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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
5b17e1cd AB |
2 | #ifndef __ASM_GENERIC_GETORDER_H |
3 | #define __ASM_GENERIC_GETORDER_H | |
fd4fd5aa | 4 | |
fd4fd5aa SR |
5 | #ifndef __ASSEMBLY__ |
6 | ||
38f33230 | 7 | #include <linux/compiler.h> |
d66acc39 DH |
8 | #include <linux/log2.h> |
9 | ||
e0891a98 DH |
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. | |
e0891a98 | 28 | */ |
0a571b08 | 29 | static __always_inline __attribute_const__ int get_order(unsigned long size) |
cbedfe11 QC |
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 | } | |
fd4fd5aa SR |
49 | |
50 | #endif /* __ASSEMBLY__ */ | |
fd4fd5aa | 51 | |
5b17e1cd | 52 | #endif /* __ASM_GENERIC_GETORDER_H */ |