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/* SPDX-License-Identifier: GPL-2.0 */
#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. Its use should be reserved for data that is used
* frequently in hot paths. Performance traces can help decide when to use
* this. You want __read_mostly data to be tightly packed, so that in the
* best case multiple frequently read variables for a hot path will be next
* to each other in order to reduce the number of cachelines needed to
* execute a critical path. We should be mindful and selective of its use.
* ie: if you're going to use it please supply a *good* justification in your
* commit log
*/
#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 __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
/*
* Helper to add padding within a struct to ensure data fall into separate
* cachelines.
*/
#if defined(CONFIG_SMP)
struct cacheline_padding {
char x[0];
} ____cacheline_internodealigned_in_smp;
#define CACHELINE_PADDING(name) struct cacheline_padding name
#else
#define CACHELINE_PADDING(name)
#endif
#endif /* __LINUX_CACHE_H */
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