v4.19.13 snapshot.
diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
new file mode 100644
index 0000000..6804d66
--- /dev/null
+++ b/arch/x86/include/asm/bug.h
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_BUG_H
+#define _ASM_X86_BUG_H
+
+#include <linux/stringify.h>
+
+/*
+ * Despite that some emulators terminate on UD2, we use it for WARN().
+ *
+ * Since various instruction decoders/specs disagree on the encoding of
+ * UD0/UD1.
+ */
+
+#define ASM_UD0 ".byte 0x0f, 0xff" /* + ModRM (for Intel) */
+#define ASM_UD1 ".byte 0x0f, 0xb9" /* + ModRM */
+#define ASM_UD2 ".byte 0x0f, 0x0b"
+
+#define INSN_UD0 0xff0f
+#define INSN_UD2 0x0b0f
+
+#define LEN_UD2 2
+
+#ifdef CONFIG_GENERIC_BUG
+
+#ifdef CONFIG_X86_32
+# define __BUG_REL(val) ".long " __stringify(val)
+#else
+# define __BUG_REL(val) ".long " __stringify(val) " - 2b"
+#endif
+
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+
+#define _BUG_FLAGS(ins, flags) \
+do { \
+ asm volatile("1:\t" ins "\n" \
+ ".pushsection __bug_table,\"aw\"\n" \
+ "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n" \
+ "\t" __BUG_REL(%c0) "\t# bug_entry::file\n" \
+ "\t.word %c1" "\t# bug_entry::line\n" \
+ "\t.word %c2" "\t# bug_entry::flags\n" \
+ "\t.org 2b+%c3\n" \
+ ".popsection" \
+ : : "i" (__FILE__), "i" (__LINE__), \
+ "i" (flags), \
+ "i" (sizeof(struct bug_entry))); \
+} while (0)
+
+#else /* !CONFIG_DEBUG_BUGVERBOSE */
+
+#define _BUG_FLAGS(ins, flags) \
+do { \
+ asm volatile("1:\t" ins "\n" \
+ ".pushsection __bug_table,\"aw\"\n" \
+ "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n" \
+ "\t.word %c0" "\t# bug_entry::flags\n" \
+ "\t.org 2b+%c1\n" \
+ ".popsection" \
+ : : "i" (flags), \
+ "i" (sizeof(struct bug_entry))); \
+} while (0)
+
+#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); \
+ unreachable(); \
+} while (0)
+
+#define __WARN_FLAGS(flags) \
+do { \
+ _BUG_FLAGS(ASM_UD2, BUGFLAG_WARNING|(flags)); \
+ annotate_reachable(); \
+} while (0)
+
+#include <asm-generic/bug.h>
+
+#endif /* _ASM_X86_BUG_H */