From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: Re: [PATCH 7/7] bug: Move WARN_ON() "cut here" into exception handler Date: Tue, 20 Aug 2019 20:50:20 -0400 Message-ID: <20190820205020.1fc22706@oasis.local.home> References: <20190819234111.9019-1-keescook@chromium.org> <20190819234111.9019-8-keescook@chromium.org> <20190820100638.GK2332@hirez.programming.kicks-ass.net> <06ba33fd-27cc-3816-1cdf-70616b1782dd@c-s.fr> <201908200908.6437DF5@keescook> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <201908200908.6437DF5@keescook> Sender: linux-kernel-owner@vger.kernel.org To: Kees Cook Cc: Christophe Leroy , Peter Zijlstra , Andrew Morton , Drew Davenport , Arnd Bergmann , Feng Tang , Petr Mladek , Mauro Carvalho Chehab , Borislav Petkov , YueHaibing , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-arch.vger.kernel.org On Tue, 20 Aug 2019 09:33:24 -0700 Kees Cook 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:60296 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726128AbfHUAu1 (ORCPT ); Tue, 20 Aug 2019 20:50:27 -0400 Date: Tue, 20 Aug 2019 20:50:20 -0400 From: Steven Rostedt Subject: Re: [PATCH 7/7] bug: Move WARN_ON() "cut here" into exception handler Message-ID: <20190820205020.1fc22706@oasis.local.home> In-Reply-To: <201908200908.6437DF5@keescook> References: <20190819234111.9019-1-keescook@chromium.org> <20190819234111.9019-8-keescook@chromium.org> <20190820100638.GK2332@hirez.programming.kicks-ass.net> <06ba33fd-27cc-3816-1cdf-70616b1782dd@c-s.fr> <201908200908.6437DF5@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Kees Cook Cc: Christophe Leroy , Peter Zijlstra , Andrew Morton , Drew Davenport , Arnd Bergmann , Feng Tang , Petr Mladek , Mauro Carvalho Chehab , Borislav Petkov , YueHaibing , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <20190821005020.nOvSyM8ADGvtuXjZJg1DLcTyWL02V7FrLRllGm-xFF8@z> On Tue, 20 Aug 2019 09:33:24 -0700 Kees Cook 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