On 3/27/24 07:44, Simon Horman wrote:

On Mon, Mar 25, 2024 at 10:52:46AM -0700, Guenter Roeck wrote:

quoted

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_SUPPRESS_BACKTRACE 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).

Tested-by: Linux Kernel Functional Testing <redacted>
Acked-by: Dan Carpenter <redacted>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
- Rebased to v6.9-rc1
- Added Tested-by:, Acked-by:, and Reviewed-by: tags
- Introduced KUNIT_SUPPRESS_BACKTRACE configuration option

  arch/sh/include/asm/bug.h | 26 ++++++++++++++++++++++----
  1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/arch/sh/include/asm/bug.h b/arch/sh/include/asm/bug.h
index 05a485c4fabc..470ce6567d20 100644
--- a/arch/sh/include/asm/bug.h
+++ b/arch/sh/include/asm/bug.h

@@ -24,21 +24,36 @@
   * The offending file and line are encoded in the __bug_table section.
   */
  #ifdef CONFIG_DEBUG_BUGVERBOSE
+
+#ifdef CONFIG_KUNIT_SUPPRESS_BACKTRACE
+# define HAVE_BUG_FUNCTION
+# define __BUG_FUNC_PTR	"\t.long %O2\n"
+#else
+# define __BUG_FUNC_PTR
+#endif /* CONFIG_KUNIT_SUPPRESS_BACKTRACE */
+

Hi Guenter,

a minor nit from my side: this change results in a Kernel doc warning.

      .../bug.h:29: warning: expecting prototype for _EMIT_BUG_ENTRY(). Prototype was for HAVE_BUG_FUNCTION() instead

Perhaps either the new code should be placed above the Kernel doc,
or scripts/kernel-doc should be enhanced?

Thanks a lot for the feedback.

The definition block needs to be inside CONFIG_DEBUG_BUGVERBOSE,
so it would be a bit odd to move it above the documentation
just to make kerneldoc happy. I am not really sure that to do
about it.

I'll wait for comments from others before making any changes.

Thanks,
Guenter

quoted

  #define _EMIT_BUG_ENTRY				\
  	"\t.pushsection __bug_table,\"aw\"\n"	\
  	"2:\t.long 1b, %O1\n"			\
-	"\t.short %O2, %O3\n"			\
-	"\t.org 2b+%O4\n"			\
+	__BUG_FUNC_PTR				\
+	"\t.short %O3, %O4\n"			\
+	"\t.org 2b+%O5\n"			\
  	"\t.popsection\n"
  #else
  #define _EMIT_BUG_ENTRY				\
  	"\t.pushsection __bug_table,\"aw\"\n"	\
  	"2:\t.long 1b\n"			\
-	"\t.short %O3\n"			\
-	"\t.org 2b+%O4\n"			\
+	"\t.short %O4\n"			\
+	"\t.org 2b+%O5\n"			\
  	"\t.popsection\n"
  #endif
  
+#ifdef HAVE_BUG_FUNCTION
+# define __BUG_FUNC	__func__
+#else
+# define __BUG_FUNC	NULL
+#endif
+
  #define BUG()						\
  do {							\
  	__asm__ __volatile__ (				\

...