| /* SPDX-License-Identifier: GPL-2.0 */ |
| #ifndef __ASM_GENERIC_GETORDER_H |
| #define __ASM_GENERIC_GETORDER_H |
| |
| #ifndef __ASSEMBLY__ |
| |
| #include <linux/compiler.h> |
| #include <linux/log2.h> |
| |
| /** |
| * get_order - Determine the allocation order of a memory size |
| * @size: The size for which to get the order |
| * |
| * Determine the allocation order of a particular sized block of memory. This |
| * is on a logarithmic scale, where: |
| * |
| * 0 -> 2^0 * PAGE_SIZE and below |
| * 1 -> 2^1 * PAGE_SIZE to 2^0 * PAGE_SIZE + 1 |
| * 2 -> 2^2 * PAGE_SIZE to 2^1 * PAGE_SIZE + 1 |
| * 3 -> 2^3 * PAGE_SIZE to 2^2 * PAGE_SIZE + 1 |
| * 4 -> 2^4 * PAGE_SIZE to 2^3 * PAGE_SIZE + 1 |
| * ... |
| * |
| * The order returned is used to find the smallest allocation granule required |
| * to hold an object of the specified size. |
| * |
| * The result is undefined if the size is 0. |
| */ |
| static inline __attribute_const__ int get_order(unsigned long size) |
| { |
| if (__builtin_constant_p(size)) { |
| if (!size) |
| return BITS_PER_LONG - PAGE_SHIFT; |
| |
| if (size < (1UL << PAGE_SHIFT)) |
| return 0; |
| |
| return ilog2((size) - 1) - PAGE_SHIFT + 1; |
| } |
| |
| size--; |
| size >>= PAGE_SHIFT; |
| #if BITS_PER_LONG == 32 |
| return fls(size); |
| #else |
| return fls64(size); |
| #endif |
| } |
| |
| #endif /* __ASSEMBLY__ */ |
| |
| #endif /* __ASM_GENERIC_GETORDER_H */ |