Subject: [PATCH 5/7] x86/boot: Disable the address-of-packed-member compiler warning

From: Matthias Kaehlcke <[email-masked]>
Date: Tue, 25 Jul 2017 14:50:53 -0700

commit 20c6c189045539d29f4854d92b7ea9c329e1edfc upstream.

The clang warning 'address-of-packed-member' is disabled for the general
kernel code, also disable it for the x86 boot code.

This suppresses a bunch of warnings like this when building with clang:

./arch/x86/include/asm/processor.h:535:30: warning: taking address of
  packed member 'sp0' of class or structure 'x86_hw_tss' may result in an
  unaligned pointer value [-Waddress-of-packed-member]
    return this_cpu_read_stable(cpu_tss.x86_tss.sp0);
                                ^~~~~~~~~~~~~~~~~~~
./arch/x86/include/asm/percpu.h:391:59: note: expanded from macro
  'this_cpu_read_stable'
    #define this_cpu_read_stable(var)       percpu_stable_op("mov", var)
                                                                    ^~~
./arch/x86/include/asm/percpu.h:228:16: note: expanded from macro
  'percpu_stable_op'
    : "p" (&(var)));
             ^~~

Signed-off-by: Matthias Kaehlcke <[email-masked]>
Cc: Doug Anderson <[email-masked]>
Cc: Linus Torvalds <[email-masked]>
Cc: Masahiro Yamada <[email-masked]>
Cc: Peter Zijlstra <[email-masked]>
Cc: Thomas Gleixner <[email-masked]>
Link: http://lkml.kernel.org/r/[email-masked]
Signed-off-by: Ingo Molnar <[email-masked]>
Signed-off-by: Nathan Chancellor <[email-masked]>
---
 arch/x86/boot/compressed/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index cda8e14bd72a..89b163351e64 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -34,6 +34,7 @@ KBUILD_CFLAGS += $(cflags-y)
 KBUILD_CFLAGS += -mno-mmx -mno-sse
 KBUILD_CFLAGS += $(call cc-option,-ffreestanding)
 KBUILD_CFLAGS += $(call cc-option,-fno-stack-protector)
+KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
 
 KBUILD_AFLAGS  := $(KBUILD_CFLAGS) -D__ASSEMBLY__
 GCOV_PROFILE := n
-- 
2.21.0