From becdcec7b9cd6b8beaa2273495b97c06de24e9e5 Mon Sep 17 00:00:00 2001
From: Tony Hutter <hutter2@llnl.gov>
Date: Wed, 6 Mar 2019 16:03:03 -0800
Subject: [PATCH] kernel_fpu fixes

This patch fixes a few issues when detecting which kernel_fpu functions
are available.

- Use kernel_fpu_begin() if it's exported on newer kernels.

- Use ZFS_LINUX_TRY_COMPILE_SYMBOL() to choose the right kernel_fpu
  function when using --enable-linux-builtin.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #8259
Closes #8363
---
 config/kernel-fpu.m4     | 34 +++++++++++++++++++++++++++++-----
 include/linux/simd_x86.h | 11 ++++++++---
 2 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/config/kernel-fpu.m4 b/config/kernel-fpu.m4
index 671fe7ea54..5fff79a74c 100644
--- a/config/kernel-fpu.m4
+++ b/config/kernel-fpu.m4
@@ -12,25 +12,49 @@ dnl # Pre-4.2:	Use kernel_fpu_{begin,end}()
 dnl #		HAVE_KERNEL_FPU & KERNEL_EXPORTS_X86_FPU
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_FPU], [
-	AC_MSG_CHECKING([which kernel_fpu function to use])
+	AC_MSG_CHECKING([which kernel_fpu header to use])
 	ZFS_LINUX_TRY_COMPILE([
+		#include <linux/module.h>
+		#include <asm/fpu/api.h>
+	],[
+	],[
+		AC_DEFINE(HAVE_KERNEL_FPU_API_HEADER, 1, [kernel has asm/fpu/api.h])
+		AC_MSG_RESULT(asm/fpu/api.h)
+	],[
+		AC_MSG_RESULT(i387.h & xcr.h)
+	])
+
+	AC_MSG_CHECKING([which kernel_fpu function to use])
+	ZFS_LINUX_TRY_COMPILE_SYMBOL([
+		#include <linux/module.h>
+		#ifdef HAVE_KERNEL_FPU_API_HEADER
+		#include <asm/fpu/api.h>
+		#else
 		#include <asm/i387.h>
 		#include <asm/xcr.h>
+		#endif
+		MODULE_LICENSE("$ZFS_META_LICENSE");
 	],[
 		kernel_fpu_begin();
 		kernel_fpu_end();
-	],[
+	], [kernel_fpu_begin], [arch/x86/kernel/fpu/core.c], [
 		AC_MSG_RESULT(kernel_fpu_*)
 		AC_DEFINE(HAVE_KERNEL_FPU, 1, [kernel has kernel_fpu_* functions])
 		AC_DEFINE(KERNEL_EXPORTS_X86_FPU, 1, [kernel exports FPU functions])
 	],[
-		ZFS_LINUX_TRY_COMPILE([
-			#include <linux/kernel.h>
+		ZFS_LINUX_TRY_COMPILE_SYMBOL([
+			#include <linux/module.h>
+			#ifdef HAVE_KERNEL_FPU_API_HEADER
 			#include <asm/fpu/api.h>
+			#else
+			#include <asm/i387.h>
+			#include <asm/xcr.h>
+			#endif
+			MODULE_LICENSE("$ZFS_META_LICENSE");
 		],[
 			__kernel_fpu_begin();
 			__kernel_fpu_end();
-		],[
+		], [__kernel_fpu_begin], [arch/x86/kernel/fpu/core.c arch/x86/kernel/i387.c], [
 			AC_MSG_RESULT(__kernel_fpu_*)
 			AC_DEFINE(HAVE_UNDERSCORE_KERNEL_FPU, 1, [kernel has __kernel_fpu_* functions])
 			AC_DEFINE(KERNEL_EXPORTS_X86_FPU, 1, [kernel exports FPU functions])
diff --git a/include/linux/simd_x86.h b/include/linux/simd_x86.h
index 5d6fbed35b..12cd746778 100644
--- a/include/linux/simd_x86.h
+++ b/include/linux/simd_x86.h
@@ -81,9 +81,16 @@
 #endif
 
 #if defined(_KERNEL)
-#if defined(HAVE_UNDERSCORE_KERNEL_FPU)
+
+#if defined(HAVE_KERNEL_FPU_API_HEADER)
 #include <asm/fpu/api.h>
 #include <asm/fpu/internal.h>
+#else
+#include <asm/i387.h>
+#include <asm/xcr.h>
+#endif
+
+#if defined(HAVE_UNDERSCORE_KERNEL_FPU)
 #define	kfpu_begin()		\
 {							\
 	preempt_disable();		\
@@ -95,8 +102,6 @@
 	preempt_enable();		\
 }
 #elif defined(HAVE_KERNEL_FPU)
-#include <asm/i387.h>
-#include <asm/xcr.h>
 #define	kfpu_begin()	kernel_fpu_begin()
 #define	kfpu_end()		kernel_fpu_end()
 #else