bug: Let report_bug_entry() provide the correct bugaddr

report_bug_entry() always provides zero for bugaddr but could easily
extract the correct address from the provided bug_entry. Just do that to
have proper warning messages.

E.g. adding an artificial:

  void foo(void) { WARN_ONCE(1, "bar"); }

function generates this warning message:

  WARNING: arch/s390/kernel/setup.c:1017 at 0x0, CPU#0: swapper/0/0
                                            ^^^

With the correct bug address this changes to:

  WARNING: arch/s390/kernel/setup.c:1017 at foo+0x1c/0x40, CPU#0: swapper/0/0
                                            ^^^^^^^^^^^^^

Fixes: 7d2c27a ("bug: Add report_bug_entry()")
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://patch.msgid.link/20251208200658.3431511-1-hca@linux.ibm.com

Author: hcahca

lib/bug.c

@@ -262,7 +262,7 @@ enum bug_trap_type report_bug_entry(struct bug_entry *bug, struct pt_regs *regs)
 	bool rcu = false;
 
 	rcu = warn_rcu_enter();
-	ret = __report_bug(bug, 0, regs);
+	ret = __report_bug(bug, bug_addr(bug), regs);
 	warn_rcu_exit(rcu);
 
 	return ret;