[PATCH 09/14] loongarch: Add support for suppressing warning backtraces

Guenter Roeck
2024-03-12T17:03:34Z

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@roeck-us.net>
---
arch/loongarch/include/asm/bug.h | 38 +++++++++++++++++++++++---------
1 file changed, 27 insertions(+), 11 deletions(-)

diff --git a/arch/loongarch/include/asm/bug.h b/arch/loongarch/include/asm/bug.h
index d4ca3ba25418..25f2b5ae7702 100644
--- a/arch/loongarch/include/asm/bug.h
+++ b/arch/loongarch/include/asm/bug.h
@@ -3,47 +3,63 @@
#define __ASM_BUG_H

#include <asm/break.h>
+#include <kunit/bug.h>
#include <linux/stringify.h>

#ifndef CONFIG_DEBUG_BUGVERBOSE
-#define _BUGVERBOSE_LOCATION(file, line)
+#define _BUGVERBOSE_LOCATION(file, func, line)
#else
-#define __BUGVERBOSE_LOCATION(file, line) \
+#if IS_ENABLED(CONFIG_KUNIT)
+# define HAVE_BUG_FUNCTION
+# define __BUG_FUNC_PTR(func) .long func - .;
+#else
+# define __BUG_FUNC_PTR(func)
+#endif
+
+#define __BUGVERBOSE_LOCATION(file, func, line) \
.pushsection .rodata.str, "aMS", @progbits, 1; \
10002: .string file; \
.popsection; \
\
.long 10002b - .; \
+ __BUG_FUNC_PTR(func) \
.short line;
-#define _BUGVERBOSE_LOCATION(file, line) __BUGVERBOSE_LOCATION(file, line)
+#define _BUGVERBOSE_LOCATION(file, func, line) __BUGVERBOSE_LOCATION(file, func, line)
#endif

#ifndef CONFIG_GENERIC_BUG
-#define __BUG_ENTRY(flags)
+#define __BUG_ENTRY(flags, func)
#else
-#define __BUG_ENTRY(flags) \
+#define __BUG_ENTRY(flags, func) \
.pushsection __bug_table, "aw"; \
.align 2; \
10000: .long 10001f - .; \
- _BUGVERBOSE_LOCATION(__FILE__, __LINE__) \
+ _BUGVERBOSE_LOCATION(__FILE__, func, __LINE__) \
.short flags; \
.popsection; \
10001:
#endif

-#define ASM_BUG_FLAGS(flags) \
- __BUG_ENTRY(flags) \
+#define ASM_BUG_FLAGS(flags, func) \
+ __BUG_ENTRY(flags, func) \
break BRK_BUG

-#define ASM_BUG() ASM_BUG_FLAGS(0)
+#define ASM_BUG() ASM_BUG_FLAGS(0, .)
+
+#ifdef HAVE_BUG_FUNCTION
+# define __BUG_FUNC __func__
+#else
+# define __BUG_FUNC NULL
+#endif

#define __BUG_FLAGS(flags) \
- asm_inline volatile (__stringify(ASM_BUG_FLAGS(flags)));
+ asm_inline volatile (__stringify(ASM_BUG_FLAGS(flags, %0)) : : "i" (__BUG_FUNC));

#define __WARN_FLAGS(flags) \
do { \
instrumentation_begin(); \
- __BUG_FLAGS(BUGFLAG_WARNING|(flags)); \
+ if (!IS_SUPPRESSED_WARNING(__func__)) \
+ __BUG_FLAGS(BUGFLAG_WARNING|(flags)); \
instrumentation_end(); \
} while (0)

--
2.39.2