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

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Date: Thu, 14 Mar 2024 06:54:33 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: linux-kselftest@...r.kernel.org, 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 11/14] s390: Add support for suppressing warning
 backtraces

On 3/14/24 00:57, Geert Uytterhoeven wrote:
> Hi Günter,
> 
> On Tue, Mar 12, 2024 at 6:06 PM Guenter Roeck <linux@...ck-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@...ck-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?
> 

Yes, I know. I'll send v2 rebased to v6.9-rc1 once it is available and,
yes, the change will be gone after that.

Thanks,
Guenter