1 files changed, 101 insertions, 0 deletions
diff --git a/include/linux/cache.h b/include/linux/cache.h
new file mode 100644
index 000000000..5da1bbd96
--- /dev/null
+++ b/include/linux/cache.h
@@ -0,0 +1,101 @@
+/* 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 */