bug: Factor out a getter for a bug's file line

There is some non-trivial config-based logic to get the file name and
line number associated with a bug. Factor this out to a getter that can
be resused.

Signed-off-by: Andrew Scull <ascull@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210318143311.839894-3-ascull@google.com

include/linux/bug.h

@@ -36,6 +36,9 @@ static inline int is_warning_bug(const struct bug_entry *bug)
 	return bug->flags & BUGFLAG_WARNING;
 }
 
+void bug_get_file_line(struct bug_entry *bug, const char **file,
+		       unsigned int *line);
+
 struct bug_entry *find_bug(unsigned long bugaddr);
 
 enum bug_trap_type report_bug(unsigned long bug_addr, struct pt_regs *regs);

lib/bug.c

@@ -127,6 +127,22 @@ static inline struct bug_entry *module_find_bug(unsigned long bugaddr)
 }
 #endif
 
+void bug_get_file_line(struct bug_entry *bug, const char **file,
+		       unsigned int *line)
+{
+	*file = NULL;
+	*line = 0;
+
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
+	*file = bug->file;
+#else
+	*file = (const char *)bug + bug->file_disp;
+#endif
+	*line = bug->line;
+#endif
+}
+
 struct bug_entry *find_bug(unsigned long bugaddr)
 {
 	struct bug_entry *bug;
@@ -153,17 +169,8 @@ enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs)
 
 	disable_trace_on_warning();
 
-	file = NULL;
-	line = 0;
+	bug_get_file_line(bug, &file, &line);
 
-#ifdef CONFIG_DEBUG_BUGVERBOSE
-#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
-	file = bug->file;
-#else
-	file = (const char *)bug + bug->file_disp;
-#endif
-	line = bug->line;
-#endif
 	warning = (bug->flags & BUGFLAG_WARNING) != 0;
 	once = (bug->flags & BUGFLAG_ONCE) != 0;
 	done = (bug->flags & BUGFLAG_DONE) != 0;