author: Linus Torvalds <torvalds@linux-foundation.org> 2020-08-03 17:21:10 -0700
committer: Linus Torvalds <torvalds@linux-foundation.org> 2020-08-03 17:21:10 -0700
commit: 0a897743ac258927dd29bb91ac663b568f53429d
parent: 335ad94c218e96ef12f56d93eadc884731aa23b1
Commit Summary:
Diffstat:
1 file changed, 23 insertions, 0 deletions
diff --git a/lib/Makefile b/lib/Makefile
index 2ba9642a3a87..7d24dd73e34c 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -99,6 +99,30 @@ obj-$(CONFIG_TEST_MEMINIT) += test_meminit.o
obj-$(CONFIG_TEST_LOCKUP) += test_lockup.o
obj-$(CONFIG_TEST_HMM) += test_hmm.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 := -mhard-float -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 += $(call cc-option,-msse -mpreferred-stack-boundary=3,-mpreferred-stack-boundary=4)
+endif
+
+obj-$(CONFIG_TEST_FPU) += test_fpu.o
+CFLAGS_test_fpu.o += $(FPU_CFLAGS)
+
obj-$(CONFIG_TEST_LIVEPATCH) += livepatch/
obj-$(CONFIG_KUNIT) += kunit/