determine the allocation order of a particular sized block of memory.  This
15 * is on a logarithmic scale, where:
16 *
17 *	0 -> 2^0 * PAGE_SIZE and below
18 *	1 -> 2^1 * PAGE_SIZE to 2^0 * PAGE_SIZE + 1
19 *	2 -> 2^2 * PAGE_SIZE to 2^1 * PAGE_SIZE + 1
20 *	3 -> 2^3 * PAGE_SIZE to 2^2 * PAGE_SIZE + 1
21 *	4 -> 2^4 * PAGE_SIZE to 2^3 * PAGE_SIZE + 1
22 *	...
23 *
24 * The order returned is used to find the smallest allocation granule required
25 * to hold an object of the specified size.
26 *
27 * The result is undefined if the size is 0.
 
 
 
28 */
29static __always_inline __attribute_const__ int get_order(unsigned long size)
30{
31	if (__builtin_constant_p(size)) {
32		if (!size)
33			return BITS_PER_LONG - PAGE_SHIFT;
34
35		if (size < (1UL << PAGE_SHIFT))
36			return 0;
37
38		return ilog2((size) - 1) - PAGE_SHIFT + 1;
39	}
40
41	size--;
42	size >>= PAGE_SHIFT;
43#if BITS_PER_LONG == 32
44	return fls(size);
45#else
46	return fls64(size);
47#endif
48}
49
50#endif	/* __ASSEMBLY__ */
51
52#endif	/* __ASM_GENERIC_GETORDER_H */

 1/* SPDX-License-Identifier: GPL-2.0 */
 2#ifndef __ASM_GENERIC_GETORDER_H
 3#define __ASM_GENERIC_GETORDER_H
 4
 5#ifndef __ASSEMBLY__
 6
 7#include <linux/compiler.h>
 8#include <linux/log2.h>
 9
10/*
11 * Runtime evaluation of get_order()
12 */
13static inline __attribute_const__
14int __get_order(unsigned long size)
15{
16	int order;
17
18	size--;
19	size >>= PAGE_SHIFT;
20#if BITS_PER_LONG == 32
21	order = fls(size);
22#else
23	order = fls64(size);
24#endif
25	return order;
26}
27
28/**
29 * get_order - Determine the allocation order of a memory size
30 * @size: The size for which to get the order
31 *
32 * Determine the allocation order of a particular sized block of memory.  This
33 * is on a logarithmic scale, where:
34 *
35 *	0 -> 2^0 * PAGE_SIZE and below
36 *	1 -> 2^1 * PAGE_SIZE to 2^0 * PAGE_SIZE + 1
37 *	2 -> 2^2 * PAGE_SIZE to 2^1 * PAGE_SIZE + 1
38 *	3 -> 2^3 * PAGE_SIZE to 2^2 * PAGE_SIZE + 1
39 *	4 -> 2^4 * PAGE_SIZE to 2^3 * PAGE_SIZE + 1
40 *	...
41 *
42 * The order returned is used to find the smallest allocation granule required
43 * to hold an object of the specified size.
44 *
45 * The result is undefined if the size is 0.
46 *
47 * This function may be used to initialise variables with compile time
48 * evaluations of constants.
49 */
50#define get_order(n)						\
51(								\
52	__builtin_constant_p(n) ? (				\
53		((n) == 0UL) ? BITS_PER_LONG - PAGE_SHIFT :	\
54		(((n) < (1UL << PAGE_SHIFT)) ? 0 :		\
55		 ilog2((n) - 1) - PAGE_SHIFT + 1)		\
56	) :							\
57	__get_order(n)						\
58)
 
 
 
 
 
 
 
 
 
 
 
59
60#endif	/* __ASSEMBLY__ */
61
62#endif	/* __ASM_GENERIC_GETORDER_H */