arm64 lib32: prepare arm64 headers to redirect to arm

In order to compile lib32 libraries and other 32-bit code on arm64,
<machine/foo.h> needs to be redirected to an arm header rather
than arm64 when building with -m32.  Ifdef the arm64 headers that
are installed in /usr/include/machine and used by user-level software
(including references from /usr/include/*.h) so that if __arm__ is
defined when including the arm64 version, <arm/foo.h> is included
rather than using the rest of the file's contents.  Some arm headers
had no arm64 equivalent; headers were added just to do the redirection.
These files use #error if __arm__ is not defined to guard against
confusion.  Also add an include/arm Makefile, and modify Makefiles
as needed to install everything, including the arm files in
/usr/include/arm.  fenv.h comes from lib/msun/arm/fenv.h.

The new arm64 headers are:
    acle-compat.h
    cpuinfo.h
    sysreg.h

Reviewed by:	jrtc27, imp
Differential Revision:	https://reviews.freebsd.org/D40944

1 files changed, 6 insertions, 0 deletions

diff --git a/sys/arm64/include/atomic.h b/sys/arm64/include/atomic.h
index b14cd303da3a..172bf051edf3 100644
--- a/sys/arm64/include/atomic.h
+++ b/sys/arm64/include/atomic.h
@@ -26,6 +26,10 @@
  * $FreeBSD$
  */
 
+#ifdef __arm__
+#include <arm/atomic.h>
+#else /* !__arm__ */
+
 #ifndef	_MACHINE_ATOMIC_H_
 #define	_MACHINE_ATOMIC_H_
 
@@ -670,3 +674,5 @@ atomic_thread_fence_seq_cst(void)
 
 #endif /* KCSAN && !KCSAN_RUNTIME */
 #endif /* _MACHINE_ATOMIC_H_ */
+
+#endif /* !__arm__ */