OpenZFS restructuring - move platform specific headers

Move platform specific Linux headers under include/os/linux/.
Update the build system accordingly to detect the platform.
This lays some of the initial groundwork to supporting building
for other platforms.

As part of this change it was necessary to create both a user
and kernel space sys/simd.h header which can be included in
either context.  No functional change, the source has been
refactored and the relevant #include's updated.

Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Signed-off-by: Matthew Macy <mmacy@FreeBSD.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #9198

module/icp/algs/aes/aes_impl.c

@@ -25,9 +25,9 @@
 #include <sys/zfs_context.h>
 #include <sys/crypto/icp.h>
 #include <sys/crypto/spi.h>
+#include <sys/simd.h>
 #include <modes/modes.h>
 #include <aes/aes_impl.h>
-#include <linux/simd.h>
 
 /*
  * Initialize AES encryption and decryption key schedules.

module/icp/algs/aes/aes_impl_aesni.c

@@ -24,7 +24,8 @@
 
 #if defined(__x86_64) && defined(HAVE_AES)
 
-#include <linux/simd_x86.h>
+#include <sys/simd.h>
+#include <sys/types.h>
 
 /* These functions are used to execute AES-NI instructions: */
 extern int rijndael_key_setup_enc_intel(uint32_t rk[],

module/icp/algs/aes/aes_impl_x86-64.c

@@ -24,7 +24,7 @@
 
 #if defined(__x86_64)
 
-#include <linux/simd_x86.h>
+#include <sys/simd.h>
 
 /* These functions are used to execute amd64 instructions for AMD or Intel: */
 extern int rijndael_key_setup_enc_amd64(uint32_t rk[],

module/icp/algs/modes/gcm.c

@@ -28,8 +28,8 @@
 #include <sys/crypto/icp.h>
 #include <sys/crypto/impl.h>
 #include <sys/byteorder.h>
+#include <sys/simd.h>
 #include <modes/gcm_impl.h>
-#include <linux/simd.h>
 
 #define	GHASH(c, d, t, o) \
 	xor_block((uint8_t *)(d), (uint8_t *)(c)->gcm_ghash); \

module/icp/algs/modes/gcm_pclmulqdq.c

@@ -24,12 +24,12 @@
 
 #if defined(__x86_64) && defined(HAVE_PCLMULQDQ)
 
-#include <linux/simd_x86.h>
+#include <sys/types.h>
+#include <sys/simd.h>
 
 /* These functions are used to execute pclmulqdq based assembly methods */
 extern void gcm_mul_pclmulqdq(uint64_t *, uint64_t *, uint64_t *);
 
-
 #include <modes/gcm_impl.h>
 
 /*

module/icp/io/aes.c

@@ -212,8 +212,8 @@ aes_mod_init(void)
 	 * are run in dedicated kernel threads to allow Linux 5.0+ kernels
 	 * to use SIMD operations.  If for some reason this isn't possible,
 	 * fallback to the generic implementations.  See the comment in
-	 * include/linux/simd_x86.h for additional details.  Additionally,
-	 * this has the benefit of allowing them to be run in parallel.
+	 * linux/simd_x86.h for additional details.  Additionally, this has
+	 * the benefit of allowing them to be run in parallel.
 	 */
 	taskqid_t aes_id = taskq_dispatch(system_taskq, aes_impl_init,
 	    NULL, TQ_SLEEP);