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: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <w...@kernel.org>
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/arm64/include/asm/asm-bug.h | 29 +++++++++++++++++++----------
 arch/arm64/include/asm/bug.h     |  8 +++++++-
 2 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/asm-bug.h b/arch/arm64/include/asm/asm-bug.h
index c762038ba400..c6d22e3cd840 100644
--- a/arch/arm64/include/asm/asm-bug.h
+++ b/arch/arm64/include/asm/asm-bug.h
@@ -8,36 +8,45 @@
 #include <asm/brk-imm.h>
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
-#define _BUGVERBOSE_LOCATION(file, line) __BUGVERBOSE_LOCATION(file, line)
-#define __BUGVERBOSE_LOCATION(file, line)                      \
+
+#ifdef CONFIG_KUNIT_SUPPRESS_BACKTRACE
+# define HAVE_BUG_FUNCTION
+# define __BUG_FUNC_PTR(func)  .long func - .;
+#else
+# define __BUG_FUNC_PTR(func)
+#endif
+
+#define _BUGVERBOSE_LOCATION(file, func, line) __BUGVERBOSE_LOCATION(file, 
func, line)
+#define __BUGVERBOSE_LOCATION(file, func, line)                \
                .pushsection .rodata.str,"aMS",@progbits,1;     \
        14472:  .string file;                                   \
                .popsection;                                    \
                                                                \
                .long 14472b - .;                               \
+               __BUG_FUNC_PTR(func)                            \
                .short line;
 #else
-#define _BUGVERBOSE_LOCATION(file, line)
+#define _BUGVERBOSE_LOCATION(file, func, line)
 #endif
 
 #ifdef CONFIG_GENERIC_BUG
 
-#define __BUG_ENTRY(flags)                             \
+#define __BUG_ENTRY(flags, func)                       \
                .pushsection __bug_table,"aw";          \
                .align 2;                               \
        14470:  .long 14471f - .;                       \
-_BUGVERBOSE_LOCATION(__FILE__, __LINE__)               \
-               .short flags;                           \
+_BUGVERBOSE_LOCATION(__FILE__, func, __LINE__)         \
+               .short flags;                           \
                .popsection;                            \
        14471:
 #else
-#define __BUG_ENTRY(flags)
+#define __BUG_ENTRY(flags, func)
 #endif
 
-#define ASM_BUG_FLAGS(flags)                           \
-       __BUG_ENTRY(flags)                              \
+#define ASM_BUG_FLAGS(flags, func)                     \
+       __BUG_ENTRY(flags, func)                        \
        brk     BUG_BRK_IMM
 
-#define ASM_BUG()      ASM_BUG_FLAGS(0)
+#define ASM_BUG()      ASM_BUG_FLAGS(0, .)
 
 #endif /* __ASM_ASM_BUG_H */
diff --git a/arch/arm64/include/asm/bug.h b/arch/arm64/include/asm/bug.h
index 28be048db3f6..044c5e24a17d 100644
--- a/arch/arm64/include/asm/bug.h
+++ b/arch/arm64/include/asm/bug.h
@@ -11,8 +11,14 @@
 
 #include <asm/asm-bug.h>
 
+#ifdef HAVE_BUG_FUNCTION
+# define __BUG_FUNC    __func__
+#else
+# define __BUG_FUNC    NULL
+#endif
+
 #define __BUG_FLAGS(flags)                             \
-       asm volatile (__stringify(ASM_BUG_FLAGS(flags)));
+       asm volatile (__stringify(ASM_BUG_FLAGS(flags, %c0)) : : "i" 
(__BUG_FUNC));
 
 #define BUG() do {                                     \
        __BUG_FLAGS(0);                                 \
-- 
2.39.2

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