[I/linux][PATCH] UBUNTU: SAUCE: arm: Fix instruction set selection for GCC 11

[Juerg Haefliger]

BugLink: https://bugs.launchpad.net/bugs/1939308

GCC 11 on ARM now complains like the following when trying to determine if
an arch is supported. Presumably because it enforces the default option
which (in our case) is '--with-float=hard'?
  $ arm-linux-gnueabihf-gcc-11 -march=armv7-a -c -x c /dev/null
  cc1: error: ‘-mfloat-abi=hard’: selected architecture lacks an FPU

Due to that, the kernel build system selects the wrong compiler options
which throws errros like this:
  /tmp/ccrHfZPj.s: Assembler messages:
  /tmp/ccrHfZPj.s:116: Error: selected processor does not support `dmb ish' in ARM mode
  /tmp/ccrHfZPj.s:150: Error: selected processor does not support `isb ' in ARM mode
  /tmp/ccrHfZPj.s:160: Error: selected processor does not support `mrrc p15,1,r4,r5,c14' in ARM mode
  /tmp/ccrHfZPj.s:245: Error: selected processor does not support `dmb ish' in ARM mode
  /tmp/ccrHfZPj.s:503: Error: selected processor does not support `dmb ish' in ARM mode
  /tmp/ccrHfZPj.s:527: Error: selected processor does not support `dmb ish' in ARM mode
  /tmp/ccrHfZPj.s:698: Error: selected processor does not support `dmb ish' in ARM mode
  /tmp/ccrHfZPj.s:731: Error: selected processor does not support `isb ' in ARM mode

Fix that by moving the option '-msoft-float' up before the
'arch-$(CONFIG_CPU_<foo>)' instruction selection macros.

Signed-off-by: Juerg Haefliger <juergh at canonical.com>
---
 arch/arm/Makefile | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 415c3514573a..efa9518223b0 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -56,6 +56,9 @@ endif
 #
 KBUILD_CFLAGS	+= $(call cc-option,-fno-ipa-sra)
 
+# Need -msoft-float for gcc 11 for the below instruction set selection
+KBUILD_CFLAGS	+= -msoft-float
+
 # This selects which instruction set is used.
 # Note that GCC does not numerically define an architecture version
 # macro, but instead defines a whole series of macros which makes
@@ -125,7 +128,7 @@ AFLAGS_ISA	:=$(CFLAGS_ISA)
 endif
 
 # Need -Uarm for gcc < 3.x
-KBUILD_CFLAGS	+=$(CFLAGS_ABI) $(CFLAGS_ISA) $(arch-y) $(tune-y) $(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) -msoft-float -Uarm
+KBUILD_CFLAGS	+=$(CFLAGS_ABI) $(CFLAGS_ISA) $(arch-y) $(tune-y) $(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) -Uarm
 KBUILD_AFLAGS	+=$(CFLAGS_ABI) $(AFLAGS_ISA) $(arch-y) $(tune-y) -include asm/unified.h -msoft-float
 
 CHECKFLAGS	+= -D__arm__
-- 
2.30.2