include/linux/cache.h

#ifndef __LINUX_CACHE_H
#define __LINUX_CACHE_H

#include <uapi/linux/kernel.h>
#include <asm/cache.h>

#ifndef L1_CACHE_ALIGN
#define L1_CACHE_ALIGN(x) __ALIGN_KERNEL(x, L1_CACHE_BYTES)
#endif

#ifndef SMP_CACHE_BYTES
#define SMP_CACHE_BYTES L1_CACHE_BYTES
#endif

/*
 * __read_mostly is used to keep rarely changing variables out of frequently
 * updated cachelines. If an architecture doesn't support it, ignore the
 * hint.
 */
#ifndef __read_mostly
#define __read_mostly
#endif

/*
 * __ro_after_init is used to mark things that are read-only after init (i.e.
 * after mark_rodata_ro() has been called). These are effectively read-only,
 * but may get written to during init, so can't live in .rodata (via "const").
 */
#ifndef __ro_after_init
#define __ro_after_init __attribute__((__section__(".data..ro_after_init")))
#endif

#ifndef ____cacheline_aligned
#define ____cacheline_aligned __attribute__((__aligned__(SMP_CACHE_BYTES)))
#endif

#ifndef ____cacheline_aligned_in_smp
#ifdef CONFIG_SMP
#define ____cacheline_aligned_in_smp ____cacheline_aligned
#else
#define ____cacheline_aligned_in_smp
#endif /* CONFIG_SMP */
#endif

#ifndef __cacheline_aligned
#define __cacheline_aligned					\
  __attribute__((__aligned__(SMP_CACHE_BYTES),			\
		 __section__(".data..cacheline_aligned")))
#endif /* __cacheline_aligned */

#ifndef __cacheline_aligned_in_smp
#ifdef CONFIG_SMP
#define __cacheline_aligned_in_smp __cacheline_aligned
#else
#define __cacheline_aligned_in_smp
#endif /* CONFIG_SMP */
#endif

/*
 * The maximum alignment needed for some critical structures
 * These could be inter-node cacheline sizes/L3 cacheline
 * size etc.  Define this in asm/cache.h for your arch
 */
#ifndef INTERNODE_CACHE_SHIFT
#define INTERNODE_CACHE_SHIFT L1_CACHE_SHIFT
#endif

#if !defined(____cacheline_internodealigned_in_smp)
#if defined(CONFIG_SMP)
#define ____cacheline_internodealigned_in_smp \
	__attribute__((__aligned__(1 << (INTERNODE_CACHE_SHIFT))))
#else
#define ____cacheline_internodealigned_in_smp
#endif
#endif

#ifndef CONFIG_ARCH_HAS_CACHE_LINE_SIZE
#define cache_line_size()	L1_CACHE_BYTES
#endif

#endif /* __LINUX_CACHE_H */