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Subject[tip:x86/urgent] x86/boot: Disable the address-of-packed-member compiler warning
Commit-ID:  20c6c189045539d29f4854d92b7ea9c329e1edfc
Gitweb: http://git.kernel.org/tip/20c6c189045539d29f4854d92b7ea9c329e1edfc
Author: Matthias Kaehlcke <mka@chromium.org>
AuthorDate: Tue, 25 Jul 2017 14:50:53 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 28 Jul 2017 08:39:08 +0200

x86/boot: Disable the address-of-packed-member compiler warning

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 <mka@chromium.org>
Cc: Doug Anderson <dianders@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170725215053.135586-1-mka@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
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 2c860ad..8a95827 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
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