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From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Thu, 14 Mar 2024 08:57:45 +0100
Message-ID: <CAMuHMdXHKfd8agPGx+MjvC4cjW5F6DEeVec3Moe-=LLkrT3CXQ@mail.gmail.com>
Subject: Re: [PATCH 11/14] s390: Add support for suppressing warning backtraces
To: Guenter Roeck <linux@roeck-us.net>
Cc: linux-kselftest@vger.kernel.org, David Airlie <airlied@gmail.com>, 
	Arnd Bergmann <arnd@arndb.de>, =?UTF-8?B?TWHDrXJhIENhbmFs?= <mcanal@igalia.com>, 
	Dan Carpenter <dan.carpenter@linaro.org>, Kees Cook <keescook@chromium.org>, 
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	Arthur Grillo <arthurgrillo@riseup.net>, Brendan Higgins <brendan.higgins@linux.dev>, 
	Naresh Kamboju <naresh.kamboju@linaro.org>, 
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, 
	Andrew Morton <akpm@linux-foundation.org>, Maxime Ripard <mripard@kernel.org>, 
	=?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= <ville.syrjala@linux.intel.com>, 
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Hi G=C3=BCnter,

On Tue, Mar 12, 2024 at 6:06=E2=80=AFPM Guenter Roeck <linux@roeck-us.net> =
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 adde=
d
> to the __bug_table section if both CONFIG_KUNIT and CONFIG_DEBUG_BUGVERBO=
SE
> 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).
>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Thanks for your patch!

> --- a/arch/s390/include/asm/bug.h
> +++ b/arch/s390/include/asm/bug.h
> @@ -8,19 +8,30 @@
>
>  #ifdef CONFIG_DEBUG_BUGVERBOSE
>
> +#if IS_ENABLED(CONFIG_KUNIT)
> +# define HAVE_BUG_FUNCTION
> +# define __BUG_FUNC_PTR        "       .long   %0-.\n"
> +# define __BUG_FUNC    __func__
> +#else
> +# define __BUG_FUNC_PTR
> +# define __BUG_FUNC    NULL
> +#endif /* IS_ENABLED(CONFIG_KUNIT) */
> +
>  #define __EMIT_BUG(x) do {                                     \
>         asm_inline volatile(                                    \
>                 "0:     mc      0,0\n"                          \
>                 ".section .rodata.str,\"aMS\",@progbits,1\n"    \
>                 "1:     .asciz  \""__FILE__"\"\n"               \
>                 ".previous\n"                                   \
> -               ".section __bug_table,\"awM\",@progbits,%2\n"   \
> +               ".section __bug_table,\"awM\",@progbits,%3\n"   \

This change conflicts with commit 3938490e78f443fb ("s390/bug:
remove entry size from __bug_table section") in linus/master.
I guess it should just be dropped?

>                 "2:     .long   0b-.\n"                         \
>                 "       .long   1b-.\n"                         \
> -               "       .short  %0,%1\n"                        \
> -               "       .org    2b+%2\n"                        \
> +               __BUG_FUNC_PTR                                  \
> +               "       .short  %1,%2\n"                        \
> +               "       .org    2b+%3\n"                        \
>                 ".previous\n"                                   \
> -               : : "i" (__LINE__),                             \
> +               : : "i" (__BUG_FUNC),                           \
> +                   "i" (__LINE__),                             \
>                     "i" (x),                                    \
>                     "i" (sizeof(struct bug_entry)));            \
>  } while (0)

Gr{oetje,eeting}s,

                        Geert

--=20
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k=
org

In personal conversations with technical people, I call myself a hacker. Bu=
t
when I'm talking to journalists I just say "programmer" or something like t=
hat.
                                -- Linus Torvalds