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1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef __ASM_GENERIC_GETORDER_H3#define __ASM_GENERIC_GETORDER_H4 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 size12 * @size: The size for which to get the order13 *14 * Determine the allocation order of a particular sized block of memory. This15 * is on a logarithmic scale, where:16 *17 * 0 -> 2^0 * PAGE_SIZE and below18 * 1 -> 2^1 * PAGE_SIZE to 2^0 * PAGE_SIZE + 119 * 2 -> 2^2 * PAGE_SIZE to 2^1 * PAGE_SIZE + 120 * 3 -> 2^3 * PAGE_SIZE to 2^2 * PAGE_SIZE + 121 * 4 -> 2^4 * PAGE_SIZE to 2^3 * PAGE_SIZE + 122 * ...23 *24 * The order returned is used to find the smallest allocation granule required25 * 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 == 3244 return fls(size);45#else46 return fls64(size);47#endif48}49 50#endif /* __ASSEMBLY__ */51 52#endif /* __ASM_GENERIC_GETORDER_H */53