[PATCH] x86/debug: define BUG() againfor !CONFIG_BUG

From: Arnd Bergmann
Date: Wed Mar 29 2017 - 17:19:23 EST


The latest change to the BUG() macro inadvertently reverted the earlier
commit b06dd879f5db ("x86: always define BUG() and HAVE_ARCH_BUG, even
with !CONFIG_BUG") that sanitized the behavior with CONFIG_BUG=n.

I noticed this as some warnings have appeared again that were previously
fixed as a side effect of that patch:

kernel/seccomp.c: In function '__seccomp_filter':
kernel/seccomp.c:670:1: error: no return statement in function returning non-void [-Werror=return-type]

drivers/gpu/drm/i915/intel_sprite.c: In function 'intel_check_sprite_plane':
drivers/gpu/drm/i915/intel_sprite.c:936:20: error: 'src_h' may be used uninitialized in this function [-Werror=maybe-uninitialized]
src->y2 = (src_y + src_h) << 16;
~~~~~~~^~~~~~~~
drivers/gpu/drm/i915/intel_sprite.c:934:20: error: 'src_w' may be used uninitialized in this function [-Werror=maybe-uninitialized]
src->x2 = (src_x + src_w) << 16;
~~~~~~~^~~~~~~~
drivers/gpu/drm/i915/intel_sprite.c:936:20: error: 'src_y' may be used uninitialized in this function [-Werror=maybe-uninitialized]
src->y2 = (src_y + src_h) << 16;
~~~~~~~^~~~~~~~
drivers/gpu/drm/i915/intel_sprite.c:934:20: error: 'src_x' may be used uninitialized in this function [-Werror=maybe-uninitialized]
src->x2 = (src_x + src_w) << 16;
~~~~~~~^~~~~~~~

This combines the two patches and uses the ud2 macro to define BUG()
in case of CONFIG_BUG=n.

Fixes: 9a93848fe787 ("x86/debug: Implement __WARN() using UD0")
Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
arch/x86/include/asm/bug.h | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
index 4fde330c44b7..cecf559d0012 100644
--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -23,7 +23,6 @@
#define LEN_UD0 2

#ifdef CONFIG_GENERIC_BUG
-#define HAVE_ARCH_BUG

#ifdef CONFIG_X86_32
# define __BUG_REL(val) ".long " __stringify(val)
@@ -64,6 +63,13 @@ do { \

#endif /* CONFIG_DEBUG_BUGVERBOSE */

+#else
+
+#define _BUG_FLAGS(ins, flags) asm volatile(ins)
+
+#endif /* CONFIG_GENERIC_BUG */
+
+#define HAVE_ARCH_BUG
#define BUG() \
do { \
_BUG_FLAGS(ASM_UD2, 0); \
@@ -72,8 +78,6 @@ do { \

#define __WARN_TAINT(taint) _BUG_FLAGS(ASM_UD0, BUGFLAG_TAINT(taint))

-#endif /* CONFIG_GENERIC_BUG */
-
#include <asm-generic/bug.h>

#endif /* _ASM_X86_BUG_H */
--
2.9.0