diff mbox series

[v3,15/15] powerpc: Add support for suppressing warning backtraces

Message ID 20240403131936.787234-16-linux@roeck-us.net (mailing list archive)
State New
Headers show
Series Add support for suppressing warning backtraces | expand

Commit Message

Guenter Roeck April 3, 2024, 1:19 p.m. UTC 
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 <lkft@linaro.org>
Acked-by: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Guenter Roeck <linux@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/powerpc/include/asm/bug.h | 37 +++++++++++++++++++++++++---------
 1 file changed, 28 insertions(+), 9 deletions(-)

Comments

Michael Ellerman April 4, 2024, 2:14 a.m. UTC | #1 
Guenter Roeck <linux@roeck-us.net> writes:
> 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 <lkft@linaro.org>
> Acked-by: Dan Carpenter <dan.carpenter@linaro.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Guenter Roeck <linux@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/powerpc/include/asm/bug.h | 37 +++++++++++++++++++++++++---------
>  1 file changed, 28 insertions(+), 9 deletions(-)

I ran it through some build and boot tests, LGTM.

Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

cheers
diff mbox series

Patch

diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
index 1db485aacbd9..5b06745d20aa 100644
--- a/arch/powerpc/include/asm/bug.h
+++ b/arch/powerpc/include/asm/bug.h
@@ -14,6 +14,9 @@ 
 	 .section __bug_table,"aw"
 5001:	 .4byte \addr - .
 	 .4byte 5002f - .
+#ifdef CONFIG_KUNIT_SUPPRESS_BACKTRACE
+	 .4byte 0
+#endif
 	 .short \line, \flags
 	 .org 5001b+BUG_ENTRY_SIZE
 	 .previous
@@ -32,30 +35,46 @@ 
 #endif /* verbose */
 
 #else /* !__ASSEMBLY__ */
-/* _EMIT_BUG_ENTRY expects args %0,%1,%2,%3 to be FILE, LINE, flags and
-   sizeof(struct bug_entry), respectively */
+/* _EMIT_BUG_ENTRY expects args %0,%1,%2,%3,%4 to be FILE, __func__, LINE, flags
+   and sizeof(struct bug_entry), respectively */
 #ifdef CONFIG_DEBUG_BUGVERBOSE
+
+#ifdef CONFIG_KUNIT_SUPPRESS_BACKTRACE
+# define HAVE_BUG_FUNCTION
+# define __BUG_FUNC_PTR	"	.4byte %1 - .\n"
+#else
+# define __BUG_FUNC_PTR
+#endif /* CONFIG_KUNIT_SUPPRESS_BACKTRACE */
+
 #define _EMIT_BUG_ENTRY				\
 	".section __bug_table,\"aw\"\n"		\
 	"2:	.4byte 1b - .\n"		\
 	"	.4byte %0 - .\n"		\
-	"	.short %1, %2\n"		\
-	".org 2b+%3\n"				\
+	__BUG_FUNC_PTR				\
+	"	.short %2, %3\n"		\
+	".org 2b+%4\n"				\
 	".previous\n"
 #else
 #define _EMIT_BUG_ENTRY				\
 	".section __bug_table,\"aw\"\n"		\
 	"2:	.4byte 1b - .\n"		\
-	"	.short %2\n"			\
-	".org 2b+%3\n"				\
+	"	.short %3\n"			\
+	".org 2b+%4\n"				\
 	".previous\n"
 #endif
 
+#ifdef HAVE_BUG_FUNCTION
+# define __BUG_FUNC	__func__
+#else
+# define __BUG_FUNC	NULL
+#endif
+
 #define BUG_ENTRY(insn, flags, ...)			\
 	__asm__ __volatile__(				\
 		"1:	" insn "\n"			\
 		_EMIT_BUG_ENTRY				\
-		: : "i" (__FILE__), "i" (__LINE__),	\
+		: : "i" (__FILE__), "i" (__BUG_FUNC),	\
+		  "i" (__LINE__),			\
 		  "i" (flags),				\
 		  "i" (sizeof(struct bug_entry)),	\
 		  ##__VA_ARGS__)
@@ -80,7 +99,7 @@ 
 		if (x)						\
 			BUG();					\
 	} else {						\
-		BUG_ENTRY(PPC_TLNEI " %4, 0", 0, "r" ((__force long)(x)));	\
+		BUG_ENTRY(PPC_TLNEI " %5, 0", 0, "r" ((__force long)(x)));	\
 	}							\
 } while (0)
 
@@ -90,7 +109,7 @@ 
 		if (__ret_warn_on)				\
 			__WARN();				\
 	} else {						\
-		BUG_ENTRY(PPC_TLNEI " %4, 0",			\
+		BUG_ENTRY(PPC_TLNEI " %5, 0",			\
 			  BUGFLAG_WARNING | BUGFLAG_TAINT(TAINT_WARN),	\
 			  "r" (__ret_warn_on));	\
 	}							\