192 lines
5.5 KiB
C
192 lines
5.5 KiB
C
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_CACHE_H
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#define __LINUX_CACHE_H
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#include <uapi/linux/kernel.h>
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#include <asm/cache.h>
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#ifndef L1_CACHE_ALIGN
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#define L1_CACHE_ALIGN(x) __ALIGN_KERNEL(x, L1_CACHE_BYTES)
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#endif
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#ifndef SMP_CACHE_BYTES
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#define SMP_CACHE_BYTES L1_CACHE_BYTES
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#endif
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/**
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* SMP_CACHE_ALIGN - align a value to the L2 cacheline size
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* @x: value to align
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*
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* On some architectures, L2 ("SMP") CL size is bigger than L1, and sometimes,
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* this needs to be accounted.
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*
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* Return: aligned value.
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*/
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#ifndef SMP_CACHE_ALIGN
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#define SMP_CACHE_ALIGN(x) ALIGN(x, SMP_CACHE_BYTES)
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#endif
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/*
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* ``__aligned_largest`` aligns a field to the value most optimal for the
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* target architecture to perform memory operations. Get the actual value
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* to be able to use it anywhere else.
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*/
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#ifndef __LARGEST_ALIGN
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#define __LARGEST_ALIGN sizeof(struct { long x; } __aligned_largest)
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#endif
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#ifndef LARGEST_ALIGN
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#define LARGEST_ALIGN(x) ALIGN(x, __LARGEST_ALIGN)
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#endif
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/*
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* __read_mostly is used to keep rarely changing variables out of frequently
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* updated cachelines. Its use should be reserved for data that is used
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* frequently in hot paths. Performance traces can help decide when to use
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* this. You want __read_mostly data to be tightly packed, so that in the
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* best case multiple frequently read variables for a hot path will be next
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* to each other in order to reduce the number of cachelines needed to
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* execute a critical path. We should be mindful and selective of its use.
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* ie: if you're going to use it please supply a *good* justification in your
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* commit log
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*/
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#ifndef __read_mostly
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#define __read_mostly
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#endif
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/*
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* __ro_after_init is used to mark things that are read-only after init (i.e.
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* after mark_rodata_ro() has been called). These are effectively read-only,
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* but may get written to during init, so can't live in .rodata (via "const").
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*/
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#ifndef __ro_after_init
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#define __ro_after_init __section(".data..ro_after_init")
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#endif
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#ifndef ____cacheline_aligned
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#define ____cacheline_aligned __attribute__((__aligned__(SMP_CACHE_BYTES)))
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#endif
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#ifndef ____cacheline_aligned_in_smp
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#ifdef CONFIG_SMP
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#define ____cacheline_aligned_in_smp ____cacheline_aligned
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#else
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#define ____cacheline_aligned_in_smp
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#endif /* CONFIG_SMP */
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#endif
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#ifndef __cacheline_aligned
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#define __cacheline_aligned \
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__attribute__((__aligned__(SMP_CACHE_BYTES), \
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__section__(".data..cacheline_aligned")))
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#endif /* __cacheline_aligned */
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#ifndef __cacheline_aligned_in_smp
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#ifdef CONFIG_SMP
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#define __cacheline_aligned_in_smp __cacheline_aligned
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#else
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#define __cacheline_aligned_in_smp
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#endif /* CONFIG_SMP */
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#endif
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/*
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* The maximum alignment needed for some critical structures
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* These could be inter-node cacheline sizes/L3 cacheline
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* size etc. Define this in asm/cache.h for your arch
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*/
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#ifndef INTERNODE_CACHE_SHIFT
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#define INTERNODE_CACHE_SHIFT L1_CACHE_SHIFT
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#endif
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#if !defined(____cacheline_internodealigned_in_smp)
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#if defined(CONFIG_SMP)
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#define ____cacheline_internodealigned_in_smp \
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__attribute__((__aligned__(1 << (INTERNODE_CACHE_SHIFT))))
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#else
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#define ____cacheline_internodealigned_in_smp
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#endif
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#endif
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#ifndef CONFIG_ARCH_HAS_CACHE_LINE_SIZE
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#define cache_line_size() L1_CACHE_BYTES
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#endif
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#ifndef __cacheline_group_begin
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#define __cacheline_group_begin(GROUP) \
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__u8 __cacheline_group_begin__##GROUP[0]
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#endif
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#ifndef __cacheline_group_end
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#define __cacheline_group_end(GROUP) \
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__u8 __cacheline_group_end__##GROUP[0]
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#endif
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/**
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* __cacheline_group_begin_aligned - declare an aligned group start
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* @GROUP: name of the group
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* @...: optional group alignment
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*
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* The following block inside a struct:
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*
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* __cacheline_group_begin_aligned(grp);
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* field a;
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* field b;
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* __cacheline_group_end_aligned(grp);
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*
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* will always be aligned to either the specified alignment or
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* ``SMP_CACHE_BYTES``.
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*/
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#define __cacheline_group_begin_aligned(GROUP, ...) \
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__cacheline_group_begin(GROUP) \
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__aligned((__VA_ARGS__ + 0) ? : SMP_CACHE_BYTES)
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/**
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* __cacheline_group_end_aligned - declare an aligned group end
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* @GROUP: name of the group
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* @...: optional alignment (same as was in __cacheline_group_begin_aligned())
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*
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* Note that the end marker is aligned to sizeof(long) to allow more precise
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* size assertion. It also declares a padding at the end to avoid next field
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* falling into this cacheline.
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*/
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#define __cacheline_group_end_aligned(GROUP, ...) \
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__cacheline_group_end(GROUP) __aligned(sizeof(long)); \
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struct { } __cacheline_group_pad__##GROUP \
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__aligned((__VA_ARGS__ + 0) ? : SMP_CACHE_BYTES)
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#ifndef CACHELINE_ASSERT_GROUP_MEMBER
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#define CACHELINE_ASSERT_GROUP_MEMBER(TYPE, GROUP, MEMBER) \
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BUILD_BUG_ON(!(offsetof(TYPE, MEMBER) >= \
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offsetofend(TYPE, __cacheline_group_begin__##GROUP) && \
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offsetofend(TYPE, MEMBER) <= \
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offsetof(TYPE, __cacheline_group_end__##GROUP)))
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#endif
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#ifndef CACHELINE_ASSERT_GROUP_SIZE
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#define CACHELINE_ASSERT_GROUP_SIZE(TYPE, GROUP, SIZE) \
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BUILD_BUG_ON(offsetof(TYPE, __cacheline_group_end__##GROUP) - \
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offsetofend(TYPE, __cacheline_group_begin__##GROUP) > \
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SIZE)
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#endif
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/*
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* Helper to add padding within a struct to ensure data fall into separate
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* cachelines.
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*/
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#if defined(CONFIG_SMP)
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struct cacheline_padding {
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char x[0];
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} ____cacheline_internodealigned_in_smp;
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#define CACHELINE_PADDING(name) struct cacheline_padding name
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#else
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#define CACHELINE_PADDING(name)
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#endif
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#ifdef ARCH_DMA_MINALIGN
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#define ARCH_HAS_DMA_MINALIGN
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#else
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#define ARCH_DMA_MINALIGN __alignof__(unsigned long long)
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#endif
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#endif /* __LINUX_CACHE_H */
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