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From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Peter Zijlstra <peterz@infradead.org>, Kees Cook <keescook@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Drew Davenport <ddavenport@chromium.org>,
	Arnd Bergmann <arnd@arndb.de>,
	"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
	Feng Tang <feng.tang@intel.com>, Petr Mladek <pmladek@suse.com>,
	Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
	Borislav Petkov <bp@suse.de>, YueHaibing <yuehaibing@huawei.com>,
	linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 7/7] bug: Move WARN_ON() "cut here" into exception handler
Date: Tue, 20 Aug 2019 12:58:49 +0200	[thread overview]
Message-ID: <06ba33fd-27cc-3816-1cdf-70616b1782dd@c-s.fr> (raw)
In-Reply-To: <20190820100638.GK2332@hirez.programming.kicks-ass.net>



Le 20/08/2019 à 12:06, Peter Zijlstra a écrit :
> On Mon, Aug 19, 2019 at 04:41:11PM -0700, Kees Cook wrote:
> 
>> diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
>> index 588dd59a5b72..da471fcc5487 100644
>> --- a/include/asm-generic/bug.h
>> +++ b/include/asm-generic/bug.h
>> @@ -10,6 +10,7 @@
>>   #define BUGFLAG_WARNING		(1 << 0)
>>   #define BUGFLAG_ONCE		(1 << 1)
>>   #define BUGFLAG_DONE		(1 << 2)
>> +#define BUGFLAG_PRINTK		(1 << 3)
>>   #define BUGFLAG_TAINT(taint)	((taint) << 8)
>>   #define BUG_GET_TAINT(bug)	((bug)->flags >> 8)
>>   #endif
> 
>> diff --git a/lib/bug.c b/lib/bug.c
>> index 1077366f496b..6c22e8a6f9de 100644
>> --- a/lib/bug.c
>> +++ b/lib/bug.c
>> @@ -181,6 +181,15 @@ enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs)
>>   		}
>>   	}
>>   
>> +	/*
>> +	 * BUG() and WARN_ON() families don't print a custom debug message
>> +	 * before triggering the exception handler, so we must add the
>> +	 * "cut here" line now. WARN() issues its own "cut here" before the
>> +	 * extra debugging message it writes before triggering the handler.
>> +	 */
>> +	if ((bug->flags & BUGFLAG_PRINTK) == 0)
>> +		printk(KERN_DEFAULT CUT_HERE);
> 
> I'm not loving that BUGFLAG_PRINTK name, BUGFLAG_CUT_HERE makes more
> sense to me.
> 

Actually it would be BUGFLAG_NO_CUT_HERE then, otherwise all arches not 
using the generic macros will have to add the flag to get the "cut here" 
line.

Christophe

  reply	other threads:[~2019-08-20 10:58 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-19 23:41 [PATCH 0/7] Clean up WARN() "cut here" handling Kees Cook
2019-08-19 23:41 ` [PATCH 1/7] bug: Refactor away warn_slowpath_fmt_taint() Kees Cook
2019-08-19 23:41 ` [PATCH 2/7] bug: Rename __WARN_printf_taint() to __WARN_printf() Kees Cook
2019-08-19 23:41 ` [PATCH 3/7] bug: Consolidate warn_slowpath_fmt() usage Kees Cook
2019-08-19 23:41 ` [PATCH 4/7] bug: Lift "cut here" out of __warn() Kees Cook
2019-08-19 23:41 ` [PATCH 5/7] bug: Clean up helper macros to remove __WARN_TAINT() Kees Cook
2019-08-19 23:41 ` [PATCH 6/7] bug: Consolidate __WARN_FLAGS usage Kees Cook
2019-08-19 23:41 ` [PATCH 7/7] bug: Move WARN_ON() "cut here" into exception handler Kees Cook
2019-08-20 10:06   ` Peter Zijlstra
2019-08-20 10:58     ` Christophe Leroy [this message]
2019-08-20 16:33       ` Kees Cook
2019-08-21  0:50         ` Steven Rostedt
2019-08-21  1:14       ` Steven Rostedt
2019-08-24 17:17         ` Kees Cook

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