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 <l...@linaro.org>
Acked-by: Dan Carpenter <dan.carpen...@linaro.org>
Cc: Yoshinori Sato <ys...@users.sourceforge.jp>
Cc: Rich Felker <dal...@libc.org>
Cc: John Paul Adrian Glaubitz <glaub...@physik.fu-berlin.de>
Signed-off-by: Guenter Roeck <li...@roeck-us.net>
---
v2:
- Rebased to v6.9-rc1
- Added Tested-by:, Acked-by:, and Reviewed-by: tags
- Introduced KUNIT_SUPPRESS_BACKTRACE configuration option
v3:
- Rebased to v6.9-rc2

 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 */
+
 #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__ (                          \
@@ -47,6 +62,7 @@ do {                                                  \
                 :                                      \
                 : "n" (TRAPA_BUG_OPCODE),              \
                   "i" (__FILE__),                      \
+                  "i" (__BUG_FUNC),                    \
                   "i" (__LINE__), "i" (0),             \
                   "i" (sizeof(struct bug_entry)));     \
        unreachable();                                  \
@@ -60,6 +76,7 @@ do {                                                  \
                 :                                      \
                 : "n" (TRAPA_BUG_OPCODE),              \
                   "i" (__FILE__),                      \
+                  "i" (__BUG_FUNC),                    \
                   "i" (__LINE__),                      \
                   "i" (BUGFLAG_WARNING|(flags)),       \
                   "i" (sizeof(struct bug_entry)));     \
@@ -85,6 +102,7 @@ do {                                                 \
                 :                                      \
                 : "n" (TRAPA_BUG_OPCODE),              \
                   "i" (__FILE__),                      \
+                  "i" (__BUG_FUNC),                    \
                   "i" (__LINE__),                      \
                   "i" (BUGFLAG_UNWINDER),              \
                   "i" (sizeof(struct bug_entry)));     \
-- 
2.39.2

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