From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH 7/7] bug: Move WARN_ON() "cut here" into exception handler Date: Tue, 20 Aug 2019 12:06:38 +0200 Message-ID: <20190820100638.GK2332@hirez.programming.kicks-ass.net> References: <20190819234111.9019-1-keescook@chromium.org> <20190819234111.9019-8-keescook@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190819234111.9019-8-keescook@chromium.org> Sender: linux-kernel-owner@vger.kernel.org To: Kees Cook Cc: Andrew Morton , Christophe Leroy , Drew Davenport , Arnd Bergmann , "Steven Rostedt (VMware)" , 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 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. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from merlin.infradead.org ([205.233.59.134]:35232 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729610AbfHTKHO (ORCPT ); Tue, 20 Aug 2019 06:07:14 -0400 Date: Tue, 20 Aug 2019 12:06:38 +0200 From: Peter Zijlstra Subject: Re: [PATCH 7/7] bug: Move WARN_ON() "cut here" into exception handler Message-ID: <20190820100638.GK2332@hirez.programming.kicks-ass.net> References: <20190819234111.9019-1-keescook@chromium.org> <20190819234111.9019-8-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190819234111.9019-8-keescook@chromium.org> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Kees Cook Cc: Andrew Morton , Christophe Leroy , Drew Davenport , Arnd Bergmann , "Steven Rostedt (VMware)" , Feng Tang , Petr Mladek , Mauro Carvalho Chehab , Borislav Petkov , YueHaibing , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <20190820100638.5Fzfi0nuQ8pnvDZrnnRSD8qq5ALYJ5yTbp5BKGNT5i0@z> 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.