[PATCH 11/14] s390: Add support for suppressing warning backtraces

[Guenter Roeck]

Add name of functions triggering warning backtraces to the __bug_table
object section to enable support for suppressing WARNING backtraces.

To limit image size impact, the pointer to the function name is only added
to the __bug_table section if both CONFIG_KUNIT and CONFIG_DEBUG_BUGVERBOSE
are enabled. Otherwise, the __func__ assembly parameter is replaced with a
(dummy) NULL parameter to avoid an image size increase due to unused
__func__ entries (this is necessary because __func__ is not a define but a
virtual variable).

Signed-off-by: Guenter Roeck <linux at roeck-us.net>
---
 arch/s390/include/asm/bug.h | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/arch/s390/include/asm/bug.h b/arch/s390/include/asm/bug.h
index aebe1e22c7be..01e2aa4069d7 100644
--- a/arch/s390/include/asm/bug.h
+++ b/arch/s390/include/asm/bug.h
@@ -8,19 +8,30 @@
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
 
+#if IS_ENABLED(CONFIG_KUNIT)
+# define HAVE_BUG_FUNCTION
+# define __BUG_FUNC_PTR	"	.long	%0-.\n"
+# define __BUG_FUNC	__func__
+#else
+# define __BUG_FUNC_PTR
+# define __BUG_FUNC	NULL
+#endif /* IS_ENABLED(CONFIG_KUNIT) */
+
 #define __EMIT_BUG(x) do {					\
 	asm_inline volatile(					\
 		"0:	mc	0,0\n"				\
 		".section .rodata.str,\"aMS\", at progbits,1\n"	\
 		"1:	.asciz	\""__FILE__"\"\n"		\
 		".previous\n"					\
-		".section __bug_table,\"awM\", at progbits,%2\n"	\
+		".section __bug_table,\"awM\", at progbits,%3\n"	\
 		"2:	.long	0b-.\n"				\
 		"	.long	1b-.\n"				\
-		"	.short	%0,%1\n"			\
-		"	.org	2b+%2\n"			\
+		__BUG_FUNC_PTR					\
+		"	.short	%1,%2\n"			\
+		"	.org	2b+%3\n"			\
 		".previous\n"					\
-		: : "i" (__LINE__),				\
+		: : "i" (__BUG_FUNC),				\
+		    "i" (__LINE__),				\
 		    "i" (x),					\
 		    "i" (sizeof(struct bug_entry)));		\
 } while (0)
-- 
2.39.2