vdso: Introduce vdso/cache.h

The vDSO implementation can only include headers from the vdso/
namespace. To enable the usage of ____cacheline_aligned from
the vDSO, move it and its dependencies into a new header vdso/cache.h.
Keep compatibility by including vdso/cache.h from linux/cache.h.

Signed-off-by: Thomas Weißschuh <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Link: https://lore.kernel.org/all/[e-mail]

include/linux/cache.h

···
 #define __LINUX_CACHE_H
 
 #include <uapi/linux/kernel.h>
+#include <vdso/cache.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
 
 /**
···
  */
 #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

include/vdso/cache.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __VDSO_CACHE_H
+#define __VDSO_CACHE_H
+
+#include <asm/cache.h>
+
+#ifndef SMP_CACHE_BYTES
+#define SMP_CACHE_BYTES L1_CACHE_BYTES
+#endif
+
+#ifndef ____cacheline_aligned
+#define ____cacheline_aligned __attribute__((__aligned__(SMP_CACHE_BYTES)))
+#endif
+
+#endif	/* __VDSO_ALIGN_H */