Commit aaa81d9e authored Oct 10, 2019 by Paul Burton Committed by Greg Kroah-Hartman Oct 17, 2019

MIPS: Disable Loongson MMI instructions for kernel build



commit 2f2b4fd674cadd8c6b40eb629e140a14db4068fd upstream.

GCC 9.x automatically enables support for Loongson MMI instructions when
using some -march= flags, and then errors out when -msoft-float is
specified with:

  cc1: error: ‘-mloongson-mmi’ must be used with ‘-mhard-float’

The kernel shouldn't be using these MMI instructions anyway, just as it
doesn't use floating point instructions. Explicitly disable them in
order to fix the build with GCC 9.x.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Fixes: 3702bba5 ("MIPS: Loongson: Add GCC 4.4 support for Loongson2E")
Fixes: 6f7a251a ("MIPS: Loongson: Add basic Loongson 2F support")
Fixes: 5188129b ("MIPS: Loongson-3: Improve -march option and move it to Platform")
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: stable@vger.kernel.org # v2.6.32+
Cc: linux-mips@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent e9360f39

arch/mips/loongson64/Platform

+4 −0

Original line number	Diff line number	Diff line
		@@ -43,6 +43,10 @@ else
		$(call cc-option,-march=mips64r2,-mips64r2 -U_MIPS_ISA -D_MIPS_ISA=_MIPS_ISA_MIPS64)
		endif

		# Some -march= flags enable MMI instructions, and GCC complains about that
		# support being enabled alongside -msoft-float. Thus explicitly disable MMI.
		cflags-y += $(call cc-option,-mno-loongson-mmi)

		#
		# Loongson Machines' Support
		#

arch/mips/vdso/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -9,6 +9,7 @@ ccflags-vdso := \
		$(filter -mmicromips,$(KBUILD_CFLAGS)) \
		$(filter -march=%,$(KBUILD_CFLAGS)) \
		$(filter -m%-float,$(KBUILD_CFLAGS)) \
		$(filter -mno-loongson-%,$(KBUILD_CFLAGS)) \
		-D__VDSO__

		ifeq ($(cc-name),clang)