[POWERPC] Fix manual assembly WARN_ON() in enter_rtas().

When we switched over to the generic BUG mechanism we forgot to change
the assembly code which open-codes a WARN_ON() in enter_rtas(), so the
bug table got corrupted.

This patch provides an EMIT_BUG_ENTRY macro for use in assembly code,
and uses it in entry_64.S. Tested with CONFIG_DEBUG_BUGVERBOSE on ppc64
but not without -- I tried to turn it off but it wouldn't go away; I
suspect Aunt Tillie probably needed it.

This version gets __FILE__ and __LINE__ right in the assembly version --
rather than saying include/asm-powerpc/bug.h line 21 every time which is
a little suboptimal.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

include/asm-powerpc/bug.h

@@ -11,10 +11,31 @@
 #define BUG_OPCODE .long 0x00b00b00  /* For asm */
 #define BUG_ILLEGAL_INSTR "0x00b00b00" /* For BUG macro */
 
-#ifndef __ASSEMBLY__
-
 #ifdef CONFIG_BUG
 
+#ifdef __ASSEMBLY__
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+.macro EMIT_BUG_ENTRY addr,file,line,flags
+	 .section __bug_table,"a"
+5001:	 PPC_LONG \addr, 5002f
+	 .short \line, \flags
+	 .org 5001b+BUG_ENTRY_SIZE
+	 .previous
+	 .section .rodata,"a"
+5002:	 .asciz "\file"
+	 .previous
+.endm
+#else
+ .macro EMIT_BUG_ENTRY addr,file,line,flags
+	 .section __bug_table,"a"
+5001:	 PPC_LONG \addr
+	 .short \flags
+	 .org 5001b+BUG_ENTRY_SIZE
+	 .previous
+.endm
+#endif /* verbose */
+
+#else /* !__ASSEMBLY__ */
 /* _EMIT_BUG_ENTRY expects args %0,%1,%2,%3 to be FILE, LINE, flags and
    sizeof(struct bug_entry), respectively */
 #ifdef CONFIG_DEBUG_BUGVERBOSE
@@ -91,8 +112,8 @@
 #define HAVE_ARCH_BUG
 #define HAVE_ARCH_BUG_ON
 #define HAVE_ARCH_WARN_ON
-#endif /* CONFIG_BUG */
 #endif /* __ASSEMBLY __ */
+#endif /* CONFIG_BUG */
 
 #include <asm-generic/bug.h>