[tip:x86/boot] x86/boot: Use common BUILD_BUG_ON

[tip-bot for Rikard Falkeborn]

Commit-ID:  d5a1baddf1585885868cbab55989401fb97118c6
Gitweb:     https://git.kernel.org/tip/d5a1baddf1585885868cbab55989401fb97118c6
Author:     Rikard Falkeborn <rikard.falkeborn@xxxxxxxxx>
AuthorDate: Sun, 11 Aug 2019 20:49:36 +0200
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Fri, 16 Aug 2019 14:15:50 +0200

x86/boot: Use common BUILD_BUG_ON

Defining BUILD_BUG_ON causes redefinition warnings when adding includes of
include/linux/build_bug.h in files unrelated to x86/boot.  For example,
adding an include of build_bug.h to include/linux/bits.h shows the
following warnings:

  CC      arch/x86/boot/cpucheck.o
  In file included from ./include/linux/bits.h:22,
                   from ./arch/x86/include/asm/msr-index.h:5,
                   from arch/x86/boot/cpucheck.c:28:
  ./include/linux/build_bug.h:49: warning: "BUILD_BUG_ON" redefined
     49 | #define BUILD_BUG_ON(condition) \
        |
  In file included from arch/x86/boot/cpucheck.c:22:
  arch/x86/boot/boot.h:31: note: this is the location of the previous definition
     31 | #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
        |

The macro was added to boot.h in commit 62bd0337d0c4 ("Top header file for
new x86 setup code"). At that time, BUILD_BUG_ON was defined in
kernel.h. Presumably BUILD_BUG_ON was redefined to avoid pulling in
kernel.h. Since then, BUILD_BUG_ON and similar macros have been split to a
separate header file.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20190811184938.1796-2-rikard.falkeborn@xxxxxxxxx


---
 arch/x86/boot/boot.h | 2 --
 arch/x86/boot/main.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h
index 19eca14b49a0..ca866f1cca2e 100644
--- a/arch/x86/boot/boot.h
+++ b/arch/x86/boot/boot.h
@@ -28,8 +28,6 @@
 #include "cpuflags.h"
 
 /* Useful macros */
-#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
-
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
 
 extern struct setup_header hdr;
diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c
index 996df3d586f0..e3add857c2c9 100644
--- a/arch/x86/boot/main.c
+++ b/arch/x86/boot/main.c
@@ -10,6 +10,7 @@
 /*
  * Main module for the real-mode kernel code
  */
+#include <linux/build_bug.h>
 
 #include "boot.h"
 #include "string.h"