Re: [PATCH 10/14] parisc: Add support for suppressing warning backtraces

[Helge Deller]

On 3/12/24 18:03, Guenter Roeck wrote:
> 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).
>
> While at it, declare assembler parameters as constants where possible.
> Refine .blockz instructions to calculate the necessary padding instead
> of using fixed values.
>
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>


Acked-by: Helge Deller <deller@xxxxxx>

Helge


> ---
>   arch/parisc/include/asm/bug.h | 29 +++++++++++++++++++++--------
>   1 file changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/arch/parisc/include/asm/bug.h b/arch/parisc/include/asm/bugh
> index 833555f74ffa..792dacc2a653 100644
> --- a/arch/parisc/include/asm/bug.h
> +++ b/arch/parisc/include/asm/bug.h
> @@ -23,8 +23,17 @@
>   # define __BUG_REL(val) ".word " __stringify(val)
>   #endif
>
> -
>   #ifdef CONFIG_DEBUG_BUGVERBOSE
> +
> +#if IS_ENABLED(CONFIG_KUNIT)
> +# define HAVE_BUG_FUNCTION
> +# define __BUG_FUNC_PTR	__BUG_REL(%c1)
> +# define __BUG_FUNC	__func__
> +#else
> +# define __BUG_FUNC_PTR
> +# define __BUG_FUNC	NULL
> +#endif /* IS_ENABLED(CONFIG_KUNIT) */
> +
>   #define BUG()								\
>   	do {								\
>   		asm volatile("\n"					\
> @@ -33,10 +42,12 @@
>   			     "\t.align 4\n"				\
>   			     "2:\t" __BUG_REL(1b) "\n"			\
>   			     "\t" __BUG_REL(%c0)  "\n"			\
> -			     "\t.short %1, %2\n"			\
> -			     "\t.blockz %3-2*4-2*2\n"			\
> +			     "\t" __BUG_FUNC_PTR  "\n"			\
> +			     "\t.short %c2, %c3\n"			\
> +			     "\t.blockz %c4-(.-2b)\n"			\
>   			     "\t.popsection"				\
> -			     : : "i" (__FILE__), "i" (__LINE__),	\
> +			     : : "i" (__FILE__), "i" (__BUG_FUNC),	\
> +			     "i" (__LINE__),				\
>   			     "i" (0), "i" (sizeof(struct bug_entry)) );	\
>   		unreachable();						\
>   	} while(0)
> @@ -58,10 +69,12 @@
>   			     "\t.align 4\n"				\
>   			     "2:\t" __BUG_REL(1b) "\n"			\
>   			     "\t" __BUG_REL(%c0)  "\n"			\
> -			     "\t.short %1, %2\n"			\
> -			     "\t.blockz %3-2*4-2*2\n"			\
> +			     "\t" __BUG_FUNC_PTR  "\n"			\
> +			     "\t.short %c2, %3\n"			\
> +			     "\t.blockz %c4-(.-2b)\n"			\
>   			     "\t.popsection"				\
> -			     : : "i" (__FILE__), "i" (__LINE__),	\
> +			     : : "i" (__FILE__), "i" (__BUG_FUNC),	\
> +			     "i" (__LINE__),				\
>   			     "i" (BUGFLAG_WARNING|(flags)),		\
>   			     "i" (sizeof(struct bug_entry)) );		\
>   	} while(0)
> @@ -74,7 +87,7 @@
>   			     "\t.align 4\n"				\
>   			     "2:\t" __BUG_REL(1b) "\n"			\
>   			     "\t.short %0\n"				\
> -			     "\t.blockz %1-4-2\n"			\
> +			     "\t.blockz %c1-(.-2b)\n"			\
>   			     "\t.popsection"				\
>   			     : : "i" (BUGFLAG_WARNING|(flags)),		\
>   			     "i" (sizeof(struct bug_entry)) );		\