diff options
| -rw-r--r-- | include/asm-generic/page.h | 38 |
1 files changed, 34 insertions, 4 deletions
diff --git a/include/asm-generic/page.h b/include/asm-generic/page.h index a96b5d986b6e..b55052ce2330 100644 --- a/include/asm-generic/page.h +++ b/include/asm-generic/page.h @@ -4,21 +4,51 @@ #ifdef __KERNEL__ #ifndef __ASSEMBLY__ -#include <linux/compiler.h> +#include <linux/log2.h> -/* Pure 2^n version of get_order */ -static __inline__ __attribute_const__ int get_order(unsigned long size) +/* + * non-const pure 2^n version of get_order + * - the arch may override these in asm/bitops.h if they can be implemented + * more efficiently than using the arch log2 routines + * - we use the non-const log2() instead if the arch has defined one suitable + */ +#ifndef ARCH_HAS_GET_ORDER +static inline __attribute__((const)) +int __get_order(unsigned long size, int page_shift) { +#if BITS_PER_LONG == 32 && defined(ARCH_HAS_ILOG2_U32) + int order = __ilog2_u32(size) - page_shift; + return order >= 0 ? order : 0; +#elif BITS_PER_LONG == 64 && defined(ARCH_HAS_ILOG2_U64) + int order = __ilog2_u64(size) - page_shift; + return order >= 0 ? order : 0; +#else int order; - size = (size - 1) >> (PAGE_SHIFT - 1); + size = (size - 1) >> (page_shift - 1); order = -1; do { size >>= 1; order++; } while (size); return order; +#endif } +#endif + +/** + * get_order - calculate log2(pages) to hold a block of the specified size + * @n - size + * + * calculate allocation order based on the current page size + * - this can be used to initialise global variables from constant data + */ +#define get_order(n) \ +( \ + __builtin_constant_p(n) ? \ + ((n < (1UL << PAGE_SHIFT)) ? 0 : ilog2(n) - PAGE_SHIFT) : \ + __get_order(n, PAGE_SHIFT) \ + ) #endif /* __ASSEMBLY__ */ #endif /* __KERNEL__ */ |