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From: Steven Rostedt <rostedt@goodmis.org>
To: Kees Cook <keescook@chromium.org>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>,
	Peter Zijlstra <peterz@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Drew Davenport <ddavenport@chromium.org>,
	Arnd Bergmann <arnd@arndb.de>, 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 20:50:20 -0400	[thread overview]
Message-ID: <20190820205020.1fc22706@oasis.local.home> (raw)
In-Reply-To: <201908200908.6437DF5@keescook>

On Tue, 20 Aug 2019 09:33:24 -0700
Kees Cook <keescook@chromium.org> wrote:
> > > > 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.  
> 
> That's fine -- easy rename. :)
> 
> > 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.  
> 
> I am testing for the lack of the flag (so that only the
> CONFIG_GENERIC_BUG with __WARN_FLAGS case needs to set it). I was
> thinking of the flag to mean "this reporting flow has already issued
> cut-here". It sounds like it would be more logical to have it named
> BUGFLAG_NO_CUT_HERE to mean "do not issue a cut-here; it has already
> happened"? I will update the patch.
> 

 BUGFLAG_HAS_CUT_HERE ?

As it shows it was already done?

-- Steve

  reply	other threads:[~2019-08-21  0:50 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
2019-08-20 16:33       ` Kees Cook
2019-08-21  0:50         ` Steven Rostedt [this message]
2019-08-21  1:14       ` Steven Rostedt
2019-08-24 17:17         ` Kees Cook

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