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x86/debug, objtool: Annotate WARN()-related UD2 as reachable

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commit 2b5db66862b95532cb6cca8165ae6eb73633cf85 upstream.

By default, objtool assumes that a UD2 is a dead end.  This is mainly
because GCC 7+ sometimes inserts a UD2 when it detects a divide-by-zero
condition.

Now that WARN() is moving back to UD2, annotate the code after it as
reachable so objtool can follow the code flow.

Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kbuild test robot <fengguang.wu@intel.com>
Link: http://lkml.kernel.org/r/0e483379275a42626ba8898117f918e1bf661e40.1518130694.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Josh Poimboeuf 2018-02-08 17:09:26 -06:00 committed by Greg Kroah-Hartman
parent 842a0d95ef
commit 4e0067c22d
1 changed files with 5 additions and 1 deletions
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6
arch/x86/include/asm/bug.h
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@ -77,7 +77,11 @@ do { \
unreachable(); \
} while (0)
#define __WARN_FLAGS(flags) _BUG_FLAGS(ASM_UD0, BUGFLAG_WARNING|(flags))
#define __WARN_FLAGS(flags) \
do { \
_BUG_FLAGS(ASM_UD0, BUGFLAG_WARNING|(flags)); \
annotate_reachable(); \
} while (0)
#include <asm-generic/bug.h>