[PATCH v4 15/15] selftests/fpu: Allow building on other architectures

[Samuel Holland <samuel.holland@sifive.com>]

Now that ARCH_HAS_KERNEL_FPU_SUPPORT provides a common way to compile
and run floating-point code, this test is no longer x86-specific.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
---

(no changes since v1)

 lib/Kconfig.debug   |  2 +-
 lib/Makefile        | 25 ++-----------------------
 lib/test_fpu_glue.c |  5 ++++-
 3 files changed, 7 insertions(+), 25 deletions(-)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c63a5fbf1f1c..f93e778e0405 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2890,7 +2890,7 @@ config TEST_FREE_PAGES
 
 config TEST_FPU
 	tristate "Test floating point operations in kernel space"
-	depends on X86 && !KCOV_INSTRUMENT_ALL
+	depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL
 	help
 	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
 	  which will trigger a sequence of floating point operations. This is used
diff --git a/lib/Makefile b/lib/Makefile
index fcb35bf50979..e44ad11f77b5 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -110,31 +110,10 @@ CFLAGS_test_fprobe.o += $(CC_FLAGS_FTRACE)
 obj-$(CONFIG_FPROBE_SANITY_TEST) += test_fprobe.o
 obj-$(CONFIG_TEST_OBJPOOL) += test_objpool.o
 
-#
-# CFLAGS for compiling floating point code inside the kernel. x86/Makefile turns
-# off the generation of FPU/SSE* instructions for kernel proper but FPU_FLAGS
-# get appended last to CFLAGS and thus override those previous compiler options.
-#
-FPU_CFLAGS := -msse -msse2
-ifdef CONFIG_CC_IS_GCC
-# Stack alignment mismatch, proceed with caution.
-# GCC < 7.1 cannot compile code using `double` and -mpreferred-stack-boundary=3
-# (8B stack alignment).
-# See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
-#
-# The "-msse" in the first argument is there so that the
-# -mpreferred-stack-boundary=3 build error:
-#
-#  -mpreferred-stack-boundary=3 is not between 4 and 12
-#
-# can be triggered. Otherwise gcc doesn't complain.
-FPU_CFLAGS += -mhard-float
-FPU_CFLAGS += $(call cc-option,-msse -mpreferred-stack-boundary=3,-mpreferred-stack-boundary=4)
-endif
-
 obj-$(CONFIG_TEST_FPU) += test_fpu.o
 test_fpu-y := test_fpu_glue.o test_fpu_impl.o
-CFLAGS_test_fpu_impl.o += $(FPU_CFLAGS)
+CFLAGS_test_fpu_impl.o += $(CC_FLAGS_FPU)
+CFLAGS_REMOVE_test_fpu_impl.o += $(CC_FLAGS_NO_FPU)
 
 # Some KUnit files (hooks.o) need to be built-in even when KUnit is a module,
 # so we can't just use obj-$(CONFIG_KUNIT).
diff --git a/lib/test_fpu_glue.c b/lib/test_fpu_glue.c
index 85963d7be826..eef282a2715f 100644
--- a/lib/test_fpu_glue.c
+++ b/lib/test_fpu_glue.c
@@ -17,7 +17,7 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/debugfs.h>
-#include <asm/fpu/api.h>
+#include <linux/fpu.h>
 
 #include "test_fpu.h"
 
@@ -38,6 +38,9 @@ static struct dentry *selftest_dir;
 
 static int __init test_fpu_init(void)
 {
+	if (!kernel_fpu_available())
+		return -EINVAL;
+
 	selftest_dir = debugfs_create_dir("selftest_helpers", NULL);
 	if (!selftest_dir)
 		return -ENOMEM;
-- 
2.44.0