Re: [PATCH 11/14] s390: Add support for suppressing warning backtraces

Geert Uytterhoeven
2024-03-14T07:57:58Z

Hi Günter,

On Tue, Mar 12, 2024 at 6:06 PM 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 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).
>
> 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

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

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds