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

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Date: Fri, 15 Mar 2024 12:45:35 +0100
From: Helge Deller <deller@....de>
To: Guenter Roeck <linux@...ck-us.net>, linux-kselftest@...r.kernel.org
Cc: David Airlie <airlied@...il.com>, Arnd Bergmann <arnd@...db.de>,
 Maíra Canal <mcanal@...lia.com>,
 Dan Carpenter <dan.carpenter@...aro.org>, Kees Cook <keescook@...omium.org>,
 Daniel Diaz <daniel.diaz@...aro.org>, David Gow <davidgow@...gle.com>,
 Arthur Grillo <arthurgrillo@...eup.net>,
 Brendan Higgins <brendan.higgins@...ux.dev>,
 Naresh Kamboju <naresh.kamboju@...aro.org>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Andrew Morton <akpm@...ux-foundation.org>, Maxime Ripard
 <mripard@...nel.org>, Ville Syrjälä
 <ville.syrjala@...ux.intel.com>, Daniel Vetter <daniel@...ll.ch>,
 Thomas Zimmermann <tzimmermann@...e.de>, dri-devel@...ts.freedesktop.org,
 kunit-dev@...glegroups.com, linux-arch@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-parisc@...r.kernel.org,
 linuxppc-dev@...ts.ozlabs.org, linux-riscv@...ts.infradead.org,
 linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
 loongarch@...ts.linux.dev, netdev@...ts.linux.dev
Subject: Re: [PATCH 10/14] parisc: Add support for suppressing warning
 backtraces

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@...ck-us.net>


Acked-by: Helge Deller <deller@....de>

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)) );		\